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

OBJECTIVE To evaluate the relationship between group A beta hemolytic streptococcus infection (GABHS) and tic disorders in children. METHODS 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. RESULTS The relationship between tic disorder and GABHS infection (if any of these laboratory tests takes place: throat culture, RADT, ASO > or = 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%. CONCLUSION The result showed correlation between GABHS infection and tic disorder, but it does not mean that GABHS infection caused tic disorder.