Frequency and Characterization of Antimicrobial Resistance and Virulence Genes of Coagulase-Negative Staphylococci from Wild Birds in Spain. Detection of tst -Carrying S. sciuri Isolates.

The objective of this study was to determine the prevalence and diversity of coagulase-negative staphylococci (CoNS) species from wild birds in Spain, as well as to analyze the antimicrobial resistance phenotype/genotype and the virulence gene content. During 2015-2016, tracheal samples of 242 wild birds were collected in different regions of Spain for staphylococci recovery. The species identification was performed using MALDI-TOF. The antimicrobial resistance phenotype and genotype was investigated by the disk diffusion method and by PCR, respectively. The presence of the virulence geneslukF/S-PV,tst,eta,etb,etdandscnwas investigated by PCR. Moreover, CoNS carrying themecAgene were subjected to SCCmectyping. Of the tested animals, 60% were CoNS-carriers, and 173 CoNS isolates were recovered from the 146 positive animals, which belonged to 11 species, with predominance ofS. sciuri(n= 118) andS. lentus(n= 25). A total of 34% of CoNS isolates showed a multidrug resistance phenotype, and 42mecA-positive methicillin-resistant CoNS (MRCoNS) were detected. The isolates showed resistance to the following antimicrobials (percentage of resistant isolates/antimicrobial resistance genes detected): penicillin (49/blaZ,mecA), cefoxitin (24/mecA), erythromycin and/or clindamycin (92/erm(B),erm(C),erm(43),msr(A),mph(C),lnu(A),lsa(B),vga(A) andsal(A)), gentamicin and/or tobramycin (5/aac(6 ')-Ie-aph(2 ")-Ia,ant(4 ')-Ia), streptomycin (12/str), tetracycline (17/tet(K),tet(L),tet(M)), ciprofloxacin (4), chloramphenicol (1/fexA), fusidic acid (86/fusB,fusD) and trimethoprim-sulfamethoxazole (1/dfrK). None of the isolates harbored thelukF/S-PV,eta,etb,etdandscngenes, but twoS. sciuriisolates (1%) carried thetstgene. Wild birds are frequently colonized by CoNS species, especiallyS. sciuri. We identified scavenging on intensively produced livestock and feeding on landfills as risk factors for CoNS carriage. High proportions of MRCoNS and multidrug resistant CoNS were detected, which coupled with the presence of important virulence genes is of concern.