title: Study of the carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii: comparison of burn and non-burn strains.
abstract: We examined the prevalence of various carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii collected from hospitalized burn and non-burn patients. Antimicrobial susceptibility testing was performed for 43 burn and 32 non-burn isolates. Carbapenem resistance genes were identified and repetitive extragenic palindromic PCR (REP-PCR) was used to define clonal relatedness. CarO disruption was investigated by PCR and its expression analyzed by real time reverse transcription-PCR. Of the sixty-four (85%) carbapenem resistant A. baumannii isolates, 42 (66%) and 22 (34%) strains were recovered from burn and non-burn patients, respectively. Isolates were categorized into 6 major REP-PCR patterns; with the highest prevalence of non-burn and burn isolates in pattern A (63%) and B (35%), respectively. Prevalence of blaOXA-23 was 68% and isolates harbored this element belonged to all REP clusters. The blaOXA-40-like was detected in 49% of isolates, with higher prevalence among burn isolates. Three of the four isolates lacked carO gene were cultured from burn patients and level of the carO expression was decreased in carbapenem resistant isolates. These findings show that blaOXA-23 is widely distributed in carbapenem resistant A. baumannii isolates and other resistance mechanisms such as blaOXA-40-like and loss or decreased carO expression could be added in burn strains.
authors.affiliation: Tabriz Research Center of Infectious and Tropical Diseases, Tabriz University of Medical Sciences, Tabriz, Iran; Microbiology Department, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Omid
authors.initials: O
authors.lastname: Pajand
authors.forename: Mohammad Ahangarzadeh
authors.initials: MA
authors.lastname: Rezaee
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Nahaei
authors.forename: Reza
authors.initials: R
authors.lastname: Mahdian
authors.forename: Mohammad
authors.initials: M
authors.lastname: Aghazadeh
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Soroush
authors.forename: Mahboube Satarzadeh
authors.initials: MS
authors.lastname: Tabrizi
authors.forename: Zoya
authors.initials: Z
authors.lastname: Hojabri
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002056:Burns / Q000382:microbiology*; D015780:Carbapenems / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D004269:DNA, Bacterial; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; C063912:carbapenemase
keywords: Acinetobacter baumannii; Burn; CarO; OXA carbapenemase; RT-PCR