DNA fingerprinting of Streptococcus zooepidemicus (Lancefield group C) as an aid to epidemiological study

A collection of Streptococcus zooepidemicus strains from human and animal infections was examined for DNA banding patterns after nuclease digestion and agarose gel electrophoresis. The large variety of DNA fingerprints found revealed the complexity of the species but showed that isolates from clusters of outbreaks had identical prints. The results confirmed the specificity of bacteriocin and bacteriophage typing of S. zooepidemicus; the technique also gave useful profiles on untypable strains. Strains with common bacteriocin and biotyping patterns from sporadic infections could be differentiated by their DNA fingerprints. In several outbreaks and incidents, more than one strain of S. zooepidemicus were encountered, and the importance of carefully interpreting typing data is stressed. Chromosomal DNA fingerprinting is a very efficient technique for demonstrating differences between strains of S. zooepidemicus, and its use is recommended for future epidemiological studies of this infectious agent.