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.

Prevalence, antimicrobial susceptibility and virulence gene profiles of Arcobacter species isolated from human stool samples, foods of animal origin, ready-to-eat salad mixes and environmental water

“…High resistance rates pose a serious risk to public health as erythromycin is critically important for treatment of campylobacteriosis and it was suggested to be used in Arcobacter infections [68]. As described in previous studies, we also found that the majority of azithromycin MICs (96.2%) were equal to or above the C. jejuni ECOFF (0.25 µg/ml) [19,63]. MIC data for azithromycin indicated the presence of a subpopulation with reduced susceptibility.…”

“…According to other authors, A. cryaerophilus and A. skirrowii can also be isolated from human stool samples. However, the latter is only rarely detected due to slow growth on culture media and overgrowth by other bacteria, while the prevalence of A. cryaerophilus is up to 6.7-fold lower compared to A. butzleri [14,17,19,36,37]. These are probably the main factors that caused lower species diversity in this study.…”

“…Therefore, elevated MICs (≥ 8 µg/ml) were determined for 130 (67.7%) A. butzleri and 2 (12.5%) A. cryaerophilus strains. Similarly, Brückner et al [19] observed elevated MIC values (> 8 µg/ml) for 54.2% A. butzleri and 10% A. cryaerophilus strains. Divergent MIC distribution patterns for macrolides are consistent with the results of a recent study from Germany that tested the in vitro susceptibility of clinical Arcobacter strains using the same methodology [19].…”

“…were detected in 1.3% (89/6774) and 1.7% (5/298) of clinical stool samples respectively [14,33]. Other studies, conducted in Turkey, Germany, New Zealand, India, Chile and Belgium, reported different prevalence rates ranging from 0.3 to 4% [17][18][19][34][35][36]. After identi cation using multiplex PCR and veri cation by rpoB sequencing all isolates were classi ed as A. butzleri.…”

“…To date, the reported prevalence of Arcobacter among humans range from 0.3 to 4% [17,18]. Recent studies have shown that Arcobacter was the second and fourth most common bacterial pathogen isolated from human stool samples in Germany and Belgium, respectively [14,19].…”