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The aim of the study was to identify potential sources of Campylobacter spp. and their prevalences in Greater Berlin area from November 2011 to June 2013. Samples collected from pet animals, farm animals, wild animals and the environment were investigated by two isolation methods – ISO (according to ISO 10272-1:2006) and the Cape Town protocol. Also the presence of antimicrobial resistance in selected C. jejuni and C. coli isolates was determined by Broth Microdilution assays and isolates were genotyped by MLST.
The congruence of both isolation procedures was 11.5 % and the detection rate of Campylobacter was increased by 37.7 % by using a combination of both procedures. The highest prevalence was detected in chicken (74 %) and quails (62.5 %), followed by pigs (32 %), pigeons (20 %), dogs (15.3 %), soil (11.8 %) and cats (11.3 %). Cats having outdoor access had significantly higher chances of being carriers of Campylobacter than cats living exclusively indoors. This could indicate a higher risk for Campylobacter infection in cats due to exposure to a wider range of sources of infection. These results show that pets and their environment should be taken into account to reduce the risk of human Campylobacter infection. The Campylobacter species varied widely depending on the source examined. In pigeons only C. jejuni and in pigs only C. coli was detected in this study. In chicken and quails, both species were detected, whereby C. jejuni was more prevalent than C. coli. Dogs, cats and water samples showed a greater diversity of species, with detection of C. jejuni, C. coli, C. upsaliensis and C. lari. Using a combination of both selective isolation methods in parallel resulted in significantly higher Campylobacter isolation rate regardless of the species examined. Using a single isolation procedure may result in underestimation of the diversity of Campylobacter spp. and multiple infections. This doesn`t refer exclusively to species like C. upsaliensis, C. lari and C. fetus but also to C. jejuni and C. coli. Antimicrobial resistance was observed in 72.3% or the isolates. All strains were sensitive to chloramphenicol and gentamicin. This also applied to erythromycin except in one isolate. Resistances to nalidixic acid (74.5 % of isolates), ciprofloxacin (61.4 %) and tetracycline (42.6 %) were common. Resistance to three antimicrobials or more was present in 86.1 % of isolates. The percentage of antimicrobial resistant isolates was comparable high in both C. jejuni (71.4 %) and C. coli (75 %). These results demonstrate that serious Campylobacter infections require an antimicrobial resistance testing.
High resistance rates were observed in pigs (100 %), quails (86.7 %) and chicken (79.4 %). Nearly half of the cat, dog and pigeon isolates were resistant, whereas environmental isolates were mostly sensitive. Multilocus sequence typing of selected C. jejuni and C. coli isolates showed a high genetic diversity and 26 of the 39 determined sequence types have already been reported for human isolates. However, there was no correlation between MLST sequence type and source of the Campylobacter isolates. The above finding suggests that there are various sources of human infection with Campylobacter.