Co-occurrence of carbapenem and aminoglycoside resistance genes among multidrug-resistant clinical isolates of Acinetobacter baumannii from Cracow, Poland.
BACKGROUND
Acinetobacter baumannii is a significant hospital pathogen, possessing a considerable degree of antimicrobial resistance. A. baumannii resistance to carbapenems and aminoglycosides is mostly conferred by class D OXA carbapenemases and aminoglycoside-modifying enzymes, respectively. The aim of this study was to determine the prevalence of selected genes encoding OXA carbapenemases and aminoglycoside-modifying enzymes in multidrug-resistant strains of A. baumannii.


METHODS
The study included 61 carbapenem-resistant and aminoglycoside-nonsusceptible A. baumannii isolates, collected between 2009 and 2011 in Cracow, Poland. Selected resistance genes, including: blaOXA-51-like, blaOXA-23-like, blaOXA-40-like, blaOXA-58-like, aac(6')-Ih, aac(3)-Ia, aac(3)-IIa, aac(6')-Ib, aph(3')-Ia and aph(3')-VI, were detected by PCR method.


RESULTS
The blaOXA-51-like genes were detected in all isolates, while acquired carbapenemase encoding genes were found in 96.7% of tested strains. Presence of blaOXA-40-like and blaOXA-23-like genes was observed among 65.6% and 27.9% of isolates, respectively. Assayed aminoglycoside resistance genes were found to harbor 98.4% of isolates. Among tested strains, we observed the following percentages of resistance determinants: aac(3)-Ia - 78.7%, aph(3')-VI - 78.7% and aph(3')-Ia - 27.9%. Analysis of co-occurrence of carbapenem and aminoglycoside resistance genes revealed the highest percentage of strains possessing blaOXA-40-like, aac(3)-Ia, and aph(3')-VI genes (44.3%).


CONCLUSIONS
The blaOXA-40-like and aac(3)-Ia/aph(3')-VI were the most prevalent genes encoding acquired OXA carbapenemases and aminoglycoside-modifying enzymes, respectively, among A. baumannii strains in Cracow, Poland. Genes conferring resistance to carbapenems and aminoglycosides coexisted in the clinical strains of A. baumannii. The phenomenon of A. baumannii resistance indicates the necessity of monitoring for the presence of the resistance genes.
Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland.
Paweł
P
Nowak
Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland.
Paulina Maria
PM
Paluchowska
Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland.
Alicja
A
Budak
D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics*; D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D015780:Carbapenems / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D011044:Poland; D001618:beta-Lactamases / Q000235:genetics
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D001618:beta-Lactamases; C063912:carbapenemase