Bacterial Isolation and Identification Protocol

Samples were plated on Blood Agar Base and Columbia Blood Agar Base with nalidixic acid and colistin sulfate (Oxoid ltd., Hampshire, UK), supplemented with 5% sterile defibrinated sheep blood and incubated both in aerobic and microaerophilic (5% CO₂) conditions at 37 °C for 48 h. Colonies were selected and identified as previously described [7 (link)]. Further biochemical identification was performed using commercial identification galleries (API®Coryne and API®20Strep, bioMérieux, Marcy-l’Etoile, France) according to manufacturer’s instructions. Isolates were identified as a species only if identification scores in the multi-substrate identification systems were excellent, very good or good (90.0–99.9% ID); otherwise, identification was made only at the genus level (spp.). Latex agglutination test (Streptococcal grouping kit, Oxoid ltd, Hampshire, UK) and Christie Atkins Munch-Petersen test (CAMP test) were used for identification according to previous reports [30 (link)]. Pure cultures of each isolate were stored at − 70 °C.