---

Background and Objective: Klebsiella species are gram-negative bacteria with positive voges proskauer (VP) reaction. Klebsiella species are found as commensal in human digestive and respiratory system. This group of organisms can create a serious health hazards in hospitalized patients, and their ability to drug resistance is a major health problems. This study was done to evaluate the efficacy of Ciprofloxacin, Ceftizoxims and Carbenicillin on Klebsiella species isolated from hospital specimens. Materials and Methods: In this laboratory study, 1200 clinical samples were isolated from patients in Imam Khomeini hospital, Tehran, Iran. The identification Klebsiella species were carried out according to conventional biochemical tests. The minimum inhibitory concentration (MIC) of carbenicillin, ceftizoxime, and ciprofloxacin antibiotics were determined using Macrodilution broth test. Results: Out of 1200 isolated samples, 25% were identified as Klebsiella species. 73% of identified Klebsiella were obtained from urine samples. Klebsiella.peumoniae with rate of 94% was the most abundant among other species. The results of MIC and minimum bactericidal concentration by using standard microdilution method showed drug resistance range of 16-1024 μg/ml, 4-256 μg/ml and 0.25-16 μg/ml for carbenicillin, ceftizoxime, and ciprofloxacin, respectivley. In general, 94%, 6% and 1% of species were resistance to carbenicillin, ceftizoxime and ciprofloxacin, respectively. Conclusion: Ciprofloxacin and Ceftizoxime are suitable for the treatment of infections due to Klebsiella species.

---

Background and Objective: Gastroenteritis due to Salmonella is common in human and considered as a global dilemma of public health. This study was done to determine the Pattern of serotyping and antibiotic resistance of Salmonella in children with diarrhea in Iran. Methods: In this laboratory study, 306 stool samples were collected from children with diarrhea in public health centers in Robat-karim, Tehran province, Iran. The specimens were enriched in Selenite F medium and then cultured on Hekton agar. The identification of Salmonella was carried out by conventional method and antimicrobial susceptibility testing was performed according to CLSI procedures. Results: Out of 306 stool samples, 7.2 % were identified as Salmonella species, as follow: 7 Salmonella typhi, 6 Salmonella paratyphi B, 3 Salmonella paratyphi C, 2 Salmonella paratyphi A and 4 samples were not identifiable. There was a significant relation between presence of WBC in fecal and salmonellosis (P<0.05). In drug sensitivity trends, 92.3% of Salmonella species were sensitive to chloramphenicol, ceftizoxime, Nalidixic acid and Amikacin. Conclusion: This study showed that Salmonella was the cause of children diarrhea in 7.2% in this region.

---

Background and Objective: Yersinia is a gram-negative bacillus that cause diarrhea through consumption of contaminated food and water.  This study was performed to identify the atypical Yersinia virulence markers isolated from children with diarrhea.

Methods: This descriptive cross -sectional study was done on 384 fecal samples of 0- 14 years old children admitted at children medical center from August 2011 to August of 2012. Fecal samples, for the enrichment, after 21 days of incubation in alkaline buffer with pH=7.2 at 4degree C, on days 7, 14 and 21 samples were cultured on CIN agar and Mac agar and then confirm the differentiation atypical Yersinia from other typical Yersinia species from fermentation of different sugars. Isolates were tested for marker of virulence including calcium dependence, auto agglutination, Congo red uptake and binding of crystal violet.

Results: Out of 384 stool samples, 4 (1.04%) were infected with Yersinia (Yersinia frederikseni, Yersinia kristensenii and Yersinia enterocolitica). Out of these three, only two samples in association was positive with virulence markers.

Conclusion: Phenotypic markers can be used to study the properties of phenotypic strains of Yersinia.

---

Background and Objective: The most common enterohemorrhagic Escherichia coli strain is the O157: H7 serotype, which is one of the most important intestinal pathogens and can cause complications such as hemorrhagic colitis, hemolytic uremic syndrome and acute renal failure. The aim of this study was to evaluate the enterohemorrhagic Escherichia coli causing molecular outbreaks of foodborne illness in Iran.
Methods: In this descriptive cross-sectional study, 189 fecal swab specimens were examined during April to September 2018. All suspected isolates were tested for biochemical tests. The isolates were confirmed by molecular PCR and evaluated by antimicrobial susceptibility tests.
Results: From 189 stool swab samples studied, 98 Escherichia coli isolates were detected based on phenotypic tests. Most of the outbreaks occurred in summer and the prevalence of enterohemorrhagic Escherichia coli was 24.5%, which 4% of them were non-O157H7. Most patients were between 1 and 12 years of age and the highest antibiotic resistance to cotrimoxazole and chloramphenicol was observed at 80% and 79%, respectively.
Conclusion: This study showed an increase in enterohemorrhagic Escherichia coli with 24.5% and an increase in antibiotic resistance to the antibiotics of chloramphenicol, cotrimoxazole and carbapenems. Increased resistance to imipenem and meropenem antibiotics makes it difficult to treat beta-lactamase-resistant strains.

---

Background and Objective: Campylobacter is one of the most important pathogens causing bacterial gastroenteritis, which is usually transmitted through the food of animal origin. This study was done to evaluate the status of Campylobacter in diarrheal food outbreaks compared to other microbial agents.
Methods: This descriptive study was performed on 305 diarrheal swab samples from 102 food outbreaks during six months from spring to the end of summer 2018. Presence of Campylobacter species were assessed according to the protocol of the General Directorate of Laboratory Affairs.
Results: Out of 305 samples, 8 (2.6%) were identified as Campylobacter species, 3 (37.5%) Campylobacter and 5 (62.5%) Campylobacter coli. The epidemiology of the outbreaks showed that female (54.5%), average age of 16-30 years (28.2%), consumption of salads and vegetables (16.1%) and living in the cities (59.7%) were the most cases.
Conclusion: This study showed that in addition to classic pathogens such as Salmonella, Shigella, Escherichia coli, attention also should be paid to Campylobacter bacteria. In addition, recognizing epidemiological factors can play an important role in preventing and controlling food outbreaks.

---

Background and Objective: Yersinia is water and foodborne organism that cause human gastroenteritis. This study was done to evaluate the frequency of Yersinia species isolated from children diarrheal samples and chicken meat in Tehran, Iran.
Methods: In this descriptive study 250 sample of diarrhea of children referred to the Children's Medical Center, Tehran, Iran and 250 samples of chicken were collected and examined for Yersinia infection during July 2016 to March 2017. Isolation method was performed based on initial enrichment in phosphate buffer for 3 weeks in refrigerator (cooling in c4 +) and then using KOH as secondary enrichment and culture on CIN agar medium. Biotyping method was used to determine pathogenic strains.
Results: In this study, 5(2%) isolates from pediatric diarrhea samples and 20 isolates (8%) from chicken meat samples were obtained from Yersiniaenterocolitica. Biotyping of human Yersiniaenterocolitica isolates identified 3 cases of biotype 1A, one case of biotype 1B, one case of biotype 2 and from chicken meat isolates, 16 isolates belonged to biotype 1A and 4 isolates belonged to biotype 1B.
Conclusion: Presence of common pathogenic 1B and non-pathogenic 1A biotypes in pediatric diarrhea samples and chicken meat can indicate the cause of diarrhea in children.