-Campylobacter spp. are the most frequent agent of human gastroenteritis worldwide,
and the spread of multidrug-resistant strains makes the clinical treatment difficult. The
current study presents the resistome analysis of 39,798 Campylobacter jejuni and
11,920 Campylobacter coli genomes available in public repositories. Determinants of
resistance to β-lactams (Be) and tetracyclines (Te) were the most frequent for both
species, with resistance to quinolones (Qu) as the third most important on C. jejuni
and to aminoglycosides (Am) on C. coli. Moreover, resistance to Te, Qu, and Am
was frequently found in co-occurrence with resistance to other antibiotic families.
Geographical differences on clonal complexes distribution were found for C. jejuni and
on resistome genotypes for both C. jejuni and C. coli species. Attending to the resistome
patterns by isolation source, three main clusters of genomes were found on C. jejuni
genomes at antimicrobial resistance gene level. The first cluster was formed by genomes
from human, food production animals (e.g., sheep, cow, and chicken), and food (e.g.,
dairy products) isolates. The higher incidence of tet(O), associated with tetracycline
resistance, and the gyrA (T86I) single-nucleotide polymorphism (SNP), associated with
quinolone resistance, among genomes from this cluster could be due to the intense use
of these antibiotics in veterinary and human clinical settings. Similarly, a high incidence
of tet(O) genes of C. coli genomes from pig, cow, and turkey was found. Moreover, the
cluster based on resistome patterns formed by C. jejuni and C. coli genomes of human,
turkey, and chicken origin is in agreement with previous observations reporting chicken
or poultry-related environments as the main source of human campylobacteriosis
infections. Most clonal complexes (CCs) associated with chicken host specialization
(e.g., ST-354, ST-573, ST-464, and ST-446) were the CCs with the highest prevalence
of determinants of resistance to Be, Qu, and Te. Finally, a clear trend toward an increase
in the occurrence of Te and Qu resistance determinants on C. jejuni, linked to the spread
of the co-occurrence of the bla OXA−61 and tet(O)-tet(O/W/O) genes and the gyrA (T86I)
SNP, was found from 2001 to date in Europe.S