Short-term evidence of Campylobacter in a treatment plant and drain water of a connected poultry abattoir

To study the prevalence of Campylobacter in a purification plant, the numbers of Campylobacter in the wastewater and the effluent of an activated sludge system and in the drain water of a poultry abattoir, connected with this plant were determined in three 24-hour periods. To study transmission routes, the Campylobacter isolates were identified by Penner serotyping and by antimicrobial susceptibility testing. The poultry abattoir drain water was considerably contaminated with Campylobacter (average >5.1 log(10) MPN/100 mL). The numbers of Campylobacter present in the wastewater and the effluent of the activated sludge system did not increase significantly during the sampling period. The purification resulted in a reduction of 1 log(10) unit, but Campylobacter was still detectable in the activated sludge effluent. Patterns in the antimicrobial susceptibility and serotypes did not match for the various types of samples, and therefore, no transmission route could be deduced. This incongruity of patterns may be due to growth competition during the enrichment. Therefore, enrichment procedures are not recommendable for studies on transmission routes.