Prevalence and antibiotic susceptibility of group A beta-haemolytic streptococcal isolates in children presenting with acute pharyngitis in Lusaka, Zambia

Abstract

Background. Group A beta-haemolytic streptococci (GABHS)-associated pharyngitis can complicate into rheumatic fever and rheumatic heart disease (RHD).

Objectives. To determine the prevalence and antibiotic susceptibility of GABHS isolates in children presenting with acute pharyngitis and assess the utility of Zambian Treatment Guideline (ZTG) criteria as a local clinical scoring system.

Methods. This descriptive cross-sectional study was conducted at the paediatric outpatient department of the University Teaching Hospital in Lusaka, Zambia. The study cohort, comprising children aged 3 - 15 years (n=146), were recruited as presenting with symptoms of pharyngitis. The children underwent a clinical assessment that included a detailed case history, presenting symptoms and a throat swab that was subsequently cultured. Microbial isolates were typed and the antibiotic sensitivity of cultured GABHS to penicillin and erythromycin determined.

Results. GABHS were cultured from 22 (15.1%) children within this study. All the GABHS isolates (n=22) were susceptible to penicillin G; however, 19% of isolates displayed reduced susceptibility to erythromycin. None of the ZTG criteria, when used individually, was sufficiently sensitive to detect GABHS pharyngitis among this cohort.

Conclusion. The prevalence of GABHS pharyngitis is similar that been described elsewhere. While GABHS remains highly susceptible to penicillin, which is used in the local RHD control programmes, concern remains for children treated with erythromycin owing to the resistance noted in some of the isolates. The ZTG clinical criteria displayed poor sensitivity in identifying GABHS pharyngitis. This has significant implications for effective diagnosis and treatment of pharyngitis and associated complications within this high RHD endemic area.