Molecular Study on Streptococcus pneumoniae Isolated from Patients Suffering From Respiratory Tract Infection Using RAPD-PCR Technique

 A total of 53 sputum samples were collected from patients suffering from respiratory tract infections attending different hospitals in Baghdad and Al-Anbar (Ramadi) governorates during the period between November /2009 and March /2010. From these samples only fifty bacterial isolates were obtained and identified. Results of identification according to the morphological and cultural characteristics showed that 14 bacterial isolates (28%) were belong to Streptocoocus spp., 26 bacterial isolates (52%) were belong to Staphylococcus spp., four bacterial isolates (8%) were pseudomonas spp., and six isolates(12%) were identified as Klebsiella spp. Then Streptocoocus isolates were further identified to species by biochemical tests, API 20 STEP system and blood hemolysis patterns. Results of full identification showed that only three isolates (21.4%) were identified as Streptococcus pneumoniae, five isolates(35.7%) were Streptococcus pyogenes, two isolates (14.3%) were Streptococcus mutans, two isolates (14.3%) were Streptococcus sangarius, one isolate (7.1%) was Streptococcus fecalis,  and one isolate (7.1%) was Streptococcus agalacticae.
 Antibiotic susceptibility for the three S. pneumoniae isolates was studied. Results showed that these isolates gave different patterns of sensitivity to different antibiotics.   For   molecular diagnosis of the three isolates of S. pneumoniae, and to study the epidemiology of these isolates, genomic DNA was extracted from these isolates symbold N6, N8 and N11 respectively; then genomic DNA for each isolates were amplified using PCR technique to study the pattern of random amplified polymorphic DNA (RAPD)by using ten of different 10-mer oligonucleotide primers.   Results of amplification showed that the three isolates of Streptococcus pneumoniae have different patterns of polymorphic DNA bands which refers that these isolates were from different ancestor.   Genetic relationship between these three isolates of S. pneumoniae was studied to determine the epidemiology of these isolates. Results showed that S. pneumoniae N6 was closer relationship with the second isolate S. pneumoniae N8 because the genetic similarity between the two isolates was 67.92%, while the genetic similarity between N6 and N11 and N8 and N11 were 52.27% and 53.76% respectively.