ISPUB.COM The Internet Journal of Infectious Diseases Volume 19 Number 1 DOI: 10.5580/IJID.55640 1 of 6 Bacitracin Differentiation Of Beta-Haemolytic Streptococci Isolated From School Children Living In Uyo, Southern Nigeria K B Edem, E E Ikpeme, M U Akpan Citation K B Edem, E E Ikpeme, M U Akpan. Bacitracin Differentiation Of Beta-Haemolytic Streptococci Isolated From School Children Living In Uyo, Southern Nigeria. The Internet Journal of Infectious Diseases. 2021 Volume 19 Number 1. DOI: 10.5580/IJID.55640 Abstract Objectives Bacitracin Susceptibility has traditionally been accepted as a means of presumptive identification/differentiation of Group A Streptococcus (GAS) from other Beta haemolytic Streptococcal (BHS) strains. This means of identification may indeed be faulty as recent studies have shown that other BHS species are also highly susceptible to Bacitracin. These species and especially Group C (GCS) and Group G (GGS) BHS strains have increasingly been shown to play an important role in human streptococcal disease and in some populations carriage rates of GCS/GGS are higher than GAS rates. The continued use of Bacitracin for presumptive identification would lead to an over-estimation of GAS rates particularly in settings where there is a changing epidemiology of BHS infections. Design and Participants This cross-sectional study was done among two hundred and seventy-six primary school children in Uyo, an urban area in Southern Nigeria. The participants were recruited by multi-stage random sampling. Methods Throat swabs taken from participants were cultured overnight on 5% sheep blood agar. Culture plates identified as positive for BHS were sub-cultured for purity and then inoculated with Bacitracin 0.04U discs for presumptive identification/differentiation of GAS. Lancefield Grouping of streptococcal isolates was also done. Main Outcome Measures The main outcome measures were BHS isolate positivity and Bacitracin susceptibility Results Nine BHS isolates were identified, giving a prevalence of 3.3% among the school children with Lancefield grouping identifying GCS in 89% GGS in 11%. No GAS isolates were found. All isolated GCS/GGS however showed susceptibility to Bacitracin. Conclusion The prevalence of BHS throat carriage in the study area was found to be relatively low. Isolates showed 100% susceptibility to Bacitracin. INTRODUCTION Beta-haemolytic streptococci (BHS) are a group of facultative anaerobic Gram-positive organisms that appear in chains or in pairs and are catalase-negative. 1 They are subdivided into groups by antibodies that recognize their respective surface antigens. These groups may include one or more species. The most important groupable beta- haemolytic streptococci are A, B, C, D, F and G. 1