[ prevalence of nosocomial infections caused by Enterobacter cloacae and antibiotic resistant patterns in samples isolated from patients in two hospitals in Tehran]

The increasing use of beta-lactam antibiotics in clinics for the treatment of different bacterial infections since early 1980s has led to increased rates of resistant bacteria isolated from patients. One of the problems in the treatment of nosocomial infections is related to resistant bacteria such as Enterobacter cloacae due to cross resistance through extended-spectrum beta-lactamase production. The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase producing E. cloacae from different clinical specimens collected from hospitalized patients. In the present study, 101 E. cloacae confirmed by standard specific microbiologic tests were collected from different specimens in Milad and Motahri hospitals in Tehran, Iran during February 2010 and September 2011. Antibiotic susceptibility tests were conducted according to the process recommended by the Clinical and Laboratory Standards Institute for 13 antibiotics of choice. Extended-spectrum beta-lactamase producing strains were screened for by combined disk method as a phenotypic diagnostic test. From a total of 101 E. cloacae, 33 [33%] were shown to produce extended-spectrum beta-lactamase by phenotypic tests; 5% of the bacteria were resistant to imipenem too. This study clearly showed the high prevalence of resistance to broad-spectrum beta-lactam antibiotics in the isolated E. cloacae among which 5% were multi drug resistant. All the isolated E. cloacae were susceptible to Colistin. These results can be alarming for physicians treating resistant E. cloacae infections, especially extended-spectrum beta-lactamase producing species

Bacteriological profile and antimicrobial resistance of blood culture isolates

Bloodstream infection [BSI] is an important cause of mortality and morbidity and among the most common health-care associated infections. In this study we described the frequency of occurrence and antimicrobial susceptibility patterns of nosocomial and community-acquired BSI isolates from a teaching hospital in Tehran, Iran. his cross-sectional study was conducted in 850-bed Rasul Akram university hospital from April 2006 to April 2007. All patients with a positive blood culture were enrolled. Antimicrobial susceptibility testing was performed with disk diffusion and E-test MIC. During the study period, 456 isolates were obtained from blood cultures, from a total of 8818 collected sets, among which 291 were felt to represent true bacteremia and 98 were nosocomial. Acinetobacter spp. were the most frequently isolated agents in the hospital and community acquired BSIs [32%], followed by Escherichia coli [13.7%] and Klebsiella spp. [12%]. The most effective antibiotics for gram-negative and gram-positive bacteria were ciprofloxacin [13% resistance rate] and vancomycin and oxacillin [with 13% resistance rate], respectively. Analysis of antibiotic resistance pattern showed that 20.43% of Acinetobacter spp. and 15.4% of Pseudomonas aeruginosa were multi drug resistant [MDR], while 48.7% of Kiebsiella spp were ESBL-producing isolates and 15% of Staphylococcus aureus were oxacillin-resistant. We did not observe any vancomycin-resistant strains among isolates of S. aureus. Rifampin and ciprofloxacin showed good activity against most of gram-positive and gram-negative organisms, respectively. Carbapenems [imipenem and meropenem] were highly active against strains of Enterobacteriaceae [E. coli, Klebsiella] that showed resistance to third generation of cephalosporines