Biochemical and serological characterisation of beta-haemolytic streptococci from various clinical samples in a tertiary care hospital, South India

Abstract

Introduction: Beta-haemolytic streptococci (BHS) are one of the most frequent human pathogens capable of producing a variety of diseases ranging from pharyngitis, impetigo, to more severe and life-threatening diseases such as toxic shock syndrome, neonatal sepsis, pneumonia, meningitis and acute rheumatic fever. Methods: This was a hospital-based prospective study which was carried out on BHS isolated from various clinical specimens submitted in microbiology laboratory from inpatients and outpatients, and these isolates were studied biochemically by pyrrolidonyl arylamidase (PYR), hippurate hydrolysis and sugar fermentation tests. Differentiation of various serogroups was done with bacitracin (0.04 U), co-trimoxazole (sulphamethoxazole-trimethoprim [23.75/1.25 mcg]) and penicillin (10 units/disc) discs (n = 220). The isolates were identified serologically by Hi Strep™ Latex agglutination test Kit (Himedia). Results: The findings showed that the highest percentage of streptococci isolated was from throat swabs (35.5%), followed by sputum (15.9%), urine (14.1%), blood (10.5%), pus (8.6%), cerebrospinal fluid (6.4%), bronchoalveolar lavage (5.9%) and endotracheal tips (3.2%). The highest percentage of BHS belongs to Group C (74, 33.6%), followed by Group G (51, 23.2%), Group B (42, 19.1%), Group F (28, 12.7%), Group A (21, 9.5%) and Group D (4, 1.8%). Conclusions: Rapid identification and consequent prompt treatment of patients with BHS can reduce the risk of spread and aid in the prevention of infections and their serious complications, such as rheumatic fever/rheumatic heart disease, nephritis and local or systemic infections.

Keywords

• endocarditis
• enterococcus
• latex agglutination test
• neonatal septicaemia
• streptococcus