[Enzymatic activities of Campylobacter jejuni, C. coli, and C. lari]

Susceptibility to nalidixic acid has been considered for a long time as an important test in the identification of the different species of the genus Campylobacter. However, due to the increasing development of resistance new laboratory tests are needed to carry out an accurate identification to the species level in combination with other typing schemes. We have evaluated the enzymatic activity of 180 Campylobacter spp. strains isolated from clinical specimens performing the Api ZYM system (bioMérieux) in order to assay whether different enzymatic patterns could help to characterize these microorganisms. Thirteen of the 19 enzymatic activities detected by the system (lipase-C14, valine arylamidase, cystine arylamidase, trypsin, chymiotrypsin, alpha-galactosidase, beta-galactosidase, beta-glucuronidase, alpha-glucosidase, beta-glucosidase, N-acetyl-beta-glucosaminidase, alpha-manosidase and alpha-fucosidase) were negative for all the strains tested, whereas 3 enzymes (alkaline phosphatase, acid phosphatase and naphtol-A-S-BI-phosphohydrolase) were detected in 96.6% of the strains. Esterase-C1, esterase lipase-C8 and leucin arylamidase showed a variable reactivity depending on isolates. Enzymatic activity patterns clearly differentiate all the C. lari strains from other Campylobacter species. No significant differences were detected among the enzymatic activities of C. jejuni and C. coli strains. Our study suggests that the Api ZYM system is easy to perform and a valuable method to be applied in the characterization of the campylobacteria as a complement to other biotyping and serotyping schemes.