DISSEMINATION OF AMINOGLYCOSIDE-MODIFYING ENZYMES (AME) ENCODING GENES AMONG ESCHERICHIA COLI CLINICAL ISOLATES COLLECTED FROM INTENSIVE CARE UNIT (ICU)

Background and Aim:E. coli is one of the most common (HCI) agents. The aim of this study was investigation of phenotypic and molecular charachterization of aminoglycoside resistance among clinical isolates of E. coli of ICU.Methods:A total of 254 E. coli isolates were collected from ICU of 16 hospitals in Qazvin, Karaj and Tehran. The antibiotic susceptibility test was conducted according to the Clinical and Laboratory Standards Institute (CLSI) guideline using seven aminoglycosides antibiotics (MAST, UK). The gentamicin (Sigma Co) MIC was determined with agar dilution using a range between 0.5-256 µg/ml. Aminoglycoside Modifying Enzyme genes (ant(2′′)-Ia, aac(3)-IIa,aac(6′)-lb, aac(3)-Ia, ant(4′)-IIb) was performed by PCR and sequencing.Results:Of total 254 E. coli isolates, 237 (93.3%) isolates were non- susceptible against at least one of the aminoglycosides tested among those gentamicin 136 (53.5%), and streptomycin 134(52.8%) showed the highest rates of resistance whereas amikacin and netilmicin revealed high susceptibility rates of 93.3% and 78.7%, respectively. MIC result showed that 53.2% of isolates were resistant to gentamicin. The lowest level of MIC for gentamicin was 0.5mg/mL, and the highest level was over 256 mg/mL The MIC50 was 64 µg/ml and MIC90 was 128 µg/m. Of 254 isolates 78.3% were positive for the presence of aac(3)-IIa as the dominant gene followed by aac(6′)-lb(50%), aac(3)-Ia(4.7%), ant(4′)-IIb(3.6%).Conclusion:The result of this study showed that here was a high rate of aminoglycoside resistance and AME genes among E. coli isolates from ICU.

کلیدواژه ها:

Escherichia coli ، aminoglycosides resistance ، aminoglycoside modifying enzymes