PREVALENCE OF HIGH-LEVEL GENTAMICIN RESISTANCE AND DISTRIBUTION OF ITS GENES IN ENTEROCOCCUS SPECIES ISOLATED FROM PATIENTS OF URINARY TRACT INFECTION IN A TERTIARY CARE HOSPITAL IN BANGLADESHTASNIM AHSAN, MUHAMMAD MANWAR MORSHED HEMEL AND S.M. SHAMSUZZAMAN
Enzymatic modification causes high-level gentamicin resistance to Enterococci which eliminate the synergistic bactericidal effect of combined exposure to a cell wall-active agent and gentamicin. This study was conducted to determine the prevalence of high level gentamicin resistant Enterococci (HLGRE) and the distribution of high level gentamicin resistant genes in them. A total of 550 urine samples were taken from patients in a tertiary care hospital. Among them, a total of 46 Enterococci were isolated and subsequently analyzed. Enterococci were screened for HLGR by Kirby-Bauer disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. Minimum inhibitory concentration (MIC) of all isolates for gentamicin was determined by agar dilution method. Polymerase chain reaction (PCR) was carried out for HLGR Enterococcus isolates to identify aminoglycoside modifying enzymes genes responsible for resistance. Among the isolated Enterococci, 17 (36.97%) were resistant to high level gentamicin by disc diffusion method. Nineteen (41.3%) Enterococci were positive for HLGR by both MIC method (MIC> 500 ïg/mL) and by PCR. Only aac (6â)- Ie- aph (2â)-Ia gene was found to responsible for HLGR and other genes such as aph (2â)-Ib and aph (2â)-Ic gene were not detected in this study. High frequency of HLGRE (41.3%) may be regarded as a warning to the community. In identifying HLGRE, along with disc diffusion method, the MIC method should also be adopted routinely.