ABSTRACT
The aim of the this study was to investigate the prevalence of toxB, paa, Ipf and iha adhesion genes in enteropathogenic Escherichia coli [EPEC] isolates lacking in two important adhesion factors, the eaeA and bfpA genes. We examined a total of 70 serologically confirmed EPEC [eaeA, bfpA] isolates. DNA from the isolates was extracted by the phenol-chloroform method. toxB, paa, Ipf and iha adhesion genes in the EPEC isolates were detected by polymerase chain reaction. Data were analyzed by SPSS software and statistical analysis using the chi square test. P-values less than 0.05 were considered significant. PCR was positive for the toxB gene in 2 [2.85%], paa in 3 [4.28%], Ipf in 32 [45.71%] and iha in 15 [21.42%] of the 70 strains. Statistically, none of the toxB.paa, and Ipf genes were associated with diarrhea. However, the iha gene showed a weak significant relation to diarrhea [P=0.11]. The main mechanism of pathogenicity for EPEC is attachment and effacement. Therefore, EPEC [eaeA, bfpA] should have another adhesin factor, which should be investigated. EPEC strains [eaeA-, bfpA-] that possess the Ipf gene are common. Further investigations of the virulence properties of these strains are necessary in order to elucidate the role of these virulence factors in diarrhea among Iranian children
Subject(s)
Humans , Bacterial Adhesion , Escherichia coli Proteins , Fimbriae Proteins , Virulence Factors , Diarrhea , SerologyABSTRACT
We intended to find out the diversity of EPEC isolates among asymptomatic or diarrheal children in Iran using ribotyping. Enteropathogenic Escherichia coli [EPEC] is responsible for gastroenteritis especially in young children. A total of 39 EPEC collected strains were serotyped and the presence of virulence genes as well as EAF plasmid among the strains was studied. Adherence assay was also performed. Clonal diversity of the isolates was investigated using ribotyping. Of 39 studied strains of E. coli, 6 serogroups of EPEC were represented. The presence of the stx gene was ascertained in 7 isolates and the eaeA, eaeB and bfpA genes were harbored by 5, 3 and 1 strains, respectively. Ribotyping yielded 9 different clusters. According to our results there was not a significant correlation between the results of serotyping and those of ribotyping. However, different serotypes of E. coli may belong to the same ribotype clusters and vice versa
ABSTRACT
Shigellosis is one of the most common causes of morbidity and mortality in children with diarrhea in developing countries. It is essential to assess the antibiotic resistance patterns of these bacteria. ipaH gene is one of the virulence factors which can be used for detection of Shigella spp. Total of 100 isolates of Shigella were collected from different provinces of Iran. This isolates were characterized by biochemical tests and serological tests using polyclonal antisera for 4 species of S. dysenteriae, S. sonnei, S. boydii and S. flexneri. Antibiotic susceptibility assay for 14 different antibiotics was carried out using agar disc diffusion method. Presence of ipaH gene was investigated by PCR using specific primers. From the results of this study the Shigella isolates were classified as follows: 36 [%73] Shigella sonnei, 9 [%18] Shigella flexneri, 3 [%5] Shigella boydii, 2 [%4] Shigella dysenteriae. Approximately%50 of the Shigella isolates were resistant to Tetracycline and Cotrimoxazole. Shigella sonnei showed more resistance than other serotypes against the studied antibiotics. PCR assays showed that all isolates harbored ipaH gene. The results showed that prevalence of Shigella sonnei is higher than other serotypes. The isolates showed high sensitivity to third generation cephalosporines and aminoglycosides. PCR detection of ipaH gene as a reliable marker for identification of Shigella species could be recommended
ABSTRACT
Different types of extended spectrum beta-lactamases [ESBLs] are encountered in the clinical settings worldwide. There are a few studies regarding the prevalence of ESBL genes among Klebsiella pneumoniae isolates at Tehran especially those of bla[PER] and bla[CTX]. The aim of this study was to determine the prevalence of bla[SHV], bla[TEM], bla[PER] andbla[CTX] genes among clinical K. pneumoniae of different hospitals in Tehran. Two hundred isolates of K. pneumoniae were received from different clinical specimens. The susceptibility of the isolates to 10 different antibiotics was examined by disk diffusion test. The MICs for ceftazidime were also determined using micro-broth dilution assay. Isolates showing MIC >/= 4 micro g/ml for ceftazidime were screened for ESBL production by phenotypic confirmatory test [PCT] and subjected to PCR for studied genes. Variation among four amplified genes was evaluated using PCR-RFLP. By disk diffusion test, resistance to ceftazidime and cefotaxime were 34.7% and 33.5% respectively. However, all strains were susceptible to imipenem. Eighty isolates showed MICs >/= 4 micro g/ml for ceftazidime of which 77 [96%] were positive for ESBL in PCT. The prevalence of bla[SHV], bla[CTX-M], bla[TEM] and bla[PER] among these isolates were 26%, 24.5%, 18% and 7.5%, respectively. No variation was detected in the genes by PCR-RFLP. As far as we know this is the first report of the bla[PER-1] in K. pneumoniae in Iran. The bla[CTX-M] was the second most common gene detected among the ESBL positive isolates of K. pneumoniae. For rapid identification of ESBL producing isolates it was recommended that clinical laboratories adopt simple test based on CLSI recommendation for confirming ESBL production in enterobacterial species