Genetic Characterization of Methicillin-Resistant <i>Staphylococcus aureus</i> Isolates from Human Bloodstream Infections: Detection of MLS<sub>B</sub> Resistance
Vanessa Silva,
Sara Hermenegildo,
Catarina Ferreira,
Célia M. Manaia,
Rosa Capita,
Carlos Alonso-Calleja,
Isabel Carvalho,
José Eduardo Pereira,
Luis Maltez,
José L. Capelo,
Gilberto Igrejas,
Patrícia Poeta
Affiliations
Vanessa Silva
Microbiology and Antibiotic Resistance Team (MicroART), Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
Sara Hermenegildo
Microbiology and Antibiotic Resistance Team (MicroART), Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
Catarina Ferreira
CBQF—Centro de Biotecnologia e Química Fina-Laboratório Associado, Universidade Católica Portuguesa, Escola Superior de Biotecnologia, 4169-005 Porto, Portugal
Célia M. Manaia
CBQF—Centro de Biotecnologia e Química Fina-Laboratório Associado, Universidade Católica Portuguesa, Escola Superior de Biotecnologia, 4169-005 Porto, Portugal
Rosa Capita
Department of Food Hygiene and Technology, Veterinary Faculty, University of León, 24071 León, Spain
Carlos Alonso-Calleja
Department of Food Hygiene and Technology, Veterinary Faculty, University of León, 24071 León, Spain
Isabel Carvalho
Microbiology and Antibiotic Resistance Team (MicroART), Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
José Eduardo Pereira
Veterinary and Animal Science Research Center (CECAV), University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
Luis Maltez
Veterinary and Animal Science Research Center (CECAV), University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
José L. Capelo
BIOSCOPE Group, LAQV@REQUIMTE, Chemistry Department, Faculty of Science and Technology, NOVA University of Lisbon, 1349-008 Almada, Portugal
Gilberto Igrejas
Department of Genetics and Biotechnology, University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
Patrícia Poeta
Microbiology and Antibiotic Resistance Team (MicroART), Department of Veterinary Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5001-801 Vila Real, Portugal
In this study we aimed to characterize antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from bloodstream infections as well as the associated genetic lineages of the isolates. Sixteen MRSA isolates were recovered from bacteremia samples from inpatients between 2016 and 2019. The antimicrobial susceptibility of these isolates was tested by the Kirby–Bauer disk diffusion method against 14 antimicrobial agents. To determine the macrolide–lincosamide–streptogramin B (MLSB) resistance phenotype of the isolates, erythromycin-resistant isolates were assessed by double-disk diffusion (D-test). The resistance and virulence genes were screened by polymerase chain reaction (PCR). All isolates were characterized by multilocus sequence typing (MLST), spa typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and accessory gene regulator (agr) typing. Isolates showed resistance to cefoxitin, penicillin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, and aminoglycosides, confirmed by the presence of the blaZ, ermA, ermC, mphC, msrA/B, aac(6’)-Ie-aph(2’’)-Ia, and ant(4’)-Ia genes. Three isolates were Panton–Valentine-leukocidin-positive. Most strains (n = 12) presented an inducible MLSB phenotype. The isolates were ascribed to eight spa-types (t747, t002, t020, t1084, t008, t10682, t18526, and t1370) and four MLSTs (ST22, ST5, ST105, and ST8). Overall, most (n = 12) MRSA isolates had a multidrug-resistance profile with inducible MLSB phenotypes and belonged to epidemic MRSA clones.
