Evaluation of the potential of animal streptococcal isolates belonging to serogroups C and G to elicit acute rheumatic fever.

ABSTRACT

OBJECTIVE: To determine whether groups C and G streptococci (GCS-GGS) isolated from animals have rheumatogenic traits associated with human GCS-GGS isolates, particularly the potential of the bacteria to interact with human collagen type IV (collagen-IV), known to be targeted during acute rheumatic fever (ARF). SAMPLE POPULATION 64 GCS and GGS bacterial strains isolated from infected animals. PROCEDURES Bacteria were analyzed for their ability to bind and aggregate collagen-IV and for the presence of collagen binding factors, such as the hyaluronic acid capsule, cne gene, and emm gene. RESULTS: Collagen-IV binding ability was detected in 19% (n = 12) of the isolates studied. Of the collagen-IV binding strains, 5 expressed hyaluronic acid capsule. Furthermore, emm was detected in the genome of 1 isolate, whereas all remaining collagen-IV binding isolates possessed the cne gene. Of the collagen binding factors investigated, the hyaluronic capsule was the only factor for which collagen-IV interaction could be detected. Investigation of the potential of these strains to aggregate collagen-IV revealed that animal isolates had a nonaggregating phenotype. CONCLUSIONS AND CLINICAL RELEVANCE Despite efficiently binding collagen-IV via hyaluronic acid, animal isolates lacked the ability to initiate aggregation of this protein. Because collagen-IV aggregation is associated with all collagen-IV-binding rheumatogenic strains, this suggested a lack of rheumatogenic potential among animal-derived GCS and GGS and, therefore, a low chance of acquiring ARF through animal contact.