fThe lack of epidemiologic data on invasive Streptococcus pyogenes infections in many developing countries is concerning, as S. pyogenes infections are commonly endemic in these areas. Here we present the results of the first prospective surveillance study of invasive Streptococcus pyogenes infections in India. Fifty-four patients with invasive S. pyogenes infections were prospectively enrolled at two study sites, one in the north and one in the south of India. Sterile-site isolates were collected, and clinical information was documented using a standardized questionnaire. Available acute-phase sera were tested for their ability to inhibit superantigens produced by the patient's own isolate using a cell-based neutralizing assay. The most common clinical presentations were bacteremia without focus (30%), pneumonia (28%), and cellulitis (17%). Only two cases of streptococcal toxic shock syndrome and no cases of necrotizing fasciitis were identified. Characterization of the isolates revealed great heterogeneity, with 32 different emm subtypes and 29 different superantigen gene profiles being represented among the 49 sterile-site isolates. Analyses of acute-phase sera showed that only 20% of the cases in the north cohort had superantigen-neutralizing activity in their sera, whereas 50% of the cases from the south site had neutralizing activity. The results demonstrate that there are important differences in both clinical presentation and strain characteristics between invasive S. pyogenes infections in India and invasive S. pyogenes infections in Western countries. The findings underscore the importance of epidemiologic studies on streptococcal infections in India and have direct implications for current vaccine developments.
The objective of this study was to determine the antibiotic resistance amongst beta-haemolytic streptococci (BHS) from North India. A total of 155 BHS isolates, comprising group A streptococci (GAS) (102), group C streptococci (GCS) (25) and group G streptococci (GGS) (28), collected from patients with pharyngitis, rheumatic fever, skin disease and invasive disease were analysed for their antimicrobial susceptibility to 20 antibiotics using the Kirby-Bauer disc diffusion method. The MICs of penicillin, tetracycline, clarithromycin, azithromycin and erythromycin were also determined using the HiComb test, following the Clinical and Laboratory Standards Institute guidelines. The results showed that 37.4 % of BHS isolates were susceptible to all antibiotics and 19.4 % were highly resistant to tetracycline; however, only 2.6-5.2 % were resistant to macrolides. The tetracycline resistance (P,0.05) of BHS was found to be statistically significant. GAS isolates from different sources of infection also showed statistically significant antibiotic resistance to azithromycin (P50.029). Multi-drug resistance was found irrespective of streptococcal emm types. No association between GAS emm types and drug resistance was seen. MIC determination showed all isolates to be susceptible to the five antibiotics tested, except for two GAS and one GGS isolates that were resistant to clarithromycin, and one GAS skin isolate that was resistant to tetracycline. This study suggests that the variation in antibiotic resistance amongst BHS isolates from North India is independent of the isolation source and emm type distribution, hence emphasizing the need for a longitudinal surveillance in different regions of India.
Results showed an association between streptococcal disease progression and the age-related development of immunity to the conserved regions. Hence, these peptides could be considered protective in impeding streptococcal infections worldwide.
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