A study of the molecular epidemiology of nosocomial strains of Acinetobacter baumannii isolated from Nepal

Genetic diversity and ERIC-PCR-based relationships of Acinetobacter baumannii isolates from hospitals

Genotypic and Phenotypic Resistance Profiles of Invasive Acinetobacter baumannii Isolates at Bulgarian University Hospital

The relationship between genotypic and phenotypic resistance profiles in 36 non-duplicate invasive A. baumannii isolates collected at a tertiary care hospital in Bulgaria over a six-year period supports the use of targeted genes, such as armA, combined with phenotypic testing to guide empirical therapy and strengthen local surveillance of high-risk A. baumannii clones in hospital settings.

Antimicrobial resistance and genes profiles of Acinetobacter baumannii isolated from University Teaching Hospital of Kigali

INTRODUCTION: Antimicrobial resistance is a growing global threat, with carbapenem-resistant A. baumannii (CRAB) identified by World Health Organisation (WHO) as a top-priority pathogen. In Rwanda, data on resistance patterns and underlying genetic determinants in A. baumannii remains limited. This study aims to assess phenotypic resistance profile and detect key resistance genes to support infection prevention and control (IPC) and antimicrobial stewardship interventions. METHODS: A cross-sectional study was conducted from February to July 2025.Acinetobacter baumannii isolates were identified and tested for antimicrobial susceptibility using the disk diffusion method. Polymerase chain reaction (PCR) was used to detect selected resistance genes. Data on patient demographics, sample types, and hospital wards were collected and analysed. RESULTS: Of 1746 clinical isolates, 3.2% (n=56) were confirmed Acinetobacter baumannnii. Most isolates were recovered from male Intensive Care Unit (ICU) patients aged 19–40. All isolates showed 100% resistance to key beta-lactams, high resistance to ciprofloxacin with 87.0%, gentamicin 78.3%, while complete susceptibility to imipenem at 100% was observed. Resistance genes; blaOXA-23 and blaCTX-M were detected in 60.9% and 52.2% of isolates respectively, confirming the genetic basis for carbapenem and ESBL resistance. CONCLUSION: The study revealed a significant burden of multidrug-resistant Acinetobacter baumannii infections, particularly among ICU patients. The high resistance of blaOXA-23 and blaCTX-M highlights the complexity of managing these infections and underscores the need for strengthened IPC measures, routine molecular surveillance, and targeted AMS strategies.

Molecular Characterization of OXA Carbapenemase Genes in Acinetobacter Baumannii Isolated from Different Clinical Samples.

It is indicated that blaOXA-23 is the predominant contributor to carbapenem resistance among A. baumannii isolates in Baghdad, while blaOXA-24 and blaOXA-58 are also increasingly prevalent.

Genomic epidemiology of carbapenemase-producing Enterobacter cloacae complex in Argentina: a retrospective analysis (2016–2022)

ABSTRACT Enterobacter spp., after Klebsiella pneumoniae, is among the most common hospital-acquired enterobacteria associated with antimicrobial resistance (AMR) worldwide, yet it remains underexplored. We determined the taxonomic and epidemiological distribution of 131 representative carbapenemase-producing Enterobacter spp. recovered from infections across Argentina between 2016 and 2022. The sample included one isolate per patient from 17 jurisdictions and 68 hospitals. Outbreak-related and surveillance isolates were excluded. Sequencing was performed using Illumina, and bioinformatic analyses were used to determine species (average nucleotide identity [ANI] ≥94%) and subspecies (ANI ≥98%) using BactInspector/fastANI. Sequence types (STs) were assigned by multilocus sequence typing (MLST) via PubMLST, and resistance genes were identified using AMRfinderPlus/Resfinder. Samples were obtained from (n; %) urine (43; 33%), blood (41; 31%), and other sites (47; 36%). Seven species were identified, with Enterobacter hormaechei (EH) predominating ( 120; 92%) and comprising five subspecies. E. hormaechei subsp. steigerwaltii was the most abundant (60; 45%), followed by E. hormaechei subsp. xiangfangensis (29; 22%). Enterobacter cloacae subsp. cloacae was underrepresented (3; 2.3%). KPC-2 was the predominant carbapenemase, followed by NDM-1 and OXA-163. A total of 58 STs were identified, 38 represented by a single isolate. EH included 50 STs, with the most abundant being ST88 (12; 9%), ST78 (12; 9%), and ST66 (8; 6%). No clear associations were observed between species/subspecies, clones, and carbapenemase types. Overall, the population structure of carbapenemase-producing Enterobacter spp. in Argentina is complex and diverse, characterized by multiple species, subspecies, clonal diversity, and varied carbapenemase types and combinations. Notably, 50% of the isolates belonged to E. hormaechei subsp. steigerwaltii, suggesting a major role of this subspecies in the dissemination of AMR. IMPORTANCE Carbapenemase-producing Enterobacter spp. rank as the most common Enterobacterales associated with carbapenemase production. Despite their clinical relevance, the taxonomy and population structure of this group remain poorly characterized. This study provides a comprehensive genomic overview of clinical carbapenemase-producing Enterobacter spp. circulating in Argentina, revealing a highly diverse population composed of species, subspecies, and clonal types, harboring mainly KPC-2, followed by NDM-1 and combinations. We identified international clones within E. hormaechei, such as ST88 and ST78, which may play important roles in the dissemination of antimicrobial resistance. Notably, 50% of the isolates belonged to E. hormaechei subsp. steigerwaltii, suggesting a major role of this subspecies in the dissemination of antimicrobial resistance (AMR). By improving our understanding of this complex bacterial group, this work supports the strengthening of antimicrobial resistance surveillance networks and the development of targeted strategies for infection control and antibiotic stewardship in healthcare settings. Carbapenemase-producing Enterobacter spp. rank as the most common Enterobacterales associated with carbapenemase production. Despite their clinical relevance, the taxonomy and population structure of this group remain poorly characterized. This study provides a comprehensive genomic overview of clinical carbapenemase-producing Enterobacter spp. circulating in Argentina, revealing a highly diverse population composed of species, subspecies, and clonal types, harboring mainly KPC-2, followed by NDM-1 and combinations. We identified international clones within E. hormaechei, such as ST88 and ST78, which may play important roles in the dissemination of antimicrobial resistance. Notably, 50% of the isolates belonged to E. hormaechei subsp. steigerwaltii, suggesting a major role of this subspecies in the dissemination of antimicrobial resistance (AMR). By improving our understanding of this complex bacterial group, this work supports the strengthening of antimicrobial resistance surveillance networks and the development of targeted strategies for infection control and antibiotic stewardship in healthcare settings.

Antimicrobial resistance and plasmidome of carbapenemase-resistant Klebsiella pneumoniae causing bloodstream infections between 2014 and 2024

The WHO has designated carbapenemase-resistant Klebsiella pneumoniae (CRKP) as a priority pathogen due to the potential for nosocomial infection outbreaks. In this study, a total of 724 non-duplicated K. pneumoniae bloodstream infection isolates were collected in Beijing between 2014 and 2024, of which 14.5% were identified as CRKP (n = 105). The incidence of CRKP isolates remained at a relatively high level since 2018, with a significant increase observed following the SARS-CoV-2 epidemic. The most common sequence type was ST11 (84.8%), followed by ST16 (5.7%) and ST15 (5.7%). Sixteen potential clonal transmissions were identified, including four clonal clusters transmitted at the ward-level. Antimicrobial resistance was severe, with almost all isolates showing resistance to 15 antimicrobials tested. The blaKPC-2 (93.3%) was the dominated carbapenemase gene, followed by blaOXA-181 (5.7%). The blaCTX-M-65 (61.0%) was the most common ESBL gene, followed by blaCTX-M-15 (14.3%) and blaSHV-12 (12.4%). Phenotype-genotype concordance was 100% for cephalosporins and carbapenemases. The correlation of plasmids with antimicrobial resistance and virulence genes were determined, with the IncFII(pHN7A8)_1_pHN7A8 plasmid showing a significant correlation with blaCTX-M-65 and blaKPC-2, and the IncHI1B_1_pNDM-MAR and IncR_1 plasmids significantly correlated with iucABC-iutA (P < 0.05). The trend of type KL64 was increasing and surpassed that of type KL47 since 2019, similar to the trend of O2a gradually surpassing O13. Our study provides insights into the epidemiology, dissemination, AMR genes, and plasmids of CRKP bloodstream infections in Beijing, China, over the long term.