Molecular and serological detection of Enterotoxigenic Staphylococcus aureus from traditionally dairy products

زمینه و هدف: استافیلوکوکوس اورئوس یکی از مهمترین عوامل مسمومیت در مواد غذایی و لبنی است. انتروتوکسین های استافیلوکوکی فاکتور اصلی ایجاد مسمومیت غذایی می باشد که از تیپ‌های مختلفی تشکیل شده‌اند. مهمترین آنها انتروتوکسین های تیپ A (SEA) و B (SEB) می باشد. هدف از این مطالعه تشخیص استافیلوکوکوس اورئوس تولید کننده انتروتوکسین تیپ A و B به روش مولکولی و سرولوژیک از مواد لبنی سنتی می باشد. روش بررسی: در این تحقیق توصیفی – تحلیلی آزمایشگاهی با رعایت شرایط استریل از 100 نمونه مواد لبنی تهیه شده به روش سنتی در سطح شهر تهران نمونه برداری و به آزمایشگاه منتقل شد. نمونه ها با استفاده از روش های متداول باکتری شناسی کشت داده شده و استافیلوکوکوس اورئوس ها شناسایی شدند. ژن های SEA و SEB در استافیلوکوکوس اورئوس های جدا شده، به روش PCR شناسایی شد. قدرت انتروتوکسین زایی سویه های دارای این ژن ها، به روش کشت در کیسه دیالیز بررسی شد و بوسیله آزمایش سرولوژیک ایمنودیفیوژن منفرد شعاعی (SRID) تایید گردید. داده ها با استفاده از آزمون آماری کای اسکوئر مورد تجزیه و تحلیل قرار گرفت. یافته ها: 32 از مواد غذایی از نظر وجود استافیلوکوکوس اورئوس مثبت بودند (خامه 18، پنیر 10 و شیر 4). نتایج آزمایش PCR نشان داد که از میان استافیلوکوک های جدا شده، 6/15 دارای ژن SEA، 3/9 دارای ژن SEB و 2/6 آنها دارای هردو ژن SEA و SEB هستند (05/0

Detection of Acinetobacter baumannii by PCR-ELISA method

زمینه و هدف: اسینتوباکتر بومانی عامل عفونت های دستگاه تنفسی، دستگاه ادراری، خون و زخم ها به خصوص در بخش مراقبت های ویژه می باشد و توانایی کسب مقاومت دارا می باشد. به منظور تشخیص به موقع و پیگیری فرایند درمان این عفونت ها، لازم است که تکنیک ها به طور مستمر اصلاح شوند. با توجه به اینکه تاکنون مطالعه ای در زمینه شناسایی و جداسازی این باکتری در نمونه های بالینی در ایران با روش PCR-ELISA انجام نشده است، این مطالعه با هدف جداسازی اسینتوباکتر بومانی با روش PCR-ELISA انجام شده است. روش بررسی: در این تحقیق روش PCR-ELISA با استفاده از آغازگرهای اختصاصی و پروب بر روی سویه استاندارد مورد بررسی قرار گرفت. بعد از تکثیر و نشاندار کردن توالی ژن gltA، محصول نشاندار در کف میکرو پلیت کوت گردید و با استفاده از آنتی بادی ضد دیگوکسی ژنین کانژوگه با پراکسیداز شناسایی شد. یافته ها: بررسی توالی bp722 از بخش حفظ شده ژن gltA اسینتوباکتر بائومانی و نتایج حاصل از مطالعه بر روی این باکتری با استفاده از روش PCR-ELISA و به کارگیری آغازگرها و پروب نشان داد که این روش علاوه بر دقت و حساسیت، برای تشخیص سریع باکتری مناسب است. نتیجه گیری: نتایج حاصل، حاکی از حساسیت بیشتر و سرعت بالای روش PCR-ELISA در مقایسه با PCR معمولی است. این تکنیک همچنین علاوه بر سهولت بررسی تعداد بیشتر نمونه، از خطر کمتری نسبت به روش PCR معمولی برخوردار است

Use of a Multiplex PCR assay for simultaneous detection of the ctxA,ctxB and zot genes of Vibrio cholerae isolated from patients

Background and objectives: Toxigenic Vibrio cholerae contains ctxA, ctxB and zot genes and comparing to non-toxigenic strains causes severe disease in human. Therefore accurate identification of toxigenic strains is very important. This study the usage of a Multiplex PCR assay for simultaneous detection of the ctxA,ctxB and zot genes of V. cholerae isolated from patients was investigated.Material and Methods: In this study, 73 stool samples were collected and were determined as V. choleraeO1 by serological and biochemical tests. Finally, all of strains. Finally the results were analyzed statistically by SPSS 16 software. Results: According to the results of the Multiplex PCR, the incidences of ctxA , ctxB and zot genes in clinical isolates were obtained as 90.4% (66 samples), 90.4% (66 samples), and 91.7% (67 samples), respectively. All of the strains were belonged to O1serogroup. The results showed that Multiplex PCR is a method for the rapid and accurate detection for toxigenic V. cholerae in clinical isolates. Also, this assay is specific for the detection of Vibrio strains that possess the ctxA, ctxB and zot genes with sensitivity up to 1/100 dilution of the genome per reaction. Conclusion: In case where specific primers were utilized (target genes of ctxA, ctxB and zot ), Multiplex PCR has proved to be a simple, fast, and relatively inexpensive method for the rapid and accurate detection of toxigenic V. cholerae strains in the clinical samples

Study of prevalence and antimicrobial susceptibility pattern of poly bacterial pneumonia

Background: Bacterial pneumonia is one of the most common causes of morbidity and mortality, and accurate diagnosis and treatment of the pneumonia causative agent, especially in polybacterial cases, is difficult and much appreciated. The aim of this study was to determine the causative agents and antimicrobial susceptibility of polybacterial pneumonia in patients with lower respiratory tract infections.Methods: In this retrospective cross-sectional study, 167 cases with symptoms of lower respiratory tract infection (LRTI), admitted since March 2010 to March 2013 to Baqiyatallah Hospital, Tehran, were studied. Bronchoalveolar lavage (BAL) samples have been obtained from all these patients and have been investigated for the presence of bacterial causative agent, presence of polybacterial pattern of the infection, and the pattern of antimicrobial susceptibility testing by disc diffusion method. Also, the samples have been studied for the presence of Mycobacterium tuberculosis through culture of specific media, separately.Results: From 167 patients (62 women and 105 men), 90 cases were positive for the presence of bacterial pathogens while 77 cases were negative by culture. The incidence of bacterial pneumonia was not statistically different between men and women. Totally 117 bacterial isolates were obtained belonging to 15 different bacterial species. Mycobacterium tuberculosis (25%), Pseudomonas aeruginosa (15%) and Staphylococcus aureus (14%) were the most frequent pathogens identified. 72 percent of pneumonic cases were monobacterial infections and the others were polybacterial infections (23% two-bacterial, and 5% three-bacteria). The highest antibiotic resistance rate was seen for amoxicillin and the lowest one was seen for vancomycin.Conclusion: This study found that the prevalence of bacterial pneumonia increases with age, and also is caused by different etiologic agents. A high percentage of negative cases may be due to fastidious bacteria, viral agents, and previous antibiotic therapy. Due to high levels of resistance to antimicrobial agents, accurate diagnosis and susceptibility testing of pneumonic patients is essential

PCR and RFLP of ureC (glmM) gene for identification and typing of Helicobacter pylori strains isolated from gastric biopsy specimens of gastric patients

Aims: Helicobacter pylori is one of the important pathogens that infected epithelial cells of stomach. The aim of this study was to analyze and type Helicobacter pylori isolated from gastric biopsy specimens with ureC (glmM) gene. Materials & Methods: Molecular method was used in order to type Helicobacter pylori. PCR-RFLP was used to determine the genetic heterogenesity of 37 specimens of Helicobacter pylori isolated from culture. 820bp amplified fragment of ureC gene was digested with the restriction enzymes HhaI, MboI. Results: 11 different patterns with HhaI and 8 different patterns with MboI were identified. In combination, 21 different RFLP patterns were identified. Conclusion: Based on the results of this study, there is no significant relationship between gastric diseases and different patterns and there is a widespread genetic diversity between the fragments. This is promising the production of effective equipment for molecular analysis of epidemiology and analyzing ancestors and understanding the bacterial origin and its scattering in different geographic region

MIRU-VNTR analysis of the Mycobacterium tuberculosis isolates from three provinces of Iran

Background: Iran borders 2 high-burden tuberculosis (TB) countries to the east, and has the highest rates of TB in one of its eastern provinces. Limited information is available on the genetic diversity and transmission dynamics of Mycobacterium tuberculosis (MTB) in Iran. To examine the genetic diversity and transmission dynamics of MTB strains we genotyped a collection of isolates from different parts of Iran. Methods: Standard 15-locus variable number tandem repeat (VNTR) typing was applied to genotype 121 MTB clinical isolates collected from 3 provinces of Iran, including Tehran (the capital of Iran), Sistan-Baluchestan (southeast province of Iran, with the highest rate of TB), and Kermanshah (western part of Iran with high TB/human immunodeficiency virus cases). Antibiotic susceptibility for all isolates was determined using the proportion method. Results: Sixty-six distinct mycobacterial interspersed repetitive unit (MIRU)-VNTR patterns were detected among 121 isolates. Seventy-five strains grouped into 20 clusters, and 46 isolates were unique. The genetic diversity of strains from Sistan-Baluchestan was higher than that in the other provinces. All isolates from Tehran or Kermanshah that grouped into clusters shared identical patterns with Sistan-Baluchestan. The Hunter-Gaston discriminatory index (HGDI) was 0.972, indicating a high power of discrimination for MIRU-VNTR typing. The MIRU 16 and ETRA loci were designated as highly discriminative. The rates of monoresistance and multidrug resistance were 9.9% and 2.4%, respectively. Conclusions: MIRU-VNTR typing revealed high genetic diversity and suggests the possibility of transmission from Sistan-Baluchestan to other provinces of Iran. This method has potential for genetic analysis and for studying the transmission routes of TB

HOSPITAL ACQUIRED PNEUMONIA: COMPARISON OF CULTURE AND REAL-TIME PCR ASSAYS FOR DETECTION OF LEGIONELLA PNEUMOPHILA FROM RESPIRATORY SPECIMENS AT TEHRAN HOSPITALS

Legionella pneumophila is an important etiological agent in both hospital and community acquired pneumonia. The sensitivity of culture for isolation of L. pneumophila from clinical specimens is low and time consuming. Similar problem also exists when the method of direct immunofluorescence is used. To detect this organism quantitatively from respiratory specimens, a Taq Man based real-time PCR targeting the mip sequence was developed. Both real-time PCR and culture methods were applied on 262 respiratory specimens from 262 ICU patients with pneumonia admitted to 5 different hospitals in Tehran. The results of real-time PCR were compared with those obtained by culture. Real-time PCR and culture found 12 and 4 specimens, respectively, as positive for L. pneumophila. Its technical specificity (100%) was checked against a panel of microorganisms consisting of both Gram-positive and Gram-negative bacteria. Our real-time PCR assay showed high sensitivity (100%) and specificity (96.9%) and could detect 200 organisms per ml from respiratory specimens. Using real-time PCR as a screening method, the frequency of nosocomial pneumonia with L. pneumophila at Tehran hospitals was estimated as 4.58%