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ABSTRACT: BACKGROUND: Methicillin is the drug of choice to treat infections caused by resistant strains of Staphylococcus aureus. However, methicillin-resistant S. aureus (MRSA) is now becoming endemic in many hospitals worldwide and is the cause of nosocomial outbreaks. METHODS: To assess clonality and dissemination of MRSA strains in the hospitals of Tehran, a total of 60 MRSA strains were isolated from hospitalized patients (n=44) and hospital equipment and environment (n=16) of three metropolitan hospitals in Tehran between July 2009 and March 2010. These strains were subjected to antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and biochemical fingerprinting using the PhPlate system. RESULTS: Results showed the presence of between one and three dominant clonal groups within each hospital, with most equipment and environmental strains being identical to the dominant clones of hospitalized patient strains. The rate of resistance of these strains to the 13 antibiotics tested ranging from 2% to 100%, with resistance being highest for penicillin, ciprofloxacin, and tetracycline (>98% of the isolates). Comparison of the strains isolated from the three hospitals using a combination of PFGE and PhP types showed the presence of 11 clonal groups of MRSA among these hospitals; of these, three common clonal groups also had identical antibiotic resistance patterns and were found in more than one hospital. CONCLUSIONS: These data suggest dissemination of a few dominant clonal groups of MRSA strains in hospitals in Tehran, with high level resistance to other commonly used antibiotics.
International journal of infectious diseases: IJID: official publication of the International Society for Infectious Diseases 04/2013; · 2.17 Impact Factor
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ABSTRACT: The aim of this study was to investigate the genetic diversity and class 2 integron content of typical and atypical enteropathogenic Escherichia coli (EPEC) strains isolated from children less than 5 years of age. Biochemical tests and serogrouping were performed for identification of isolated strains, and each isolate was tested for susceptibility to 7 antimicrobial agents. The identity of EPEC and their class 2 integron content was confirmed by PCR analysis and sequencing. Subtyping of Escherichia coli spp. was performed through pulsed-field gel electrophoresis (PFGE) analysis. All EPEC strains were resistant to 6 antimicrobial agents except for gentamycin. The most prevalent serogroups among EPEC strains were found to be members of O86 and O127 serogroups (37.7 %) and O44, O125, and O128 (42.8 %). The majority of our EPEC isolates (60.7 %) were identified as atypical. Among the total 28 isolates, 4 (14.2 %) harbored a class 2 integron 1,500 or 2,300 bp in size, corresponding to dfrA1-sat1 and dfrA1-sat1-aadA1 resistance gene cassette arrays, respectively. PFGE analysis showed an extensive diversity among the isolates. No PFGE clustering was observed according to bundle-forming pilus (bfp) bacteria, suggesting that PFGE analysis could not discriminate between typical and atypical EPEC strains. The high ratio of antibiotic-resistant strains and the large heterogeneity among EPEC isolates with low prevalence of class 2 integrons signify the need to examine for other mechanism(s) involved in conferring resistance in typical and atypical populations of EPEC.
Journal of Infection and Chemotherapy 12/2012; · 1.80 Impact Factor
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ABSTRACT: A total of 114 isolates of methicillin-resistant Staphylococcus aureus (MRSA) were collected from hospitals in Tehran, Iran. A multiplex PCR was designed to examine the presence of six different prophage classes. The results showed high diversity of bacteriophages, with four different prophage types and eight prophage patterns. An important S. aureus phage coding for several virulence factors, Φ-77-like phage, was detected in 97 % of the isolates. We found a high rate of resistance of MRSA isolates to penicillin, ciprofloxacin, tobramycin and kanamycin. This is the first study showing high prevalence and diverse bacteriophage populations in MRSA strains in Iranian hospitals.
Archives of Virology 06/2012; 157(9):1807-11. · 2.11 Impact Factor
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ABSTRACT: The objective of this study was to investigate the molecular diversity of CTX genetic element within toxigenic Vibrio cholerae genomes and to determine the genetic diversity of V. cholerae population collected in a 6-year period (2004-2009) in Iran.
The results of mismatch amplification mutation assay (MAMA)-PCR and sequencing showed cytosine nucleotide in positions 203 and 115 in all 50 El Tor V. cholerae strains, which is the same as classical ctxB sequence. One strain yielded amplicons with both El Tor and classical biotype primers in MAMA-PCR indicative of presence of two copies of CTX phages with different genotypes (rstR(ET) ctxB(class) and rstR(ET) ctxB(ET)) integrated within the genome of this isolate, which suggested the integration of two different CTX phages at different occasions or point mutation in one copy of CTX. Sequencing and PCR analysis indicated the presence of hybrid CTX genotype (rstR(ET) ctx(class)) in 70.6% of the isolates; however, only El Tor RS1 phage has been integrated in flanking to the CTX phages with different genotypes.
Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and ribosomal gene spacer-PCR (RS-PCR) showed a relatively homogenous population in different years. Our findings indicate that sequence analysis of RS and ctxB regions has more discriminative power than restriction-based methods.
Investigating the molecular diversity of CTX prophage among V. cholerae strains helps to establish a new valuable database of genetic information about isolates, which is of great importance for epidemiologic studies in Iran and other countries encountering cholera epidemics.
Letters in Applied Microbiology 04/2012; 55(1):27-32. · 1.62 Impact Factor
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ABSTRACT: In this study 86 isolates of Vibrio cholerae were analysed for their adhesive properties and the presence of pathogenicity island genes. With the exception of three isolates, all of the other clinical isolates (92.5%) contained an intact TCP (toxin-co-regulated pilus) gene cluster. In contrast, 95% of all environmental non-O1-non-O139 isolates were negative for the TCP gene cluster. The majority of clinical isolates (82.5%) possessed the complete vibrio pathogenicity island (VPI) gene cluster and had a similar RFLP pattern, while only a single environmental strain possessed an almost complete VPI cluster (lacking 0.4 kb in the tcpA and toxT region). The result showed that the isolates with tcpA(+)/toxT(+) had a strong attachment for HT-29 and Vero cells, whereas isolates with tcpA(+)/toxT(-) or tcpA(-)/toxT(-) genomic characteristics showed no autoagglutination and weak attachment for the cell lines. Two environmental strains (tcpA(-)/toxT(-)) showed strong adhesive properties to the cell lines, indicating that non-fimbrial adhesive factors are involved in the environmental V. cholerae strains in the absence of TCP.
Journal of Medical Microbiology 08/2011; 60(Pt 12):1742-9. · 2.50 Impact Factor
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ABSTRACT: The occurrence of drug-resistant Vibrio cholerae is being reported with increasing frequency worldwide. Spread of resistant strains has been attributed, in part, to class I integrons and sulfamethoxazole trimethoprim-constin (SXT-C). Sixty clinical V. cholerae isolates were isolated from four different provinces in Iran, which were subjected to antibiotic susceptibility testing, polymerase chain reaction amplification of class I integron and SXT-C, and sequencing of the amplified fragments. Ribotyping technique was used to assess the clonality of the isolates. The highest and the least levels of antibiotic resistance were seen to SXT, streptomycin, and chloramphenicol (95%, 95%, and 92%, respectively) and doxycycline, gentamicin, and oxytetracycline (0%, 3%, and 3%, respectively). The results showed that out of the total of 60 isolates, only 1 contained class I integron, which harbored streptomycin resistance gene cassette (aadA2). This isolate showed ribotype pattern similar to the other strains (lacking class I integron) obtained in the same year (2006). On the contrary, the SXT-C was found in 95% of the isolates. These isolates showed three different but related ribotype patterns. Overall, the results of this study showed insignificant contribution of class I integron in antibiotic resistance of our V. cholerae isolates. On the other hand, V. cholerae resistance to SXT, streptomycin, and chloramphenicol could be, in part, due to wide distribution of SXT-C among the isolates. In addition, the ribotype data suggest that the clinical V. cholerae population from 2004 to 2006 were homogeneous.
Microbial drug resistance (Larchmont, N.Y.) 10/2009; 15(3):179-84. · 1.99 Impact Factor
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ABSTRACT: Genotypic and phenotypic characterizations of 50 clinical Vibrio cholerae isolates obtained during 4 consecutive y from 2004 to 2007 in Iran were studied. Antimicrobial susceptibility test, biochemical fingerprinting with Phene Plate system (PhP-RV) and pulsed-field gel electrophoresis (PFGE) were performed. Antibiotic susceptibility test of all isolates showed 12 different profiles. The predominant antimicrobial resistance profile (62%) was simultaneous resistance to SXT, streptomycin, chloramphenicol and erythromycin. PFGE revealed a total of 9 pulsotypes with a single dominant type in each y under study. PhP-RV revealed 6 common and 10 single types constituting 80% and 20% of the isolates, respectively. Diversity index of PhP-RV was 0.853, indicative of homogeneity among the isolates. Data obtained from PhP-RV was in close agreement with the results of PFGE genotyping. A comparison of the published PFGE patterns performed using the PulseNet protocol revealed the presence of similar patterns between some of our isolates and the isolates from Pakistan, Nepal and India, suggestive of dissemination of common V. cholerae clones in this region of the world. This could, in part, be due to human travel or occurrence of analogous DNA rearrangements, resulting in the emergence of similar V. cholerae genotypes in regional countries.
Scandinavian Journal of Infectious Diseases 02/2009; 41(4):256-62. · 1.72 Impact Factor
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ABSTRACT: Shigella flexneri has been the most frequent cause of shigellosis in children in Iran. To evaluate the changes in frequency of serogroups, 302 Shigella species were isolated in 2003 from hospitalized children, aged less than 12 years, with acute diarrhoea in Tehran, Iran. The number of collected S. sonnei, S. flexneri, S. boydii, and S. dysenteriae isolates was 178 (58.9%), 110 (37.4%), 10 (3.3%), and 4 (1.3%) respectively. Most (94%) S. sonnei isolates were resistant to co-trimoxazole. They were, however, relatively or completely sensitive to 15 commonly-used antibiotics. The extracted plasmids showed 12 different profiles with two closely-related patterns constituting 70% of the total isolates. Ribotyping, using PvuII, HindIII or SalI restriction enzymes, generated a single pattern for all S. sonnei isolates. Data suggest that S. sonnei has become the predominant serogroup in children in the hospitals of Tehran.
Journal of Health Population and Nutrition 01/2009; 26(4):426-30. · 0.95 Impact Factor
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ABSTRACT: Vancomycin (glycopeptide)-resistant enterococci (VRE or GRE) can cause serious problems for hospitalized patients due to the limited options for treatment of VRE infections. As infection with VRE increases in hospitals, further knowledge about vancomycin resistant genes is needed.
Isolates of Enterococcus spp. were collected from hospitalized patients in Tehran (Iran) during 2006. Detailed molecular analysis was performed for vancomycin resistance genotype and vanHAX using conventional PCR and PCR- RFLP (restriction fragment length polymorphism), respectively.
out of 830 enterococci spp., 48 VRE isolates (5.8 percent) were obtained. All of VRE isolates carried vanA gene. DdeI digestion of vanHAX element showed the presence of point mutation at 8234 position.
This study indicates that vanA is a predominant genotype in Iranian isolates. In addition, PCR-RFLP analysis revealed the presence of two types of vanHAX element in vanA harboring transposons.
Iranian biomedical journal 11/2008; 12(4):223-8.
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ABSTRACT: We investigated the prevalence of vancomycin-resistant enterococci (VRE) isolated from wastewater (n = 593) and clinical (n = 450) samples, and the genetic linkage between the isolates was compared. Out of the total samples, 38 Enterococcus faecium (3.6%) from sewage (n = 19) and clinical (n = 19) isolates were found to be highly resistant to vancomycin. The majority of the VRE isolates from the two sources showed distinct phenotyping and genotyping patterns. At the same time, one common pulsed-field gel electrophoresis pattern was found among the VRE obtained from wastewater and human clinical isolates, suggestive of an epidemiological link.
Current Microbiology 06/2008; 56(5):468-73. · 1.82 Impact Factor
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ABSTRACT: To examine the clonal diversity of vancomycin-resistant enterococci (VRE).
A total of 900 clinical isolates of enterococci were obtained, and VRE isolates were subjected to antimicrobial susceptibility tests, biochemical fingerprinting with the PhPlate system (PhP), ribotyping and pulsed-field gel electrophoresis (PFGE) typing.
Forty-nine of all enterococcal isolates were resistant to high levels of vancomycin (MIC >or= 128) and identified as Enterococcus faecium. Biochemical fingerprinting with PhP showed that the VRE isolates were highly diverse (diversity index, D(i) = 0.93) and belonged to 24 PhP-types. The VRE could be separated into 34 and 27 types with PFGE and ribotyping, giving diversity indices of 0.98 and 0.97, respectively. The PFGE method was more discriminatory than ribotyping and PhP system for E. faecium isolates. A combination of either of the two typing methods resulted in at least 44 types. Furthermore, sequencing analysis of vanS of Tn1546 showed one nucleotide mutation (C-->A) at position 5727 in comparison with the prototype BM4147, which was found to be unique in all Iranian VRE isolates.
The isolated clinical VRE strains were highly diverse in Tehran.
Tropical Medicine & International Health 06/2008; 13(5):722-7. · 2.80 Impact Factor
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ABSTRACT: In this study, antimicrobial susceptibility test and genetic typing were used to characterize 15 Salmonella enterica serotype Typhi (S. Typhi) isolates recovered from sporadic cases of typhoid fever in Tehran, Iran during 2004. Antimicrobial susceptibility test showed that all isolates were susceptible to 20 antimicrobials examined in this study. Analysis of insertion elements showed that 2 IS200 types with 10 and 11 copies were present. 11 of the 15 isolates were found to possess 10 IS200 elements residing on fragments from 23 to 2.3 kb. Comparison of the RiboPrinter (automated ribotyping) patterns of S. Typhi showed that 60% (9/15) of the isolates belonged to a single ribotype. PCR based random amplified polymorphic DNA analysis (RAPD) and enterobacterial repetitive intergenic consensus (ERIC) and pulsed-field gel electrophresis (PFGE) were also performed. ERIC and RAPD-PCR method showed 2 and 3 genotyping patterns amongst the isolates, respectively. The PFGE typing was carried out by using XbaI restriction enzyme, and 7 restriction patterns were observed. Overall, the molecular typing methods applied in this study showed that the isolated S. Typhi populations were highly polyclonal as shown by PFGE.
Scandinavian Journal of Infectious Diseases 02/2008; 40(1):18-23. · 1.72 Impact Factor
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ABSTRACT: Enterococci are important because of their role as the leading cause of nosocomial infections which have a significant role in the dissemination and persistence of antimicrobial resistance genes.
In this study, we determined the distribution of enterococcal species in the sewage treatment plants in Iran. Furthermore, we improved a rapid and specific PCR method using primers (sodA and ddl genes) for identification of enterococci spp.
A total number of 712 enterococci spp. were isolated and the results showed that 56%, 24%, 12%, 4%, 2%, 1% and 1% isolates were E. faecium, E. hirae, E. faecalis, E. gallinarum, E. casseliflavus, E. mundtii and other enterococcal spp., respectively. The use of species-specific PCR was in agreement with the biochemical tests. Furthermore, multiplex PCR was developed to study the presence of vancomycin resistant genes in E. faecium or E. faecalis. The multiplex PCR appeared to be a useful, rapid and specific method for detecting and discriminating genotypes for vancomycin-resistant Enterococcus.
Iranian biomedical journal 08/2007; 11(3):161-7.
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ABSTRACT: The aim of the study was to determine the rates of detection of enteropathogenic Escherichia coli (EPEC) and Shiga toxin-producing E. coli (STEC) strains among children in two randomly-selected populations in Iran. In total, 1,292 randomly-selected faecal samples from children aged less than 10 years were screened for EPEC and STEC. Of the 1,292 cases participated in the study, 184 had diarrhoea, and 1,108 were healthy/asymptomatic children. The conventional culture method and slide agglutination with 12 different commercial EPEC antisera were used for the detection of EPEC. The colony sweep polymyxin-B extraction method, non-sorbitol fermentation (NSF) phenotype, and slide agglutination with O157: H7 antisera were used for the screening and detection of STEC. Of EPEC belonging to 11 different serogroups, 0111 and 0127 were most commonly found in 36.4% of the diarrhoeal cases and 7.2% of the asymptomatic children. A significant association (p<0.05) was found between isolation of EPEC and diarrhoea. 8.7% of the diarrhoeal cases and 2% of children without diarrhoea were infected with STEC, but none of the isolates belonged to the 0157:H7 serotype. A significant association (p<0.05) was found between STEC and diarrhoeal cases. Based on these findings, it can be concluded that different EPEC serogroups may be agents of endemic infantile diarrhoea, and STEC strains are an important enteropathogen among young children.
Journal of Health Population and Nutrition 04/2007; 25(1):88-93. · 0.95 Impact Factor
