فهرست مطالب بهرام نیک منش

Salmonella is considered as a main cause of community-acquired diarrhea in humans, however, sources of the multi-drug resistant (MDR) strains and their link with the disease are not well known.

This study aimed to investigate the frequency, serogroup diversity, and antimicrobial susceptibility patterns of Salmonella strains in poultry meat and stool samples of patients with community acquired diarrhea in Tehran.

We compared the frequency of non-typhoidal Salmonella serogroups, the similarities of their resistance patterns to 10 antimicrobial compounds, the prevalence of extended spectrum β-lactamase (ESBL) and ampicillinase C (AmpC) genetic determinants, and class 1 and 2 integrons in 100 chicken meat and 400 stool samples of symptomatic patients in Tehran during June 2018 to March 2019.

Salmonella was isolated from 75% and 5.5% of the chicken meats and human stool samples, respectively. The chicken meat isolates mainly belonged to serogroup C (88%, 66/75), while the human stool isolates were mainly related to serogroup D (59.1%, 13/22). The MDR phenotype and the most common rates of resistance to antibiotics, including tetracycline, trimethoprim/sulfamethoxazole (TS) and azithromycin, were detected in 4.5% and 45.3%, 59% and 13.6%, 43% and 9.1%, 42% and 9.1% of the human stool and chicken meat samples, respectively. Carriage of blaCTX, blaSHV, and blaPER genes in the meat isolate with ESBL resistance phenotype and blaACC, blaFOX, and blaCMY-2 among the 7 meat strains with AmpC resistance phenotype was not confirmed using polymerase chain reaction (PCR). High prevalence of class 1 and 2 integrons was characterized and showed a correlation with resistance to TS and chloramphenicol.

These findings showed a lack of association between chicken meats and human isolates due to discrepancy between the characterized serogroups and resistance phenotypes.

Pathogenic species of Campylobacter, in addition to diarrhea and gastrointestinal diseases, could cause debilitating auto-immune and chronic diseases in humans. Investigation of the existence of this bacterium in food sources and clinical samples, and detection of antibiotic resistance could be helpful in the control of its spread and treatment procedures. The aim of this study was to evaluate the frequency and antibiotic resistance of Campylobacter isolates isolated from poultry meat.

In this study, a total of 100 poultry meat samples were collected from 22 districts of Tehran from July 2018 until March 2019. Accordingly, standard enrichment of the collected samples and their culture in selective medium was done. The isolates were characterized biochemically and by polymerase chain reaction for genus and species specific primers for C. jejuni, C. coli, C. upsaliensis, and C. lari. Antimicrobial susceptibility of the isolates to 7 antibiotics were done using E-test and disk diffusion methods. Moreover, resistance to three or greater classes of antibiotics was determined as multiple drug resistance phenotype (MDR) and the results were statistically analyzed using SPSS16 software.

Campylobacter was isolated from 35% of the poultry meat samples. C. jejuni (23%), C. coli (1%), and C. lari (1%) were among the Campylobacter isolates from these samples. Highest resistance phenotype and the lowest ones were detected against tetracycline (62.8%), and ampicillin and clindamycin (17.1%, each one), respectively. The MDR phenotype was detected among 42.8% of the isolates.

Our results showed high level of contamination with Campylobacter in the poultry meat samples which proposed increased risk of the infection with MDR strains among the consumers in Tehran. Further studies on human clinical samples could better determine this correlation.

Staphylococcus aureus is an opportunistic pathogenic bacterium that can provide invasive conditions by secreting various toxins. It is involved in the development of skin infections, such as swollen and ulcers. Today, one of the main problems is the treatment of Staphylococcus aureus resistant strains. The aim of the current study was to detect virulence factors and antibiotic resistance among strains isolated from wound infections of children who referred to Tehran Children’s Medical Hospital in 1396-97. A total of 59 strains of Staphylococcus aureus isolated from wound infection were collected during one year. Staphylococcus aureus was detected using biochemical tests. For antibiotic susceptibility test, antibiotic disks (Mast، UK) were used according to the CLSI 2017. For detection of virulance genes, including nuc، mecA، tsst-1، hla، hlb، hld، eta، etb، etc, PCR method was used. Vancomycin and linezolid were sensitives for all isolates and the highest resistance antibiotic was penicillin with 98.3%. The frequency distribution of genes s mecA، tsst-1، hla، hlb، hld، eta، etb، and etd were 59.3%, 37.7%, 71.2%, 57.6%, 96.6%, 100%, 11.9%, 27.1%, respectively. All isolates were sensitive to vancomycin and linezolid, and these antibiotics were the best choices for the first line of treatment for staphylococcus aureus strains. Since all isolates of Staphylococcus aureus were obtained from children wound infections and all of them contained oxfolitic A gene, control and disinfection measures seem to be important among children, because these strains have the potential to spread this gene among hospitalized patients.

In recent years, tuberculosis is a major cause of illness and mortality due to infectious diseases. In fact, one of the reasons for increasing the incidence of tuberculosis is that it is often associated with HIV infection. The present study aimed to design and establish a mobile-based self-care system for controlling tuberculosis. The data required in this research for evaluating the information and designing the application were collected in two main steps: first, the data required in this research for information needs assessment and application design were collected by searching in library resources. A questionnaire was applied by physicians to validate and determine the significance of these elements. Afterwards, based on information elements and the self-care, application was designed in the Android Studio environment. Information elements and functional capabilities required by the program were determined. Web-based services as a system interface, not only provided the communication between the patient and the care provider, also allowed for patient monitoring and disease control. Then evaluation of the performance and performance of the program was done by doctors and software experts. The findings showed user satisfaction with the application. Monitoring of treatment electronically allows for less costly monitoring of the patient. In this study, we present a prototype of the relationship between self-care application and portal and its potential benefits, which will allow future studies to improve and add new capabilities.

Staphylococcus is a bacterium responsible for a wide range of diseases, from mild skin infections to lethal necrosis pneumonia. The aim of this study was to determine the virulence factors among methicillin resistant and sensitive strains isolated from clinical specimens of children referred to the pediatric medical center and also to be aware of their antibiotic resistance.
In the present study, 100 strains of Staphylococcus aureus, susceptible and resistant to methicillin, were collected during one year. First Biochemical tests were performed to detect Staphylococcus aureus bacteria. Then antibiotic susceptibility test was performed using antibiotic disks (MAST;England) according to CLSI guidelines. The presence of hlg, mecA, nuc and pvl genes was investigated by PCR method and sequenced.
30 samples (30%) were methicillin-resistant (MRSA) using the cefoxitin disk. The most susceptible to antibiotics, vancomycin with 100% and the highest resistance to antibiotics, penicillin with 98% were determined. The prevalence of hlg, mecA, and pvl genes was 30%, 95% and 6%, respectively.
The present study showed that vancomycin and cotrimoxazole antibiotics were the best effect against MRSA strains.

In today’s world, antibiotic resistance is inevitable. This has been the case since the discovery of antibiotics. The aim of this research is to study serotyping and multiple antibiotic resistance pattern of Shigella sonnei isolated from diarrheal stool of patients hospitalized in Children’s Medical Center in Tehran.
In this descriptive study, 600 diarrheal stool specimens were obtained from patients hospitalized in Children’s Medical Center in Tehran over a period of twelve months. The stool samples were collected in Cary-Blair transport medium and transferred to the laboratory. The identification was carried out according to the standard cultivation method, and the antibiotic susceptibility test was performed by Kerry Bauer disk method according to with CLSI procedure.
Out of 600 samples, only 18 (3%) were found to be contaminated with Shigella sonnei. The results of antibiotic resistance patterns of these isolates showed that they were resistant to tetracycline; streptomycin, clindamycin and cortimoxazol. Furthermore, 66.67% of isolates had multiple resistance to tetracycline, cortimoxazol, streptomycin, ticarcillin and clindamycin antibiotics.
The results of this study showed that multiple resistance of Shigella sonnei to tested antibiotics is increasing. This is alarming; necessary steps should be taken to prevent such a phenomenon.

Campylobacter spp. is the major cause of bacterial gastroenteritis, called campylobacteriosis, in the worldwide. Post-infectious complications of this infection are reactive arthritis and Guillain–Barré syndrome. Despite the importance of this infection, the isolation of fastidiousbacteria cannot be performed in most clinical laboratories. The aim this study was to design an alternative transport medium with mCCDA and evaluation the bacteria survival time into this medium, optimization of culture conditions of bacteria and then performance of direct duplex-PCR on colonies and stool samples. Finally, the results of the PCR and culture were compared.
Fifty eight children suspected to campylobacteriosis were enrolled in this study. Fecal specimens were inoculated in depth inside the altered transport medium with mCCDA and then sent to laboratory. The specimens from transport media were cultured on two media of mCCDA&brucella agar daily and up to 7 days. Each plate was evaluated for bacterial growth up to 72 hours. The duplex-PCR on colonies and stool were carried out directly.
Total of isolated bacteria in this study was 9 cases (16%). The colonies were visible on the media after 48 to 72 h. The duplex-PCR assay on colonies detected 8 isolates of C. jejuni and 1 isolate C. coli. The results of the direct duplex-PCR on fecal specimens and cultures were the same.
The results indicate that the presented method in this study with sensitivity equal to the PCR is useful for isolation of Campylobacter spp. It seems that using the changed transport medium and optimization of bacterial culture conditions will be isolated these fastidiousbacteria better than basic transport media.

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

Aeromonas hydrophila (A. hydrophila)and other motile Aeromonas (A. sobria and A.caviae) are receiving increasing attention as a human pathogens, especially as causative agents of gastroenteritis, wound infections and septicemia. The purpose of this study was to investigate the prevalence of Aeromonas in children with diarrhea in city of Tehran and to determine their antibiotic susceptibility. This study was performed on 391 stool samples from Children's Hospital Medical Center, Tehran. Fecal samples were collected and transferred in a transport medium to laboratory. The samples were placed in alkaline peptone water for 24 hours at 37 ° C. Then the samples were cultured on blood agar containing ampicillin, MacConkey and CIN agar. The suspicious colonies were identified with biochemical tests and API kit. The antibiotic susceptibility test was performed for identified isolates. In total 12 isolates (3.1%) were identified as Aeromonas, which were confirmed with API-20E. five strains of Aeromonas caviae (42%), four strains of Aeromonas veronii biovar sobria (33%) and three strains of Aeromonas hydrophila (25%) were identified. All the strains were sensitive to gentamycin, amikacin, cepime, and resistance to ampicillin. Aeromonas species could cause substantial amount of diarrhea in children, therefore in isolation and identification of diarrhea these fecal pathogens also should be considered.

Yersinia enterocolitica is a worldwide pathogen belong to genus Yersinia. The association between acute childhood diarrhea and other diseases caused by Yersinia enterocolitica has been established by several researchers. Due to the lack of sufficient information on other pathogenic Yersinia species, this study was done to determine the prevalence and the pattern of antibiotic susceptibility of atypical Yersinia spp isolated from children, less than 14 years old. This descriptive cross - sectional study was carried on 384 children with diarrhea whom referred to the Tehran children medical center, Tehran, Iran during August 2011 to August 2012. 384 fecal specimens of children were transferd to the laboratory and cold enrichment in alkaline buffer with pH of 7.2 for 21 days. The samples were cultured in Cefsulodin-Irgasan-Novobiocin Agar (CIN) differential media in 7, 14, and 21 days. The identification of Yersinia species were carried out by conventional procedure. Antibiotic susceptibility test to Ciprofloxacin, Co-trimoxazole, Tetracycline, Chloramphenicol, Erythromycin, Ampicillin, Gentamicin, Penicillin were determined by standard disk diffusion method. Out of 384 fecal samples, 3 (0.7%) were infected with Yersinia. Three species of Yersinia were Y.enterocolitica, Y.Kristensenii and Y.frederiksenii. All three strains were sensitive to Cotrimoxazole, Tetracycline, Chloramphenicol, Ciprofloxacin and Gentamicin. This study showed that atypical Yersinia play important role in diarrhea. Therefore, more attention should be noticed to atypical Yersinia species in addition to Yersinia enterocolitica.

Attention has largely been focused on appearance of multiple drug resistance enterococci in the last 20 years. One of the methods to overcome this problem is to combine different antibiotics in order to increase antimicrobial activity and reduce toxicity. The combination of fluor quinolones with other antibiotics has been widely investigated. The aim of this study was to investigate the synergistic effect of ciprofloxacin in several antibiotics Beta-lactam (piperacillin, ceftazidime and imipenem) on isolated enterococci. In this cross sectional study, 67 Streptococci strains were isolated from clinical samples from March to September 2012. The serial broth dilution method in test tubes was used for the MIC, and the check board Format was used for the synergistic effect of ciprofloxacin with Beta-lactam antibiotics. The synergistic effect was determined with four- fold reduction of initial MIC. Totally, 67 strains of Streptococci were used, in which 50 strains (74.6%) were enterococci, 6(9%) were group B streptococcus, 5(7.5%) were non-group A streptococci, 2 (3%) were pneumococci, and 2 were strains of alpha streptococci (3%), respectively. All results were determined by the MIC and MBC of each antibiotic individually and also in combination with ciprofloxacin. The effect of ciprofloxacin on other antibiotics was indifferent, and the synergistic effect was not observed.

Septicaemia is a leading cause of morbidity and mortality of infant’s and childerens espicially in first week of their life، both in developed and underdeveloped countries. The aim of this research was to study of bacterial agents causing septicaemia and to determine their antibiotic suseptibility patternes. This was a descriptive study، it was performed during eight months from October 2011 till May 2011. In total 216 blood culture samples of children suspected of septicaemia in children health centre hospital were send to the laboratory for investigation. The bacterial identification was carried out by culturing and conventional biomedical tests. The antibiotic sensitivity tests were performed by disk diffusion method. These data are analyzed by SPSS and the results Expressed as relative frequencies. Out of 216 tested samples 55 (25. 6%) were positive and 161 (74. 54%) negative. The dominated bacteria was Escherichia coli (31. 42%)، followed by Staphylococcus aureus (22. 86 %)، Klebsiella pneumonia (20%))، Staphylococcus epidermidis (14. 28%)، Streptococcus pneumonia (2. 86%)، Salmonella typhi (2. 86%)، Enterobacter cloacae (2. 86%) and Stenotrophomonas maltophilia (2. 86%). In general gram-negative bacteria were isolated more than gram-positive. Staphylococcus bacteria were more resistant to antibiotics than other isolated bacteria، and were 100% resistant to penicillin. The enterobacteriaceae were more sensitive to norfloxacin، amikacin، tobramycin، and they were 100% resistant to ampicillin. The results obtained in this study showed that gram-negative bacteria are more responsible in septicaemia in children ward، and norfloxacin is the more effective antibiotic in comparison with others.

The aim of this study was to determine the prevalence of virulence-associated genes and enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) analysis of Campylobacter spp. isolated from children with diarrhea in Iran. A total of 200 stool specimens were obtained from children under 5 years during July 2012 to July 2013. Detection of C. jejuni and C. coli was performed by standard biochemical and molecular methods. The presence of virulence-associated genes and genetic diversity of isolates was examined using PCR and ERIC-PCR analyses. A total of 12 (6%) Campylobacter spp. were isolated from patients including 10 (4. 5%) C. jejuni and 2 (1. 5%) C. coli. The flaA، cadF and ciaB genes were present in 100% of isolates، while no plasmid of virB11 gene was present in their genome. The prevalence of invasion-associated marker was 100% among C. coli and was not detected in C. jejuni isolates. The distribution of both pldA and the genes associated with cytolethal distending toxin (CDT) was 58. 3% in C. jejuni isolates. Seven distinct ERIC-PCR profiles were distinguished in three clusters using ERIC-PCR analysis. Genotyping analysis showed a relative correlation with geographic location of patients and virulence gene content of isolates. To our knowledge، this is the first molecular survey of Campylobacter spp. in Iran concerning genotyping and virulence gene content of both C. jejuni and C. coli. ERIC-PCR revealed appropriate discriminatory power for clustering C. jejuni isolates with identical virulence gene content. However، more studies are needed to clearly understand the pathogenesis properties of specific genotypes.

Diarrhea is one of the most prevalent cause of children`s death in developing countries. Gastrointestinal diseases are the cause of much death among the children under the age of 5 every year. In this study the invasiveness character of Shigella strains was investigated by HEp-2cell cell culture technique. In this descriptive study، 280 rectal swabs (140 with dysentery and 140 watery diarrhea) from patients suffering from diarrhea before using any antibiotic and 140 from healthy people as control group were collected. These specimens were cultured in Hektoen and XLD agar as selective and differential media، then after 24 hours incubation in 37˚C their morphology were studied and finally the isolates were confirmed with biochemical tests. Shigella spp strains consist of 20 collection strains were used for consideration of invasiveness in Shigella. Antibiotic typing also performed according to CLSI instructions. Thirty six strains of Shigella (8. 6%) were isolated from thesamples under the study. Most strains isolated from patients، were Shigella flexneri isolated with 16. Our study on HEp-2 cell cultures showed that only 14 (9 isolates، 5 collections) had invasive properties of Shigella strains. The results show that firstly all Shigella isolates are not capable of invading intestinal epithelial cells; Secondly invasion is not a constant attitude and it would not go away by time

gasterointertidis is one of the most common forms of Salmonellosis، which is a worldwide problem. The invasive characteristic of intestinal bacteria is one of their pathogenicity Mechanisms، which can be easily investigated by cell culture technique. In this study، the invasive characteristic of some Salmonella serogroup were investigated by using HEP-2 cell. Methods and Material: The rectals soap were prepared from 280 diarrhea patients referred to Imam Khomeyni and children medical centres، 140 with bloody diarrhea and 140 with watery diarrhea as a comparison group. The rectal soap was taken before patients taking any antibiotics، and 140 rectal specimens were taken from healthy people as a control group. All the samples were inoculated in differential and selective media، like Hektoen enteric agar and Xylose lysine deoxycholate (XLD) agar. After incubation at 37C for 24 hours، the colonies were examined and identified by conventional biochemical and serological tests. Using HEP-2، cellular invasion characteristic of Salmonella serogroups was assessed. Moreover، the antibiotic resistance patterns were performed according to Clinical and Laboratory Standards Institute (CLSI). Of all tested samples، 35 (8. 3%) are Salmonella strains. The frequency of Salmonella is reported for bloody diarrhea (5. 2%)، watery diarrhea (1. 7%) and control group (1. 4%). The most abundant serogroups with invasive characteristic، using HEP-2 cell culture، are serogroup B (62. 9%) and D (17. 2%). The results obtained in this study show that the majority of Salmonella isolates are without invasive characteristic.

Laboratory tests are used to diagnose diseases, monitor its progress and response to treatment. So the goal of the laboratory medicine is reporting accurate and on time test results. The aim of this study was to evaluate rate and causes of post-analytical errors in the Clinical Laboratory of Children’s Medical Center. We especially focused on 1) delay in reporting test results and 2) inaccuracy of test results. This descriptive study was conducted in Children’s Medical Center in 2008. Any complaint related to accurate reporting and on time test results from inpatients and outpatients, physicians and wards during 3 months period were registered. The reasons were investigated then recorded in predesigned forms; data were analysed with SPSS version 15, Chi square and Fischer’s tests. A total of 375 of 425 complaints were related to delay in reporting test results. We also recorded 50 cases of erroneous result complaints. Also 72% of delayed reports and 34% of complaints of unaccepted results were caused in post-analytical phase (i.e. after test was performed). “Failure to input the results in computer” was the main reason (37%). “Lost results “(25%) and transcription error (22.6%), “absence of laboratory request form” (9.8%) and “wrong method of filing” (4.2%) were the other observed causes. Microbiology, hematology and clinical chemistry were departments with the highest rate of complaints; whereas urine culture, CBC and biochemistry tests were the most frequent problematic tests. The rate of complaints was 1:108 patients or 1:541 tests, and 4.8% of results were not reported in timely manner. Our findings revealed that the source of most of the errors related to reporting test results were in post-analytical phases. Therefore along with continuing the educational programme, and improvement of automation, it seems necessary to add periodic evaluation and investigation of errors to benchmarks programmes, especially in reporting test result processes, in order to provide error free service to physician and their patients. Cooperation with the clinicians and the other personnel outside the laboratory is also important for error reduction.

Salmonellosis is a gastroenteritis caused by different serotypes of Salmonella and is the most common type of food poisoning in the world. The purpose of this research study is to optimize the conventional method for the isolation of Salmonella SPP from the diarrheic specimens of children. Stool specimens were obtained from one hundred patients admitted to Children's Medical Center for diarrhea. The enrichment media were prepared by 3 Rappaport Vassiliadis broth (RV), Tetrathionate broth (TT), and Selenite Cystine broth (SC). Then, for the isolation of Salmonella SPP, the enrichment methods RV and TT were used and incubated at 42° C, and SC at 37° C. After 24 hours of incubation, the enrichment samples were inoculated into the following 6 different media: Hektone Enteric agar (HE), Rambach agar (RA), CHROMagar Salmnella (CHROMagar Salmonella), Brilliant Green agar (BG), Salmonella-Shigella agar (SS), and Xylose-Lysine-Deoxycholate agar (XLD). In total, 13 out of one hundred samples were identified as Salmonella SPP. All of these 13 Salmonella SPP samples (i. e., 100%) were positive on RV broth; the figures were 8 (61.5%) and 3 (23%) on SC and TT broths, respectively. The highest amount of isolation was found by the combination of RV broth and RA agar (100%). The lowest rate, however, was obtained by the combination of TT agar and BG broth (15.4%). The comparison results of 3 enrichment media and 6 selective media showed that the mixture of RV broth and RA agar would be very fine for the isolation of Salmonella SPP.

Salmonellosis is a bacterial gasteroenteritis caused by different serovars of Salmonella. In the recent years, Salmonella enterica subspecies. Enterica serovar enteritidis is a major cause of gastroenteritis and food poisoning in the worldwide. Different genus of salmonella is increasingly being resistant to common antibiotics. The aim of this study was to determine the frequency and the antibiotic resistance patterns of Salmonella enterica isolated from medical health centers in Tehran. In this descriptive cross- sectional study from April to December 2008, 1950 fecal specimens from children

Nowadays one of the problems in developing countries is pediatric diseases and their mortalities. In this respect diarrhea plays a significant role. Cryptosporidium is recognized as an important widespread cause of severe and prolonged diarrhea mainly in immunocompromised or malnourished children, but there is no attention to identifying the parasite. The present study was designed and undertaken to assess the prevalence rate of agents causing diarrhea and determine the role of cryptosporidium and its relationship to some potential risk factors. In this cross-sectional study carried out during twelve months(from June 2002 to June 2003), stool samples from 420 children under 10 years of age with diarrhea who were admitted to Tehran Children Medical Center were screened. To identify parasites, direct smear, formalin-ether and modified acid fast staining techniques were applied. In addition, in order to distinguish pathogenic bacteria, differential media and polyvalent standard antisera were used. The obtained data was analyzed using descriptive and analytical statistics, i.e. Chi-square, t-test and Fisher exact test. This study showed that after bacteria, parasites were important causes of diarrhea, and cryptosporidium(2.4%) following giardia(2.9%) was the second parasite isolated in children with diarrhea. Statistical analysis of our results indicated that existence of cryptosporidium was significantly related to the presence of mucus in stool(P<0.003), immune deficiency(P<0.01), and age(P<0.017). This study emphasized that laboratories include appropriate diagnostic techniques for cryptosporidium in the routine examination of watery or mucoid diarrheal stool specimens, particularly for immunosuppressed patients.

Cyclospora cayetanensis is a new-emerging pathogenic protozoan parasite. It is a rare coccidian associated with gastrointestinal disorders. Cyclosporiasis occurs in persons of all age groups and either in immunocompetent or immunocompromised hosts. The most characteristic feature of this infection is a syndrome of acute or chronic diarrhea. This parasite is worldwide in distribution. Cyclospora can be transmitted by ingestion of water or food contaminated with oocysts. The present study was undertaken to assess the prevalence of cyclospora cayetanensis in children with diarrhea. During twelve months(from June 2002 to June 2003) 420 stool samples from children under 10 years of age with diarrhea, admitted into Tehran Children Medical Center were screened. To detect and identify the organism, direct smear, formalin-ether concentration, and staining(modified acid fast) techniques were used. In this cross-sectional study, 31 out of 420 specimens(7.3%) showed parasite infection, but cyclospora cayetanensis was not detected in any of the stool samples. According to our study, it seems that cyclospora infection in Tehran is very rare and further studies with larger volume size of stool are necessary for cyclospora identification. We also suggest that medical practitioners and laboratories should be more aware of this infection and its diagnosis.

Aeromons is the cause of various infections in humans and has been isolated from different food samples and even drinking water. Research studies report the prevalence of the bacteria in diarrheic patients to be equal to or higher than shigella. Regarding the contradictory reports this study was conducted to investigate the prevalence and significance of Aeromonas in children's dysentery and their sensitivity to antibiotics in Tehran in 2003-2004. In this descrpitive study 310 stool samples of diarrheic children under 10 years of age were tested for infection to Aeromonas, plesiomonas, bacterial pathogens such as salmonella, shigella, enteropathogenic E.coli and enteric parasites and susceptibity of these agents to antibiotics was assessed through diffusion disc method on aeromonas isolates. Data were analysed using discriptive and analytical statistics (χ 2, t-test and, Fisher exact test). The results showed that Aeromonas prevalence was 4.5% and higher than salmonella and enteropathogenic E.coli in diarrheic children and it was the second leading pathogen after shigella. All Aeromonas strains were susceptible to ceftizoxime, ciprofloxacin, gentamicin and resistant to ampicillin. Aeromonas species are of etioloical significance in diarrheic children and they must be taken into account in bacteriologic survey of the stool samples. More research is recommended.