Effect of Incubation Temperature on the Detection of Thermophilic Campylobacter Species from Freshwater Beaches, Nearby Wastewater Effluents, and Bird Fecal Droppings

Abstract

ABSTRACTThis large-scale study compared incubation temperatures (37°C versus 42°C) to study the detection of thermophilicCampylobacterspecies, includingCampylobacter jejuni,C. coli, andC. lari, in various surface water samples and bird fecal droppings around Hamilton Harbor, Lake Ontario. The putative culture isolates obtained from incubation temperatures of 37 and 42°C were confirmed byCampylobactergenus- and species-specific triplex PCR assays targeting the 16S rRNA gene and the 16S-23S rRNA gene internal transcribed spacer (ITS) region. A total of 759 water, wastewater, and bird fecal dropping samples were tested. Positive amplification reactions for the genusCampylobacterwere found for 454 (60%) samples incubated at 37°C, compared to 258 (34%) samples incubated at 42°C.C. jejuni(16%) andC. lari(12%) were detected significantly more frequently at the 42°C incubation temperature than at 37°C (8% and 5%, respectively). In contrast, significantly higher rates ofC. coli(14%) and otherCampylobacterspp. (36%) were detected at the 37°C incubation temperature than at 42°C (8% and 7%, respectively). These results were consistent across surface water, wastewater, and bird fecal dropping samples. At times,Campylobacterspp. were recovered and detected at 37°C (3% forC. jejuni, 10% forC. coli, and 3% forC. lari) when the same samples incubated at 42°C were negative. A significantly higher rate of otherCampylobacterspp. was detected only at 37°C (32%) than only at 42°C (3%). These results indicate that incubation temperature can significantly influence the culturability and detection of thermophilic and other fastidiousCampylobacterspp. and that a comprehensive characterization of theCampylobacterspp. in surface water, wastewaters, or bird fecal droppings will require incubation at both 37 and 42°C.