Evaluation of PCR method for diagnosis of Group B Streptococcus carriage in pregnant women

Group B Streptococcus [GBS] [Streptococcus agalactiae] is the leading cause of morbidity and mortality of newborn infants and accounted as a leading factor causing septicemia after birth in mothers. Infections in infants are usually acquired by contact with the genital tract of the mothers during labor and delivery. In two last decades, significant progress toward detection, prevention and treatment of pregnant women carrying GBS has been achieved. A rapid screening test for GBS that could accurately identify pregnant women carrying the bacteria at the time of delivery would obviate the need for prenatal screening. The standard method for the diagnosis of GBS colonization consists of culturing vaginal and anal secretions in a selective broth medium which inhibits the growth of other microorganisms. Today, it is accepted that PCR has a high sensitivity and specifically in diagnosis. The goal of this study was to screen pregnant woman carrying GBS by PCR. Samples were taken from anal and vaginal mucus of 125 pregnant women who were at 28-38 weeks of ingestion by swab. Samples were tested by standard culture using Todd Hewitt Broth and Blood Agar and also by PCR using primers specific for cfb gene. Culture identified 10 [8%] women as carriage of GBS out of 125 women tested. On the other hand, the PCR assay could identify 12 [9/6%] women positive for GBS. In comparison to culture results, sensitivity, NPV, specificity, and PPV of PCR were 100%, 100%, 98%, and 83%, respectively. The time required for PCR assay and culture were 2h and 36h, respectively. We found that GBS can be detected rapidly and reliably by a PCR assay using combined vaginal and anal secretions from pregnant women at the time of delivery. Also this study shows that the rate of incidence of GBS is high in Iranian pregnant women. We, therefore, recommend screening of pregnant women for detecting of GBS emphatically

Genotyping of Helicobacter pylori strains isolated from patients with NUD, DU, GU and GC by RAPD-PCR

Helicobacter pylori is a genetically diverse gastric pathogen that chronically infects billions of people worldwide, typically beginning in infancy and lasting for decades. It is a major cause of peptic ulcers and it is an early risk factor for gastric cancer which is the most frequently lethal malignancy globally. This project was designed to genotype H. pylori isolates isolated from patients with NUD, DU, GU and GC by the polymerase chain reaction [PCR]-based on Randomly Amplified Polymorphic DNA [RAPD] fingerprinting technique. Eighty patients admitted to the gastroenterology unit at Sharyati hospital in Iran were included in this study. Gastric biopsy specimens were inoculated onto selective medium then were cultured for 3 to 5 days at 37 °C under microaerobic conditions. Genomic DNA was extracted using a commercially available Qiagen kit. RAPD-PCR was used to genotype isolates. Six different RAPD patterns [A-F] were seen in more than one isolate which were as follow; pattern A: 9 [16.98%], B: 6 [11.33%], C: 5 [9.43%], D: 3 [5.66%], E: 2 [3.77%] and F: 2 [3.77%]. Twenty six [49.06%] of 53 isolates showed a unique RAPD pattern that were not similar to each other. A significant relationship was not seen between a single RAPD pattern and a gastric disorder [P>0.05]. The results of this study suggest a high level of DNA sequence diversity among H. pylori isolates and it is better to use sequencing method for surveying of Helicobacter pylori genome rather than RAPD-PCR