Drug-resistant Pantoea agglomerans Causing Bacteremia at a Tertiary Care Hospital in Kolkata, India: First Report of Carbapenem Resistance Mediated by OXA-181.

The spread of antibiotic resistance (ABR) in uncommon human pathogens endangers global public health, escalating morbidity, death, and healthcare expenditures. Pantoea agglomerans, a member of the Erwiniaceae family that rarely infects humans, is emerging as a drug-resistant nosocomial pathogen. Seven P. agglomerans isolates were recovered from bacteremia patients at a tertiary care hospital in Kolkata, West Bengal, between March 2022 and October 2022. The isolates were evaluated for phenotypic resistance, ß-lactamase and plasmid-mediated quinolone resistance (PMQR) genes, plasmid profiling, and clonality assessment. All isolates were resistant to fluoroquinolones and third-generation cephalosporins, with four resistant to carbapenems. The following ß-lactamases and PMQR genes were identified: blaOXA-1 (n = 1), blaTEM (n = 1), blaCTX-M-1 (n = 2), blaNDM (n = 5), blaOXA-181 (n = 1), qnrB (n = 2), and qnrS (n = 4). Six isolates carried up to seven plasmids ranging in size from 2 kb to > 212 kb. IncFI, FII, HI, and X3 plasmid types were detected in three isolates, while the rest remained untypable. Four different genetic patterns were noted. Four isolates were clonally related, with three being clonal. The swap of environmental isolates to human pathogens exacerbates the ABR dilemma, periling patient care and outcomes. This is the first report in India of a carbapenem-resistant P. agglomerans blood isolate carrying blaOXA-181. In-depth genomic research of drug-resistant microbes adapted to the environment-human interfaces might underpin the source-route-containment of ABR.

Characterization of the Anti-Biofilm and Anti-Quorum Sensing Activities of the ß-Adrenoreceptor Antagonist Atenolol against Gram-Negative Bacterial Pathogens.

The development of bacterial resistance to antibiotics is an increasing public health issue that worsens with the formation of biofilms. Quorum sensing (QS) orchestrates the bacterial virulence and controls the formation of biofilm. Targeting bacterial virulence is promising approach to overcome the resistance increment to antibiotics. In a previous detailed in silico study, the anti-QS activities of twenty-two ß-adrenoreceptor blockers were screened supposing atenolol as a promising candidate. The current study aims to evaluate the anti-QS, anti-biofilm and anti-virulence activities of the ß-adrenoreceptor blocker atenolol against Gram-negative bacteria Serratia marcescens, Pseudomonas aeruginosa, and Proteus mirabilis. An in silico study was conducted to evaluate the binding affinity of atenolol to S. marcescens SmaR QS receptor, P. aeruginosa QscR QS receptor, and P. mirabilis MrpH adhesin. The atenolol anti-virulence activity was evaluated against the tested strains in vitro and in vivo. The present finding shows considerable ability of atenolol to compete with QS proteins and significantly downregulated the expression of QS- and virulence-encoding genes. Atenolol showed significant reduction in the tested bacterial biofilm formation, virulence enzyme production, and motility. Furthermore, atenolol significantly diminished the bacterial capacity for killing and protected mice. In conclusion, atenolol has potential anti-QS and anti-virulence activities against S. marcescens, P. aeruginosa, and P. mirabilis and can be used as an adjuvant in treatment of aggressive bacterial infections.

Going virtual: a report from the sixth Young Microbiologists Symposium on 'Microbe Signalling, Organisation and Pathogenesis'.

The sixth Young Microbiologists Symposium on 'Microbe Signalling, Organisation and Pathogenesis' was scheduled to be held at the University of Southampton, UK, in late August 2020. However, due to the health and safety guidelines and travel restrictions as a response to the COVID-19 pandemic, the symposium was transitioned to a virtual format, a change embraced enthusiastically as the meeting attracted over 200 microbiologists from 40 countries. The event allowed junior scientists to present their work to a broad audience and was supported by the European Molecular Biology Organization, the Federation of European Microbiological Societies, the Society of Applied Microbiology, the Biochemical Society, the Microbiology Society and the National Biofilms Innovation Centre. Sessions covered recent advances in all areas of microbiology including: Secretion and transport across membranes, Gene regulation and signalling, Host-microbe interactions, and Microbial communities and biofilm formation. This report focuses on several of the highlights and exciting developments communicated during the talks and poster presentations.

Genomic insights into the phylogeny of Bacillus strains and elucidation of their secondary metabolic potential.

The genus Bacillus constitutes a plethora of species that have medical, environmental, and industrial applications. While genus Bacillus has been the focus of several studies where genomic data have been used to resolve many taxonomic issues, there still exist several ambiguities. Through the use of in-silico genome-based methods, we tried to resolve the taxonomic anomalies of a large set of Bacillus genomes (n = 178). We also proposed species names for uncharacterized strains and reported genome sequence of a novel isolate Bacillus sp. RL. In the hierarchical clustering on genome-to-genome distances, we observed 11 distinct monophyletic clusters and investigated the functional pathways annotated as the property of these clusters and core-gene content of the entire dataset. Thus, we were able to assert the possible outlier strains (n = 17) for this genus. Analyses of secondary metabolite potential of each strain helped us unravel still unexplored diversity for various biosynthetic genes.

The transferability of blaOXA-23 gene in multidrug-resistant Acinetobacter baumannii isolates from Saudi Arabia and Egypt.

Carbapenem-resistant Acinetobacter spp. have been increasingly reported worldwide including Saudi Arabia and Egypt. We examined 64, non-repetitive, Acinetobacter baumannii isolates collected in 2013 and 2014 from four different medical centres (two from Saudi Arabia and two from Egypt). All the isolates were resistant to ceftazidime and ciprofloxacin. The intI1 harbouring blaGES-11 and aac-6'-1b was detected in 19% (n=12) of the isolates. ISAba1 over-expression of blaADC gene was observed in 65% (n=42) of isolates. Of all the isolates 19% (n=12) had ISAba1 upstream of the blaOXA-51-like gene, 69% (n=44) carried the blaOXA-23 gene within the Tn2006 structure, 8% (n=5) had blaOXA-24-like gene and 9% (n=6) harboured either blaVIM-2 or blaNDM-1 gene. Eighty nine percent (n=57) of isolates were resistant to imipenem and had an MIC of ≥8mg/L. Pulsed-field gel electrophoresis (PFGE) typing revealed the presence of 23 different PFGE. Three PFGE types were very widespread, ST236 (CC104) (PFGE type 1, n=15), ST208 (CC92) (PFGE type 2, n=10), ST884 (CC unassigned) (PFGE type 3, n=7) in and across all four medical centres. The blaOXA-23 gene was found to be present on a 60kb transferable plasmid in both PFGE type 1 and 2 but was absent in PFGE type 3. This is the first study to report on the emergence of ST236 in Saudi Arabia and Egypt, and spread of distinct carbapenem resistant A. baumannii clones belonging to ST884, ST945 and ST1096 in Saudi Arabia.

Antimicrobial Resistance in Diverse Escherichia coli Pathotypes from Nigeria.

Escherichia coli is a gram-negative commensal bacterium living in human and animal intestines. Its pathogenic strains lead to high morbidity and mortality, which can adversely affect people by causing urinary tract infections, food poisoning, septic shock, or meningitis. Humans can contract E. coli by eating contaminated food-such as raw or undercooked raw milk, meat products, and fresh produce sold in open markets-as well as by coming into contact with contaminated settings like wastewater, municipal water, soil, and faeces. Some pathogenic strains identified in Nigeria, include Enterohemorrhagic (Verotoxigenic), Enterotoxigenic, Enteropathogenic, Enteroinvasive, and Enteroaggregative E. coli. This causes acute watery or bloody diarrhoea, stomach cramps, and vomiting. Apart from the virulence profile of E. coli, antibiotic resistance mechanisms such as the presence of blaCTX-M found in humans, animals, and environmental isolates are of great importance and require surveillance and monitoring for emerging threats in resource-limited countries. This review is aimed at understanding the underlying mechanisms of evolution and antibiotic resistance in E. coli in Nigeria and highlights the use of improving One Health approaches to combat the problem of emerging infectious diseases.

Genetic landscape of ESBL producing international clone ST410 of Escherichia coli from pediatric infections in Shenzhen, China.

Background: The emergence of ESBLs producing cephalosporin-resistant Escherichia coli isolates poses a threat to public health. This study aims to decipher the genetic landscape and gain insights into ESBL-producing E. coli strains belonging to the high-risk clone ST410 from pediatric patients. Methods: 29 E. coli ST410 isolates were collected from young children and subjected to antimicrobial susceptibility testing, Whole-genome sequencing (WGS), serotype analysis, MLST, ESBL genes, virulence genes, and plasmid profiling. Results: Antimicrobial susceptibility testing demonstrated a high level of resistance to cephalosporins followed by aminoglycoside, sulfonamide, carbapenem and penicillin group of antibiotics. However, n=20/29 shows MDR phenotype. Phylogenetic group B2 (n=15) dominated, followed by group D (n=7), group A (n=4), and group B1 (n=3). Serotyping analysis identified O1:H7 (n=8), O2:H1 (n=6), O8:H4 (n=5), O16:H5 (n=4), and O25:H4 (n=3). Other serotypes identified included O6:H1, O15:H5, and O18:H7 (n=1 each). The most commonly detected ESBL genes were bla CTX-M, (n=26), followed by bla TEM (n=23), and bla SHV (n=18). Additionally, bla OXA-1 (n=10), bla OXA-48 (n=5), bla KPC-2 (n=3), bla KPC-3 (n=2), bla NDM-1 (n=4), bla NDM-5 (n=1), bla GES-1 (n=2), bla GES-5 (n=1), and bla CYM-1 (n=3). Notable virulence genes identified within the ST410 isolates included fimH (n=29), papC (n=24), hlyA (n=22), and cnf1 (n=18), among others. Diverse plasmids were observed including IncFIS, IncX4, IncFIA, IncCol, IncI2 and IncFIC with transmission frequency ranges from 1.3X10-2 to 2.7X10-3. Conclusion: The ST410 clone exhibited a complex resistance profile, diverse serotypes, the presence of specific resistance genes (ESBL genes), virulence gene repertoire, and diverse plasmids. The bla CTX-M was the most prevalent ESBL gene detected.

Computational exploration of molecular flexibility and interaction of meropenem analogs with the active site of oxacillinase-23 in Acinetobacter baumannii.

Background: Carbapenem-resistant Acinetobacter baumannii is an opportunistic pathogen responsible for nosocomial infections and is one of the biggest global threats according to the World Health Organization (WHO), particularly causing substantial morbidity and mortality. Objectives: This study aimed at using computational approaches to screen meropenem and its analogs against OXA-23-positive Acinetobacter baumannii, analyzing the correlations between kinetic and phenotypic characteristics. Methods: A total of 5,450 compounds were screened using virtual screening workflow (HTVS, Glide-SP, and Glide-XP) to identify the best compounds based on their binding energy and interactions against OXA-23 and OXA-27 as they had phenotypic data available. Molecular dynamics simulation and density functional theory (DFT) studies were performed from the outcome of molecular docking analysis. Results: During simulations, meropenem and its analogs exhibited high-level stable interactions with Ser79, Ser126, Thr217, Trp219, and Arg259 of OXA-23. Meropenem displayed a CovDock energy of about -3.5 and -1.9 kcal mol-1 against OXA-23 and OXA-27, respectively. Among the 5,450 compounds, Pubchem_10645796, Pubchem_25224737, and ChEMBL_14 recorded CovDock energy between -6.0 and -9.0 kcal mol-1. Moreover, the infra-red (IR) spectrophotometric analysis revealed C=O and C-N atoms showing bands at 1,800 and 1,125 cm-1, respectively. These observed data are in congruence with the experimental observations. Conclusion: The identified compounds showed good agreement with the spectrophotometric analysis using DFT methods. In the earlier studies, meropenem's MIC value was 32 µg mL-1 in OXA-23-positive isolate A2265 compared to the MIC of 1 µg mL-1 in Δbla OXA-23 A2265. Comparing the CovDock energy and hydrogen-bonding interactions, the predicted results are in good agreement with the experimental data reported earlier. Our results highlight the importance of OXA-23 molecular docking studies and their compliance with the phenotypic results. It will help further in developing newer antibiotics for treating severe infections associated with carbapenem-resistant A. baumannii.

Molecular Epidemiology and Characterization of Multidrug-Resistant MRSA ST398 and ST239 in Himachal Pradesh, India.

Aim: Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of severe and difficult-to-treat infections in humans and animals. We aimed to identify the predominant lineages of methicillin-resistant S. aureus in Himachal Pradesh, India, to understand the genomic epidemiology along with the genotypic and phenotypic characteristics. Methods: We isolated 250 S. aureus from two district hospitals in Himachal Pradesh, India. Methicillin-Resistant S. aureus (MRSA) isolates were subjected to MLST, SCCmec typing, and resistance as well as virulence determinants were determined by PCR and sequencing. Bio-typing was also performed for source tracking. Results: A 17.6% (44/250) of isolates were classified as MRSA by both the MRSA detection kit and disc diffusion methods. Antimicrobial Susceptibility Testing of MRSA isolates (n = 44) showed high resistance to oxacillin (77.27%), erythromycin (77.27%), tetracycline (75%), cefoxitin (65.9%), and gentamicin (61.36%), while low resistance was observed for teicoplanin (36.36%), vancomycin and levofloxacin (31.81%) and fusidic acid (18.18%). All isolates were sensitive to linezolid, quinupristin-dulfopristin, dalbavancin, and cefazoline. The SCCmec-II was observed in 20.45% of isolates, SCCmec-I in 11.36%, SCCmec-III in 9%, SCCmec-IV in 40.9% and SCCmec-V in 18.18%. The mecA gene was present in all isolates (n = 44) and 50% also had the vanA gene. 35% of isolates had the lukS-PV/lukf-PV toxin gene and 11.36% had the co-existence of mecA, vanA, and lukS-PV/lukf-PV. The major strain was ST398 (39%) followed by ST239 (27%), ST217 (16%), ST121 (11%), and ST338 (7%). The MRSA isolates produced staphylokinase and ß-hemolysis but were negative for bovine plasma coagulation tests. In Conclusion: The predominant MRSA clones in Himachal Pradesh, India, were hospital-associated multi-drug resistant-MRSA ST239 with PVL and community-associated MRSA ST398.

Resistance genomics and molecular epidemiology of high-risk clones of ESBL-producing Pseudomonas aeruginosa in young children.

Introduction: The emergence of multidrug-resistant Pseudomonas aeruginosa poses a global threat, but the distribution and resistance profiling are unclear, especially in young children. Infections due to P. aeruginosa are common, associated with high mortality, and increasingly ß-lactam drug resistant. Methods: We studied the molecular epidemiology and antibiotic resistance mechanisms in 294 clinicalisolates of P. aeruginosa from a pediatric hospital in China. Non-duplicate isolates were recovered from clinical cases and were identified using an API-20 kit followed by antimicrobial susceptibility testing using the VITEK®2 compact system (BioMerieux, France) and also by broth dilution method. In addition, a double-disc synergy test for the ESBL/E-test for MBL was performed. The presence of beta-lactamases, plasmid types, and sequence types was determined by PCR and sequencing. Results: Fifty-six percent (n = 164) of the isolates were resistant to piperacillin-tazobactam, followed by cefepime (40%; n = 117), ceftazidime (39%; n = 115), imipenem (36%; n = 106), meropenem (33%; n = 97), and ciprofloxacin (32%; n = 94). Forty-two percent (n = 126) of the isolates were positive for ESBL according to the double-disc synergy test. The blaCTX-M-15 cephalosporinase was observed in 32% (n = 40/126), while 26% (n = 33/126) werepositive for blaNDM-1 carbapenemase. Aminoglycoside resistance gene aac(3)IIIawas observed in 16% (n = 20/126), and glycylcyclines resistance gene tet(A) was observed in 12% (n = 15/126) of the isolates. A total of 23 sequence types were detected, including ST1963 (12%; n = 16), followed by ST381 (11%; n = 14), ST234 (10%; n = 13), ST145 (58%; n = 10), ST304 (57%; n = 9), ST663 (5%; n = 7), and a novel strain. In ESBL-producing P. aeruginosa, 12 different Incompatibility groups (Inc) were observed, the most common being IncFI, IncFIS, and IncA/C. The MOBP was the most common plasmid type, followed by MOBH, MOBF, and MOBQ. Discussion: Our data suggest that the spread of antibiotic resistance is likely due toclonal spread and dissemination of different clinical strains of P. aeruginosa harbouring different plasmids. This is a growing threat in hospitals particularly in young children which needs robust prevention strategies.

Trends in Antibiotic Resistance Patterns and Burden of Escherichia Coli Infections in Young Children: A Retrospective Cross-Sectional Study in Shenzhen, China from 2014-2018.

Purpose: The emergence of multi-drug resistant ESBL-producing E. coli poses a global health problem. In this study, we aimed to investigate the prevalence of E. coli infections and their antibiotic susceptibility profiles in paediatric clinical cases in Shenzhen, China from Jan 1, 2014, to Jan 30, 2019, while also determining temporal trends, identifying ESBL-producing strains, and recommending potential empirical antibiotic therapy options. Methods: We isolated a total of 4148 E. coli from different specimens from a single paediatric healthcare centre. Additionally, we obtained relevant demographic data from the hospital's electronic health records. Subsequently, we performed antimicrobial susceptibility testing for 8 classes of antibiotics and assessed ESBL production. Results: Out of the 4148 isolates, 2645 were from males. The highest burden of E. coli was observed in the age group of 0-1 years, which gradually declined over the five-year study period. Antimicrobial susceptibility results indicated that 82% of E. coli isolates were highly resistant to ampicillin, followed by 52.36% resistant to cefazolin and 47.46% resistant to trimethoprim/sulfamethoxazole. Notably, a high prevalence of ESBL production (49.54%) was observed among the E. coli isolates, with 60% of them displaying a multi-drug resistance phenotype. However, it is worth mentioning that a majority of the isolates remained susceptible to ertapenem and imipenem. Our findings also highlighted a decrease in E. coli infections in Shenzhen, primarily among hospitalized patients in the 0-1 year age group. However, this decline was accompanied by a considerably high rate of ESBL production and increasing resistance to multiple antibiotics. Conclusion: Our study underscores the urgent need for effective strategies to combat multi-drug resistant ESBL-producing E. coli Infections.

Molecular insights into novel environmental strains of Klebsiella quasipneumoniae harboring different antimicrobial-resistance genes.

Introduction: The emergence of bacterial pathogens in environmental hosts represents a major risk to public health. This study aimed at characterizing seven novel environmental strains of K. quasipneumoniae using a genomic approach which was misidentified by phenotypic methods in a previous batch of 27 species thought to be K. pneumoniae. Methods: Whole-genome sequencing was performed using the Illumina platform, and the generated raw reads were de novo assembled. Comparative genomic, resistome, virulome, mobilome, and phylogeny were then investigated using dierent bioinformatics tools. Results: Six strains were identified as K. quasipneumoniae subsp similipneumoniae and one as K. quasipneumoniae subsp. quasipneumoniae. All isolates were resistant to ampicillin, cephalexin, and amoxicillin-clavulanic acid and harbored the fosA, bla OKP types, oqxB, and oqxA genes. One isolate additionally harbored a gene cassettes consisting of bla SHV-1, bla OXA-1, aac(6')-Ib-cr, catB genes. The aminoglycoside-modifying enzyme gene aph(3")-Ia was bracketed by two insertion elements. Plasmid analyses showed that IncFIBK was the most prevalent plasmid, circulating in six isolates, while one isolate exhibited seven different plasmids. The isolates have virulence genes responsible for capsule formation, lipopolysaccharide, iron uptake aerobactin (iutA), salmochelins (iroE, iroN), enterobactin siderophore, adherence, and biofilm formation (mrkA, mrkB, mrkC, mrkD, mrkF, and mrkH). Conclusion: Our study highlights the ecology and transmission of K. quasipneumoniae (which have the ability to disseminate to other environmental sources including animals) outside the clinical setting and the contribution of water, vegetables, and table surfaces as potential reservoirs of farm-to-fork transmission of disease via local markets in Khartoum, Sudan.

Healthcare Facilities as Potential Reservoirs of Antimicrobial Resistant Klebsiella pneumoniae: An Emerging Concern to Public Health in Bangladesh.

The emergence of virulent extended spectrum ß-lactamase producing Klebsiella pneumoniae (ESBL-KP) including carbapenem-resistant Klebsiella pneumoniae (CRKP) in hospital-acquired infections has resulted in significant morbidity and mortality worldwide. We investigated the antibiotic resistance and virulence factors associated with ESBL-KP and CRKP in tertiary care hospitals in Bangladesh and explored their ability to form biofilm. A total of 67 ESBL-KP were isolated from 285 Klebsiella pneumoniae isolates from environmental and patient samples from January 2019 to April 2019. For ESBL-KP isolates, molecular typing was carried out using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR), antibiotic susceptibility testing, PCR for virulence and drug-resistant genes, and biofilm assays were also performed. All 67 isolates were multidrug-resistant (MDR) to different antibiotics at high levels and 42 isolates were also carbapenem-resistant. The most common ß-lactam resistance gene was blaCTX-M-1 (91%), followed by blaTEM (76.1%), blaSHV (68.7%), blaOXA-1 (29.9%), blaGES (14.9%), blaCTX-M-9 (11.9%), and blaCTX-M-2 (4.5%). The carbapenemase genes blaKPC (55.2%), blaIMP (28.4%), blaVIM (14.9%), blaNDM-1 (13.4%), and blaOXA-48 (10.4%) and virulence-associated genes such as fimH (71.6%), ugeF (58.2%), wabG (56.7%), ureA (47.8%) and kfuBC (28.4%) were also detected. About 96.2% of the environmental and 100% of the patient isolates were able to form biofilms. ERIC-PCR-based genotyping and hierarchical clustering of K. pneumoniae isolates revealed an association between environmental and patient samples, indicating clonal association with possible transmission of antimicrobial resistance genes. Our findings can help in improving patient care and infection control, and the development of public health policies related to hospital-acquired infections.

Prevalence of Bacterial Pathogens among Symptomatic-SARS-CoV-2 PCR-Negative Patients.

The epidemiological and clinical aspects of coronavirus disease-2019 (COVID-19) have been subjected to several investigations, but little is known about symptomatic patients with negative SARS-CoV-2 PCR results. The current study investigated patients who presented to the hospital with respiratory symptoms (but negative SARS-CoV-2 RT-PCR results) to determine the prevalence of bacterial pathogens among these patients. A total of 1246 different samples were collected and 453 species of bacterial pathogens were identified by culture. Antibiotic susceptibility testing was performed via the Kirby Bauer disc diffusion test. Patients showed symptoms, such as fever (100%), cough (83%), tiredness (77%), loss of taste and smell (23%), rigors (93%), sweating (62%), and nausea (81%), but all tested negative for COVID-19 by PCR tests. Further examinations revealed additional and severe symptoms, such as sore throats (27%), body aches and pain (83%), diarrhea (11%), skin rashes (5%), eye irritation (21%), vomiting (42%), difficulty breathing (32%), and chest pain (67%). The sum of n = 1246 included the following: males, 289 were between 5 and 14 years, 183 (15-24 years), 157 (25-34 years), 113 (35-49 years), and 43 were 50+ years. Females: 138 were between 5 and 14 years, 93 (15-24 years), 72 (25-34 years), 89 (35-49 years), and 68 were 50+ years. The Gram-positive organisms isolated were Staphylococcus aureus (n = 111, 80.43%, MRSA 16.6%), E. faecalis (n = 20, 14.49%, VRE: 9.4%), and Streptococcus agalactiae (n = 7, 5.07%), while, Gram-negative organisms, such as E. coli (n = 135, 42.85%, CRE: 3.49%), K. pneumoniae (n = 93, 29.52%, CRE: 1.58%), P. aeruginosa (n = 43, 13.65%), C. freundii (n = 21, 6.66%), Serratia spp. (n = 8, 2.53%), and Proteus spp. (n = 15, 4.76%) were identified.

Antimicrobial Resistance Mechanisms and Genetic Diversity of Multidrug-Resistant Acinetobacter baumannii Isolated from a Teaching Hospital in Malaysia.

Multidrug-resistant (MDR) Acinetobacter baumannii has increasingly emerged as an important nosocomial pathogen. The aim of this study was to determine the resistance profiles and genetic diversity in A. baumannii clinical isolates in a tertiary medical center in Malaysia. The minimum inhibitory concentrations of carbapenems (imipenem and meropenem), cephalosporins (ceftazidime and cefepime), and ciprofloxacin were determined by E-test. PCR and sequencing were carried out for the detection of antibiotic resistance genes and mutations. Clonal relatedness among A. baumannii isolates was determined by REP-PCR. Sequence-based typing of OXA-51 and multilocus sequence typing were performed. One hundred twenty-five of 162 (77.2%) A. baumannii isolates had MDR phenotype. From the 162 A. baumannii isolates, 20 strain types were identified and majority of A. baumannii isolates (66%, n = 107) were classified as strain type 1 and were positive for ISAba1-blaOXA-23 and ISAba1-blaADC and had mutations in both gyrA and parC genes at positions, 83 and 80, resulting in serine-to-leucine conversion. REP-PCR analysis showed 129 REP types that generated 31 clones with a 90% similarity cutoff value. OXA-66 variant of the blaOXA-51-like genes was predominantly detected among our A. baumannii clinical isolates belonging to ST195 (found in six clones: 1, 8, 9, 19, 27, and 30) and ST208 (found in clone 21). The study helps us in understanding the genetic diversity of A. baumannii isolates in our setting and confirms that international clone II is the most widely distributed clone in Universiti Kebangsaan Malaysia Medical Centre, Malaysia.

Multi-drug resistance profiles and the genetic features of Acinetobacter baumannii isolates from Bolivia.

INTRODUCTION: Acinetobacter baumannii is opportunistic in debilitated hospitalised patients. Because information from some South American countries was previously lacking, this study examined the emergence of multi-resistant A. baumannii in three hospitals in Cochabamba, Bolivia, from 2008 to 2009. METHODOLOGY: Multiplex PCR was used to identify the main resistance genes in 15 multi-resistant A. baumannii isolates. RT-PCR was used to measure gene expression. The genetic environment of these genes was also analysed by PCR amplification and sequencing. Minimum inhibitory concentrations were determined for key antibiotics and some were determined in the presence of an efflux pump inhibitor, 1-(1-napthylmethyl) piperazine. RESULTS: Fourteen strains were found to be multi-resistant. Each strain was found to have the blaOXA-58 gene with the ISAba3-like element upstream, responsible for over-expression of the latter and subsequent carbapenem resistance. Similarly, ISAba1, upstream of the blaADC gene caused over-expression of the latter and cephalosporin resistance; mutations in the gyrA(Ser83 to Leu) and parC (Ser-80 to Phe) genes were commensurate with fluoroquinolone resistance. In addition, the adeA, adeB efflux genes were over-expressed. All 15 isolates were positive for at least two aminoglycoside resistance genes. CONCLUSIONS: This is one of the first reports analyzing the multi-drug resistance profile of A. baumannii strains isolated in Bolivia and shows that the over-expression of theblaOXA-58, blaADC and efflux genes together with aminoglycoside modifying enzymes and mutations in DNA topoisomerases are responsible for the multi-resistance of the bacteria and the subsequent difficulty in treating infections caused by them.