Increasing Blood Culture Positivity for Streptococcus pneumoniae Using Tryptic Soy Sheep Blood Agar with Gentamicin (TSSBA-G) in Suspected Bacteremia and Pneumonia at Universitas Sumatera Utara Hospital, Indonesia

Conventional blood culture media often fail to isolate Streptococcus pneumoniae, a key cause of pneumonia and bacteremia. This study aimed to improve the detection rate of S. pneumoniae using selective media. The study involved 45 blood samples from patients suspected of bacteremia and pneumonia at the Universitas Sumatera Utara Hospital. The samples were cultured using tryptic soy to make sheep blood 5% with and without gentamicin (TSSBA-G and TSSBA) in detecting S. pneumoniae in the blood of patients with bacteremia and pneumonia. Blood samples were incubated in the BAcT/Alert tube to detect the presence or absence of microorganism growth in blood samples. S. pneumoniae was isolated in 6 of 45 samples (13%) using TSSBA-G. TSSBA without gentamicin yielded 11 cultures (24%) including potential contaminants. Routine media (blood agar and MacConkey agar) detected 12 positive cultures (27%) but failed to isolate S. pneumoniae. Combined use of TSSBA-G and TSSBA increased total positivity to 29/45 (64%). The use of TSSBA-G, especially alongside TSSBA, substantially increases blood culture positivity, particularly for isolating S. pneumoniae a key cause of bacteremia. These findings support the adoption of selective media to improve diagnostic yield.