Studies on the identification of Campylobacter species using biochemical tests and high-performance liquid chromatography

Abstract

A total of 56 strains of Campylobacter jejuni (C. jejuni) isolated from diarrhoeal patients were characterized by biochemical tests. The following reactions were performed: hydrolysis of hippurate, reduction of nitrate and nitrite, activity of deoxyribonuclease, hydrolysis of Tween(R) 40, 60 and 80. Including the hydrolysis of the different Tweens(R), 14 biotypes could be distinguished. 19 out of the 56 strains of C. jejuni and the nomenclatural type strains of C. jejuni, C. coli, C. laridis, C. fetus subsp. fetus, subsp. venerealis, C. faecalis, C. sputorum subsp. sputorum, subsp. mucosalis, subsp. bubulus were examined for the production of volatile (VFA) and non-volatile (NVFA) short-chain fatty acids using high performance liquid chromatography (HPLC) with a column for organic acids (Aminex HPX-87 H). A standard mixture of 21 short-chain fatty acids was taken as reference. By this method 5 biotypes of C. jejuni could be characterized. The most frequent biotype was type 1 (78.9%). All the biotypes produced succinic, acetic and butyric acids. Differences existed in the production of pyruvic, malonic, formic and isobutyric acids. C. jejuni could rapidly and clearly be distinguished from C. coli, C. fetus subspp. and catalase-negative Campylobacter species. No qualitative differences were found between the subspecies of C. fetus, C. sputorum subsp. sputorum and subsp. bubulus, C. sputorum subsp. mucosalis and C. faecalis were characterized by presence of fumaric and malonic acid, respectively.