Factors associated with colonization of Streptococcus pneumoniae among under-fives attending clinic in Mwanza City, Tanzania

Abstract

Background: Streptococcus pneumoniae is a known cause of severe invasive bacterial infection leading to morbidity and mortality among children in sub-Saharan Africa. Nasopharyngeal colonization of S. pneumoniae is a critical step towards invasive disease progression. The objective of this study was to investigate the magnitude of nasopharyngeal carriage of S. pneumoniae and its associated factors in Mwanza, Tanzania. 

Methods: Children underfives attending Reproductive and Child Health (RCH) clinics in Mwanza, Tanzania clinics were enrolled and investigated for nasopharyngeal carriage of S. pneumoniae.  Demographic and clinical data were collected using standardized data collection tool. Nasopharyngeal swabs were taken and processed as per standard laboratory procedures. S. pneumoniae isolates were identified using conventional methods. Antimicrobial susceptibility testing was performed using the disc diffusion method as described by Clinical Laboratory Standard Institute.Results: Among 350 children enrolled in the study, 172 (49.1) were females and 309 (88.3%) were below 2 years of age.  A total of 253 (72.3%) children had received at least one dose of pneumococcal vaccine (Prevanar 13) whereas 83 (23.7%) had used antibiotics at median duration of 5 days in the past 14 days.  Out of 350 underfives, 43 (12.3%) were found to carry S. pneumoniae in their nasopharynx. Children with chronic diseases and those at school were 3.4 and 4.4 times more at risk to be carriers of S. pneumoniae than their counterpart group (OR; 3.4 (CI(1.0-11.6) 95%, p=0.05) and OR; 4.4 (CI (1.2-15.7) 95%, p=0.023), respectively.  Number of children at home, positive HIV status and someone smoking showed association with S. pneumoniae carriage but the differences were not statistically significant. The resistance levels of S. pneumoniae to penicillin, co-trimoxazole and erythromycin were 40%, 88.2% and 41.7%, respectively. However all of the S. pneumoniae isolates were found to be 100% sensitive to ciprofloxacin.

Conclusion: A high nasopharyngeal carriage of penicillin resistant S. pneumoniae is observed in Mwanza, Tanzania despite a good coverage of pneumococcal vaccination. The carriage is significantly associated with schooling and presence chronic diseases. Continuous surveillance of penicillin resistant strains coupled with serotyping of the isolates is highly recommended to determine the influence of the pneumococcal vaccination.