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

This large-scale study compared incubation temperatures (37 degrees C versus 42 degrees C) to study the detection of thermophilic Campylobacter species, including Campylobacter jejuni, C. coli, and C. 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 degrees C were confirmed by Campylobacter genus-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 genus Campylobacter were found for 454 (60%) samples incubated at 37 degrees C, compared to 258 (34%) samples incubated at 42 degrees C. C. jejuni (16%) and C. lari (12%) were detected significantly more frequently at the 42 degrees C incubation temperature than at 37 degrees C (8% and 5%, respectively). In contrast, significantly higher rates of C. coli (14%) and other Campylobacter spp. (36%) were detected at the 37 degrees C incubation temperature than at 42 degrees C (8% and 7%, respectively). These results were consistent across surface water, wastewater, and bird fecal dropping samples. At times, Campylobacter spp. were recovered and detected at 37 degrees C (3% for C. jejuni, 10% for C. coli, and 3% for C. lari) when the same samples incubated at 42 degrees C were negative. A significantly higher rate of other Campylobacter spp. was detected only at 37 degrees C (32%) than only at 42 degrees C (3%). These results indicate that incubation temperature can significantly influence the culturability and detection of thermophilic and other fastidious Campylobacter spp. and that a comprehensive characterization of the Campylobacter spp. in surface water, wastewaters, or bird fecal droppings will require incubation at both 37 and 42 degrees C.