title: Co-existence ofblaOXA-23andblaNDM-1genes ofAcinetobacter baumanniiisolated from Nepal: antimicrobial resistance and clinical significance.
abstract: BACKGROUND
  Molecular analysis of carbapenem-resistant genes inAcinetobacter baumannii, an emerging pathogen, is less commonly reported from Nepal. In this study we determined the antibiotic susceptibility profile and genetic mechanism of carbapenem resistance in clinical isolates ofA. baumannii.
  
  
  METHODS
  A. baumanniiwere isolated from various clinical specimens and identified based on Gram staining, biochemical tests, and PCR amplification of organism specific 16S rRNA andblaOXA-51genes. The antibiotic susceptibility testing was performed using disc diffusion and E-test method. Multiplex PCR assays were used to detect the following β-lactamase genes: four class D carbapenem hydrolyzing oxacillinases (blaOXA-51,blaOXA-23,blaOXA-24andblaOXA-58). Uniplex PCRs were used to detect three class B metallo-β-lactamases genes (blaIMP,blaVIMandblaNDM-1), class C cephalosporin resistance genes (blaADC), aminoglycoside resistance gene (aphA6), and ISAba1of all isolates. Insertion sequence ISAba125among NDM-1 positive strains was detected. Clonal relatedness of all isolates were analyzed using repetitive sequence-based PCR (rep-PCR).
  
  
  RESULTS
  Of total 44 analyzed isolates, 97.7% (n= 43) were carbapenem-resistantA. baumannii(CR-AB) and 97.7% (n= 43) were multidrug resistantA. baumannii(MDR-AB). One isolate was detected to be extremely drug resistantA. baumannii(XDR-AB). All the isolates were fully susceptible to colistin (MICs < 2 μg/ml). TheblaOXA-23gene was detected in all isolates, whileblaNDM-1was detected in 6 isolates (13.6%). Insertion sequence, ISAba1was detected in all ofblaOXA-23positive isolates. ISAba125was detected in allblaNDM-1positive strains. TheblaADCandaphA6genes were detected in 90.1 and 40.1%, respectively. The rep-PCR of all isolates represented 7 different genotypes.
  
  
  CONCLUSIONS
  We found high prevalence of CR-AB and MDR-AB withblaOXA-23gene in a tertiary care hospital in Nepal. Systemic network surveillance should be established for monitoring and controlling the spread of these resistant strains.
authors.affiliation: Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu Nepal.
authors.forename: Prabhu Raj
authors.initials: PR
authors.lastname: Joshi
authors.affiliation: Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu Nepal.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Acharya
authors.affiliation: Annapurna Neurological Institute and Allied Sciences, Maitighar, Kathmandu Nepal.
authors.forename: Trishna
authors.initials: T
authors.lastname: Kakshapati
authors.affiliation: Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand.
authors.forename: Udomluk
authors.initials: U
authors.lastname: Leungtongkam
authors.affiliation: Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand.
authors.forename: Rapee
authors.initials: R
authors.lastname: Thummeepak
authors.affiliation: Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand.|Centre of Excellence in Medical Biotechnology, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand.
authors.forename: Sutthirat
authors.identifier: 0000-0003-4992-7635
authors.initials: S
authors.lastname: Sitthisak
keywords: Acinetobacter baumannii; Carbapenem resistance; blaOXA-23 and blaNDM-1 carbapenemase genes