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Background:
Systematic Review

Global Epidemiology and Antimicrobial Resistance of Metallo-β-Lactamase (MBL)-Producing Acinetobacter Clinical Isolates: A Systematic Review

by
Matthew E. Falagas
1,2,3,*,
Dimitrios S. Kontogiannis
1,
Maria Zidrou
1,
Charalampos Filippou
2 and
Giannoula S. Tansarli
4
1
Alfa Institute of Biomedical Sciences (AIBS), 9 Neapoleos Street, 151 23 Marousi, Athens, Greece
2
School of Medicine, European University Cyprus, 2404 Nicosia, Cyprus
3
Department of Medicine, Tufts University School of Medicine, Boston, MA 02111, USA
4
Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA
*
Author to whom correspondence should be addressed.
Pathogens 2025, 14(6), 557; https://doi.org/10.3390/pathogens14060557
Submission received: 13 May 2025 / Revised: 28 May 2025 / Accepted: 31 May 2025 / Published: 3 June 2025
Browse Figure
Versions Notes

Abstract

This systematic review assessed the global epidemiology of metallo-β-lactamase (MBL)-producing Acinetobacter clinical isolates and the associated antimicrobial resistance. A total of 475 relevant articles from the Cochrane Library, Google Scholar, PubMed, Scopus, and Web of Science were identified and screened as potentially eligible articles. Data from 85 articles were extracted for the analysis. Most reports on MBL-producing Acinetobacter clinical isolates originated from Asia [68/85 (80%) studies] and Africa [14/85 (16.5%) studies]. There were also scarce reports from Europe and America. The blaVIM (in 31 studies), blaIMP (in 29 studies), and blaNDM (in 21 studies) genes were the most commonly identified genes. In 22 out of 28 (78.6%) studies with comparable data, the proportions of MBL-producing pathogens detected using phenotypic methods were numerically higher than those using genotypic methods. MBL-producing Acinetobacter isolates showed high resistance (up to 100%) to several antibiotic classes, including carbapenems, cephalosporins, fluoroquinolones, and monobactams. However, they showed low resistance to colistin [ranging from 0% (in six studies) to 14.3% (in one study)] and to tigecycline [0% (in three studies)]. No risk of bias assessment was conducted. The findings emphasize the global spread of MBL-producing Acinetobacter and the need for enhanced antimicrobial stewardship, infection control measures, and surveillance.

1. Introduction

Pathogens resistant to antimicrobial agents are increasing worldwide and pose a threat to public health because they cause significant mortality, morbidity, and increased healthcare costs [1]. Many of the most frequently encountered resistant isolates belong to the so-called ‘ESKAPE’ pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacterales), for which the treatment options are limited [2,3].
Among these, Acinetobacter baumannii infections are particularly associated with advanced antimicrobial resistance [4]. Such infections are usually healthcare associated, but may also be community acquired [5]. Moreover, patients with Acinetobacter baumannii infections experience high mortality [6], especially when caused by carbapenem-resistant strains [7].
The World Health Organization (WHO) has designated carbapenem-resistant Acinetobacter baumannii as a critical priority pathogen and has called for the development of new therapeutic options to treat these infections [8]. Furthermore, the resistance of Acinetobacter clinical isolates to carbapenems is increasing worldwide, driven by various mechanisms, including the production of β-lactamases [9].
Beta-lactamases inactivate β-lactam antibiotics by hydrolyzing the β-lactam ring. According to the Ambler classification, β-lactamases are divided into four molecular classes: A, B, C, and D [10,11]. Classes A, C, and D have an active serine site, whereas class B [also called metallo-β-lactamases (MBLs)] uses zinc as a cofactor [12,13]. Metal ion chelators like ethylene-diamine-tetra-acetic acid (EDTA) inhibit MBL activity [12], a property utilized in phenotypic tests to detect MBL production [14]. MBLs can hydrolyze almost all β-lactam antibiotics, including carbapenems, with the notable exception of monobactams [15,16].
Previous studies are limited in scope: some examined the regional prevalence of carbapenemase-producing Acinetobacter [17,18,19,20], while others focused specifically on Acinetobacter isolates carrying the blaNDM gene [21]. However, a gap remains in understanding the global epidemiology of MBL-producing Acinetobacter. The therapeutic options for such infections are limited, as these pathogens are often resistant to most antibiotics. Potential therapeutic options include carbapenems (imipenem and meropenem), polymyxins (colistin and polymyxin B), tigecycline, and new β-lactamase inhibitor combinations (sulbactam–durlobactam and aztreonam–avibactam) [22,23,24,25]. Also, there are antibiotics in the pipeline for treating patients with these infections that could potentially be used as alternatives to the available agents, but currently they are under development in clinical trials [26]. Thus, as it is useful to evaluate the global epidemiology of MBL-producing Acinetobacter, this systematic review aims to address the knowledge gap by assessing the data on this clinically important issue.

2. Methods

2.1. Objectives

The objective of this review was to assess the global epidemiology of MBL-producing Acinetobacter clinical isolates and their resistance profiles in regard to various antimicrobial agents.

2.2. Eligibility Criteria

We included all the research articles reporting on Acinetobacter clinical isolates, with no restrictions in terms of the language, publication date, journal, region, patient demographics (adult or pediatric), or setting (inpatient or outpatient). We excluded gray literature (e.g., conference abstracts and industry reports) and any studies analyzing fewer than 5 Acinetobacter isolates.
We included studies that detected MBLs using genotypic methods [polymerase chain reaction (PCR)] and/or phenotypic methods [combined disk test (CDT), double-disk synergy test (DDST), or E-test]. Both CDT and DDST methods use imipenem plus EDTA disks in different settings to test for MBL production, as EDTA inhibits the action of MBLs. Thus, imipenem can act against the growth of MBL-producing strains [27,28]. For the CDT, a zone of inhibition more than 7 mm around the EDTA–imipenem-containing disk is considered a positive result for the production of MBL [27,29]. For the DDST, inhibition between the imipenem and EDTA disks, placed at a 10 mm distance, is a positive result [28,29]. For the E-test, a strip containing imipenem and EDTA is used [30]. We extracted antimicrobial susceptibility data from the studies that used antibiotic diffusion or microdilution methods for antimicrobial susceptibility testing.

2.3. Search Strategy

We searched five databases on 5 February 2025 (the Cochrane Library, Google Scholar, PubMed, Scopus, and Web of Science), using specific search strings (see Supplementary Table S1). Additionally, we screened the reference lists of the included studies for any further relevant articles.

2.4. Selection of Articles

Two investigators (DSK and MZ) conducted the searches. In Google Scholar, only the first 1000 results were accessible, and no bulk export option is available; therefore, we screened the Google Scholar results by title/abstract manually, before deduplication. All the citations from the Cochrane Library, PubMed, Scopus, and Web of Science were exported into Zotero version 7.0.11 (citation management software). These, combined with the Google Scholar selections, were deduplicated using the SR Accelerator tool. Two reviewers (DSK and MZ) independently screened the articles first based on the title and/or abstract and then by reviewing the full text. Any disagreements were resolved by consensus, during scientific meetings with a senior author (MEF).

2.5. Data Extraction

Two investigators (DSK and MZ) independently extracted and tabulated the key data from each study, including first author and publication year; study location (continent and country); patient population characteristics (e.g., age group, inpatient vs. outpatient); hospital/department setting; specimen type from which Acinetobacter isolates were obtained; identified Acinetobacter species; and the MBL genes tested. The main text was translated, using a web software program, if the studies were in a language other than English. For each study, we evaluated the proportion of Acinetobacter isolates that were MBL producers, as determined by genotypic and/or phenotypic methods. The studies were grouped based on the continent and country where the isolates were detected. If multiple data points were provided in a study regarding the isolation of MBL-producing Acinetobacter isolates, they were all extracted and presented separately (e.g., per isolation period). We also noted the proportion of MBL-producing isolates that were non-susceptible to various antibiotics, when such antimicrobial susceptibility data were available.

2.6. Adherence to the PRISMA Guidelines

This systematic review complies with the most recent “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) guidelines, and any omission is explicitly reported in the discussion section of this study. The study research protocol was not registered in a database. The PRISMA checklists for the abstract and full-text review are provided in Supplementary Tables S2 and S3, respectively.

3. Results

Identification of Relevant Articles

Figure 1 presents a PRISMA flow diagram on the identification, selection, and inclusion of articles included in this systematic review. In total, our searches yielded 73 articles from Google Scholar and 622 from the other sources. After removing duplicates, 475 articles remained for screening. Ultimately, 85 studies met the inclusion criteria and were included in our analysis, and nine articles were excluded after a full-text evaluation (Figure 1). Three studies did not present data specifically for MBL production in Acinetobacter isolates, three studies reported the isolation of less than five Acinetobacter pathogens, one study reported the isolation of pathogens from surfaces and healthcare workers, one study was a dissertation, and one study was a conference abstract. Sixty-eight of the included studies originated from Asia [31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98], fourteen from Africa [99,100,101,102,103,104,105,106,107,108,109,110,111,112], two from America [113,114], and one from Europe [115].
Table 1 presents the proportions of MBL-producing Acinetobacter isolates identified using genotypic and phenotypic methods, sorted by continent and country. In summary, 68 studies reported clinical Acinetobacter strains isolated from patients in countries in Asia (26 in India, 14 in Iran, 9 in Nepal, 5 in Iraq, 5 in Pakistan, 2 in Japan, 1 in Bangladesh, China, Lebanon, Malaysia, Saudi Arabia, South Korea, Taiwan), 14 in Africa (7 in Egypt, 1 in Algeria, Ghana, Libya, Morocco, South Africa, Sudan, Uganda), 2 in America (1 in Canada and the USA, 1 in Colombia), and 1 in Europe (1 in Romania). Seventy-eight studies included clinical isolates from hospitalized patients, six from both hospitalized patients and outpatients, and only one from outpatients [76]. The isolates were obtained from a variety of clinical specimens, most frequently respiratory sources (e.g., sputum and other respiratory secretions) [in 64 of 76 (84.2%) studies with available relevant data], blood [in 56/76 (73.7%)], and urine [in 50/76 (65.8%)]. Wound swabs were the next most common [in 34/76 (44.7%)], followed by cerebrospinal fluid [in 18/76 (23.7%)], pleural fluid [in 9/76 (11.8%)], burn wound samples [in 3/76 (3.9%)], and other sources.
In the 85 included studies, the most commonly identified Acinetobacter species were Acinetobacter baumannii [in 63/85 (74.1%)], followed by Acinetobacter baumannii–calcoaceticus complex [in 6/85 (7.1%)], and Acinetobacter hemolyticus [in 5/85 (5.9%)]. Other Acinetobacter species were also reported in 12 studies. However, 18/85 (21.2%) studies did not specify the isolated Acinetobacter species.
Forty-seven of the 85 studies included in our analysis (55.3%) employed genotypic methods (PCR) to detect MBL genes. In total, blaVIM was tested in 31 studies, blaIMP in 29, blaNDM in 21, blaSPM in 7, blaGIM in 7, blaSIM in 5, and blaDIM in 1 study. In Africa, 10/13 (76.9%) studies tested for blaNDM, 6/13 (46.2%) for blaVIM, and 5/13 (38.5%) for blaIMP. However, in Asia, 23/31 (74.2%) studies tested for blaIMP, 22/31 (71%) for blaVIM, and 11/31 (35.5%) for blaNDM. In America, two studies tested for blaVIM, and 1/2 (50%) studies tested for blaNDM, blaVIM, and blaIMP. In Europe, the one relevant study tested for blaVIM. Only 8 of the 85 studies (9%) included in our analysis reported data on clones of Acinetobacter baumannii isolates.
Seventy of the 85 studies (82.4%) employed phenotypic tests (CDT, DDST, and/or E-test) for MBL detection. Notably, six studies used modified versions of these tests [52,77,79,80,109,117]. Thirty-two studies (37.6%) used both genotypic and phenotypic methods. In four of those thirty-two studies [55,59,79,112], the data were not directly comparable because the number of isolates tested using each method differed. Thus, 28 studies had directly comparable results between genotypic and phenotypic detection and were analyzed for concordance.
In 22 of the 28 studies (78.6%), phenotypic methods detected a higher proportion of MBL-producing Acinetobacter isolates than genotypic methods. Of those twenty-two studies, eight relied solely on the CDT for phenotypic testing [50,62,65,72,73,102,103,107], six used only the E-test [63,67,68,98,111,117], and three used only the DDST [53,57,64] method. One study used all the CDT, DDST, and E-test methods [100], and two studies used both CDT and E-test methods [51,61]. In one of the last studies, the E-test method had a lower proportion of phenotypic MBL-production detection [117/172 (68.0%)] than the genotypic method [139/172 (80.8%)] in contrast to the CDT method [144/172 (83.7%)] [51]. Also, one study used a modified CDT method, with an increase of more than 10 mm in the zone of inhibition for a positive result [80], and one used the EDTA-modified carbapenem inactivation method [117].
In 4/28 (14.3%) studies, the proportion of MBL-producing Acinetobacter detected was higher using genotypic than phenotypic methods. Among these four studies, two used only the DDST method [39,94], one used only the CDT method [101], and one used both CDT and DDST methods [69]. Finally, in 2/28 (7.1%) studies, the proportion of MBL-producing Acinetobacter detected was equal using the genotypic and phenotypic methods. One study used the CDT [31] and one used the DDST phenotypic method [99].
Table 2 presents data on the antimicrobial resistance of the studied clinical isolates. Among the 33 studies that reported antimicrobial susceptibility data for MBL-producing Acinetobacter, the resistance rates were as high as 100% in regard to most of the tested antibiotics, including carbapenems, cephalosporins, and fluoroquinolones. In five studies, MBL-producing pathogens showed resistance to monobactams too. Notably, in six of seven studies (85.7%) that evaluated colistin (six using antibiotic diffusion methods [34,36,55,66,71,84] and one using the agar dilution method [101]), no colistin resistance was detected among the MBL-producing isolates [34,36,55,66,71,84]. In the remaining study, colistin resistance was 14.3% (6 of 42 MBL-producing isolates) [101]. In addition, in all three studies that evaluated tigecycline, no tigecycline resistance was detected [34,44,87].

4. Discussion

The objective of this study was the assessment of the global epidemiology of MBL-producing Acinetobacter isolates and their resistance to various antimicrobial agents. Our main finding confirms that these isolates have now spread worldwide, with most reported cases coming from Asia and Africa. In most studies, MBL-producing Acinetobacter isolates were 100% resistant to most of the tested antibiotics, including all carbapenems. Interestingly, although MBLs do not hydrolyze monobactams, the studies that tested for aztreonam susceptibility showed high resistance to this agent. This finding implies that these isolates were co-producing other types of lactamases (such as extended-spectrum β-lactamases), thus making them resistant to aztreonam, a monobactam antibiotic.
Colistin was the only agent that retained activity against the majority of these isolates (as most studies reported 0% resistance to colistin). However, all six studies that reported 0% resistance to colistin used disk diffusion methods for antimicrobial susceptibility testing. According to the joint Clinical and Laboratory Standards Institute (CLSI)/European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines on colistin susceptibility testing, broth and agar microdilution methods are recommended over diffusion methods [118]. Thus, colistin resistance could be underestimated in these studies, with more false-susceptible pathogens reported, and the 0% percentage of resistance to colistin could have been higher if microdilution methods had been used.
In most studies with comparable data (78.6%), MBL-producing Acinetobacter was more frequently detected using phenotypic methods, specifically the CDT, followed by the DDST and E-test methods. This finding indicates that the genes encoding MBLs in the isolates from these studies possibly differed from those included in the PCR assay. The fact that the CDT detected more MBL-producing isolates compared to the other phenotypic methods is in keeping with results from previous studies demonstrating that this method is more sensitive than the DDST or E-test in regard to identifying MBL-producing pathogens [119,120,121]. Moreover, in Africa, most studies tested for the presence of the blaNDM, whereas in Asia most studies tested for blaIMP and blaVIM, highlighting the different prevalence of MBL genes between these geographical regions. Only a small proportion of studies reported data on the clones of Acinetobacter baumannii isolates.
Data from the included studies were heterogeneous, as patients were in different settings (ICU, other clinical departments, or outpatients) and had various infections. Also, the sources of isolation varied from study to study. These limitations made the analyses and synthesis of the data in the subgroups challenging and, thus, only a descriptive evaluation was conducted.
Antimicrobial resistance (AMR) is a growing global threat in regard to the treatment of infectious diseases. In response to rising AMR, standardized definitions for multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) bacteria have been adopted [122]. Briefly, MDR organisms are non-susceptible to ≥1 agent in at least three antibiotic categories, XDR organisms are resistant to all but one or two available categories, and PDR organisms are resistant to all categories [122].
Gram-negative bacteria have emerged as the most problematic causes of MDR/XDR/PDR infections from a public health perspective. In particular, Acinetobacter baumannii, once dismissed as a harmless colonizer, is now understood to cause severe infections. Numerous studies have demonstrated that Acinetobacter baumannii infections lead to considerable morbidity, prolonged hospital stays, higher healthcare costs, and attributable mortality [6,123]. Today, the need for immediate interventions and targeted research initiatives related to Acinetobacter baumannii infections is more urgent than ever. There is an urgent need for immediate interventions and targeted research to address Acinetobacter baumannii infections. Developing new antimicrobials, implementing personalized therapeutic approaches, and strengthening infection prevention and control programs are all crucial strategies to stem this crisis.
The global spread of MDR, XDR, and PDR Acinetobacter baumannii infections, including those caused by MBL-producing isolates, is not solely a consequence of antibiotic misuse and overuse, due to a lack of adherence to antimicrobial stewardship policies. Multiple factors, including inadequate infection control in hospitals and transmission via contaminated medical devices, also drive the spread [124]. Additionally, the genetic flexibility of Acinetobacter baumannii enables it to acquire and maintain resistance genes, complicating efforts to eradicate the bacteria [125]. The increasing use of invasive medical procedures, exposure to disinfectants, and heavy metals, further promote the persistence of resistant strains. Particularly concerning is the spread of MBL-producing strains, facilitated by horizontal gene transfer, plasmids, and resistance islands [125].
Extensive antibiotic resistance dramatically limits treatment options, making the management of patients with MDR Acinetobacter infections extremely challenging. The remaining therapeutic choices, such as polymyxins, tigecycline, and sulbactam, come with significant drawbacks, including nephrotoxicity, gastrointestinal disturbances, and limited effectiveness in certain cases [124,126,127,128]. Also, there are limited data on the clinical use of new antibiotics (cefiderocol and sulbactam–durlobactam) that may have activity against MDR Acinetobacter isolates. Cefiderocol was demonstrated to have considerable antimicrobial activity against Gram-negative bacterial isolates, including Acinetobacter baumannii [129]. Although higher mortality was observed in patients who received cefiderocol in a randomized controlled clinical trial for Acinetobacter baumannii infection, subsequent observational studies suggested better clinical outcomes in patients with Acinetobacter baumannii infection treated with this new siderophore, cephalosporin [130,131,132]. In addition, a non-inferiority randomized controlled trial comparing sulbactam–durlobactam with colistin (both combined with imipenem–cilastatin) in patients with carbapenem-resistant Acinetobacter baumannii infection showed promising results for this new combination of two β-lactamase inhibitors [133,134]. Notably, sulbactam may have activity against Acinetobacter baumannii isolates and has been used in high doses for patients with such infections [135]. This underscores the complexity of managing such infections, highlighting the urgent need for stricter surveillance, enhanced infection control programs, and the development of new therapeutic strategies [126].
Our analysis has several limitations. First, most of the included studies were from single hospitals or limited geographic areas rather than broad multicenter surveillance efforts, which may limit the generalizability of their findings. Second, there was inconsistency in the phenotypic MBL detection methods used among the studies, some used modified tests with different zone diameter cut-offs, which complicates direct comparisons of the MBL rates. Third, our analysis did not include data on some of the newest antimicrobials (e.g., recently developed β-lactam/β-lactamase inhibitor combinations), since most of the included studies were published before those agents became available. In addition, we did not perform a formal quality assessment of the included studies, sensitivity analyses, statistical methods to assess the heterogeneity of the studies, and publication bias (e.g., a tendency to report outbreaks or unusually resistant cases), which might have influenced the literature available. These factors should be kept in mind when interpreting our results.

5. Conclusions

The assessed data show that MBL-producing Acinetobacter strains that cause infections have spread globally. These isolates are associated with advanced antimicrobial resistance and pose a critical therapeutic challenge, with important consequences for global public health. These findings underscore the urgent need for a multifaceted approach, including enhanced antimicrobial stewardship, strengthened infection control measures, and sustained global surveillance, to mitigate the spread of MBL-producing Acinetobacter isolates.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/pathogens14060557/s1, Table S1: Search strings for each resource; Table S2: “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) checklist for the abstract; Table S3: “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) checklist for the full-text review.

Author Contributions

M.E.F. had the idea for the article. All authors contributed to the methodology used in the article. D.S.K. and M.Z. conducted the literature search, data extraction, and tabulation. M.E.F., D.S.K. and M.Z. contributed to the first version of the manuscript. C.F. and G.S.T. revised the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data used in the conduction of this study are available upon request.

Conflicts of Interest

The authors declare that there are no conflicts of interest.

Abbreviations

AMRAntimicrobial resistance
CDTCombined disk test
CLSIClinical and Laboratory Standards Institute
DDSTDouble-disk synergy test
EDTAEthylene-diamine-tetra-acetic acid
EUCASTEuropean Committee on Antimicrobial Susceptibility Testing
MBLMetallo-β-lactamase
MDRMultidrug resistant
PCRPolymerase chain reaction
PDRPandrug resistant
PRISMAPreferred Reporting Items for Systematic Reviews and Meta-Analyses
WHOWorld Health Organization
XDRExtensively drug resistant

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Pathogens 14 00557 g001
Figure 1. “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) flow diagram for identification, screening, and inclusion of articles. i Even though 16,300 results were retrieved with the Google Scholar search, only the first 1000 results could be accessed. Source: Page MJ, et al. BMJ 2021;372:n71. doi: 10.1136/bmj.n71 [116]. This work is licensed under CC BY 4.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/ (accessed on 6 February 2025).
Figure 1. “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) flow diagram for identification, screening, and inclusion of articles. i Even though 16,300 results were retrieved with the Google Scholar search, only the first 1000 results could be accessed. Source: Page MJ, et al. BMJ 2021;372:n71. doi: 10.1136/bmj.n71 [116]. This work is licensed under CC BY 4.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/ (accessed on 6 February 2025).
Pathogens 14 00557 g001
Table 1. Proportion of phenotypic and genotypic detection of MBLs in various Acinetobacter species.
Table 1. Proportion of phenotypic and genotypic detection of MBLs in various Acinetobacter species.
Author, YearContinentCountryPopulation, Department, HospitalIsolate Sources [n/N (%)]Isolates (n)Genes (n)Genotypic Detection; Genes, n/N (%)Phenotypic Detection; n/N (%), Method
Mesli, 2013 [99]AfricaAlgeriaThree different hospitals in western Algeria,
hospital environment and patients admitted to ICU, hematology, surgery, and neurosurgery wards		Tracheal aspirate, urine, rectal swab, woundA. baumannii (106)
A. radioresistens (1)
A. nosocomialis (2)
A. pittii (4)		blaNDM-15/113 (4.4)5/113 (4.4), DDST
Abd El-Glil, 2015 [100]AfricaEgyptICU patients, Benha University, and Benha Teaching hospitalsSputum [11/40 (17.5)], exudates [9/10 (22.5)], BAL [7/40 (17.5)], blood [6/40 (15)], urine [3/40 (7.5)]A. baumannii (40)blaNDM-15/40 (12.5)26/40 (65), E-test
25/40 (62.5), CDT 22/40 (55.0), DDST
Elbrolosy, 2019 [101]AfricaEgyptPatients with VAP in different ICUs in Menoufia and Kasr Al Ainy University HospitalsTracheal aspirate [64/64 (100)]A. baumannii (37)
A. calcoaceticus (15)
A. baumannii–calcoaceticus complex (12)		blaNDM-142/64 (65.6)22/64 (34.4), CDT
El-Din, 2014 [102]AfricaEgyptHospitalized patients, Tanta University HospitalDiabetic ulcers [26/26 (100)]A. baumannii (26)blaVIM
blaIMP		Total 6/26 (23.1)
blaVIM 4/26 (15.4)
blaIMP 2/26 (7.7)		9/26 (34.6), CDT
Fattouh, 2014 [103]AfricaEgyptICU patients, Microbiology Department, Sohag UniversityEndotracheal secretion [7/21 (33.3)], urine [6/21 (28.6)], blood [4/21 (19)], pus [4/21 (19)]A. baumannii (21)blaIMP-1
blaVIM-1		0/21 (0)13/21 (61.9), CDT
Fouad, 2013 [104]AfricaEgyptICU patients, three hospitals (6th October hospital, MUST hospital, National Cancer Institute)Respiratory tract [24/53 (45.3)], wound [22/53 (41.5)], urine [6/53 (11.3)], blood [1/53 (1.9)]A. baumannii (53)blaVIM1/53 (1.9)NR
Hassan, 2021 [105]AfricaEgyptHospitalized and ICU patients, Kasr Al-Aini hospitalWound [77/206 (37.4)], respiratory secretions [56/206 (27.2), blood [37/206 (18)], urine [27/206 (13.1)], body fluid and drains [9/206 (4.4)]A. baumannii (206)blaVIM
blaIMP
blaGIM
blaSPM
blaSIM-1
blaNDM-1		Total 39/206 (18.9)
blaNDM-1 24/106 (11.7)
blaSPM 13/206 (6.3)
blaVIM 1/206 (0.5)
blaSIM-1 1/206 (0.5)		NR
Wasfi, 2021 [106]AfricaEgyptCancer patients at the National Cancer Institute, Giza, Egypt,Blood [48/48 (100)]A. baumannii (48)blaNDM
blaGIM
blaSPM
blaSIM
blaIMP		31/48 (63.6)NR
Olu-Taiwo, 2020 [107]AfricaGhanaClinical isolates, patients over 50 years old, Korle-Bu Teaching HospitalWound [(45/87 (51.7)], urine [25/87 (28.7)], ear swabs [8/87 (9.2)], eye swabs [6/48 (6.9)] aspirates [3/48 (3.5)]Acinetobacter spp. (87)blaNDM7/87 (8)23/87 (26.4), CDT
Mathlouthi, 2016 [108]AfricaLibyaClinical isolates, Tripoli Medical Center and Burn and Plastic Surgery Hospital in TripoliWound [15/36 (41.6)], catheter [3/36 (8.3)], septum [3/36 (8.3)], swab [3/36 (8.3)], urine [3/36 (8.3)], blood [2/36 (5.6)], CSF [2/36 (5.6)], chest tube [1/36 (2.8)], endotracheal tube [1/36 (2.8)], GT tube [1/36 (2.8)], mouth [1/36 (2.8)], throat [1/36 (2.8)]A. baumannii (36)blaNDM-17/36 (22.2)NR
Kabbaj, 2013 [109]AfricaMoroccoHospitalized patients, ICU, neurosurgery ward, neurology ward, Rabat Specialty HospitalRespiratory tract (69), urine (22), surgical site infection (5), CSF (4)A. baumannii (47)NRNR20/47 (24.6) i
Nogbou, 2021 [110]AfricaSouth AfricaClinical isolates, teaching hospital in PretoriaNR iiA. baumannii (70)blaVIM
blaIMP-5
blaNDM
blaSIM-1		blaVIM 60/70 (85.7)
blaNDM 41/70 (58.6)
blaIMP-5 5/70 (7.1)
blaSIM-1 2/70 (2.9)		NR
Elbadawi, 2021 [111]AfricaSudanChildren and adults, neonatal ICU, medicine, pediatric, and surgery wards, ICU, renal unit, Soba University HospitalBlood (36), wound (24), urine (21), body fluids (7), catheter tips (6), sputum (6)A. baumannii (36)blaNDM17/36 (47.2)19/36 (52.8), E-test
Kateete, 2016 [112]AfricaUgandaHospitalized patients, hospital environment, Mulago Hospital in KampalaHospital environment [11/40 (27.5)], tracheal aspirate [9/40 (22.5)], ear swabs [8/40 (20)], pus [4/40 (10)], blood [4/40 (10)], sputum [2/40 (5)], body fluids [1/40 (2.5)] A. baumannii (40)blaVIM-12/15 (40)3/40 (7.5), DDST
Rakhi, 2019 [31]AsiaBangladeshClinical isolates, Dhaka Medical College HospitalBlood, pleural fluid, pus, tracheal aspirate, urine, vaginal swab, woundA. baumannii (4)blaNDMblaNDM + blaOXA-48 1/4 (25)1/4 (25), CDT
Li, 2013 [32]AsiaChinaMedical and surgical wards, ICU, burn department, teaching hospital in GuangzhouRespiratory tract [35/42 (83.3)], blood [3/42 (7.1)], wound [2/42 (4.8)], urine [1/42 (2.4)], CSF [1/42 (2.4)]A. baumannii (42)NRNR1/42 (2.4), E-test
Ahir, 2012 [33]AsiaIndiaHospitalized patients, tertiary care teaching hospital, GujaratSwab [40/78 (51.3)], urine [8/78 (10.3)], sputum [7/78 (9)], pleural fluid [7/78 (9)], pus [5/78 (6.4)], blood [67.7)], other body fluid [5/78 (6.4)] iiiA. baumannii (40)
A. lwoffii (20)
A. hemolyticus (10)
A. calcoaceticus (8)		NRNR78/750 (10.4), CDT and DDST
Archana Rao, 2024 [34]AsiaIndiaPediatrics, medical, surgery, ENT, and gynecology wards, Raja Rajeswari Medical College tertiary care hospitalSputum [14/25 (56)], pus [4/25 (16)], urine [3/25 (12)], ear discharge [2/25 (8)], blood [2/25 (8)]Acinetobacter spp. (25)NRNR5/25 (20), CDT
Banerjee, 2015 [35]AsiaIndiaClinical isolates, Mayo Institute of Medical Sciences and Hospital, BarabankiEndotracheal tube [17/67 (25.4)], sputum [16/67 (23.9)], pus [13/67 (19.4)], blood [9/67 (13.4)], urine [7/67 (10.4)], ascitic fluid [5/67 (7.5)]Acinetobacter spp. (67)NRNR16/67 (23.9), CDT
Binnani, 2018 [36]AsiaIndiaClinical isolates, Tertiary Care Institute in the North West Region of Rajasthan, IndiaUrine [6/21 (28.6)], sputum and respiratory tract specimens [8/21 (38.1)], blood [5/21 (23.8)], pus and other wound
discharges [2/21 (9.5)]		Acinetobacter spp. (21)NRNR8/21 (38.1), CDT
De, 2010 [37]AsiaIndiaAdults, children, intensive care areas in Lokmanya Tilak Municipal Medical College and HospitalBlood, endotracheal secretionsAcinetobacter spp. (25)ΝRNR9/25 (36), DDST
Gautam, 2023 [38]AsiaIndiaHospitalized and outpatients, children and adults, Central Referral Hospital located in Gangtok, SikkimEndotracheal tube, sputum, pus, urine, blood, catheter tips, urogenital swabsA. baumannii (307)blaIMP-1
blaVIM-1		blaIMP-1 4/100 (4)
blaVIM-1 8/100 (8)		NR
Girija, 2018 [39]AsiaIndiaPatients with severe urinary tract infectionsUrine [73/73 (100)]A. baumannii (73)blaVIM
blaGIM		Total 37/73 (50.7)
blaVIM 25/73 (34.2)
blaGIM 12/73 (16.4)		31/73 (42.5), DDST
Goel, 2017 [40]AsiaIndiaICU patients, teaching tertiary care hospitalTranstracheal or bronchoscopic aspirates [88/88 (100)]A. baumannii (88)NRNR28/37 (75.7), DDST iv
Hodiwala, 2013 [41]AsiaIndiaClinical isolatesBlood, catheter tips, CSF, endotracheal secretions, pus, sputum, urine, various body fluids (synovial, ascitic, pleural)A. baumannii (68)NRNR9/68 (13.2), CDT and DDST
Jena, 2014 [42]AsiaIndiaOutpatients, ICU, neonatal ICU, IMS and SUM Hospital in BhubaneswarBlood, urine, stool, pus, sputum, wound, tracheal aspiration, CSF, high vaginal swabAcinetobacter spp. (66)NRNR23/66 (34.8), DDST
Jethwa, 2013 [43]AsiaIndiaClinical isolates, tertiary care hospitalSwab [334/854 (39.1)], blood [278/854 (32.6)], body fluids [94/854 (11)], sputum [65/854 (7.6)], pus [39/854 (4.6)], urine [35/854 (4.1)], other [9/854 (1.1)]Acinetobacter spp. (854)NRNR68/854 (8), CDT
John, 2011 [44]AsiaIndiaClinical isolates, ICU patientsUrine, blood, sputum, pus, endotracheal aspirates, bronchial secretions, wound swabs, vaginal swabsA. baumannii (242)NRNR36/242 (14.8), DDST
Kaur, 2014 [45]AsiaIndiaClinical isolates, microbiology departmentRespiratory samples, pus, blood, others, urineA. baumannii (389)NRNR313/389 (80.5), CDT
Kaur, 2018 [46]AsiaIndiaClinical isolates, ICU and medical wards, Microbiology Department, Adesh Institute of Medical Sciences and Research, BathindaEndotracheal tube secretions [34/116 (29.3)], tracheal aspirate [28/116 (24.1)], pus [29/116 (25)], urine [9/116 (7.8)], sputum [7/116 (6)], blood [6/116 (5.2)], various body fluids [3/116 (2.6)]A. baumannii (116)NRNR52/116 (44.8), CDT
Kumar, 2013 [47]AsiaIndiaClinical isolates, tertiary care hospitalNR iiAcinetobacter spp. (180)NRNR43/180 (29.3), DDST
Pandya, 2016 [48]AsiaIndiaClinical isolates, medical wards including ICU, Teaching Hospital in rural GujaratEndotracheal secretions [26/81 (32.1)], pus [16/81 (19.8)], tracheostomy secretions [12/81 (14.8)], blood [6/81 (7.4)], sputum [6/81 (7.4)], urine [6/81 (7.4)], broncho-alveolar lavage [3/81 (3.7)], central venous catheter tip [2/81 (2.5)], ascitic fluid [1/81 (1.2)], catheter tip [1/81 (1.2)], drain [1/81 (1.2)], pleural fluid [1/81 (1.2)]A. baumannii (81)NRNR24/81 (29.6), CDT
Patil, 2021 [49]AsiaIndiaClinical isolates, patients with VAP, ICU, tertiary care hospitalRespiratory tract [246/246 (100)]Total (188)
A. baumannii (156)
A. lwoffii (15)
A. calcoaceticus (9)
A. hemotyticus (5)
A. baumannii–calcoaceticus complex (3)		NRNR146/188 (77.7), CDT
141/188 (75), DDST
152/188 (80.9), E-test
Rynga, 2015 [50]AsiaIndiaICU (28%), burns (15%), respiratory (15%), surgery (14%), burns ICU (10%), gynecology (9%), orthopedic (5%) wards, respiratory medicine outpatient department (2%)Endotracheal aspirate [31/100 (31)], pus [28/100 (28)], wound [25/100 (25)], sputum [14/100 (14)], drain fluid [1/100 (1)], high vaginal swab [1/100 (1)]A. baumannii (100)blaVIM
blaGIM
blaSIM
blaIMP		Total 18/100 (18)
blaVIM 9/100 (9)
blaGIM 6/100 (6)
blaSIM 2/100 (2)
blaIMP 1/100 (1)		25/100 (25), CDT
Saikia, 2023 [51]AsiaIndiaHospitalized patients, ICU, internal medicine wards, Dibrugarh UniversityNR iiA. baumannii (172)blaNDM
blaIMP
blaVIM		Total 139/172 (80.8)
blaNDM 121/172 (70.3)
blaIMP 88/172 (51.2)
blaVIM 42/172 (24.4)		144/172 (83.7), CDT
117/172 (68), E-test
Singla, 2013 [52]AsiaIndiaOutpatients, hospitalized patients, adults and children, tertiary care hospitalBlood, BAL, CSF, endotracheal aspirates, high vaginal swabs, pus, sputum, throat swabs, urine, wound, other body fluidsTotal (70)
A. baumannii (66)
A. lwoffii (4)		NRNRA. baumannii 38/66 (57.6)
A. lwoffii 1/4 (25), modified CDT method v
Sinha, 2013 [53]AsiaIndiaHospitalized patients, tertiary care centerPus [52/140 (37.1)], blood [32/140 (22.6)], urine [19/140 (13.6)]Total (140)
A. baumannii (129)
A. lwoffii (9)
A. hemolyticus (2)		blaIMP-1
blaVIM-1
blaVIM-2		10/140 (7.1)16/140 (11.4), DDST
Sugumaran, 2019 [54]AsiaIndiaHospitalized patients (81.2%), outpatients (18.8%), Mahatma Gandhi Medical College and Research Institute, PuducherryAspirates, central line catheter tip, ear swab, endotracheal tube, groin swab, pus, sputum, synovial fluid, tissue, urine, woundA. baumannii (19)NRNR10/19 (90.9), imipenem CDT
10/19 (90.9), imipenem DDST
13/19 (68.9), ceftazidime CDT
13/19 (68.9), ceftazidime DDST
Thakar, 2021 [55]AsiaIndiaHospitalized patients, outpatients, tertiary care hospitalPus [30/72 (41.7)], respiratory tract [16/72 (22.2)], urine [16/72 (22.2)], blood [6/72 (8.3)], others [4/72 (5.6)]Acinetobacter spp. (72)blaVIM15/15 (100)32/72 (44.4), CDT
Tripathi, 2013 [56]AsiaIndiaClinical isolates, microbiology departmentNR iiAcinetobacter spp. (46)NRNR40/46 (87), CDT
Uma Karthika, 2009 [57]AsiaIndiaICU, acute medical care units, Pondicherry Institute of Medical Sciences tertiary care hospitalBlood, CSF, endotracheal tube, urine, woundA. baumannii (36)blaIMP-1
blaVIM-2		Total 23/54 (42.6)
blaIMP-1 23/54 (42.6)
blaVIM-2 0/54 (0)		39/54 (72.2), DDST
Vamsi, 2021 [58]AsiaIndiaHospitalized patients, SVS Medical College, Hospital in MahabubnagarEndotracheal tube [12/17 (70.6)], pus [2/17 (11.8)], blood [1/17 (5.9)], CSF [1/17 (5.9)], urine [1/17 (5.9)]Acinetobacter spp. (23)NRNR17/23 (73.9) vi
Aghamiri, 2016 [59]AsiaIranHospitalized patients, 11 hospitals in TehranWound [59/176 (33.5)], tracheal aspirate [34/176 (19.3)], urine [24/176 (13.6)], body fluids [20/176 (11.4)], sputum [11/176 (6.3)], catheter [10/176 (5.7)], blood [18/176 (1)]A. baumannii (176)blaIMP
blaVIM		123/176 (69.9)165/169 (97.6), DDST
Jahantigh, 2023 [60]AsiaIranHospitalized patients, Ali Ebne Abitaleb Hospital in Zahedan, IranBlood (39.5), endotracheal tube (34.4), wound (20.7)A. baumannii (372)NRNR352/372 (94.6), CDT
Khaledi, 2019 [61]AsiaIranHospitalized patients, Kashani and Hajar Hospitals in ShahrekordBlood, CSF, pleural effusion, trachea, urine, woundA. baumannii (100)blaVIM-1
blaIMP-1		Total 26/100 (26)
blaVIM-1 23/100 (23)
blaIMP-1 3/100 (3)		65/100 (65), E-test
59/100 (59), CDT
Maspi, 2016 [62]AsiaIranHospitalized patients, Baqiyatallah hospitalsWound, pleural effusion, urine, blood, tracheal aspirate, BAL, sputum, ascites, abscessA. baumannii (86)blaIMP
blaSPM
blaVIM
blaGIM
blaSIM		Total 23/86 (26.7)
blaIMP 13/86 (15.1)
blaSPM 4/86 (4.7)
blaVIM 2/86 (2.3)
blaGIM 2/86 (2.3)
blaSIM 2/86 (2.3)		44/86 (51.2), CDT
Moghadam, 2016 [63]AsiaIranHospitalized patients, Nemazee and Faghihi hospitalsSputum [35/98 (35.7)], wound (15/98 (15.3)], body fluids [13/98 (13.3)], blood [9/98 (9.2)], urine [9/98 (9.2)], endotracheal tube [8/98 (8.2)], CSF [5/98 (5.1)], BAL [2/98 (2)], axillary swab [1/98 (1)], eye swab [1/98 (1)]A. baumannii (96)blaIMP
blaVIM
blaSPM		Total 37/96 (38.5)
blaIMP 23/96 (24)
blaVIM 14/96 (14.6)
blaSPM 0/96 (0)		43/96 (44.8), E-test
Moulana, 2020 [64]AsiaIranClinical isolates, units at Babol University of Medical Sciences affiliated hospitalsEndotracheal aspirates, sputum [30/50 (60)], ulcers [12/50 (24)], urinary specimens [6/50 (12)], blood [2/50 (4)]A. baumannii (50)blaVIM13/50 (26)15/50 (30), DDST
Noori, 2014 [65]AsiaIranHospitalized patients, Loghman Hakim and Milad hospitalsTracheal tube [57/108 (52.8)], urine [29/108 (26.9)], blood [8/108 (7.4)], pleural fluid [8/108 (7.4)], wound [4/108 (3.7)], other [2/108 (1.9)]A. baumannii (108)blaIMP
blaSPM		Total 3/108 (2.8)
blaIMP 3/108 (2.8)
blaSPM 0/108 (0)		86/108 (88.9), CDT
Owlia, 2012 [66]AsiaIranHospitalized patients, burn unit in Motahari Hospital, TehranBurns [126/126 (100)]A. baumannii (126)NRNR42/126 (33.3), DDST
Peymani, 2011 [67]AsiaIranHospitalized patients, tertiary care teaching hospitalTracheal aspirate [37/100 (37)], urine [21/100 (21)], sputum [9/100 (9)], blood [7/100 (7)], catheter [6/100 (6)], bronchial washings [6/100 (6)], wound [5/100 (5)], abscess [3/100 (3)], CSF [2/100 (2)], ascites [2/100 (2)], pleural effusion [2/100 (2)]A. baumannii (100)blaIMP
blaVIM		Total 28/100 (28)
blaIMP 19/100 (19)
blaVIM 9/100 (9)		31/100 (31), E-test
Ranjbar, 2019 [68]AsiaIranPatients with burns, three major hospital centersBurns [163/163 (100)]A. baumannii (163)blaIMP
blaVIM		111/163 (68.1)147/163 (90.2), E-test
Rezaei, 2018 [69]AsiaIranICU patients, three teaching hospitals located in IsfahanTracheal aspirate (68/100 (68)], CSF [10/100 (10)], wound [9/100 (9)], sputum [3/100 (3)], blood [3/100 (3)], catheters [2/100 (2)], other samples [5/100 (5)]A. baumannii (100)blaIMP-1
blaVIM-1
blaVIM-2
blaIMP-2		Total 38/100 (38)
blaIMP-1 21/100 (21)
blaVIM-1 7/100 (7)
blaVIM-2 6/100 (6)
blaIMP-2 4/100 (4)		36/100 (36), CDT
21/100 (21), DDST
Safari, 2013 [70]AsiaIranHospitalized patients, ICU, three educational hospitals in Hamadan cityTracheal aspirate [74/100 (74)], blood [16/100 (16)], urine [5/100 (5)], sputum [4/100 (4)], wound [1/100 (1)]A. baumannii (100)NRNR99/100 (99), E-test
Soltani, 2018 [71]AsiaIranHospitalized patients, Nemazee tertiary care hospitalRespiratory tract [61/92 (66.3)], blood [11/92 (12)], skin [8/92 (8.7)], urine [5/92 (5.4)], body fluids [5/92 (5.4)], eyes [2/92 (2.2)]A. baumannii (92)blaVIM
blaIMP
blaSPM		76/92 (82.6)NR
Vala, 2014 [72]AsiaIranHospitalized patients, burn unit at Shahid Motahari HospitalWound [28/28 (100)]A. baumannii (28)blaSPM
blaIMP
blaVIM
blaDIM
blaNDM
blaGIM		blaSPM 1/28 (3.6)12/28 (42.9), CDT
Al Marjani, 2013 [73]AsiaIraqClinical isolates, medical centers in BaghdadNR iiA. baumannii (17)blaIMP-13/17 (42.8)7/17 (41.1), CDT
Anoar, 2014 [74]AsiaIraqClinical isolate, Burn and Plastic Surgery Hospital in Sulaimani cityWound [44/44 (100)]Acinetobacter spp. (44)blaIMP
blaVIM		blaIMP 19/44 (43.2)
blaVIM 5/44 (11.4)		NR
Numan, 2022 [75]AsiaIraqHospitalized patients, four hospitals in BaghdadSputum [35/69 (50.7)], blood [21/69 (30.4)], urine [9/69 (13)], CSF [2/69 (2.9)], wound [2/69 (2.9)]A. baumannii (69)NRNR51/69 (74), CDT
Radhi, 2019 [76]AsiaIraqOutpatients, Hillah Teaching Hospital and Babylon Teaching Hospital for Maternity and PediatricsBurns [24/30 (80)], blood [4/30 (13.3)], urine [1/30 (3.3)], wound [1/30 (3.3)]A. baumannii (30)NRNR22/30 (73.3), E-test
Smail, 2019 [77]AsiaIraqHospitalized patients, ICU, three educational hospitals in Hamadan cityBlood, CSF, pleural fluid, pus, sputum, urine, woundA. baumannii (112)NRNR112/112 (100) vii
Kishii, 2014 [78]AsiaJapanClinical isolates, two university hospitalsBlood [123/123 (100)]Acinetobacter spp. (123)blaIMP3/123 (2.4)NR
Yamamoto, 2013 [79]AsiaJapanClinical isolates, three university hospitals, two city hospitals in Kyoto and Shiga PrefectureNR iiAcinetobacter spp. (82)blaIMP
blaVIM
blaNDM-1		48/54 (88.9)44/82 (53.7) viii
Soudeiha, 2018 [80]AsiaLebanonHospitalized patients, Saint George Hospital University Medical CenterRespiratory tract [62/100 (62)], wound [21/100 (21)], urine [10/100 (10)], blood [4/100 (4)], catheters [3/100 (3)]Total (100)
A. baumannii–calcoaceticus complex (95)
A. hemolyticus (3)
A. radioresistens (1)
A. junii (1)		blaVIM
blaIMP
blaNDM		0/100 (0)Total 4/100 (4) ix
Maziz, 2021 [81]AsiaMalaysiaClinical isolates, Selayang Hospital, Kuala LumpurUrine [16/50 (38)], blood [14/50 (26)], pus [7/50 (14)], skin [5/50 (10)], respiratory secretions [3/50 (6)] and sputum [3/50 (6)]Acinetobacter spp. (50)NRNR0/50 (0), DDST and E-test
Koirala, 2017 [82]AsiaNepalClinical isolates, B&B Hospital KathmanduPus [36/109 (33)], suction tip [23/109 (21.1)], sputum [19/109 (17.4)], tracheostomy [16/109 (14.7)], catheter tip [7/109 (6.4)], central venous catheter [6/109 (5.5)], body fluids [1/109 (0.9)], urine [1/109 (0.9)]Acinetobacter spp. (109)NRNR48/109 (44), CDT
Kumari, 2021 [117]AsiaNepalClinical isolates, Koirala Institute of Health SciencesBlood, pus, urine, sputum, endotracheal aspirate, exudate body fluid, central venous catheter, CSF, high vaginal swab, nasal swab, tissue, semenTotal (324)
A. baumannii–calcoaceticus complex (167)
A. lwoffii (83)
A. hemolyticus (38)
A. radioresistens (30)
A. junii (6)		blaNDM-1Total 33/324 (10.2)
A. baumannii–calcoaceticus complex 28/167 (16.8)
A. junii 1/6 (16.7)
A. hemolyticus 2/38 (5.2)
A. lwoffii 2/83 (2.4)		Total 70/324 (21.6)
A. baumannii–calcoaceticus complex 56/167 (33.5)
A. lwoffii 3/83 (3.6)
A. hemolyticus 7/38 (18.4)
A. radioresistens 3/30 (10.0)
A. junii 1/6 (16.7), EDTA-modified carbapenem inactivation method
Mishra, 2012 [84]AsiaNepalClinical isolates, bacteriology laboratory at Tribhuvan University Teaching HospitalLower respiratory tract [60/60 (100)]Total (62)
A. baumannii–calcoaceticus complex (60)
A. lwoffii (2)		NRNR3/62 (4.8), CDT and DDST
Pandey, 2021 [85]AsiaNepalClinical isolates, 100-bed hospital in the capital city of NepalSputum [25/39 (64.1)], urine [9/39 (23.1)], pus [2/39 (5.1)], catheters and tubes [2/39 (5.1)], blood [1/39 (2.6)]A. baumannii (39)NRNR4/39 (10.3), CDT and E-test
Pathak, 2017 [86]AsiaNepalClinical isolates, Shahid Gangalal National Heart Centre, Kathmandu, NepalUrine [5/11 (45.5)], endotracheal tube [2/11 (18.2)], suction tip [2/11 (18.2)], central venous catheter tip [1/11 (9.1)], pericardial fluid [1/11 (9.1)]Acinetobacter spp. (11)NRNR1/11 (9.1), CDT
Sakuma, 2024 [87]AsiaNepalClinical isolates, university hospital in NepalRespiratory tract [28/66 (42.4)], pus [16/66 (24.2)], blood [9/66 (13.6)], wound [7/66 (10.6)], urine [3/66 (4.5)], body fluids [3/66 (4.5)]A. baumannii (66)blaNDM-126/66 (39.4)NR
Shrestha, 2015 [88]AsiaNepalHospitalized patients, Tribhuvan University Teaching HospitalRespiratory tract [60/122 (49.2)], pus [31/122 (25.4)], urine [13/122 (10.7)]A. baumannii (122)NRNR50/122 (41), CDT
Thapa, 2017 [89]AsiaNepalHospitalized and outpatients, Nepal Medical College, KathmanduPus [21/58 (36.2)], urine [21/58 (36.2], sputum [10/58 17.2)], body fluids [6/58 (10.3)]A. baumannii–calcoaceticus complex (58)NRNR18/58 (31), CDT
Yadav, 2020 [90]AsiaNepalHospitalized patients, Tribhuvan University Teaching HospitalRespiratory tract [76/161 (47.2)], pus [44/161 (27.3)], CSF [18/161 (11.1)], urine [11/161 (6.8)], blood [10/161 (6.2)], catheters [2/161 (1.2)]A. baumannii (161)ΝRNR109/161 (67.7), CDT
Anwar, 2016 [91]AsiaPakistanClinical isolates, children, Children’s Hospital and Institute of Child Health LahoreBlood, body fluids, pus, sputum, tracheal secretions, urineA. baumannii (66)NRNR63/66 (95.5), CDT
51/66 (72.3), DDST
Hasan, 2014 [92]AsiaPakistanClinical isolates, patients with secondary or nosocomial infections from different hospitals in PakistanCatheters and tubes [5/19 (26.3)], tracheal aspirate [4/19 (21.1)], blood [4/19 (21.1)], pus [2/19 (10.5)], wound [2/19 (10.5)], body fluids [1/19 (5.3)]A. baumannii (90)blaNDM-11/90 (1.1)NR
Irfan, 2008 [93]AsiaPakistanClinical isolates, Aga Khan University HospitalBlood, respiratory secretions, urine, woundAcinetobacter spp. (90)NRNR83/90 (92.2), CDT
Rashid, 2020 [94]AsiaPakistanClinical isolates, tertiary care referral hospitalsBlood, CSF, pus, sputum, urine, vaginal swabA. baumannii (12)blaNDM-12/12 (16.7)(5), DDST
Sajjad, 2019 [95]AsiaPakistanClinical isolates, Lahore General HospitalNR iiA. baumannii (13)
A. junii (1)		NRNRA. baumannii 11/13 (84.6), DDST
A. junii 0/1 (0), DDST
Shah, 2019 [96]AsiaSaudi ArabiaClinical isolates, King Abdulaziz University Hospital, an 845-bed major territory care hospital in JeddahTracheal aspirate [29/135 (21.5)], blood [28/135 (20.7)], wound [19/135 (14.1), urine [19/135 (14.1)], body fluids [7/135 (5.2)], catheters and tubes [9/135 (6.7)], skin [5/135 (3.7)], others [19/135 (14.1)]A. baumannii (135)blaIMP
blaVIM
blaNDM		blaIMP 113/135 (83.7)
blaVIM 25/135 (18.5)
blaNDM 2/135 (1.5)		NR
Sung, 2015 [97]AsiaSouth KoreaClinical isolates, university hospital in DaejeonUrine [18/21 (85.7)], sputum [2/21 (9.5)], wound [1/21 (4.8)]A. pittii (21)blaIMP-1
blaNDM-1		blaIMP-1 19/21 (90.5)
blaNDM-1 2/21 (9.5)		NR
Lee, 2008 [98]AsiaTaiwanClinical isolates, Kaohsiung Medical University HospitalNR iiTotal (185)
A. baumannii (184)
A. hemolyticus (1)		blaVIM-2
blaVIM-3
blaVIM-11
blaIMP-8		Total 79/185 (42.7)
A. hemolyticus 1/1 (100)
A. baumannii 78/184 (42.3)		Total 80/185 (43.2), E-test
A. baumannii 79/184 (42.9)
A. hemolyticus 1/1 (100)
Mereuţă, 2013 [115]EuropeRomaniaClinical isolates, five university hospitals in IasiUrine [5/16 (31.3)], pus [5/16 (31.3)], sputum [3/16 (18.8)], tracheal aspirate [1/16 (6.3)], blood [1/16 (6.3)], CSF [1/16 (6.3)]A. baumannii (16)blaVIM2/16 (12.5)3/16 (18.8), E-test
Takemura, 2023 [113]North AmericaCanadaClinical specimensNR iiA. baumannii (20)blaIMP
blaVIM
blaNDM
blaGIM		blaNDM 1/20 (5)NR
Takemura, 2023 [113]North AmericaUSAClinical isolates, SIDERO-WT surveillance studiesNR iiA. baumannii (20)blaIMP
blaVIM
blaNDM
blaGIM		blaNDM 2/20 (10)NR
Hernández-Gómez, 2014 [114]South AmericaColombiaAdult, pediatric, and neonatal ICU patients, 23 clinics and hospitalsBlood, urine, respiratory tract, otherA. baumannii (241)blaVIM0/241 (0)NR
Abbreviations: MBL, metallo-β-lactamase; DDST, double-disk synergy test; BAL, bronchoalveolar lavage; CDT combined disk test; VAP, ventilator-associated pneumonia; CSF, cerebrospinal fluid. Notes: i >17 mm zone of inhibition positive for MBL production; ii not available data for the specific sources of isolation; iii information available only for MBL-producing strains; iv 37 meropenem-resistant isolates were tested for MBL production; v 30 μg ceftazidime, 10 μg imipenem, 0.5 M EDTA, ceftazidime with ≥5 mm zone of inhibition, and/or meropenem with ≥7 mm zone of inhibition positive for MBL production; vi does not specify which test produced the specific results for Acinetobacter spp. (CDT, DDST, or E-test); vii modified CDT method: meropenem, imipenem, 0.35 M EDTA, ≥2 mm zone of inhibition considered positive for MBL production; viii modified CDT method: two disks 30 μg ceftazidime, one disk 3 mg sodium mercaptoacetic acid, ≥5 mm zone of inhibition considered positive for MBL production; ix modified CDT method: meropenem and imipenem, 5 mM EDTA, ≥10 mm zone of inhibition considered positive for MBL production.
Table 2. Proportion of the studied resistant MBL-producing Acinetobacter clinical isolates to various antimicrobial agents.
Table 2. Proportion of the studied resistant MBL-producing Acinetobacter clinical isolates to various antimicrobial agents.
Author, YearContinentCountryIsolates (n)Resistance n/N (%) to Antimicrobial Agent(s) i
Abd El-Glil, 2015 [100]AfricaEgyptA. baumannii (40)5/5 (100) imipenem, meropenem, piperacillin, cefotaxime, ceftazidime, cefepime, aztreonam, ciprofloxacin
4/5 (80) amikacin
3/5 (60) gentamicin
Elbrolosy, 2019 [101]AfricaEgyptA. baumannii (37), A. calcoaceticus (15), A. baumannii–calcoaceticus complex (12)42/42 (100) imipenem, meropenem, cefotaxime, ceftriaxone, ceftazidime, cefepime, cotrimoxazole, piperacillin–tazobactam, tetracycline, aztreonam, ciprofloxacin, amikacin
6/42 (14.3) colistin
Olu-Taiwo, 2020 [107]AfricaGhanaAcinetobacter spp. (87)23/23 (100) ampicillin, cefotaxime, ceftazidime, cefuroxime, meropenem
22/23 (95.7) amoxicillin–clavulanate, levofloxacin
21/23 (91.3) gentamicin
20/23 (87) ciprofloxacin
17/23 (73.9) cotrimoxazole
14/23 (60.9) nitrofurantoin
8/23 (34.8) amikacin
Kateete, 2016 [112]AfricaUgandaA. baumannii (40)3/3 (100) ciprofloxacin, imipenem, meropenem, piperacillin–tazobactam
2/3 (66.7) gentamicin, ceftazidime, aztreonam, amikacin
Archana Rao, 2024 [34]AsiaIndiaAcinetobacter spp. (25)0/5 (0) colistin, tigecycline
5/5 imipenem and/or meropenem
Binnani, 2018 [36]AsiaIndiaAcinetobacter spp. (21)8/8 (100) ceftazidime, doxycycline, imipenem, meropenem, nitrofurantoin
7/8 (87.5) ceftriaxone, ciprofloxacin
5/8 (62.5) amikacin
0/8 (0) colistin, polymyxin B
De, 2010 [37]AsiaIndiaAcinetobacter spp. (25)9/9 (100) imipenem, gentamicin, amikacin, netilmicin, amoxicillin–clavulanic acid, cefotaxime, ceftriaxone, ceftazidime, cefepime, ciprofloxacin, ofloxacin, piperacillin, piperacillin–tazobactam
John, 2011 [44]AsiaIndiaA. baumannii (242)36/36 (100) ciprofloxacin, piperacillin, gentamicin, ceftazidime
0/36 (0) tigecycline
Kaur, 2014 [45]AsiaIndiaTotal (1017), A. baumannii (964), A. lwoffii (48), A. hemolyticus (5)A. baumannii: ii
313/313 (100) imipenem
309/313 (98.7) ceftazidime
307/313 (98.1) ciprofloxacin
305/313 (97.4) cotrimoxazole
304/313 (97.1) cefepime
295/313 (94.2) gentamicin
285/313 (91.1) piperacillin
273/313 (87.2) amikacin
209/313 (66.8) netilmicin
179/313 (57.2) piperacillin–tazobactam
Pandya, 2016 [48]AsiaIndiaA. baumannii (81)24/24 (100) ampicillin–sulbactam, ceftazidime, ciprofloxacin, gentamicin, ticarcillin–clavulanic acid, ceftriaxone, piperacillin
Patil, 2021 [49]AsiaIndiaTotal (188), A. baumannii (156), A. lwoffii (15), A. calcoaceticus (9), A. hemotyticus (5), A. baumannii–calcoaceticus complex (3)164/164 (100) piperacillin, piperacillin–tazobactam, ciprofloxacin, ceftazidime, cefepime, imipenem, meropenem
162/164 (98.8) ceftriaxone
152/164 (92.7) tetracycline
147/164 (89.6) doxycycline
143/164 (87.2) gentamicin
137/164 (83.5) amikacin
131/164 (79.9) cotrimoxazole
Singla, 2013 [52]AsiaIndiaTotal (70), A. baumannii (66), A. lwoffii (4)39/39 (100) cefepime, ceftriaxone, imipenem
38/39 (97.4) amoxicillin–clavulanic acid, ticarcillin–clavulanic acid
37/39 (94.8) cefotaxime, ceftazidime
35/39 (89.7) cotrimoxazole
34/39 (87.1) gentamicin
33/39 (84.6) doxycycline
30/39 (76.9) amikacin, ciprofloxacin
27/39 (69.2) netilmicin
25/39 (64.1) piperacillin–tazobactam
Thakar, 2021 [55]AsiaIndiaAcinetobacter spp. (72)32/32 (100) ampicillin–sulbactam, carbapenem, third and fourth generation cephalosporins
29/32 (90.6) fluoroquinolones
28/32 (87.5) amikacin
0/32 (0) colistin
Khaledi, 2019 [61]AsiaIranA. baumannii (100)65/65 (100) imipenem, meropenem
Owlia, 2012 [66]AsiaIranA. baumannii (126)42/42 (100) cefotaxime, ceftazidime, piperacillin–tazobactam, aztreonam, ciprofloxacin, amikacin, imipenem, piperacillin, ticarcillin, ticarcillin–clavulanic acid, kanamycin
12/42 (28.6) tobramycin, gentamicin
0/42 (0) colistin
Soltani, 2018 [71]AsiaIranA. baumannii (92)76/76 (100) cotrimoxazole, ciprofloxacin, imipenem, meropenem, ticarcillin–clavulanic acid, levofloxacin
0/76 (0) colistin, polymyxin B
Al-Marjani, 2013 [73]AsiaIraqA. baumannii (17)7/7 (100) cefoxitin, ceftriaxone, amoxicillin–clavulanic acid, cefepime, aztreonam
Kishii, 2014 [78]AsiaJapanAcinetobacter spp. (123)3/3 (100) imipenem, meropenem
2/3 (66.7) levofloxacin, ciprofloxacin
1/3 (33.3) amikacin
Mishra, 2012 [84]AsiaNepalA. baumannii–calcoaceticus
complex (60)		2/3 (66.7) imipenem, meropenem
0/3 (0) colistin, polymyxin B
Pandey, 2021 [85]AsiaNepalA. baumannii (39)4/4 (100) imipenem
0/4 (0) polymyxin B
Sakuma, 2024 [87]AsiaNepalA. baumannii (66)26/26 (100) imipenem, meropenem, ceftazidime, cefotaxime, amikacin, ciprofloxacin
0/26 (0) tigecycline
Irfan, 2008 [93]AsiaPakistanAcinetobacter spp. (90)83/83 (100) imipenem
Notes: i defined as the proportion of resistant MBL-producing Acinetobacter isolates to specific antimicrobial agents among all the studied MBL-producing Acinetobacter isolates; ii only 313 Acinetobacter baumannii isolates were tested for antimicrobial susceptibility.
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Falagas, M.E.; Kontogiannis, D.S.; Zidrou, M.; Filippou, C.; Tansarli, G.S. Global Epidemiology and Antimicrobial Resistance of Metallo-β-Lactamase (MBL)-Producing Acinetobacter Clinical Isolates: A Systematic Review. Pathogens 2025, 14, 557. https://doi.org/10.3390/pathogens14060557

AMA Style

Falagas ME, Kontogiannis DS, Zidrou M, Filippou C, Tansarli GS. Global Epidemiology and Antimicrobial Resistance of Metallo-β-Lactamase (MBL)-Producing Acinetobacter Clinical Isolates: A Systematic Review. Pathogens. 2025; 14(6):557. https://doi.org/10.3390/pathogens14060557

Chicago/Turabian Style

Falagas, Matthew E., Dimitrios S. Kontogiannis, Maria Zidrou, Charalampos Filippou, and Giannoula S. Tansarli. 2025. "Global Epidemiology and Antimicrobial Resistance of Metallo-β-Lactamase (MBL)-Producing Acinetobacter Clinical Isolates: A Systematic Review" Pathogens 14, no. 6: 557. https://doi.org/10.3390/pathogens14060557

APA Style

Falagas, M. E., Kontogiannis, D. S., Zidrou, M., Filippou, C., & Tansarli, G. S. (2025). Global Epidemiology and Antimicrobial Resistance of Metallo-β-Lactamase (MBL)-Producing Acinetobacter Clinical Isolates: A Systematic Review. Pathogens, 14(6), 557. https://doi.org/10.3390/pathogens14060557

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