Prevalence of extended spectrum beta-lactamase-producing enterobac-teriaceae by phenotypic and genotypic methods in intensive care units in Tehran, Iran

The occurrence of Extended Spectrum beta-Lactamase [ESBL]-producing Entrobacteriaceae has been steadily increased in recent years, resulting in limitation of therapeutic options. The purpose of this study was to determine prevalence of ESBL-producing Entrobacteriaceae isolated from Intensive Care Units [ICUs] and to investigate their phenotypic and genotypic characteristics. A total of one hundred fifty isolates were collected from urine and urinary catheter, sputum, blood, wound and other clinical samples from patient admitted in ICUs. All isolates were identified by biochemical tests and then were screened for ESBL production by Disk Agar Diffusion [DAD] according to the Clinical and Laboratory Standards Institute [CLSI] guideline. The species that met screening criteria were further tested for the effects of clavulanic acid by confirmatory method. ESBL-positive species were tested for bla[TEM] and bla[SHV] genes by PCR assay. Of total of 150 bacterial isolates, 133 [89.3%] isolates were positive in the resistance to all tested cephalosporin indicators; and 89 [59.3%] isolates were confirmed as ESBL producer. Klebsiella pneumoniae, Escherichia coli and Entrobacter spp. were the most ESBL-producing species. All isolates were sensitive to imipenem. The bla[TEM] [55.5%] was the most common gene detected in ESBL phenotypic-positive isolates using PCR method. The present study shows high prevalence of ESBL-producing Entrobacteriaceae from ICU patients. The increased rate of these species is mainly due to the inadequate and unnecessary antimicrobial therapy. Rational administration of beta-lactams and appropriate infection control policies may reduce prevalence of ESBL-producing bacteria in ICUs

Antimicrobial susceptibility testing of Escherichia coli strains isolated from urinary tract infections to fluoroquinolones and detection of gyrA mutations in resistant strains

Widespread uses of fluoroquinolones have resulted in increasing incidences of resistance against these agents all over the world. The aim of this study was to assess, susceptibility of Escherichia coli strains from patients with Urinary Tract Infection against common fluoroquinolones and detection of mutations in the gyrA gene. Antimicrobial susceptibility testing of 164 E.coli isolates from patients with UTI, was evaluated by disk agar diffusion [DAD] and MIC methods. Polymerase chain reaction of E.coli strains were performed by amplification of Quinolone Resistance Determining Region [QRDR] of gyrA gene. PCR products were tested by Conformational Sensitive Gel Electrophoresis [CSGE] and those with hetrodublexes were selected and examined by DNA sequencing. According to disc agar diffusion, 49.3% were resistant to nalidixic acid, 41.4% to norfloxacin, 44.5% to ofloxacin and 40.2% to ciprofloxacin. By Minimal Inhibitory Concentration [MIC] testing a high-level of resistance [42.1%] to ciprofloxacin was observed. Mutations in codons 83 and 87 in all 81 isolates were positive by CSGE method

Titration of specific antibodies to mycoplasma pneuomoniae, Chlamydia pneumoniae and Legionella pneumophila among Iranian pilgrims' sera during Hajj season in 2004

Respiratory tract infection is the most common diseases among Iranian pilgrims during Hajj season. To understand the possibility of bacterial involvement in such infections, we screened the pilgrims' sera to determine the titer of antibodies against Mycoplasma pneuomoniae [MP], Chlamydia pneumoniae [CP] and Legionella pneumophila [LP]. Serum samples from 128 pilgrims were collected, before the trip and one month after returning home. Antibodies to MP, CP, LP were assayed using Immunoflourecent and ELISA methods. IgM antibody titre to CP did not elevated, but IgG antibody titer was increased in 34.58% [n=48] and 15.82% [n=22] of cases, indicating of recent infection. The specific antibodies to MP and LP were not increased. In pilgrims infected with an atypical respiratory pathogen, C. pneumoniae should be considered as an important causative. The true prevalence of this pathogen should be investigated since it relies on the sensitivity and specificity of currently available diagnostic methods

Antimicrobial susceptibility testing for escherichia coli strains to fluoroquinolones, in urinary tract infections

Urinary Tract Infections [UTIs] are one of the most common infectious diseases diagnosed all over the world. Meanwhile most episode of UTIs are caused by Escherichia coli [up to 85%] and frequently fluoroquinolones are preferred as initial agents for empiric therapy of UTIs. Widespread use of fluoroquinolones has resulted in an increasing incidence of resistance these agents all over the world. The aim of this study was to assess, susceptibility of Escherichia coli strains from UTI patients against common fluoroquinolones. Antimicrobial susceptibility testing was determined by disk agar diffusion [DAD] and Minimal Inhibitory Concentration methods as described by the National Committee for Clinical Laboratory Standards [NCCLS]. One hundred sixty four clinical isolates of E. coli were collected by urine cultures from patients with UTI. The extent of resistant to nalidixic acid, ofloxacin, norfloxacin and ciprofloxacin, by disk diffusion method was 49.3%, 44.5%, 41.4% and 40.2%, respectively. Resistance to ciprofloxacin by MIC method was 4.9%. This study represents high level resistant of E. coli isolates from UTI patients. It is because of inappropriate and incorrect administration of antimicrobial agents in blind cases. This problem remarks significance of performing antimicrobial susceptibility testing before empiric antibiotic therapy. To overcome this problem use of unnecessary antibiotics therapy should be limited