Antimicrobial resistome of coagulase-negative staphylococci from nasotracheal cavities of nestlings of Ciconia ciconia in Southern Spain: Detection of mecC-SCCmec type-XI-carrying S. lentus.

The antimicrobial resistance (AMR) genes of 268 non-duplicated coagulase-negative staphylococci (CoNS) previously obtained from nasotracheal cavities of nestling storks were characterized. They included S. sciuri isolates (n = 191), and non-sciuri-CoNS isolates (NSc-CoNS, n = 77). All S. sciuri carried the intrinsic salA gene (for clindamycin-resistance) and so, clindamycin was not considered for general analysis in this species. About 71.7%/41.6% of the S. sciuri/NSc-CoNS isolates were susceptible to all antibiotics tested; moreover, 14.1%/16.9% and 3.1%/20.8% of S. sciuri/NSc-CoNS showed single antibiotic resistance and multidrug resistance (MDR) phenotype, respectively. Of the ten mecA-positive CoNS isolates, six were associated with SCCmec types-III, -IV or -V elements. Remarkably was the detection of one MDR-S. lentus isolate carrying both mecA and mecC genes, as well as the SCCmec type-XI element. MDR-CoNS was relatively higher in nestlings of parent storks foraging in landfills (21.3%) than those in natural areas (9.7%) (χ ² = 3.421, df=1, p = 0.064). AMR phenotypes (and genes detected) include penicillin (blaZ, bla _ARL ), erythromycin-clindamycin-constitutive (ermA, ermC, ermT), clindamycin (lnuA, salA, vgaA), erythromycin (msrA, mphC), tetracycline (tetK, tetL, tetM), tobramycin (ant4'), tobramycin-gentamicin (aac6'-aph2″), sulfamethoxazole-trimethoprim (dfrA, dfrG, dfrK), chloramphenicol (fexA, fexB, catPC221), and mupirocin (mupA). Interestingly, one S. epidermidis isolate carried the ermT gene. About 29.9% of nestlings harboured more than one non-duplicated CoNS (with varied 2-5 AMR profiles). This study demonstrated that most of the CoNS isolates were susceptible to all the antibiotics tested (63.1%). However, AMR genes of public health importance were found, including the mecC-mediated methicillin resistance trait.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023. Published by Elsevier Ltd.)