ABSTRACT
Catheter-Associated Urinary Tract Infection (CAUTI) is the second most commonly reported healthcare associated infection, accounting for upto 40% of all nosocomial infections. Silent catheter associated bacteriuria comprises a huge reservoir of resistant organism in hospitals particularly in critical care units. We prospectively studied 100 newly short term catheterized patients in a tertiary care hospital. Samples collected on day three and daily thereafter for semi quantitative urine culture and pus cell count. Antibiotic sensitivity was tested using Kirby-Bauer disc diffusion method. Out of hundred patients, 32 showed growth on fifth day and remaining 68 samples were culture negative up to seventh day. None of the culture positive samples had pus cells. Escherichia coli (35%) was the predominant isolate followed by Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterococcus faecium, Candida spp (15% each) and Coagulase negative Staphylococcus (5%). Among the Gram negative organisms, four strains of Escherichia coli and two strains of Klebsiella pneumonia were Extended Spectrum Beta Lactamases (ESBL) producers and 33.3% were Multidrug resistant Pseudomonas aeruginosa. Multidrug resistant pathogens in an asymptomatic short term catheterized patient are a major reservoir in hospitals. This emphasizes the importance of periodic surveillance for nosocomial infections in hospital and the periodic screening will also help us to frame antibiotic policy in a new tertiary care hospital.
ABSTRACT
BACKGROUND: This study was designed to characterize urinary isolates of Escherichia coli that produce extended-spectrum beta-lactamases (ESBLs) and to determine the prevalence of other antimicrobial resistance genes. METHODS: A total of 264 non-duplicate clinical isolates of E. coli were recovered from urine specimens in a tertiary-care hospital in Busan in 2005. Antimicrobial susceptibility was determined by disk diffusion and agar dilution methods, ESBL production was confirmed using the double-disk synergy (DDS) test, and antimicrobial resistance genes were detected by direct sequencing of PCR amplification products. E. coli isolates were classified into four phylogenetic biotypes according to the presence of chuA, yjaA, and TSPE4. RESULTS: DDS testing detected ESBLs in 27 (10.2%) of the 264 isolates. The most common type of ESBL was CTX-M-15 (N=14), followed by CTX-M-3 (N=8) and CTX-M-14 (N=6). All of the ESBL-producing isolates were resistant to ciprofloxacin. PCR experiments detected genes encoding DHA-1 and CMY-10 AmpC beta-lactamases in one and two isolates, respectively. Also isolated were 5 isolates harboring 16S rRNA methylases, 2 isolates harboring Qnr, and 19 isolates harboring AAC(6')-Ib-cr. Most ESBL-producing isolates clustered within phylogenetic groups B2 (N=14) and D (N=7). CONCLUSION: CTX-M enzymes were the dominant type of ESBLs in urinary isolates of E. coli, and ESBL-producing isolates frequently contained other antimicrobial resistance genes. More than half of the urinary E. coli isolates harboring CTX-M enzymes were within the phylogenetic group B2.