Evidence Indicating That Desulfovibrio Species May Play An Important Role In Autism, Pilot Study

Background:  In 2007, the incidence of autism in the US was 1%. We previously documented significant differences in bacterial phyla in feces of autistic children and controls. 

Objectives:   To study the incidence of Desulfovibrio in stools of children with regressive autism.

Methods:  Blinded stool specimens from children with autism, healthy sibling controls, and non-sibling controls were studied by anaerobic culture and real-time PCR.  Desulfovibrio was identified by 16S rRNA sequencing.  Desulfovibrio was tested for antimicrobial susceptibility using the CSLI procedure.

Results: There was overall agreement between culture and real-time PCR results (p value = 0.005). Autistic subjects had statistically significantly higher percent of stools positive for Desulfovibrio by culture or real-time PCR compared to control subjects (p value=0.003).  Comparison of autism severity with percent positive for Desulfovibrio by culture or real-time PCR showed a dose response (p value = 0.03).  Using culture or real-time PCR showed a sensitivity of 47%, specificity of 90%, and unweighted accuracy of 68%. The Desulfovibrio strains were β-lactamase-positive and resistant to various antimicrobials, such as trimethoprim/sulfamethoxazole.

 Conclusions:   Our results indicate that Desulfovibrio may account for the pathophysiology of autism and its resistance to antimicrobials may precipitate autism in predisposed children. If these studies are confirmed and extended by a treatment trial that correlate elimination of Desulfovibrio with clinical  and physiologic improvement, they could lead to 1) reliable classification of autism, 2) a diagnostic test for regressive autism (real-time PCR gives accurate, quantitative results in 2-3 hours), 3) antimicrobial therapy,  4) treatment with preformed antibodies against the organism,  5) tailored probiotics /prebiotics for therapy and prophylaxis, 6) prevention with an oral vaccine, 7) clues to diets that might limit colonization with Desulfovibrio and  8) epidemiologic information that could explain the rapid increase in autism and the presence of multiple cases in families and confirm the important role of certain antimicrobial agents in causation of autism.