Cellular fatty acid analysis and enzyme profiles of Porphyromonas catoniae - A frequent colonizer of the oral cavity in children

During a previous study on the Gram-negative anaerobic microflora in children we frequently isolated a non-pigmented Prevotella-like species with phenotypic characteristics not conforming to those of previously described species at the time. Among recently described Gram-negative anaerobic bacilli isolated from gingival crevices Porphyromonas catoniae (Bacteroides D26) most closely resembled our isolates biochemically which also typically produced a large amount of propionic acid. Sixty-three isolates originated from oral mucosal surfaces pooled to saliva and from the gingival crevices of 23 healthy children (mean age 32 months). In addition, one biochemically similar strain which was isolated from an abdominal abscess was included in the tests. The aim of the present study was to determine the cellular fatty acid (CFA) composition for the precise identification of our isolates, and further, to determine the enzyme profiles by API ZYM to emend the description of this species. CFA profiles agreed with the identification of Bacteroides D26 (P. catoniae). API ZYM patterns revealed positive reactions for beta-galactosidase, alpha-glucosidase (except for one isolate), N-acetyl-beta-glucosaminidase and alpha-fucosidase, and variable reactions for leucine arylamidase, trypsin, chymotrypsin and alpha-galactosidase. However, numerical analysis of the CFA data separated this species into at least three subgroups. Twenty-five oral isolates formed one subgroup which most closely resembled the type strain (ATCC 51270). The ubiquitous presence of P. catoniae in moderate numbers in the studied oral samples suggests that this anaerobic species belongs to the normal oral nora of children even at this young age; nevertheless, it may occasionally act as an opportunistic pathogen outside the oral cavity. (C) 1996 Academic Press