[Evaluation of presence of the bla-SHV and bla-AmpC [CITM, FOX] beta-lactamase genes in clinical isolates of Escherichia coli]

Resistance to beta-lactam antibiotics along with clinical isolates is frequently resulting production of beta-lactamase enzymes. In recent years, the production of extended spectrum beta-lactamases [ESBLs] and AmpC beta-lactamase among clinical isolate especially Escherichia coli is greatly increased. On the other hand, beta lactamase genes have several subfamilies, and designing universal primers could be valuable to detect all of them. Therefore, the aim of this study was to survey prevalence of phenotypic ESBLs and detection of SHV and AmpC [CITM, FOX]-type beta-lactamase genes by using universal primers through PCR. A total of 500 clinical samples were collected from hospitals of Tehran and 200 E.coli isolates were detected by standard biochemical tests. Subsequently, these isolates were screened for beta-lactamase production by Disk diffusion method and combined disk. Resistant isolates were evaluated for molecular assessing of SHV, CITM and FOX genes by using PCR. Among entire of 200 E.coli, 128 [64%] isolates were selected via phenotypic tests for detection of bla-SHV and bla-AmpC [CITM, FOX] genes via PCR. With 95% confidence, 7[5.5%] and 13[10.2%] E.coli harbor bla-SHV and bla-CITM, respectively. Fox gene was not detected in any samples. Results were showed that complete detection of beta-lactamase enzymes is essential for resistant control and the appropriate prescription of beta-lactam drugs. So using molecular assay with phenotypic test is important

Evaluation of a PCR based approach to study the relatedness among Shigella sonnei strains

Infections caused by Shigella re a major cause of diarrheal disease in the developing and developed countries. The present study was conducted to apply and evaluate arbitrarily primed PCR [AP-PCR] for investigation of genetic relatedness among the strains of Shigella sonnei isolated from cases of acute diarrhea in Tehran. Totally, 60 S. sonnei strains isolated from children hospitalized due to enteritis at five hospitals in Tehran during 2003 and two sporadic isolates recovered in 1984 were investigated. Molecular typing was performed by AP-PCR. Depending on the number and size of amplified DNA bands, the strains were clustered into AP-PCR profiles. All strains of S. sonnei were typeable with this approach. AP-PCR generated nine indistinguishable bands ranged from 0.35 to 2.5 kbp in all studied strains. Only a single AP-PCR pattern was observed among the S. sonnei strains recovered in 2003. Two sporadic isolates recovered in 1984 showed different AP-PCR patterns compared to recent clinical isolates. Results suggest that a very homogeneous AP-PCR cluster types might be responsible for shigellosis caused by S. sonnei in Tehran in 2003. Further molecular analysis conducted on a larger selection of isolates could confirm our findings