Emergence of <i>Cfr</i>-Mediated Linezolid Resistance among Livestock-Associated Methicillin-Resistant <i>Staphylococcus aureus</i> (LA-MRSA) from Healthy Pigs in Portugal

• Main Authors: Célia Leão (Author), Lurdes Clemente (Author), Maria Cara d'Anjo (Author), Teresa Albuquerque (Author), Ana Amaro (Author)
• Format: Book
• Published: MDPI AG, 2022-10-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antibiotics11101439; 2079-6382
• Keywords: LA-MRSA; pigs; linezolid resistance; <i>cfr</i> gene; WGS; ST398; Therapeutics. Pharmacology; RM1-950
• Source: Antibiotics, Vol 11, Iss 10, p 1439 (2022)

Livestock-associated methicillin-resistant <i>Staphylococcus aureus</i> (LA-MRSA) ST398 is mainly found in Europe and North America, colonizing the nasal cavity of pigs. This study characterized the MRSA isolates recovered from pig nasal swabs (<i>n</i> = 171) by evaluating the antimicrobial susceptibility profile by broth microdilution and characterizing the genetic lineages by <i>spa</i>-typing. Three linezolid-resistant isolates were subjected to Whole-Genome Sequencing (WGS). All strains harbored the <i>mecA</i> gene and were resistant to tetracycline and susceptible to vancomycin. A high frequency of multidrug resistance (97.6%) was evidenced, with 55 different multidrug resistance profiles identified. The MRSA strains were found to belong to 17 <i>spa</i>-types, three being novel. The linezolid-resistant strains appeared to belong to the ST398 type, <i>spa</i>-type t011, and SCC<i>mec</i>_type_Vc and to harbor the <i>cfr</i>, <i>fex</i>A, <i>bla</i>Z, <i>mec</i>A, <i>tet</i>M, and <i>tet</i>K genes. The <i>cfr</i> gene was predicted to be carried in the plasmid, flanked by <i>IS</i>Sau9 and the transposon TnpR. MRSA from Portuguese fattening pigs present a high diversity of genetic lineages. The presence of <i>cfr</i>-positive LA-MRSA may represent a risk of transmission to humans, mainly to those in contact with livestock.