Throat carriage rate and antimicrobial susceptibility pattern of group A Streptococci (GAS) in healthy Ethiopian school children.

BACKGROUND: Group A Streptococci (GAS) or Streptococcus pyogenes are the most frequent cause of pharyngitis and skin infection in children and lead to post infection complications including acute rheumatic fever and glomerulonephritis. Pharyngeal carriage rates of GAS among healthy school children vary with geographical location and seasons. There is not much information on the screening of children for carriage of GAS in Ethiopia. OBJECTIVES: The study aimed at assessing the carriage rate of Group A Streptococci and antimicrobial susceptibility of the isolates in healthy Ethiopian school children. METHODS: A total of 937 children residing in Addis Ababa (n=491), Gondar (n=265) and Dire-Dawa (n=181) were investigated during a period between November 2004 and January 2005. Throat specimens were collected and cultured using standard procedure. Beta haemolytic streptococci were serogrouped by agglutination tests using specific antisera. Antimicrobial susceptibility testing of the isolates was performed by diffusion method. RESULTS: The median and the mean ages of the study participants were 11 (range 6-14) years. Girls constituted 52% (486/937) of the study participants. A total of 167 (17.8%) beta haemolytic streptococci were recovered from 937 children investigated GAS accounted for 91/167 (54.5%) of beta hemolytic streptococcal isolates. The carrier rate for GAS was 9.7% (91/937) of the screened children followed by group G with 3.2% (30/937) and group C streptococci with 2.2% (21/937). All GAS isolates were sensitive to oxacillin, penicillin, erythromycin, clindamycin and trimethoprim-sulphamethoxazole. Lower frequency of resistance was observed against tetracycline and vanocmycin. CONCLUSION: The present study revealed that GAS was the most predominant beta-haemolytic streptococcus among healthy Ethiopian school children. Our results showed that pharyngeal carriage of GAS in school children should not be underestimated. Therefore it is recommended to conduct regular screening and GAS surveillance in schools, and maintain rational use of antibiotics to minimize GAS resistance.

Long-term antibiotic resistance surveillance of gram-negative pathogens suggests that temporal trends can be used as a resistance warning system.

Antibiotic resistance among Gram-negative bacteria and antibiotic consumption were investigated at the Karolinska Hospital, Stockholm, Sweden over a 12-y period. The investigation showed an increase in ciprofloxacin resistance of Escherichia coli from 0% in 1991 to 7% in 1997 and to 11% in 1999. Resistance among Pseudomonas aeruginosa isolates to ciprofloxacin increased from 2.5% in 1991 to 9.0% in 1997 and to 13% in 1999. Resistance levels for norfloxacin showed the same high statistical significance in terms of the temporal trend. A more detailed analysis showed higher resistance against norfloxacin in specific wards. Relationships between antibiotic use and antibiotic susceptibility showed different patterns. The increased ciprofloxacin resistance of E. coli and P. aeruginosa during the study period was paralleled by an increased consumption of quinolones. During the 12-y study period the total use of cephalosporins increased 2.5-fold, while the levels of E. coli resistance to cefuroxime and cefotaxime remained stable. A third pattern was seen with trimethoprim-sulfamethoxazole, namely increasing resistance of E. coli as the use of trimethoprim-sulfamethoxazole declined. The analysis of resistance levels and antibiotic consumption in the present study suggests different mechanisms for the increased resistance. The significant trend of increased resistance to antibiotics over time constitutes an important warning system.