Brief reportDetection of a cfr-positive MRSA CC398 strain in a pig farmer in SpainDetección de una cepa SARM del linaje CC398 y portadora del gen cfr en un granjero de cerdos en España
Introduction
Staphylococcus aureus clonal complex CC398 is the most common genetic lineage of livestock-associated (LA) methicillin-resistant S. aureus (MRSA) in Europe. Pigs are the main host of MRSA-CC398, however, its detection in humans is increasing in recent years either as colonizer or as causative agent of infection.1
Besides methicillin resistance, MRSA-CC398 usually exhibits a multiresistance phenotype which limits the therapeutic options. In this context, linezolid is an important antimicrobial agent for the treatment of serious infections caused by Gram-positive bacteria, including MRSA. Point mutations in the domain V of the 23S rRNA, as well as amino acid changes in the ribosomal proteins L3, L4, and L22 are the most common mechanisms of linezolid resistance in staphylococci.2 Moreover, linezolid resistance mediated by acquired resistance genes is of concern due to they are often located on mobile genetic elements, which can move between bacteria by horizontal gene transfer. To date, three transferable linezolid resistance genes have been described in staphylococcal species: cfr, optrA, and poxtA.3, 4, 5 Furthermore, these genes also confer reduced susceptibility to other antimicrobial agents, such as phenicols.2
In this study, we report, as far as we know, the first description of MRSA-CC398 harbouring the cfr gene in Spain, recovered from a nasal sample of a patient with professional contact with pigs.
Section snippets
Methods
A pig farmer was hospitalized in the Intensive Care Unit (ICU) of the Hospital Universitari Arnau de Vilanova (Lleida, Spain) due to a non-infectious disease. Active surveillance for multiresistant bacteria was performed upon ICU admission, and MRSA were isolated from nasal, pharyngeal, and bronchoalveolar lavage samples, that were considered as colonization.
The susceptibility to penicillin, oxacillin, erythromycin, clindamycin, gentamicin, tobramycin, amikacin, minocycline, tetracycline,
Results and discussion
The MRSA isolate was resistant to thirteen of the twenty-three antimicrobial agents tested, including linezolid (MIC 8 mg/L), but remained susceptible to vancomycin and daptomycin. It carried the mecA, blaZ, ant(4′)-Ia, tet(K), tet(M), cfr, and fexA resistance genes and showed the amino acid changes S80F and S84L in GrlA and GyrA proteins, respectively, related to fluoroquinolone resistance (Table 1). The cfr gene, which encodes a rRNA methyltransferase, mediates combined resistance to
Funding
This work was partially supported by project SAF2016-76571-R from the Agencia Estatal de Investigación (AEI) of Spain and the Fondo Europeo de Desarrollo Regional (FEDER) of EU. Laura Ruiz-Ripa has a pre-doctoral fellowship from the Universidad de La Rioja (Spain).
Conflict of interest
The authors declare no conflict of interest.
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