Abstract
The present study investigated the genomic constitution and antimicrobial resistance (AMR) of 238 Campylobacter from pigs and wild boars in Italy between 2012 and 2019. Campylobacter strains were genotyped using multilocus sequence typing (MLST) and whole genome MLST (wgMLST), screened for antimicrobial resistance genes, and tested for phenotypic susceptibility to six different antibiotics. C. coli was detected in 98.31% and 91.66% of pigs and wild boars, while C. jejuni was isolated in the remaining cases. MLST assigned 73 STs and 13 STs in pigs and wild boars, respectively, including 44 novel STs. The predominant ST in pigs was ST-854 (12.36%), followed by ST-9264 (6.18%). ST-1055 and ST-1417 were predominant in wild boars (30% and 13.33%, respectively). The minimum spanning tree using 1,121 global MLST profiles showed specific Italian clusters and a clear separation between pig and wild boar profiles. The wgMLST confirmed the MLST clustering and revealed a high genetic diversity within C. coli population in Italy. Minimum inhibitory concentrations (MIC) of six antibiotics revealed higher resistance in pigs to ciprofloxacin, nalidixic acid, streptomycin and tetracycline, compared to wild boar. In contrast, most strains were susceptible to gentamicin. Worrying levels of multidrug resistance (MDR) were observed mostly in pig isolates. Molecular screening of AMR mechanisms revealed the predominance of gyrA T86I substitution among fluoroquinolone- and quinolone-resistant isolates, and the 23S rRNA A2075G mutation among macrolide-resistant isolates. Other resistance determinants were observed: (i) tet(O) gene was present among tetracycline-resistant isolates; (ii) rpsL and aph(3’)-III genes conferring resistance to aminoglycosides, were identified only in streptomycin or gentamicin-resistant pig isolates; (iii) cmeA, cmeB, cmeC, cmeR genes responsible of pump efflux mechanisms, were observed in almost all the strains; (iv) OXA-61, encoding β-lactamase, was found in the half of the strains. Genotypic and phenotypic AMR profiling was fairly correlated for quinolones/fluoroquinolones. Campylobacter infection is common also in wild boar populations in Italy, suggesting that wild boars could be a reservoir of resistant and multi-resistant Campylobacter species, which may be of public health concern. The present study adds to our knowledge on the epidemiological and ecological traits of this pathogen in domesticated and wild swine.
Highlights
Campylobacter is known as the most common cause of bacterial gastrointestinal infection in Europe, with the annual number of cases exceeding those of salmonellosis and shigellosis (EFSA & ECDC, 2019)
We analyzed 178 Campylobacter strains isolated from carcasses (53.37%) and fecal content of pigs (46.62%), and 60 Campylobacter strains isolated from feces (83.33%), liver (10%), and muscle (6.67%) of wild boars (Table 1)
We presented a cross-sectional study on Campylobacter from Italian fattening pigs and wild boars using a multiplex approach that included antimicrobial susceptibility test, multilocus sequence typing (MLST), whole genome MLST (wgMLST), and genetic determination of antimicrobial resistance (AMR)
Summary
Campylobacter is known as the most common cause of bacterial gastrointestinal infection in Europe, with the annual number of cases exceeding those of salmonellosis and shigellosis (EFSA & ECDC, 2019). Campylobacter jejuni and Campylobacter coli are the main causative agents of campylobacteriosis, posing a threat to public health worldwide (EFSA & ECDC, 2019). Bloody diarrhea, headache and abdominal pain, nausea and vomiting are the main symptoms of campylobacteriosis in humans. The infection is self-limiting after 3-5 days, but in immunocompromised individuals it can spread into the bloodstream and become potentially lethal (Whitehouse et al, 2018). The antibiotic treatment is required, with macrolides and fluoroquinolones being the drugs of first choice (Mourkas et al, 2019). Campylobacteriosis is a mainly foodborne disease in which foods of animal origin, such as poultry meat, beef and pork, play a primary role (Sheppard et al, 2011)
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