Identification of Gram-Positive Bacteria and Their Virulence Characteristics From Pig Tonsil Isolates Based on Catalase Test and Hemolytic Properties

Tonsils are an entry and growth site for microbial colonisation and pathogenic bacteria. The tonsils of pig harbour both Gram-positive and Gram-negative bacteria. Some Gram-positive bacteria, such as Staphylococcus, Enterococcus, lactobacillus and Streptococcus can threaten pig productivity. Therefore, this study aimed to identify Gram-positive bacterial species isolated from pig tonsils using the catalase test and to determine their virulence characteristics based on hemolysis types on blood agar. A total of 74 presumptive Gram-positive isolates preserved in 30% glycerol were cultured and tested using Gram staining, catalase tests, and hemolysis assays. The results indicated that all isolates were Gram-positive, with 56.7% identified as Staphylococcus (catalase-positive) and 43.3% as Streptococcus (catalase-negative). Hemolysis tests showed that 43.2% of the isolates were alpha-hemolytic, 41.8% beta-hemolytic, and 15% gamma-hemolytic. Beta hemolysis is associated with high virulence, while alpha and gamma hemolysis are generally linked to opportunistic or non-pathogenic bacteria. This study provides preliminary insights into the identification of potential pathogenic bacteria in pig tonsils and their virulence characteristics based on hemolysis types.