Occurrence of ‘thermophilic’ campylobacters in sewage and their removal by treatment processes

Abstract

SUMMARYRemoval of thermophilic campylobacters from sewage at three different stages of treatment at a trickling filter sewage works has been assessed. Samples of incoming sewage, primary sedimentation effluent and final effluent were taken daily from 06.00 h to 20.00 h for 5 consecutive days and the numbers of campylobacters determined by using a most probable number method. Each sample was cultured using 2 h pre-enrichment followed by enrichment in Preston broth for 48 h and detection by plating. Over 78 % of the incoming campylobacters were removed after primary sedimentation and < 0-1 % remained in the final effluent. Campylobacter jejuni biotype I and biotype II constituted 81-5 % and 15-9 % respectively of the 232 isolates tested. Serotypes common in sewage were common in human faeces. It appears that the trickling filter sewage works removes most of the campylobacters entering the sewage works, but large numbers, estimated to be approximately 1010, are released into the environment daily from a local sewage works.

Diversity of Campylobacter Isolates from Three Activated Sludge Systems

“…Finally, analysis of species and biotype distribution at the sewage plants showed the predominance of C. jejuni biotypes I and II, in agreement with data reported by others (Taylor et al 1983, Carter et al 1987, Arimi et al 1988, Jones et al 1990c, Stampi et al 1992. This is explained by the fact that C. jejuni is the species most frequently detected in man and most frequently responsible for enteritis caused by campylobacters, probably reflecting its best adaptation and diffusion among human beings.…”

“…Furthermore, Arimi et al (1988) and Höller (1988) have reported that the reduction of campylobacters during the final step of treatment reached levels of 99.6 and 100%, respectively. In this respect, it should be pointed out that the Governador Island sewage plant was working at reduced capacity throughout 1990 due to repairs (Table IV), what may explain the lower rate of Campylobacter elimination obtained at this plant compared to the Penha plant (Table V).…”

“…Another interesting aspect was the detection of a high percentage of untyped strains at all sewage treatment plants (Tables III, IV, V). A possible explanation for this fact is the hypothesis of environmental effects or even selective pressure on the microorganisms (Arimi et al 1988, Höller 1988, Jacob et al 1990, Jones et al 1990b. In general, survival of campylobacters in sewage may be limited by the high organic load (Höller & Schomakers-Revaka 1994).…”

Specific Detection of Arcobacter and Campylobacter Strains in Water and Sewage by PCR and Fluorescent In Situ Hybridization

“…It has been suggested that the distribution of sewage sludge to land may be one of the routes by which thermophilic campylobacters reenter the human food chain (3). Previous studies have shown that sewage and sewage sludge, respectively, contain campylobacters in concentrations of 10 2 to 10 5 CFU/100 ml and 10 1 to 10 3 CFU/100 ml, respectively (12,27).…”

Use of Pulsed-Field Gel Electrophoresis and Flagellin Gene Typing in Identifying Clonal Groups of Campylobacter jejuni and Campylobacter coli in Farm and Clinical Environments

“…They have been isolated from the feces of domestic farm animals, including beef cattle (8,10), dairy cows, and sheep (21). In order to elucidate possible sources of sporadic Campylobacter infection, phenotypic typing methods such as biotyping and serotyping have been applied to Campylobacter isolates from animal and environmental sources, as well as clinical strains (2,10,23). Epidemiological traceback conclusions based on these typing methods are tentative because of the limited discriminatory potential of the techniques.…”