title: Emergence of Aminoglycoside Resistance Due to armA methylase in Multi-drug Resistant Acinetobacter Baumannii Isolates in a University Hospital in Nepal.
abstract: BACKGROUND
  The emergence of multidrug-resistant Acinetobacter baumannii associated with hospital-acquired infections has been increasingly reported worldwide. 16S rRNA methylase producing Gram-negative bacteria are highly resistant to all clinically important aminoglycosides. We analyzed A. baumannii clinical isolates resistant to aminoglycosides from hospitalized patients. The objective of this study was to investigate the emergence of armA in A.baumannii species associated with nosocomial infection in a university hospital in Nepal.
  
  
  METHODS
  This was a cross-sectional study conducted at the department of Clinical Microbiology, Tribhuvan University Teaching Hospital (TUTH), from December 2013 to December 2014. A total of 246 Acinetobacter species were isolated from different patients were screened for MDR A. baumannii. Identification at the species level was confirmed by 16S rRNA sequencing. Drug susceptibility testing was performed by Kirby- Bauer disc diffusion method and minimum inhibitory concentrations (MICs) were determined using the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Screening for 16S rRNA methylase-production was done for the isolates resistant to gentamicin and amikacin. Detection of 16S rRNA methylase gene was done by PCR.
  
  
  RESULTS
  All 122 multidrug-resistant A. baumanniiisolates were resistant to majority of the antibiotics used except polymyxin and tigecycline. Ninty-six MDR A. baumannii isolates had MICs of > 512 mg/L to amikacin and arbekacin indicating their high resistance to aminoglycosides.Of the 96 pan-aminoglycoside resistant isolates, 75 isolates had 16SrRNAmethylasewith all isolates harboring armA gene.
  
  
  CONCLUSIONS
  This is the first report describing multidrug-resistant A. baumannii strains harboring armA from hospitalized patients in Nepal. A methylase gene (armA), conferring high level of resistance to aminoglycosides, was detected in majority of our isolates.
authors.affiliation: Department of Microbiology, Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal.
authors.forename: S
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tada
authors.affiliation: Department of Microbiology, Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal.
authors.forename: B
authors.initials: B
authors.lastname: Shrestha
authors.affiliation: National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kirikae
authors.affiliation: National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohara
authors.affiliation: Department of Microbiology, Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal.
authors.forename: B P
authors.initials: BP
authors.lastname: Rijal
authors.affiliation: Department of Microbiology, Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal.
authors.forename: B M
authors.initials: BM
authors.lastname: Pokhrel
authors.affiliation: Department of Microbiology, Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal.
authors.forename: J B
authors.initials: JB
authors.lastname: Sherchand
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000453:epidemiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D000617:Aminoglycosides / Q000494:pharmacology / Q000627:therapeutic use*; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D003428:Cross Infection / Q000188:drug therapy* / Q000453:epidemiology; D003430:Cross-Sectional Studies; D052978:Disk Diffusion Antimicrobial Tests; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D006785:Hospitals, University; D006801:Humans; D008826:Microbial Sensitivity Tests; D009390:Nepal / Q000453:epidemiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S
keywords: Acinetobacterbaumannii; aminoglycosideresistance; 16S rRNAmethylase; multidrug-resistant.