Phenotypic and Molecular Characterization of Streptococci Isolated from Sudanese Patient’s

Abstract

A total of 500 samples were collected from patients with suspected Streptococcal infection. These included throat swabs (150 samples) collected from patients who attended Khartoum Ear Nose Throat (ENT) Teaching Hospital, suffering from sore throat, vaginal swabs (125 samples) collected from pregnant women (35-37 weeks of gestation) who attended the Saudi Maternal Hospital, Urine (125 samples) and blood (100 samples) samples collected from patients who attended Omdurman and Khartoum North Teaching Hospitals. All samples were collected from suspected patients regardless of their age. The samples were cultured on 5% sheep blood agar. The type of haemolysis and the colony morphology were recorded as part of the diagnosis and the Gram’s stain was done from overnight cultures using the standard technique. Suspected Streptococcus isolates were subjected to different biochemical reactions to confirm the diagnosis. Commercial Lancefield grouping kits were then used to confirm the group identification.

VI Finally Polymerase Chain Reaction (PCR) was done to confirm the results of traditional diagnosis. Three types of primers were used: genus specific primer to confirm that the organism isolated was Streptococcus and the other two were used for sequencing in an attempt to identify isolates at the level of species Antimicrobial sensitivity was done to find out the susceptibility of these organisms to antibiotics. The results showed that group F Streptococci was isolated from swabs of patients suffering from sore throat (3.48%) beside group A Streptococci (96.52%). Out of 125 samples of vaginal swabs, 4 samples (3.2%) were diagnosed as group B Streptococci, while 8 samples were isolated from 125 samples of urine and 5 samples were isolated from 100 samples of blood cultures. Out of the 35 samples selected for sequencing, 28 samples were identified to the level of species. PCR results using genus specific primer indicated that ~ 100% of the isolates were of Streptococcus species. Sequencing results indicated that isolates were similar to the GenBank data base.