Molecular and epidemiological study of Streptococcus pneumonia in Thi-Qar province

Between 3/5/2022 and 28/8/2022,100 samples of sputum were taken from patients with respiratory tract infections (ages 15 to 80) of both sexes who were seen at various hospitals in the Dhi-Qar Governorate of Iraq including the Chest and Respiratory Hospital and the Respiratory Disease Centers dispersed throughout the governorate. Only 88 bacterial isolates could be isolated and identified from these samples. Thirty bacterial isolates (34.1%) were found to belong to Streptocoocus spp., 36 (40.90%) to Staphylococcus spp., nine (10.23%) to Pseudomonas spp., and thirteen (14.7%) to Klebsiella spp., due to the findings of identification based on morphological and cultural features. Then, using biochemical assays, the API 20 STEP system, and blood hemolysis patterns, Streptococcal isolates were further identified as species. Full identification revealed that only 20 (66.7%) of the thirty isolates of Streptococcus were Streptococcus pneumoniae. There was no statistically significant difference in the percentage of S. pneumoniae isolates detected in males (65%) versus females (35%). For the twenty S. pneumoniae isolates, antibiotic susceptibility was investigated. Results revealed that these isolates had various patterns of antibiotic sensitivity. Erythromycin (100%), azithromycin (85.0%), and clindamycin (80.0%) had the highest rates of resistance, while ceftriaxone (70.0%), cefotaxime (65.0%), chloramphenicol (65.0%), tetracycline (60.0%), and penicillin (45.0%) had moderate rates of resistance. Other antibiotics had relatively lower rates of resistance. The findings of this investigation demonstrated that S. pneumoniae isolates were remarkably responsive to Imipenem (100%) and Vancomycin (100%). The final diagnosis required the presence of the genes LytA, Ply, and CpsA, which are believed to be specific for the identification of S. pneumoniae using Polymerase Chain Reaction (PCR) technology, in all 20 isolates. All of the S. pneumoniae isolates tested positive for the LytA gene and the Ply gene, each of which had a band size of 480 and 420 base pairs, respectively. The results of this work agree 100% with the results of a study done in Iran by (Hajia et al. 2013), and a study that was conducted in Spain showed that the sensitivity for detection of the LytA and Ply in S. pneumoniae isolates was 100%. Both of these studies were conducted in Spain. The result that was reported in Iran was 84.74%, while the result that was published in the United Kingdom was (97.5%). The result that was found in this study is higher than both of those figures. In addition to being useful in diagnosis, the LytA gene also carries the coding for the enzyme autolysin, also known as LytA. This enzyme dissolves the peptidoglycan backbone of bacterial cells, which ultimately results in bacterial autolysis. LytA is the enzyme that is responsible for the autolytic action that is distinctive of pneumococcus. It is positioned in the cell envelope and is engaged in a range of other physiological cell processes. In light of research, LytA may be responsible for facilitating the release of intracellular toxins such as pneumolysin (Ply) and producing pro-inflammatory cell wall fragments. Both of these factors may contribute to the pathogenesis of pneumococcal disease. In addition, the CpsA gene can be found in all S. pneumoniae strains that have been isolated. Therefore, the conclusion that can be drawn from these findings is that CpsA is present in this bacterium. This gene was picked for molecular identification since it is known to operate as a housekeeping gene. Furthermore, the positive isolates for PCR confirmation were completely consistent with the nigrosin stain test results. These results correlate with the results obtained via, who pointed out that all clinical isolates of S. pnumoniae contained this gene in their samples. The invasiveness of particular isolates is related to the level of expression of the CpsA gene, which is the first gene in the pneumococcal capsule operon.