Search Results (72)

Introduction: Carbapenem-resistant Klebsiella pneumoniae (CRKP) represents a critical public health threat due to its rapid nosocomial dissemination, limited therapeutic options, and elevated mortality rates. This study aimed to characterize the epidemiology, carbapenemase profiles, and antimicrobial susceptibility patterns of CRKP isolates, as well as the clinical features and outcomes observed in infected or colonized patients. Materials and Methods: We conducted a retrospective analysis of clinical and microbiological data from patients with CRKP infections or colonization admitted between January 2023 and January 2024. Descriptive statistics were used to assess prevalence, resistance patterns, and patient outcomes. Two binary logistic regression models were applied to identify independent predictors of sepsis and in-hospital mortality. Results: Among 89 CRKP isolates, 45 underwent carbapenemase typing. More than half were metallo-β-lactamase (MBL) producers, with 44.4% co-harbouring NDM and OXA-48-like enzymes. Surgical intervention was associated with a significantly lower risk of sepsis (p < 0.01) and in-hospital mortality (p = 0.045), whereas intensive care unit (ICU) stay was a strong predictor of both outcomes. ICU admission conferred a 10-fold higher risk of sepsis (95%Cl 2.4–41.0) and a 40.8-fold higher risk of in-hospital death (95% Cl 3.5–473.3). Limitations: This single-center retrospective study included a limited number of isolates in certain groups. Additionally, cefiderocol (FDC) susceptibility was assessed by disk diffusion rather than by the broth microdilution method. Conclusions: Our study underscores the increasing prevalence of metallo-beta-lactamase-producing CRKP, particularly strains harbouring dual carbapenemases. Timely recognition of high-risk patients, combined with the implementation of targeted infection control measures and the integration of novel therapeutic options, is crucial to optimize clinical management and reduce mortality associated with CRKP. Full article

Klebsiella pneumoniae is a major public health concern due to its role in Gram-negative bacteremia, which leads to high mortality and increased healthcare costs. This study characterizes phenotypic and genomic features of K. pneumoniae isolates from clinical samples in Karachi, Pakistan. Among 507 isolates, 213 (42%) were carbapenem-resistant based on disk diffusion and MIC testing. Urine (29.7%) and blood (28.3%) were the most common sources, with infections predominantly affecting males (64.7%) and individuals aged 50–70 years. Colistin was the only antibiotic showing consistent activity against these isolates. The whole-genome sequencing of 24 carbapenem-resistant K. pneumoniae (CR-KP) isolates revealed bla_NDM-5 (45.8%) as the dominant carbapenemase gene, followed by bla_NDM-1 (12.5%) and bla_OXA-232 (54.2%). Other detected bla_OXA variants included bla_OXA-1, bla_OXA-4, bla_OXA-10, and bla_OXA-18. The predominant beta-lactamase gene was bla_CTX-M-15 (91.6%), followed by bla_CTX-M-163, bla_CTX-M-186, and bla_CTX-M-194. Sequence types ST147, ST231, ST29, and ST11 were associated with resistance. Plasmid profiling revealed IncR (61.5%), IncL (15.4%), and IncC (7.7%) as common plasmid types. Importantly, resistance was driven not only by acquired genes but also by chromosomal mutations. Porin mutations in OmpK36 and OmpK37 (e.g., P170M, I128M, N230G, A217S) reduced drug influx, while acrR and ramR mutations (e.g., P161R, G164A, P157*) led to efflux pump overexpression, enhancing resistance to fluoroquinolones and tigecycline. These findings highlight a complex resistance landscape driven by diverse carbapenemases and ESBLs, underlining the urgent need for robust antimicrobial stewardship and surveillance strategies. Full article

Background: The combination of aztreonam (ATM) and avibactam (AVI) presents an important therapeutic option for carbapenem-resistant Enterobacterales, particularly the NDM-producing Enterobacterales. In 2024, both the CLSI and EUCAST published their methods in antimicrobial susceptibility testing for this combination of agents. Materials and Methods: Forty carbapenem-resistant Enterobacterales isolates, including Escherichia coli (n = 35), Enterobacter cloacae complex (n = 2), Klebsiella pneumoniae complex (n = 2), and Citrobacter freundii complex (n = 1) were included in this study. All isolates harbored the NDM carbapenemase except one, which had no known detected carbapenemases. Four antimicrobial susceptibility testing methods of the combination of ATM and AVI were evaluated on these isolates, including the CLSI broth disk elution (BDE) method, the disk diffusion (DD) method of aztreonam–avibactam (AZA) following the EUCAST breakpoints, the MIC test strip (MTS) method of AZA following the EUCAST breakpoints, and the gradient strip stacking (SS) method. BDE was used as the standard of comparison. Results: Using BDE as the standard of comparison, the AZA DD, AZA MTS, and SS methods had 100% categorical agreement (CA), 0% very major error (VME), and 0% major error (ME). The essential agreement (EA) between the AZA MTS and SS method was 57.5%. Conclusions: The AZA DD, AZA MTS, and the SS methods showed complete concordance with the BDE method. However, the MICs obtained from the AZA MTS and SS were not comparable. Full article

Background/Objectives: Antibiotic resistance is a significant and escalating challenge that limits available therapeutic options. This issue is further exacerbated by the decreasing number of new antibiotics being developed. Our study aims to describe the epidemiology and pattern of antibiotic resistance in Gram-negative infections isolated from a cohort of hospitalized patients and to analyze the distribution of infections within the hospital setting. Methods: A retrospective study was conducted on all patients admitted to Vito Fazzi Hospital in Lecce, Italy, who required an infectious disease consultation due to the isolation of Gram-negative bacteria from 1 January 2018 to 31 December 2022. Results: During the study period, 402 isolates obtained from 382 patients (240 men and 142 women) with infections caused by Gram-negative bacteria were identified. Among these isolated, 226 exhibited multidrug resistance, defined as resistance to at least one antimicrobial agent from three or more different classes. In 2018, the percentage of multidrug-resistant isolates peaked at 87.6%, before decreasing to the lowest level (66.2%) in 2021. Overall, of the 402 isolates, 154 (38.3%) displayed resistance to carbapenems, while 73 (18.1%) were resistant to extended-spectrum beta-lactamases (ESBLs). Among the resistant microorganisms, Klebsiella pneumoniae showed the highest resistance to carbapenems, accounting for 85.2% of all resistant strains. Escherichia coli exhibited the greatest resistance to ESBLs, with a rate of 86.7%. Among carbapenem-resistant K. pneumoniae isolates, the following resistance rates were observed: KPC-1 at 98.2%, IMP-1 at 0.9%, VIM-1 at 0.9%, and NDM-1 at 0.9%. Conclusions: Patients with infections caused by multidrug-resistant bacteria have limited treatment options and are therefore at an increased risk of death, complications, and longer hospital stays. Rapid diagnostic techniques and antimicrobial stewardship programs—especially for ESBLs and carbapenemases—can significantly shorten the time needed to identify the infection and initiate appropriate antimicrobial therapy compared to traditional methods. Additionally, enhancing surveillance of antimicrobial resistance within populations is crucial to address this emerging public health challenge. Full article

Antimicrobial resistance (AMR) constitutes a critical threat to global public health, with carbapenem-resistant Enterobacterales (CRE) presenting significant challenges due to their resistance to last-line antibiotics. Among these, New Delhi metallo-beta-lactamase (NDM)-producing Klebsiella pneumoniae (KP) is of particular concern. This study describes an outbreak of NDM-producing KP in the hematology unit of the University Hospital of Verona, Italy. This represents the second reported hospital outbreak of this strain in Italy, and the first to occur within a hematology ward. The outbreak involved four patients, all of whom were identified through active surveillance and microbiological screening. In response, a multidisciplinary team implemented a series of infection prevention and control (IPC) measures, which included enhanced environmental cleaning, strict hand hygiene protocols, patient isolation, and the development of a tailored IPC checklist. The outbreak was effectively contained within three weeks following the identification of the last case. This outcome underscores the importance of rapid and coordinated responses to NDM-producing KP outbreaks. This case study emphasizes the necessity of robust IPC protocols, rapid intervention, and continuous staff education in mitigating the spread of multidrug-resistant pathogens in healthcare settings. It further highlights the urgent need for healthcare systems to be adequately prepared and resilient in addressing the growing threat of AMR. Full article

A backyard cat with symptoms of otitis was transferred to a veterinary clinic in Central Greece. A sample was obtained and P. aeruginosa was isolated. The strain exhibited an extensively drug-resistant (XDR) profile, as it was non-susceptible to all tested agents except colistin. DNA extraction and whole-genome sequencing (WGS) were performed using a robotic extractor and Ion Torrent technology, respectively. The genome was assembled and screened for resistance and virulence determinants. The isolate belonged to the high-risk clone ST308 with a total of 67 antibiotic resistance genes (ARGs) and 221 virulence factor-related genes being identified. No plasmids were detected. The metallo-beta-lactamase (MBL) bla_NDM-1 gene and 46 efflux pumps were included in the strain’s resistome. Both ARGs conferring tolerance to disinfecting agents and biofilm-related genes were identified, associated with the ability of this clone to adapt and persist in healthcare facilities. This case highlights the risk of relevant bacterial clones spreading in the community and even being transmitted to companion animals, causing challenging opportunistic infections to susceptible individuals, while others may become carriers, further spreading the clones to their owners, other animals and the environment. Full article

Background: In this study, molecular mechanisms contributing to delafloxacin resistance in Pseudomonas aeruginosa strains were investigated. Delafloxacin is a recently approved fluoroquinolone currently introduced to clinical applications. Methods: A total of 52 P. aeruginosa strains were collected from clinical isolates. Antimicrobial susceptibility testing was performed via broth microdilution, and the minimum inhibitory concentration (MIC) values for ciprofloxacin, levofloxacin, delafloxacin, ceftazidime and imipenem were determined. Five delafloxacin-resistant P. aeruginosa strains were selected for whole-genome sequencing (WGS). Results: MIC50 values were determined, and the following results were obtained: ciprofloxacin 0.25 mg/L, levofloxacin 0.25 mg/L and delafloxacin 1 mg/L. All five selected strains showed both extended-spectrum beta-lactamase and carbapenemase production. WGS analysis of these strains determined the sequence types (STs), namely, ST235 (two strains), ST316 (two strains) and ST395. Several mutations in quinolone-resistance-determining regions (QRDRs) were detected in all five delafloxacin-resistant P. aeruginosa strains as follows: gyrA Thr83Ile and parC Ser87Leu mutations were present in all five strains, while parE Thr223Ala in ST235, Glu459Val in ST316 and Val200Met in ST395 were detected. MexAB-OprM and MexCD-OprJ efflux pumps were uniformly present in all delafloxacin-resistant P. aeruginosa strains. All strains of ST235 and ST316 carried bla_NDM-1 in combination with other beta-lactamases. In our study, the in vitro efficacy of delafloxacin is inferior compared to previous fluoroquinolones based on MIC50 values; however, MIC values of delafloxacin ranged between 0.125 and 128 mg/L in our P. aeruginosa collection, and 21 out of 52 strains showed susceptibility to delafloxacin. Conclusions: Multiple QRDR mutations combined with several efflux pumps confer delafloxacin resistance in P. aeruginosa. Among the different detected multidrug-resistant P. aeruginosa strains in this study, we also report on an NDM-1 producing P. aeruginosa ST316 in Hungary. Full article

Background: Mapping the local etiology and susceptibility of common pathogens causing complicated urinary tract infection (cUTI) is important for promoting evidence-based antimicrobial prescribing. Evaluating the prevalence of extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase (AmpC), and carbapenemase-producing Enterobacterales (CPEs) is equally important as it informs treatment guidelines and empiric management. Whole genome sequencing (WGS) enhances antimicrobial resistance (AMR) surveillance by complementing phenotypic antimicrobial susceptibility testing, offering deeper insights into resistance mechanisms, transmissions, and evolutions. Integrating it into routine AMR monitoring can significantly improve global efforts to combat antimicrobial resistance. Methods: Antimicrobial susceptibility profiles of isolates from cUTI were collected from patients presenting with Sultan Qaboos University Hospital, Muscat and Suhar Hospital, Suhar, Oman. Automated systems as well as manual methods were used for detection of ESBL, AmpC, and CPE. ESBLs, AmpC β-lactamases, and CPEs were further detected by manual methods: double-disk synergy test for ESBL; disk approximation assay and D69C AmpC detection set for AmpC, and mCIM and KPC/IMP/NDM/VIM/OXA-48 Combo test kit for CPE. WGS was carried out in 11 FOX-resistant E. coli and (22 carbapenem-resistant K. pneumoniae) isolates with varying susceptibilities to identify circulating clades, AMR genes, and plasmids. Bioinformatic analysis was performed using online tools. Results: The susceptibility patterns of E. coli from cUTI were as follows: nitrofurantoin (96%), fosfomycin (100%), fluoroquinolones (44%), aminoglycosides (93%), piperacillin-tazobactam (95%), and carbapenems (98%). In comparison, susceptibility rates of K. pneumoniae were far lower: nitrofurantoin (38%), fosfomycin (89%), aminoglycosides (82%), piperacillin-tazobactam (72%), and carbapenems (83%). K. pneumoniae, however, was more susceptible to fluoroquinolones at 47% in comparison to E. coli. The prevalence of ESBL among E. coli and K. pneumoniae was 37.2% and CRE was 6.2% while the estimated prevalence of AmpC was 5.4%. It was observed that E. coli was the predominant ESBL and AmpC producer, while K. pneumoniae was the major carbapenem-resistant Enterobacterales (CREs) producer. No predominant multi-locus sequence typing (MLST) lineage was observed in AmpC-producing E. coli with nine E. coli MLST lineages being identified from eleven isolates: ST-10, ST-69, ST-77, ST-131, ST-156, ST-167, ST-361, ST-1125, and ST-2520. On the other hand, a less diverse MLST spectrum (ST-2096, ST-231, ST-147, ST-1770, and ST-111) was observed in the CRE K. pneumoniae. Among the five MLST lineages, ST-2096 (twelve isolates) and ST-147 (seven isolates) predominated. WGS revealed that DHA-1 was the predominant plasmid-mediated AmpC gene in E. coli, while OXA-232 and NDM-5 were the most common carbapenemase genes in K. pneumoniae. All E. coli DHA-1-positive isolates co-harbored the quinolone resistance gene qnrB4 and the sulfonamide resistance gene sul1 while no aminoglycoside resistance genes were detected. The majority of CPE CRE K. pneumoniae carried other β-lactamase genes, such as blaCTX-M-15, blaSHV, and blaTEM; all co-harbored the quinolone resistance gene OqxAB; and 77% carried the aminoglycoside resistance gene armA. Conclusions: Our results suggest that fosfomycin is an excellent empiric choice for treating complicated cystitis caused by both E. coli and K. pneumoniae, while nitrofurantoin is an appropriate choice for E. coli cystitis but not for K. pneumoniae. Aminoglycosides and piperacillin-tazobactam are excellent intravenous alternatives that spare carbapenems. DHA-1 was the predominant AmpC in E. coli, while OXA-232 and NDM-5 were the predominant carbapenemases in K. pneumoniae. In AmpC-producing E. coli, no MLST predominated, suggesting a significant flux in E. coli with lack of stable clades in this region. In contrast, ST-2096 and ST-147 predominated in CRE Klebsiella pneumoniae, suggesting a stable circulation of these in Oman. WGS profiling provides a deeper understanding of the genetic basis of resistance and enhances surveillance and offers comprehensive insights into pathogen evolution and transmission patterns. Full article

Antibiotic resistance to Klebsiella pneumoniae poses a major public health threat, particularly in intensive care unit (ICU) settings. The emergence of extensively drug-resistant (XDR) strains complicates treatment options, requiring a deeper understanding of their genetic makeup and potential therapeutic targets. This research delineated an extensively drug-resistant (XDR) Klebsiella pneumoniae strain obtained from an ICU patient and telomeric temperate phage derived from hospital effluent. The bacteria showed strong resistance to multiple antibiotics, including penicillin (≥16 μg/mL), ceftriaxone (≥32 μg/mL), and meropenem (≥8 μg/mL), which was caused by SHV-11 beta-lactamase, NDM-1 carbapenemase, and porin mutations (OmpK37, MdtQ). The strain was categorized as K46 and O2a types and carried virulence genes involved in iron acquisition, adhesion, and immune evasion, as well as plasmids (IncHI1B_1_pNDM-MAR, IncFIB) and eleven prophage regions, reflecting its genetic adaptability and resistance dissemination. The 172,025 bp linear genome and 46.3% GC content of the N-15-like phage showed strong genomic similarities to phages of the Sugarlandvirus genus, especially those that infect K. pneumoniae. There were structural proteins (11.8%), DNA replication and repair enzymes (9.3%), and a toxin–antitoxin system (0.4%) encoded by the phage genome. A protelomerase and ParA/B partitioning proteins indicate that the phage is replicating and maintaining itself in a manner similar to the N15 phage, which is renowned for maintaining a linear plasmid prophage throughout lysogeny. Understanding the dynamics of antibiotic resistance and pathogen development requires knowledge of phages like this one, which are known for their temperate nature and their function in altering bacterial virulence and resistance profiles. The regulatory and structural proteins of the phage also provide a model for research into the biology of temperate phages and their effects on microbial communities. The importance of temperate phages in bacterial genomes and their function in the larger framework of microbial ecology and evolution is emphasized in this research. Full article

Background: Citrobacter freundii (CFC) and Enterobacter cloacae (ECLC) species complexes represent important causes of hospital-associated infections, frequently are related to outbreaks, and have a great ability to develop antimicrobial resistance. We evaluated a large collection of CFC and ECLC isolates with decreased susceptibility to broad-spectrum cephalosporins (Ceph-DS) from United States (US) hospitals. Methods: A total of 43,325 Enterobacterales (1/patient) were collected in 2019–2023 and susceptibility tested by broth microdilution; among those, 5106 (11.8%) were CFC (n = 1374) or ECLC (n = 3732). Ceph-DS CFC (n = 379) and ECLC isolates (n = 1065), defined as isolates with ceftazidime MICs ≥ 16 mg/L and/or cefepime MICs ≥ 2 mg/L, were screened for β-lactamase genes by whole genome sequencing. Results: The most common ESBLs were CTX-M type (n = 98; 47.6% of ESBL producers), SHV type (n = 94; 45.6%), and OXA type (n = 78; 37.9%); ≥2 ESBLs were identified in 65 isolates (31.6%), mainly OXA-1/30 plus a CTX-M. A carbapenemase was identified in 55 of 64 (85.9%) carbapenem-resistant (CB-R) isolates, including KPC type (40 isolates; 62.5% of CB-R) and NDM-1 (16; 23.4% of CB-R). Aztreonam–avibactam was active against 99.6% of Ceph-DS and 100.0% of ESBL producers and CB-R isolates, including NDM producers. Ceftazidime–avibactam and meropenem–vaborbactam were active against 100.0% of ESBL producers (excluding carbapenemase co-producers) and 70.3–71.9% of CB-R isolates. Cefiderocol was active against 82.8% of CB-R isolates but only 46.7% of MBL producers. Conclusions: Aztreonam–avibactam was highly active against cephalosporin-nonsusceptible ECLC and CFC, including MBL producers. The activities of ceftazidime–avibactam, meropenem–vaborbactam, and cefiderocol were compromised against CB-R isolates due to the high frequency of NDM producers. Full article

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a significant opportunistic human pathogen, posing a considerable threat to public health due to its antimicrobial resistance and limited treatment options. The incidence of CRPA is high in the Philippines; however, genomic analysis of CRPA in this setting is limited. Here, we provide the phenotypic and molecular characterization of 35 non-duplicate CRPA obtained from three tertiary hospitals in Metro Manila, Philippines, from August 2022 to January 2023. Six sequence types (STs), including international high-risk clones ST111 and ST357, were identified. This article highlights the first report in the Philippines on the identification of P. aeruginosa harboring Klebsiella pneumoniae Carbapenemase-2 (KPC-2), coproduced with Verona Integron-encoded Metallo-beta-lactamase-2 (VIM-2) and Oxacillinase-74 (OXA-74). Notably, this is also the first report of KPC in the Philippines identified in P. aeruginosa. New Delhi Metallo-beta-lactamase-7 (NDM-7), coproduced with Cefotaxime-Munich-15 (CTX-M-15) and Temoneira-2 (TEM-2), was also identified from a novel ST4b1c. The relentless identification of NDM in the Philippines’ healthcare setting poses a significant global public health risk. The initial detection of the P. aeruginosa strain harboring KPC exacerbated the situation, indicating the inception of potential dissemination of these resistance determinants within P. aeruginosa in the Philippines. Full article

Proteus mirabilis (P. mirabilis) is an opportunistic pathogen involved in urinary tract infections as well as various nosocomial infections. Emerging resistances to beta-lactams in this species complicates potential treatment since it is intrinsically resistant to colistin. Eleven isolates of carbapenem-non-susceptible P. mirabilis were identified in Sousse Hospital, Tunisia, from January 2018 to December 2022. MICs were determined and isolates were sequenced to determine their resistomes, sequence types, virulence factors, and their clonal relationships. Susceptibility testing showed that all isolates were resistant to carbapenems, aminoglycosides, fluoroquinolones, chloramphenicol, and the trimethoprim/sulfamethoxazole combination. They remained susceptible to the aztreonam/avibactam combination. All isolates produced NDM-1 carbapenemase and ArmA 16S rRNA methylase. In addition, one isolate co-produced the bla_VEB-6 gene. All isolates belonged to ST135, and phylogenetic analysis revealed that they were closely related. This study described the first outbreak of NDM-1-producing P. mirabilis in Tunisia. Full article

Bloodstream infection (BSI) is a critical medical emergency associated with a high mortality rate. Rapid and accurate identification of the causative pathogen and the results of antimicrobial susceptibility testing are crucial for initiating appropriate antimicrobial therapy. The aim of this study was to evaluate the performance of a new rapid PCR Molecular Mouse System (MMS) for the identification of Gram-negative bacteria (GNB) and GNB resistance genes directly from a positive blood culture (BC). The validation of these rapid multiplex assays was carried out in a real hospital setting. A total of 80 BSI episodes were included in our study and the results were compared with culture-based methods. BC samples in which GNB had previously been detected microscopically and which originated from different hospital wards were analysed. The MMS GNB identification assay achieved a sensitivity of 98.7% and a specificity of 100% for the covered pathogens. In one BC sample, Klebsiella aerogenes was identified at the family level (Enterobacteriaceae) with MMS. However, in three polymicrobial samples, MMS identified bacteria that were not detected by culture-based methods (Klebsiella pneumoniae, K. aerogenes and Stenotrophomonas maltophilia). MMS also showed excellent overall performance in the detection of GNB resistance markers (100% sensitivity and 100% specificity). The type of extended-spectrum beta-lactamase (ESBL) resistance gene identified correctly with MMS was CTX-M-1/9 (n = 17/20), alone or in combination with SHV-type β-lactamase or with the different types of carbapenemase genes. MMS detected one carbapenemase gene of each type (KPC, NDM and OXA-23) and six OXA-48 genes. In addition, the colistin resistance gene mcr-1 was detected in one positive BC with Escherichia coli (E. coli). The time to result was significantly shorter for MMS than for routine culture methods. A retrospective analysis of the patients’ medical records revealed that a change in empirical antimicrobial therapy would have been made in around half of the patients following the MMS results. These results support the use of MMS as a valuable complement to conventional culture methods for more rapid BSI diagnosis and adjustment of empirical therapy. Full article

Ceftazidime–avibactam (CZA) is a potent broad-spectrum drug combination covering extended-spectrum β-lactamases, AmpC, and carbapenemases of class A and D, OXA-48-type producers. Rapid antimicrobial susceptibility testing is crucial for the timely de-escalation/escalation of therapy. We evaluate CZA susceptibility using the CE-IVD FASTgramneg kit (FASTinov^®), a ground-breaking 2 h assay, based on flow cytometry technology for antimicrobial susceptibility testing. The assay involved rapid bacterial extraction and purification from positive blood cultures (PBCs), followed by a 1 h 37 °C incubation and flow cytometry analysis (Cytoflex, Beckman-Coulter). The susceptibility report was generated using a proprietary software and interpreted using EUCAST and CLSI 2024 criteria. Sensitivity and specificity were calculated against a reference standardized method (disk diffusion) according to ISO20776-2:2021. Overall, 135 Enterobacterales and 73 Pseudomonas aeruginosa isolates were studied. Thirty-four isolates were resistant to CZA, including six P. aeruginosa and 28 Enterobacterales (24 metallo-beta-lactamase producers, three KPC variants, and one co-producing KPC+NDM). Sensitivity and specificity reached 100% when using EUCAST and CLSI criteria compared with the reference method. The FASTinov ultra-rapid susceptibility assay for CZA demonstrated excellent results, potentially enabling de-escalation/escalation even before the second dose. Combining the speed of a molecular assay with the comprehensive information of a phenotypic test offers valuable insights for treatment decisions. Full article

The widespread application of carbapenems and other broad-spectrum antibiotics has significantly escalated the threat posed by highly drug-resistant Klebsiella pneumoniae to human public health. In this research, we isolated a carbapenem-resistant K. pneumoniae strain from the feces of pet dogs at a veterinary hospital in Changchun, Jilin Province, China. To gain insights into its genetic makeup and resistance mechanisms, we conducted comprehensive whole-genome sequencing and antimicrobial susceptibility testing on the isolated strain. Our findings revealed the presence of three distinct plasmids within the strain, classified as IncFIB&IncFII, IncR, and IncX3. Notably, the bla_NDM-5 gene, conferring resistance to carbapenems, was uniquely harbored on the IncX3 plasmid, which was devoid of any other resistance genes beyond bla_NDM-5. In contrast, the remaining two plasmids, IncFIB&IncFII and IncR, were found to encode an array of additional drug resistance genes, contributing to the strain’s broad-spectrum resistance phenotype. The IncX3 plasmid, specifically, measures 45,829 bp in length and harbors the IS5D-bla_NDM-5-Ble-MBL-PRAI cassette, which has been closely linked to the dissemination of bla_NDM-5 genes in K. pneumoniae strains. We reported the bla_NDM-5-carrying IncX3 in K. pneumoniae isolates recovered from the pet dog and revealed the molecular characterization. Emphasis should be placed on, and continuous monitoring carried out for, the dissemination of K. pneumoniae harboring the bla_NDM-5 gene among humans, companion animals, and their related environments. Full article