Abstract
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 genes lukF/S-PV, tst, eta, etb, etd and scn was investigated by PCR. Moreover, CoNS carrying the mecA gene were subjected to SCCmec typing. 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 of S. sciuri (n = 118) and S. lentus (n = 25). A total of 34% of CoNS isolates showed a multidrug resistance phenotype, and 42 mecA-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) and sal(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 the lukF/S-PV, eta, etb, etd and scn genes, but two S. sciuri isolates (1%) carried the tst gene. Wild birds are frequently colonized by CoNS species, especially S. 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.
Highlights
Staphylococci can be divided in two major groups based on their capacity to produce the enzyme coagulase and, their ability to clot the blood plasma: coagulase-positive (CoPS) and coagulase-negative staphylococci (CoNS)
CoNS have been postulated as an important reservoir of antimicrobial resistance genes that are often located on mobile genetic elements, and, could be transferred to more pathogenic bacteria, such as S. aureus, by horizontal gene transfer [3,4,9,10]
The following patterns of co-carriage of CoNS species were detected among the positive birds: S. sciuri/S. lentus (12/red kite), S. sciuri/S. fleurettii (5/cinereous vulture), S. sciuri/S. xylosus (2/cinereous vulture), S. sciuri/S. kloosii (2/cinereous vulture and European honey buzzard), S. epidermidis/S. capitis (1/magpie), S sciuri/S. epidermidis (1/ northern bald ibis), S. saprophyticus/ S. kloosii (1/ European honey buzzard), S. sciuri/S. fleurettii/S. schleiferi subsp. schleiferi (1/ bearded vulture), and S. sciuri/S. lentus/S. vitulinus/S. xylosus (1/ western marsh harrier)
Summary
Staphylococci can be divided in two major groups based on their capacity to produce the enzyme coagulase and, their ability to clot the blood plasma: coagulase-positive (CoPS) and coagulase-negative staphylococci (CoNS). CoNS constitute a very heterogeneous group that comprise over 40 commensal species of the mucous membranes and skin of humans and other animals, especially mammals and birds [1,2,3,4]. CoNS have been postulated as an important reservoir of antimicrobial resistance genes that are often located on mobile genetic elements, and, could be transferred to more pathogenic bacteria, such as S. aureus, by horizontal gene transfer [3,4,9,10]. The CoNS belonging to the Staphylococcus sciuri group, which includes S. sciuri, S. fleurettii, S. lentus, S. vitulinus and S. stepanovicii, are especially relevant because of their role in the origin, evolution and spread of the mecA gene [4,11]. Regarding the pathogenicity of CoNS, former studies have reported major virulence factors of S. aureus (e.g., Panton–Valentine leukocidin, toxic shock syndrome toxin and exfoliative toxins) in CoNS recovered from humans, livestock and the livestock environment, their detection is still highly unusual [1,2,12,13]
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