Throat colonization and antibiotic susceptibility of group a β-hemolytic streptococci among rheumatic heart disease patients attending Jakaya Kikwete Cardiac Institute

Abstract

Background: Rheumatic Heart Disease (RHD), a complication of Acute Rheumatic Fever (ARF) caused by Group A β-hemolytic Streptococci (GAS) is a major cause of cardiovascular morbidity and mortality in young people in developing countries. If not prevented, recurrence of ARF causes worsening of RHD. Therefore, WHO recommends that all patients with confirmed RHD receive secondary prophylaxis against repeated attacks of ARF. The recommended drug is a long-acting penicillin. For patients allergic to penicillin; sulfadiazine, sulfisoxazole or erythromycin is recommended. Implementation of effective secondary prophylaxis is faced with challenges due to inadequate access to healthcare, prevailing threat of antibiotic resistance as well as physicians’ awareness on the importance of secondary prophylaxis to RHD patients. Therefore, there is a need to explore the prevalence and factors causing GAS colonization among RHD patients. Aim: The aim of this study was to assess throat colonization, antibiotic susceptibility and factors associated with GAS colonization among RHD patients attending Jakaya Kikwete Cardiac Institute (JKCI) in Dar es Salaam.

Methodology: A cross sectional study was conducted at JKCI in which 194 RHD patients aged ≥5 years were enrolled in the study over a period of two months from March to May 2018 to. A structured questionnaire was used to obtain socio-demographic information of the patients as well as factors associated with GAS colonization. In addition, a Morisky drug adherence tool was used to assess the status of penicillin prophylaxis adherence. Throat swabs were taken and cultured to determine the presence of GAS among patients. Isolates of GAS were tested for antibiotic susceptibility by using Kirby-Bauer disk diffusion method according to the Clinical and Laboratory Standards Institute(CLSI) version 2015 standards procedures. Antibiotics of interest were chosen according to the Tanzania Treatment Guidelines and the prescribing patterns of physicians

Results: Out of 194 patients, 12.9% had positive cultures for GAS. Prophylaxis status was independently and significantly associated (p = 0.043) with GAS colonization in multivariate logistic regression analysis. Specifically, patients who stopped prophylaxis were 3.26 times more likely (95% CI = 1.04-10.24) to be colonized by GAS when compared to patients on regular prophylaxis. Majority (96%) of GAS isolates were susceptible to Penicillin, Ceftriaxone and Ciprofloxacin. A small proportion (4%) resistance was observed among Erythromycin, Oxacillin and Co-trimoxazole, with 8% resistance observed for chloramphenicol and 20% for Vancomycin. No GAS resistance was observed against Penicillin, Ceftriaxone, Tetracycline, Ciprofloxacin and Clindamycin. Conclusion and Recommendations: The throat colonization of GAS among RHD patients suggest inadequate prophylaxis. It is recommended that guidelines should be followed with regard to initiation and duration of prophylaxis. In addition, education on the importance of prophylaxis should be provided to patients and health care providers.