evaluation of relationship between group A streptococcal infection with tic disorders in children

To evaluate the relationship between group A beta hemolytic streptococcus infection [GABHS] and tic disorders in children. This is a case-control study that was conducted in Child and Adolescent Psychiatric Clinic, Isfahan, Iran, between May 2008 and February 2009. Thirty-six children [aged 5-15] with tic and 36 children without tic and obsessive-compulsive disorder [OCD] were investigated for clinical and laboratory signs of GABHS. The tools utilized in this research were clinical interview according to the DSM IV-TR and laboratory tests [throat culture, rapid antigen detection test [RADT], anti streptolysin O [ASO] and yale global tics severity scale [YGTSS]]. The control group was of the same gender and age as the tic group who had come to the clinic for other illnesses and was in need of blood test. None of the subjects in the case and control groups had a clinical history of GABHS infection. The relationship between tic disorder and GABHS infection [if any of these laboratory tests takes place: throat culture, RADT, ASO >/= 250] in the tic group was 16 [44.4%] and in the control group was 9 [25%], there were significant differences [p<0.05]. No significant correlation was found between ASO titer and YGTSS scores. The specificity of RADT was 100%. The result showed correlation between GABHS infection and tic disorder, but it does not mean that GABHS infection caused tic disorder

Characterisation of group A streptococcal (GAS) isolates from children with tic disorders.

BACKGROUND & OBJECTIVES: An association between the onset or recrudescence of some neuropsychiatric disorders in children such as tic disorders and group A streptococcal (GAS) infections has been suggested. No information is available on the characterization of GAS strains associated with such disorders. The present study was undertaken to characterize the GAS strains isolated from children with tic disorders and to determine and correlate the antistreptolysin O (ASO) titre with the presence of GAS. METHODS: During 1996-2001, 368 children with tic disorders were investigated for possible exposition to streptococcal antigens. All children, at the time of the first visit and during the follow up visits were apparently healthy and showed no clinical evidence of streptococcal infections or post streptococcal sequelae. Blood and throat swab samples were collected and serological and bacteriological tests done. The isolates obtained were investigated for T pattern, M protein and emm type, as well as for the production of protease. RESULTS: Of the 800 throat swabs studied 100, corresponding to 67 patients, were positive for GAS; 49 children were found positive for GAS only once during the study, 18 had more than one sample positive for different serotypes, 8 were positive twice or more for the same type. ASO titres of these children were, in general, elevated. Five types, namely type M12, 3, 13, 11, 1, accounted for 39 per cent of the isolates, M12 being the most common, but a large number of different types were also found. A large number of isolates (62%) showed an elevated prodution of protease in the casein plate assay. INTERPRETATION & CONCLUSION: Despite the high level of ASO titres found, the results were not in favour of a particular virulence or invasivity of the isolates. Only a few colonies per sample were found indicating that factors different from the microbial virulence play a role in this type of disease.