Prevalence and antimicrobial susceptibility of Arcobacter species in human stool samples derived from out- and inpatients: the prospective German Arcobacter prevalence study Arcopath

Abstract Background: Arcobacter species, particularly A. butzleri, but also A. cryaerophilus constitute emerging pathogens causing gastroenteritis in humans. However, isolation of Arcobacter may often fail during routine diagnostic procedures due to the lack of standard protocols. Furthermore, defined breakpoints for the interpretation of antimicrobial susceptibilities of Arcobacter are missing. Hence, reliable epidemiological data of human Arcobacter infections are scarce and lacking for Germany. We therefore performed a 13-month prospective Arcobacter prevalence study in German patients. Results: A total of 4646 human stool samples was included and Arcobacter spp. were identified from 0.85% of specimens in 3884 outpatients and from 0.40% of specimens in 752 hospitalized patients. Overall, A. butzleri was the most prevalent species (n = 24; 67%), followed by A. cryaerophilus (n = 10; 28%) and A. lanthieri (n = 2; 6%). Whereas A. butzleri, A. cryaerophilus and A. lanthieri were identified in outpatients, only A. butzleri could be isolated from samples of hospitalized patients. Antimicrobial susceptibility testing of Arcobacter isolates revealed high susceptibilities to ciprofloxacin, whereas bimodal distributions of MICs were observed for azithromycin and ampicillin.Conclusions: In summary, Arcobacter including A. butzleri, A. cryaerophilus and A. lanthieri could be isolated in 0.85% of German outpatients and ciprofloxacin rather than other antibiotics might be appropriate for antibiotic treatment of infections. Further epidemiological studies are needed, however, to provide a sufficient risk assessment of Arcobacter infections in humans.