Search Results (846)

Background: The COVID-19 pandemic profoundly affected healthcare delivery and antibiotic prescribing, raising concerns about increasing antimicrobial resistance. This study investigated seven-year trends in bacterial resistance, underlying resistance mechanisms, and antibiotic consumption in COVID-19 and non-COVID-19 units at a tertiary hospital in Slovakia. Methods: A retrospective cohort analysis (2018–2024) was conducted using clinical isolates of Klebsiella sp., Acinetobacter sp., and P. aeruginosa. Data on hospitalizations, resistance profiles, resistance mechanisms, and standardized antibiotic use were compared between COVID-19 and non-COVID-19 departments. Results: Hospitalizations markedly decreased in COVID-19 units, while pathogen occurrence—particularly of Acinetobacter sp.—was substantially higher compared with non-COVID-19 units. Resistance in Klebsiella sp. shifted from extended-spectrum beta-lactamase production to carbapenemase production. Acinetobacter sp. remained highly resistant, although some declines were observed in ceftazidime and gentamicin resistance. P. aeruginosa showed a gradual reduction in resistance, notably to piperacillin/tazobactam and imipenem. Antibiotic consumption was consistently higher in COVID-19 units, particularly for broad-spectrum beta-lactams and carbapenems, whereas fluoroquinolone use decreased over time. Clinically effective treatment options were considerably fewer in COVID-19 units, often limited to colistin. Conclusions: COVID-19 units experienced greater pathogen burden, higher broad-spectrum antibiotic exposure, and increased prevalence of critical resistance mechanisms. Tailored antimicrobial stewardship and infection prevention, and control are essential to reduce selective pressure and preserve last-line antibiotics. Full article

Background/Objectives: Klebsiella pneumoniae ST258 and ST11 are global high-risk antimicrobial-resistant clones known for their virulence and resistance gene dissemination. This study aims to identify these clones in a Greek tertiary hospital and understand their resistance profiles and transmission dynamics. Methods: In January 2025, we isolated two distinct carbapenem-resistant K. pneumoniae in a Greek tertiary hospital: INT18S from an ICU patient’s bronchioalveolar lavage and INT20U from a urine sample in the emergency unit. Antimicrobial susceptibility testing (via Microscan system) and Whole-Genome Sequencing (WGS) were conducted on both isolates and their genomes were submitted to the NCBI. Results: The INT18S isolate carried the bla_KPC-2 gene and belonged to the ST258 clone. The INT20U isolate carried the bla_NDM-1 gene and belonged to the ST11 clone lineage. Both isolates contained at least one of the extended spectra β-lactamase genes tested (TEM, SHV, OXA-1 and CTX-M group). Conclusions: The co-existence of the high-risk K. pneumoniae clones ST258 and ST11 in different hospital departments increases the risk of resistance gene transfer and suggests potential intra-hospital transmission pathways. Understanding their resistance profiles is critical for guiding treatment strategies and preventing the spread of multidrug-resistant pathogens. Full article

Background/Objectives: Klebsiella spp., particularly K. pneumoniae, are major opportunistic pathogens in healthcare settings driven by carbapenemase- and ESBL-producing strains. We assessed antimicrobial resistance and biofilm formation abilities in Klebsiella spp. from a Brazilian tertiary hospital and related environments and characterized capsular types. Methods: Over six months (July–December 2023), 303 carbapenem-resistant Klebsiella spp. were collected from clinical specimens (n = 198), ICU/non-ICU surfaces (n = 79), hospital sewage (n = 22), and stream water (n = 4). Species were identified by MALDI-TOF. Susceptibility testing covered eight antibiotic classes, focusing on carbapenems and polymyxin B. Biofilm formation was quantified by crystal violet, and capsular typing used wzi/K-locus approaches. Results: Most isolates (70.95%) had meropenem MICs ≥ 128 μg/mL, while 77.6% (n = 235) remained susceptible to polymyxin B. Resistance profiles largely consisted of extensive drug resistance (95.4%), with 1.3% exhibiting pandrug resistance, including isolates from bed rails. Biofilm formation was detected in 96.7% of isolates, mainly weak (67.6%) or moderate (28%), with 4.4% being strong producers. Among the Klebsiella isolates analyzed, 21 K types were identified with an uneven distribution dominated by K64, followed by K24, K173, and K50. K75 was the only K type detected across all sources—clinical isolates, bed-rail surfaces (non-ICU), wastewater, and fluvial water. Conclusions: Carbapenem-resistant Klebsiella spp. exhibited widespread resistance, with residual susceptibility to aminoglycosides, ceftazidime–avibactam, and polymyxins. Environmental reservoirs—hospital surfaces, sewage, and stream water—harbored resistant biofilm producers, reinforcing their role in persistence and dissemination. K-typing revealed concentrated distribution (predominantly K64) and cross-source K75. These findings underscore the urgency of integrated strategies combining molecular surveillance, antimicrobial stewardship, and environmental control. Full article

Background: Acinetobacter baumannii (A. baumannii), a critical nosocomial pathogen, poses a significant threat in intensive care units (ICUs) due to its multidrug-resistant (MDR) strains. This study systematically reviews and performs a meta-analysis on the prevalence and antibiotic resistance profiles of MDR A baumannii (MDR-A. baumannii) in ICU patients in Saudi Arabia. Methods: A comprehensive search in PubMed, Saudi Digital Library, Scopus, and Web of Science, focusing on studies from January 2014 to September 2025, was performed. The present study followed the reporting guidelines of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA-2020). Data on study characteristics, sample sizes, patient demographics, prevalence of MDR-AB, and antibiotic resistance profiles were extracted and analyzed. Quality assessment was conducted using the Joanna Briggs Institute. Results: The prevalence of MDR-AB in ICU patients varied significantly across studies, with retrospective studies reporting rates from 3.37% to 69% and prospective studies ranging from 3.9% to 72.73%. Colistin remained highly effective, showing 100% susceptibility in some studies. Meanwhile, resistance to carbapenems like imipenem and meropenem often exceeds 50%. Additional antibiotics with notable resistance included gentamicin, tigecycline, ampicillin/sulbactam, trimethoprim-sulfamethoxazole, ceftazidime, piperacillin/tazobactam, and third-generation cephalosporins. Mechanisms of resistance frequently involved OXA-type carbapenemases, particularly OXA-23. While OXA-23 was the most frequently detected carbapenemase, recent genomic data have also revealed the presence of metallo-β-lactamases, such as IMP-type genes, in ICU isolates. Conclusions: MDR-A. baumannii poses a substantial challenge in Saudi Arabian ICUs, with high prevalence and significant resistance to commonly used antibiotics. The results highlight the critical need for continuous monitoring, cautious antibiotic stewardship, and strict infection control methods to manage and lessen the effects of MDR-AB in ICUs. Full article

The COVID-19 pandemic has profoundly influenced healthcare systems and infection control worldwide, with important implications for the epidemiology of antimicrobial resistance. This study examined the prevalence and characteristics of carbapenem-resistant Enterobacterales (CRE) isolates in Southeastern Austria from 2018 to 2022 to assess potential pandemic-related effects. A total of 63 isolates were analyzed using phenotypic and molecular methods, including carbapenemase detection, genotyping, and multilocus sequence typing. The number of CRE isolates appeared to decline during the pandemic years (2021–2022) compared to the pre-pandemic period, with Enterobacter cloacae notably detected in both full pandemic years. Carbapenemase-producing CRE accounted for 44 out of the 63 isolates (69.8%), with metallo-beta-lactamases (VIM-1 and NDM-1) and OXA-48-like carbapenemases predominating. Resistance mechanisms not based on carbapenemase production were more common before the pandemic but rarely detected thereafter. To our knowledge, this is the first report of dual-carbapenemase-producing CRE isolates in Austria. Multi-locus-sequence typing indicated limited nosocomial transmission, with most isolates representing independent introductions linked to external sources. The decline in CRE prevalence may reflect reduced international travel and healthcare access during the pandemic, which could have limited the importation of resistant strains. These findings reflect the potential role of global mobility in the spread of CRE and illustrate how public health interventions can shape antimicrobial resistance trends. Full article

Background/Objectives: Gram-negative bacteria with acquired carbapenem resistance have become increasingly common in serious infections. This study aimed to evaluate the in vitro activity of cefiderocol against multidrug-resistant Gram-negative clinical isolates collected from a tertiary care hospital in Romania. Methods: A retrospective study (November 2024–February 2025) involving 89 consecutive Multi-Drug Resistant (MDR) Gram-negative isolates, 66 Enterobacterales and 23 non-fermenters (P. aeruginosa, S. maltophilia, A. baumannii), was conducted. Results: Overall, 52.8% of Enterobacterales and P. aeruginosa isolates were susceptible to cefiderocol, with higher susceptibility among Enterobacterales alone (63.6%). Using disk diffusion, 66.3% of all isolates were classified as susceptible to the antibiotic. K. pneumoniae isolates co-harboring NDM and OXA-48 were susceptible in 65.3% of cases, while NDM-only producers were resistant. All P. aeruginosa isolates tested were susceptible to the antibiotic. Susceptibility rates in A. baumannii were lower (68.8%), with variability between testing methods. Conclusions: The presence of NDM-producing isolates with complete resistance to cefiderocol in our study highlights the risk that resistance may spread rapidly once the drug becomes widely used. Cefiderocol may be an effective option for treating MDR bacterial infections, but strict microbiological monitoring remains essential. Full article

The global rise of multi-drug resistant (MDR) pathogens, including the widespread resistance to beta-lactams through the production of β-lactamases, like extended spectrum β-lactamases (ESBLs), has led to the increasing use of last-line antibiotics such as carbapenems. Subsequently, the worldwide emergence of carbapenemase-producing pathogens poses a formidable challenge. The combination ceftazidime/avibactam (CAZ/AVI) has emerged as a pivotal agent in the management of multidrug-resistant Gram-negative infections. Avibactam, a novel β-lactamase inhibitor, demonstrates a wider spectrum of activity against Ambler Class A, C, and partially D β-lactamases in comparison to older inhibitors, thus enhancing the antimicrobial activity of ceftazidime against organisms producing ESBL and carbapenemases, such as oxacillinase (OXA)-type and Klebsiella pneumoniae Carbapenemase (KPC). This review synthesizes findings from randomized controlled trials and cohort studies, evaluating the efficacy of CAZ/AVI across diverse clinical settings, including complicated intra-abdominal infections, urinary tract infections, nosocomial pneumonia, skin and soft tissue infections, and bloodstream infections. The non-inferiority of CAZ-AVI with respect to carbapenems and superiority over polymyxins in terms of both clinical outcomes and safety are outlined, along with evidence supporting the use of CAZ/AVI in high-risk populations such as immunocompromised and critically ill patients. Overall, CAZ/AVI represents a compelling therapeutic option with favorable efficacy and safety, thus appearing as a reasonable frontline treatment for resistant Gram-negative infections. Full article

Wastewater treatment plants (WWTPs) are recognized hotspots for the convergence and dissemination of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs) into the environment. Among ARB, carbapenem-resistant Enterobacterales (CR-E) and extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae (ESBL-Ec/Kp) are of particular concern due to their clinical relevance. We characterized 30 CR-E and 176 ESBL-Ec/Kp isolates (two of them were both ESBL-producing and carbapenem-resistant) recovered from influent, intermediate, effluent, sludge, and downstream river samples collected from two WWTPs in northern Spain. Isolates were evaluated for resistance phenotypes against 12 antimicrobials, and β-lactamase-encoding genes were assessed by PCR and sequencing. Notably, among CR-E isolates, bla_KPC-2 was the most prevalent (93%), followed by bla_OXA-48-like, detected in two isolates from non-treated and pasteurized sludge; both isolates also carried bla_CTX-M-15, a finding not previously reported specifically in sludge samples. Among ESBL-Ec/Kp, a broad diversity of ESBL genes was identified, including bla_{CTX-M group 1} (variants 1, 3, 15, 32, 55), bla_{CTX-M group 9} (variants 14, 27, 65, 97), bla_SHV-12 and bla_TEM-169. The most prevalent ESBL gene was bla_CTX-M-15 (48.3%), followed by bla_CTX-M-14, bla_CTX-M-32, and bla_SHV-12, detected in 10.8%, 8.5%, and 6.8% of isolates, respectively. CR-E and ESBL-Ec/Kp were found in all sample types and were still detectable at terminal stages, indicating persistence throughout treatment. These findings support the need to improve and optimize current wastewater treatment methods and underscore the importance of integrating culture-based and molecular methods into routine WWTP monitoring for early detection of microbiological hazards, although further research is still needed. Full article

In recent decades, the problem of resistant strains, which present resistance to different types of antimicrobials, has increased. Klebsiella pneumoniae is one of the most important species that exhibits an acquired resistance phenotype to at least one agent in three or more classes of antimicrobials and is thus characterized as a multidrug-resistant bacterium (MDR). 98 nosocomial strains of K. pneumoniae were isolated during the pre-COVID-19 period, and more specifically, from February 2015 to March 2019, were analyzed for the detection of class A, D, and B carbapenemase genes. The existence of KPC, OXA-48 like, IMP, VIM, and NDM carbapenemases has been examined. The immunochromatography showed that NDM carbapenemases are more frequently detected in the samples, reaching a percentage of 30.7%, while correspondingly the percentage for VIM carbapenemases was 7.68% among the strains with resistant phenotypes. No strain with carbapenemase IMP was found. Real-time multiplex polymerase chain reaction (PCR) showed, in contrast to immunochromatography kits, that a high percentage of bacterial isolates (94.26%) carry NDM and VIM carbapenemase genes, while no IMP carbapenemase genes were detected. Regarding the KPC enzymes, the immunochromatography kits showed that KPC positive strains are reaching 53.1%, and OXA-48 positive strains are reaching 3.1% among the strains with resistant phenotypes. Real-time multiplex polymerase chain reaction revealed a much higher percentage of 89.6% KPC positive isolates and a percentage of 14.6% OXA-48 carbapenemase producers. The aforementioned results indicate the dominance of the Multiplex Real-Time PCR as a “gold standard” method. This study could not fully support the usefulness of rapid immunochromatographic tests as a fast and useful diagnostic tool in the laboratory daily routine, as per the results of previous studies. Thus, more studies need to be conducted in this field to introduce these rapid tests safely into the daily laboratory workflow as a screening tool. Additionally, this study underlines the predominance of KPC enzymes from clinical isolates of ICUs and a significant shift over the OXA-48 like enzymes that are not limited to the ICU environment. Full article

Klebsiella pneumoniae is one of the top pathogens causing bloodstream infections (BSIs) worldwide. The rise of carbapenem-resistant K. pneumoniae (CRKP) and multidrug-resistant (MDR) strains is of particular concern as therapeutic options are limited. Analyzing local resistance profiles is essential for the success of antibiotic stewardship strategies. This study aims to explore the resistance profiles of K. pneumoniae strains identified in BSI in a tertiary care hospital over 7 years. Automated systems were used to test antibiotic susceptibility. Results were interpreted according to EUCAST clinical breakpoints. The rate of multidrug resistance (MDR) was 57.6%. The percentage of ESBL producers was 54.5%, and the percentage of carbapenemase producers was 43.2%. Overall resistance rates to other antibiotics were 47.1% to ciprofloxacin, 31.4% to gentamicin, 25.7% to amikacin, 20.9% to colistin, 19.6% to Fosfomycin, and 44.5% to trimethoprim/sulfamethoxazole. The highest resistance to colistin was recorded in 2023 (28%). More than half of the strains in the study were MDR and ESBL producers. K. pneumoniae resistance to colistin has increased during the last 7 years. The rates of carbapenemase-producing bacteria (CPB) are on the rise. The most frequently co-harboring carbapenemases were NDM and OXA-48. Local antibiotic resistance rates are crucial in implementing an effective antibiotic stewardship strategy. Full article

Background and Objectives: Catheter-associated urinary tract infections (CAUTIs) caused by extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant Enterobacterales (CRE) significantly contribute to global rates of UTI. This study aimed to compare the prevalence and trends of ESBL-producing Enterobacterales and CRE in patients with CAUTIs and non-CAUTIs. Materials and Methods: A retrospective review of 4262 UTI-positive urine cultures was conducted at King Fahad Hospital of the University, Al Khobar, Saudi Arabia (January 2022–November 2023). Demographic, clinical, and microbiological data were obtained from hospital records. Antimicrobial susceptibility was tested using the Vitek^® System; ESBL and CRE were identified using Ezy MIC™ strips and Xpert^® Carba-R assay, respectively. Results: ESBL-producing Enterobacterales accounted for 11.3% of cases; CRE comprised 1.8%. ESBL was significantly more prevalent in non-catheterized patients and those in emergency care. CRE was significantly associated with catheterized patients and inpatient settings. Escherichia coli and Klebsiella pneumoniae were the predominant ESBL-producing and CRE isolates, respectively. bla-OXA-48 was the most frequently detected carbapenemase gene (66.7%). ESBL was prevalent in younger, non-catheterized females, suggesting increasing community transmission. Conversely, CRE were primarily observed in older, catheterized inpatients, emphasizing the role of invasive devices in resistance spread. Conclusions: These findings highlight the importance of targeted infection control and early catheter removal to mitigate resistance trends. Full article

Background/Objectives: Bloodstream infections (BSIs) caused by carbapenem-resistant Enterobacterales (CREs) are a growing public health threat due to limited therapeutic options and high mortality. In Turkey, oxacillinase-48 (OXA-48) producers predominate, while OXA-48/New Delhi metallo-β-lactamase (NDM) co-producers are increasingly detected. Although ceftazidime–avibactam (CAZ-AVI) is effective against OXA-48, treating NDM-positive isolates remains challenging. Cefiderocol, a novel siderophore cephalosporin active against both serine- and metallo-β-lactamases, is not yet available in Turkey. Establishing baseline susceptibility rates and identifying clinical predictors of resistance are, therefore, crucial before its introduction. Methods: This retrospective study included adult patients with CRE-BSIs diagnosed at a tertiary university hospital in Istanbul between January and December 2023. Demographic, clinical, and microbiological data were collected from electronic medical records. Susceptibility to cefiderocol, CAZ-AVI, and colistin was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2023 criteria. Risk factors for cefiderocol resistance were analyzed. Results: Among 202 isolates, cefiderocol showed the highest susceptibility (94%, n = 190), followed by CAZ-AVI (82%, n = 166) and colistin (70%, n = 141), with all pairwise differences being statistically significant (p < 0.001). Cefiderocol resistance (6%, n = 12) was significantly associated with hematologic malignancy, hematopoietic stem cell transplantation, prior CAZ-AVI or polymyxin exposure, prolonged hospitalization, and repeated admissions. Conclusions: Cefiderocol demonstrated potent in vitro activity against CRE-BSI isolates, with resistance confined to distinct high-risk clinical settings. This pre-implementation study provides baseline microbiological and epidemiological data from an OXA-48 endemic region with rising NDM prevalence, underscoring the importance of early surveillance and stewardship strategies before cefiderocol becomes clinically available. Full article

Wound infections pose a significant challenge in modern medicine, driven by multimorbidity, weakened immunity, microbial virulence factors, and resistance to antibiotics and antiseptics. This study aims to evaluate the antibacterial properties of carvacrol (CAR), its impact on biofilm formation, and its capacity to trigger oxidative stress in clinical strains of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterobacter cloacae. Carbapenemases in the studied bacteria were detected using culture on CarbaId agar. The presence of genes encoding bacterial virulence factors and carbapenemase production was confirmed using the PCR method. The antimicrobial activity of carvacrol was evaluated using the broth microdilution method. The ability of strains to form biofilm was determined using a modified crystal violet assay. Oxidative stress levels in bacterial cells in response to carvacrol treatment were measured using 2′,7′-dichlorofluorescein diacetate. Real-TimePCR was used to confirm the presence of NDM family carbapenemase genes in K. pneumoniae strains, KPC genes in E. cloacae strains, and VIM genes in P. aeruginosa strains. CAR exhibited a broad spectrum of antibacterial activity against the tested bacteria, with MIC values ranging from 125 to 1000 μg/mL. Treatment with 1/2 MIC of CAR did not significantly influence biofilm formation, except in a K. pneumoniae isolate. At 1/2 MIC, CAR induced an increase in intracellular ROS in most tested strains, with the exception of P. aeruginosa 25521221. This study provides insights into the antimicrobial efficacy of carvacrol against carbapenemase-producing pathogens isolated from wound infections—specifically P. aeruginosa, K. pneumoniae, and E. cloacae. CAR demonstrated promising bactericidal properties, likely mediated through the induction of oxidative stress, as evidenced by increased ROS generation in most studied isolates. Full article

Introduction: Klebsiella variicola, a member of Klebsiella pneumoniae complex, has emerged as an opportunistic pathogen for human infection; however, antimicrobial resistance and hypervirulent characteristics of K. variicola have rarely been investigated in South Korea. Methods: We analyzed 76 clinical K. variicola isolates collected from 12 hospitals between September 2022 and October 2023. Bacterial identification was performed by MALDI-TOF MS. Antimicrobial susceptibility was tested by disk diffusion tests. Resistance determinants and virulence traits were investigated, and whole-genome sequencing was performed for hypermucoviscous or carbapenem-resistant K. variicola isolates. Results: Most (89.5%, 68/76) were susceptible to all 18 antimicrobials tested in this study, and 3 isolates harbored bla_CTX-M-15. One isolate carried bla_KPC-2 on its IncX3 plasmid, which is closely related to carbapenem-resistant K. pneumoniae plasmids. Capsular typing revealed 51 wzi allelic types. Ten isolates showed mucoid phenotype, mainly with KL60 and KL61. Conclusions: This study reveals relatively low resistance rates in K. variicola strains but the presence of multidrug-resistant and hypermucoviscous K. variicola strains. In addition, the evidence of interspecies dissemination of bla_KPC-2 highlights the need for continuous genomic surveillance. Full article

Antimicrobial resistance (AMR) poses a critical global health challenge, with carbapenemase-producing Enterobacterales (CPE) representing one of the most urgent threats. While Klebsiella pneumoniae and Escherichia coli have been the focus of most surveillance programs, Enterobacter spp., members of the Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli (ESKAPEE) group, remain an underrecognized but increasingly important reservoir of carbapenemase genes in Europe. Despite being categorized by the World Health Organization (WHO) as “critical-priority” pathogens, Enterobacter spp. are largely excluded from major AMR surveillance frameworks, creating blind spots in detection and control. This review summarizes the taxonomy, intrinsic resistance mechanisms, and clinical relevance of Enterobacter spp., with a particular focus on carbapenemase epidemiology across Europe. We highlight the distribution and genetic context of major carbapenemases, including VIM, OXA-48-like, KPC, and NDM, and discuss emerging or minor enzymes such as IMI, FRI, GES, and IMP. Epidemiological data reveal shifting dominance patterns over time, with VIM enzymes consolidating their prevalence after 2015, while OXA-48-like and KPC declined, and NDM gained ground. The genetic diversity of Enterobacter spp., coupled with their ability to act as both nosocomial pathogens and silent intestinal or environmental reservoirs, facilitates the dissemination of carbapenemase genes via epidemic plasmids and clonal expansion. Addressing the growing impact of carbapenemase-producing Enterobacter spp. requires their systematic inclusion in national and international monitoring programs, expanded use of genomic epidemiology in clinical microbiology, and better alignment between research, clinical practice, and policy. A One Health approach is essential to curb the spread of carbapenemases across human, environmental, and animal reservoirs, and to safeguard the remaining therapeutic options. Full article