Pasteur Institute of Iran

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Introduction: Awareness of the species of Shigella has particular importance in the way of dealing with an outbreak, controlling it, and treating patients. The purpose of this study was to use the Multiplex PCR method and comparison with the culture method to detect Shigella species, as well as analysing the antibiotic resistance pattern in its different species. Methods: Simultaneously, the fecal samples of the patients with diarrhea and a sample from each patient in Cary-Blair medium were sent to the laboratory. Cultivation, serotyping, and antibiogram analysis were performed using the samples inoculated in the Cary-Blair medium. DNA extraction of the fecal samples and amplifying of invC, rfc, wbgZ, and rfpB genes were performed. Results: Totally, 300 samples from the patients were analyzed, out of which 240 Shigella isolated (80%) were detected using the culture method and serotyping, and 260 Shigella isolated (86.6%) using the PCR method (Shigella flexneri (77%), Shigella sonnei (19.2%), and Shigella dysenteriae (3.8%)). 20 samples suspicious of Shigella were observed in the culture method but were not identified by serotyping. However, in the PCR assay, they were identified as S. flexneri (n=16) and S. sonnei (n=4). The resistance of Shigella isolated to Co-trimoxazole was observed to be (78.3%), Ceftriaxone (42.5%), Cefixime (42%), Azithromycin (40.7%), Ofloxacin (34.5%), Nalidixic acid (25 %), and Ciprofloxacin (16%). Conclusion: Due to annual outbreaks of various Shigella species in the country, it is recommended that the Multiplex PCR method, be used along with culture method in laboratories to identify Shigella isolated. The antibiogram results showed increasing resistance of Shigella to the available antibiotics.

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Introduction: Diarrheagenic Escherichia coli (DEC) including enteropathogenic (EPEC), enteroaggregative (EAEC), enterotoxigenic (ETEC), and shiga toxin producing E. coli are among the most common agents of diarrhea. There are various classes of iron uptake receptors, but there is not much data on the presence of these iron receptors in DEC isolates. The present study aimed to evaluate the presence of iron receptor genes and also hemolysis activity in these isolates. Methods: Totally, 88 DEC isolates (EAEC, ETEC, STEC, and EPEC) from a previous microbial collection were included in this study. The isolates were tested for the production of hemolysin on blood agar plates. Then, Polymerase Chain Reaction (PCR) was used for detection of iron acquisition genes, including chuA, hma, iroN, fyuA, iutA and ireA. Results: Our results showed that 8 (66.7%), 25 (89.3%), 17 (44.4%) and 10 (83.4%) of EPEC, STEC, ETEC and EAEC isolates, respectively had hemolytic activity. All the EPEC isolates were negative for hma gene, and iroN and ireA genes were absent in the EAEC isolates. The frequency of chuA, hma and fyuA genes in the STEC and EAEC isolates was higher, whereas EPEC and ETEC isolates revealed a higher frequency of iroN gene than the STEC and EAEC isolates. Conclusion: This study reports the presence of various iron receptor genes with a significant hemolysin activity in DEC isolates from Iran. The presence of these genes may contribute to the increased pathogenesis of these isolates in the intestinal tract.

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Introduction: Calf diarrhea is one of the significant problems in dairy farms associated with treatment costs and reduced livestock production. Salmonellae are among the most common and the major causative agents of diarrhea in calves and humans. The present study was carried out to isolate and identify Salmonella in fecal samples of calves in industrial dairy farms of Hamedan and to determine antibiotic resistance profiles of the probable isolates. Methods: Salmonella were presumptively isolated based on the cultural characteristics and biochemical tests, and the identity of the isolates was further confirmed using genus- and serotype-specific PCR assays. Kirby-Bauer disk diffusion method was performed to determine antibiotic resistance profiles of the isolates. Results: Out of 120 stool samples collected from 8 industrial farms, 22 (18.33%) isolates possessing rfbJ, fliC and fljB genes were identified as Salmonella Typhimurium serotype. Antibiotic susceptibility test revealed all isolates (100%) were susceptible to gentamicin, amoxicillin-clavulanic acid, kanamycin, and ciprofloxacin and resistant against cotrimoxazole, cefazolin, and cefixime. Conclusion: To our knowledge, this study was the first report of Salmonella infection in Hamedan's dairy farms, indicating a relatively high prevalence rate of S. Typhimurium infection as the only detected serotype. Antibiotic resistance should also be considered a severe public health concern. Thus, effective hygiene measures should be adopted to prevent or reduce the infection, and monitoring antibiotic susceptibility is required to choose the drug of choice for treatment.

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Introduction: Diarrheal disease is a major cause of morbidity and mortality among children under the age of 10 worldwide, particularly in low- and middle-income countries. Diarrheagenic Escherichia coli (DEC) is a common cause of gastroenteritis in children. This study investigated the frequency, virulence markers, and antibiotic resistance patterns of DEC in children below 10 years with acute diarrhea in Zahedan, Iran. Methods: In this cross-sectional study, 300 E. coli isolates were collected from stool samples of children aged below 10 years with diarrhea who presented to hospitals and clinical laboratories in Zahedan. DEC pathotypes were identified using multiplex PCR and confirmed by standard biochemical tests and polyvalent antisera. Results: Of the 300 E. coli isolates examined, 89 (29.6%) were identified as diarrheagenic E. coli (DEC) using polyvalent antisera targeting known DEC pathotypes. Enteroaggregative E. coli (EAEC) was identified in 31 isolates (34.83%) based on reaction with antiserum No. 1. Enterotoxigenic E. coli (ETEC) was identified in 35 isolates (39.33%) based on reaction with antiserum No. 2. Enteropathogenic E. coli (EPEC) was identified in 23 isolates (25.84%) based on reaction with antiserum No. 3 (anti-coli3). Multiplex PCR identified the most common pathotype as EAEC (37.6%), followed by EPEC (21.7%), ETEC (15.9%), and EIEC (11.5%). Statistical analysis revealed no significant correlation between the presence of specific virulence genes (e.g., eae, pcvd432, elt, est, and iaH) and antibiotic resistance patterns in the DEC isolates. Conclusion: Given the distribution of DEC pathotypes among children in Zahedan and their increased antibiotic resistance, antibiotic treatment should be guided by molecular typing and antimicrobial susceptibility testing of isolates, when appropriate.