Prevalence and Antibiotic Resistance of Enterococcus Species Isolated from Blood Cultures over a Five-Year Period, in a Tertiary Hospital, Iran

Background and Objectives: The enterococci have emerged as a major cause of bloodstream infections (BSI), particularly in the nosocomial settings, partly due to increasing resistance to antimicrobial therapy. This study aimed to report the five-year trend of prevalence and antimicrobial susceptibility patterns of Enterococcus spp. to a range of antibiotics such as gentamycin-high, ampicillin, ciprofloxacin and vancomycin, widely administered to humans. Materials and Methods: We conducted a cross-sectional study of blood cultures transferred to the Professor Alborzi Clinical Microbiology Research Center. All Enterococci bacteria isolated from 1393 to 1397 were included. The isolates were identified by conventional biochemical assays and assessed for susceptibility to ampicillin, ciprofloxacin, vancomycin, and gentamicin-high using an agar dilution procedure, according to the recommendations by the National Committee for Clinical Laboratory Standards (NCCLS). The data entry and analysis were performed using the WHONET 5.6 software. Results: Enterococcus spp. were the fourth frequently isolated bacteria from blood cultures in recent years. The percentages of Enterococcus Spp. isolates per total number of pathogenic isolates were as follows: (34/355) 9.6%in 1393, (106/611)17.3% in 1394, (109/1127) 9.7% in 1395, (109/1370) 8%in 1396 and (79/1404) 5.6% in 1397. The rates of resistance were as follows: ciprofloxacin 87.6%, ampicillin 72%, vancomycin 67.3% and gentamicin- high 66.1%. Conclusion: Enterococci isolated from the blood cultures indicated an alarming rate of increased resistance to the standard antimicrobial agents used for therapy.