Immune response against M protein-conserved region peptides from prevalent group A Streptococcus in a North Indian population.

BACKGROUND: Group A streptococci (GAS) cause infections with a high prevalence in most developing countries. A GAS vaccine under trial that is based on the amino-terminus of the M protein provides type-specific immunity, and hence seems ineffective in India because of heterogeneous emm types. However, the conserved C-terminal region of the M protein protects against multiple serotypes. In this paper, the immune response generated against the conserved C-repeat region of the M protein was checked in an Indian population to establish their vaccine candidature. METHODS: When screened for GAS, patients with pharyngitis, rheumatic fever/rheumatic heart disease (RF/RHD), and invasive disease showed heterogeneous emm types, out of which five prevalent types (1-2, 11, 49, 75 and 112) were selected for the study. The C-terminal region of their M proteins showed conserved C1-, C2-, and C3-repeats. The C1-repeat was more diverse and had two different J14-like sequences. Peptides to these C-terminal regions (J14.1 and J14-R6) were designed. Antibodies against these peptides were analyzed using the sera of 130 GAS-infected volunteers. RESULTS: Serum antibodies were significantly higher in patients with acute rheumatic fever, RHD, and invasive disease than in patients with pharyngitis or the healthy controls. The serum antibodies to these peptides was higher in teenagers and adults than in children. CONCLUSION: 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.

Streptococcal pharyngitis, rheumatic fever and rheumatic heart disease: Eight-year prospective surveillance in Rupnagar district of Punjab, India.

BACKGROUND: Rheumatic fever (RF)/rheumatic heart disease (RHD) continue to be a neglected public health priority. We carried out a registry-based control project, prospective surveillance and sample surveys to estimate the burden of disease. METHODS: We trained healthcare providers and established a surveillance system for the 1.1 million population of Rupnagar district in Punjab. In sample surveys conducted among schools, physicians examined the sampled children. Children with a cardiac murmur were investigated by echocardiography. Throat swabs were obtained from a sub-sample, and group A streptococci (GAS) were identified and emm typed by standard laboratory methods. We estimated the morbidity rates for RF/RHD from surveillance data and school surveys using a correction factor to account for under-registration of cases in the registry. RESULTS: A total of 813 RF/RHD cases were registered from 2002 to 2009. Of the 203 RF and 610 RHD cases, respectively, 51.2% and 36.7% were males. In the age group of 5-14 years, RF was more common (80%) than RHD (27%). The prevalence of RF/RHD in 5-14-year-old students was 1.0/1000 (95% CI 0.8-1.3). The school survey indicated that about two-thirds of the RF/RHD cases were enrolled in the hospital-based registries. Based on the school survey, the prevalence of RF/RHD was estimated to be 143/100,000 population. In the registry, the annual incidence of acute RF was estimated to be at least 8.7/100 000 children in the age group of 5-14 years. The prevalence of GAS was 2% (13/656) in children with sore throat and 0.5% (14/2920) among those not having sore throat. Typing of 27 GAS revealed 16 emm types. We estimate that about 1000 episodes of GAS pharyngitis lead to one episode of acute RF. CONCLUSION: RF/RHD continue to be a public health problem in Punjab, India.

Antimicrobial susceptibility pattern of ß-haemolytic group A, C and G streptococci isolated from North India.

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 (P=0.029). 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.

Clinical and microbiologic characteristics of invasive Streptococcus pyogenes infections in north and south India.

The 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.