Background: Streptococcus pneumoniae, the pneumococcus, is major human pathogen that causes more than 820,000 deaths worldwide annually, especially in developing countries. The most diseases presentations are acute respiratory tract infection (ARTI), otitis media, septicemia and meningitis. Pneumococcal meningitis has a higher fatality rate than meningitis caused by other bacteria. On the basis of the capsular polysaccharide type of the cell wall, can be serotyped into more than 90 serotypes. It is a vaccine preventable disease, and several vaccines based on different combinations of capsular component have been developed. The serotype distribution of this organism differs by geographical areas and the prevalent serotypes in one region could not necessary be the basis for vaccine formulation for another. Thus, it is essential to know the epidemiology and prevalence of the different serotypes.
Methods: To characterize pneumococcal strains in Ethiopia among diagnosed for pneumococcal infection by the physician and referred to the clinical microbiology laboratory of selected health institutions in Addis Ababa and Gondar from July to December 2012. All samples were cultured on appropriate culture media and typical pneumococcal colonies were confirmed by biochemical tests. Antibiotics resistance test was done by E-test strips and interpreted according to European guidelines. Serotyping was done by Quellung reactions, and isolates were characterized by multilocus sequence typing (MLST) to determine phylogenetic classification. Culture negative CSF from pyogenic meningitis were tested by Real time PCR.
Results: A total of 460 samples were collected, sixty one pneumococcal isolates were identified and most of them from cerebrospinal fluid (CSF). 15 serotypes were identified, with serotype 1 (21%) being the leading followed by 19F , 20 (10%) and 14 (8%). In seven samples more than one serotype were identified. Predicted coverage of 10 valent vaccine is 44%. Twenty four isolates were intermediate resistant for penicillin and except, for one and three all of them were susceptible to ceftriaxone and chlorampheinicol respectively. Seven new sequence types were identified by MLST. From 140 culture negative CSF, 12 were positive for meningococcus 9 for pneumococcus and 2 were mixed.
Conclusion: This study has a contribution evaluating the current vaccine program in the country.