Comparison of four methods for isolation of Yersinia enterocolitica from raw and pasteurized milk from northern Iran

Four methods for isolation of Yersinia enterocolitica from raw and pasteurized milk from northern Iran were compared. Three hundred and ten raw milk samples were collected from tanks on their arrival at various central dairies, and 40 pasteurized milk samples were collected from tanks on their arrival at a manufacturing plant. Each sample was examined for the presence of Y. enterocolitica by (1) direct culture; (2) enrichment in double-strength buffered peptone water at 4°C for 1 month; (3) enrichment in modified Rappaport medium at room temperature for 72 h after a preenrichment in double-strength peptone water at 4°C for 1 month; and (4) enrichment in a medium containing sucrose, tris (hydroxymethyl) aminomethane, sodium azide, and ampicillin at 28°C for 48 h after a preenrichment in double-strength peptone water at 4°C for 1 month. All samples and enrichments were spread on MacConkey agar plus calcium chloride and Tween 80, Yersinia selective agar, and Hektoen medium plus ampicillin. Five samples (1.6%) of raw milk but no pasteurized milk samples were positive for Y. enterocolitica. No Y. enterocolitica were recovered by methods 1 or 2. Y. enterocolitica were recovered from 2 samples by method 3 followed by culture on Yersinia selective agar, and from 5 samples by method 4 followed by culture on Hektoen medium plus ampicillin. The isolates were biotype 1A or 1B, serotype O:7-13 or O:9 and phage type Xo or Xz. All isolates were resistant to ampicillin and amoxicillin, and sensitive to tetracycline, streptomycin, chloramphenicol, and trimethoprim-sulfamethoxazole. © 2004 Elsevier B.V. All rights reserved

Molecular typing of cytotoxin-producing Klebsiella oxytoca isolates by 16S-23S internal transcribed spacer PCR

Cytotoxin is one of the important pathogenic factors, which plays a role in the virulence of Klebsiella oxytoca. The aim of this study was to investigate molecular typing of clinical isolates of the cytotoxin-producing K. oxytoca using internal transcribed spacer (ITS)PCR. A total of 75 isolates of K. oxytoca were isolated from clinical samples; they were verified as K. oxytoca by standard microbiological tests and PCR. Production of toxin determines the cytotoxic effects on HEp-2 cells. The genetic diversity of isolates of the cytotoxin-producing K. oxytoca were defined by ITS-PCR. Of all the isolates investigated, five K. oxytoca strains isolated from stool cultures, two strains from blood samples, one strain from a wound and one strain isolated from urine had cytotoxic effects on HEp-2 cells. The ITS-PCR patterns showed genetic diversity among cytotoxin-producing isolates. The ITS-PCR method had good discriminatory power; performance of this method and interpretation of the results were easy and repeatable. Five genetic diversity patterns were identified by ITS-PC

Molecular typing of cytotoxin-producing Klebsiella oxytoca isolates by 16S-23S internal transcribed spacer PCR

Cytotoxin is one of the important pathogenic factors, which plays a role in the virulence of Klebsiella oxytoca. The aim of this study was to investigate molecular typing of clinical isolates of the cytotoxin-producing K. oxytoca using internal transcribed spacer (ITS)PCR. A total of 75 isolates of K. oxytoca were isolated from clinical samples; they were verified as K. oxytoca by standard microbiological tests and PCR. Production of toxin determines the cytotoxic effects on HEp-2 cells. The genetic diversity of isolates of the cytotoxin-producing K. oxytoca were defined by ITS-PCR. Of all the isolates investigated, five K. oxytoca strains isolated from stool cultures, two strains from blood samples, one strain from a wound and one strain isolated from urine had cytotoxic effects on HEp-2 cells. The ITS-PCR patterns showed genetic diversity among cytotoxin-producing isolates. The ITS-PCR method had good discriminatory power; performance of this method and interpretation of the results were easy and repeatable. Five genetic diversity patterns were identified by ITS-PCR

Characterization of endemic Shigella boydii strains isolated in Iran by serotyping, antimicrobial resistance, plasmid profile, ribotyping and pulsed-field gel electrophoresis

Background: Shigellosis is one of the major causes of morbidity in children with diarrhea in Iran. The present study was undertaken to characterize apparently sporadic Shigella boydii strains isolated from pediatric patients in Iran. Findings: Ten S. boydii strains isolated from pediatric cases of gastroenteritis and acute diarrhea in Tehran between December 2002 and November 2003 were submitted to serotyping, antimicrobial susceptibility testing, plasmid profile analysis, ribotyping and pulsed field gel electrophoresis (PFGE). Seven isolates were attributed to serotype 2, whereas the remaining three belonged to serotypes 14, 18, 19, respectively. Six drug resistance phenotypes (R1 to R6) were defined with R4 - streptomycin (STR), ampicillin (AMP), sulfamethoxazole-trimethoprim (SXT) - being the most prevalent. Plasmid analysis resulted in seven different plasmid profiles with one to five DNA bands. All strains, but one, shared the same ribotype, but PFGE differentiated them in four groups. Conclusion: Based upon ribotyping and PFGE results, endemic circulation of S. boydii in Tehran, Iran, could be attributed to a few clones. Resistance pattern and plasmid profile analysis proved to be very effective in discriminating apparently unrelated strains of S. boydi

Increased Isolation and Characterization of Shigella sonnei Obtained from Hospitalized Children in Tehran, Iran

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

STUDY OF CAMPYLOBACTER DIARRHEA IN ZAHEDAN REGION, IRAN

During a period of 5 months of 276 faecal specimens of inpatients, aged 0 to 5 years old, with diarrhea in Zahedan, were screened for evidence of enteric Campylobacteria For isolation, the stool was plated on a selective medium and incubated at 42oc in a microaerophilic atmosphere for 48-72 hours. On Gram stain, the organisms were small, curved, comma shaped and gram negative rods. The following tests, which have been done, were among the most important differential characteristics for Campylobacter species: catalase, oxidase, hippurate hydrolysis, growth in the presence of 1% glycin, 3.5% Nacl and 42oC, susceptible to nalidixic acid and cephalotin. The results were shown that out of 276 specimens, 15(5.4%) were positive for Campylobacter, 10 organisms were C. jejuni, whereas 5 were identified to be C. coli. All strains were isolated from children below 2 years of age. These were sensitive to nalidixic acid, erythromycin, streptomycin and nitrofuranotoin, while the isolates were resistant to cephalotin, penicillin G, co-trimoxazol and amoxicillin

Prevalence of Yersinia Enterocolitis in pediatric dysentery

Yersinia enterocolitis causes a wide spectrum of human diseases including gasteroentritis, which is the most frequent of its manifestation. Other diseases and clinical syndromes resulting from Yersinia enterocolitica are septicemia, mesenteric lymphadenitis, apendisitis, exudative pharyngitis, reactive artiritis, nodosum erythema and rarely Reiter's syndrome. In many countries such as western European, Scandinavian and north American countries, Australia and Japan the role of Yersinia enterocolitica particularly the 0:3, 0:8 and 0:9 serotypes in human diseases have been clearly identified. In spite of significant development in the field of separating Yersinia enterocolitica from feces as well as from the environmental specimens during the last decade, there has been only one documented report of isolating Yersinia enterocolitica in Iran in 1977. Thus we decided to test 300 samples of feces within 5 months. In this method, CIN agar as a selective and special medium and Mac conkey agar as classic medium were used. Also cold enrichment method in PBS (pH=7.8) was used. In order to determine importance of enterocolitica, we separated other pathogens of intestine such as salmonella, shigella and entropathogenic E.Coli. The achieved results from abundance points of view are as follows: 17 strains of EPEC (5.66%), 9 strains of shigella (3%), 8 strains of Yersinia enterocolitica (2.66%) and 6 strains of salmonella (2%

Bacillus cereus Assessment in Dried Vegetables Distributed in Tehran, Iran

Background: Bacillus cereus is one of the important agents of the food-borne diseases worldwide. In the present study, the dried vegetable samples distributed in Tehran, Iran were evaluated in order to isolation, identification, and enumeration of B. cereus. Methods: A total of 140 samples containing open and packed dried vegetables were randomly purchased from different areas of Tehran, Iran from March to August 2015. Dried vegetable samples were equally divided into seven groups, including dill, parsley, coriander, tarragon, mint, his, and pot roast. After culturing of samples, isolated B. cereus colonies were enumerated and identified using biochemical tests. The statistical tests were done by SPSS 16 (Chicago, IL, USA) software. Results: Totally, 44 out of 140 (31.4%) dried vegetable samples were contamintaed with B. cereus. The B. cereus contamination were found in 25 out of 70 (35.7%) and 19 out of 70 (27.1%) open and packed dried vegetable samples, respectively. There was no statistically significant difference (p>0.05) between contamination rate of B. cereus in open and packed dried vegetable samples. Also, contamination rate of B. cereus was not significantly different (p>0.05) among various kinds of vegetable samples.  Conclusion: Our study showed that dried vegetables sampled from Tehran, capital of Iran were contaminated with B. cereus. More researches are required in order to evaluate the prevalence of B. cereus contamination in raw and fresh vegetable samples consumed in the country. DOI: 10.29252/jfqhc.5.1.29 &nbsp