Unusual presence of the immune evasion gene cluster in livestock-associated MRSA of lineage CC398 causing peridural and psoas abscesses in a poultry farmer / Hallazgo inusual de los genes del sistema de evasión inmune en SARM-CC398, asociado a animales, causante de absceso epidural y de psoas en un granjero avícola

Objective: To characterize a methicillin-resistant Staphylococcus aureus (MRSA) isolate responsible for an aggressive infection (peridural and psoas abscess secondary to haematogenous septic arthritis) in a poultry farmer. Methods: Molecular characterization was performed, including spa- and multilocus sequence typing of the isolate, assessment of its resistance phenotype and detection of tetracycline resistance and of virulence and immune evasion cluster (IEC) genes were performed. Results: The MRSA isolate was tetracycline- and fluorquinolone-resistant, and was ascribed to CC398, spa-t1451. The isolate harboured tet(M) (distinctive of livestock-associated (LA) MRSA-CC398 clade) and IEC-type B system (characteristic of the methicillin-susceptible human lineage, but typically absent in LA-MRSA-CC398 strains), and lacked toxin-coding genes lukF/lukS-PV, tsst-1, eta and etb. Conclusion: IEC re-acquisition by LA-MRSA-CC398-LA strains is an unusual finding, but could constitute an emerging public health problem. It would represent an evolutionary step towards LA-MRSA-CC398's adaptation to human hosts, and might enhance its invasiveness and ability to be transmitted to humans (AU)

Objetivo: Caracterizar un aislado de Staphylococcus aureus resistente a meticilina (SARM), causante de una infección muy agresiva (absceso epidural y de psoas secundarios a artritis séptica hematógena) en un granjero avícola. Métodos: El aislado fue caracterizado molecularmente (spa- y multilocus sequence typing), y se estudió su fenotipo de resistencia y la presencia de genes de resistencia a tetraciclina, de virulencia y del sistema immune evasion cluster (IEC). Resultados: El aislado de SARM, resistente a tetraciclina y fluoroquinolonas, fue tipado como spa-t1451-CC398, albergaba el gen tet(M) (distintivo de SARM-CC398 asociado al ganado [AG]) y el sistema IEC-tipo B (característico de S. aureus meticilin-sensible-CC398 adscrito al clado humano, pero no de SARM-CC398-AG), carecía de lukF/lukS-PV, tsst-1, eta, y etb. Conclusión: La readquisición del sistema IEC por aislados SARM-CC398-AG es excepcional, pero constituiría un problema emergente de salud pública. Representaría un paso evolutivo en la readaptación de SARM-CC398-AG al hombre, pudiendo incrementar su invasividad y transmisibilidad a humanos (AU)

Unusual presence of the immune evasion gene cluster in livestock-associated MRSA of lineage CC398 causing peridural and psoas abscesses in a poultry farmer.

OBJECTIVE: To characterize a methicillin-resistant Staphylococcus aureus (MRSA) isolate responsible for an aggressive infection (peridural and psoas abscess secondary to haematogenous septic arthritis) in a poultry farmer. METHODS: Molecular characterization was performed, including spa- and multilocus sequence typing of the isolate, assessment of its resistance phenotype and detection of tetracycline resistance and of virulence and immune evasion cluster (IEC) genes were performed. RESULTS: The MRSA isolate was tetracycline- and fluorquinolone-resistant, and was ascribed to CC398, spa-t1451. The isolate harboured tet(M) (distinctive of livestock-associated (LA) MRSA-CC398 clade) and IEC-type B system (characteristic of the methicillin-susceptible human lineage, but typically absent in LA-MRSA-CC398 strains), and lacked toxin-coding genes lukF/lukS-PV, tsst-1, eta and etb. CONCLUSION: IEC re-acquisition by LA-MRSA-CC398-LA strains is an unusual finding, but could constitute an emerging public health problem. It would represent an evolutionary step towards LA-MRSA-CC398's adaptation to human hosts, and might enhance its invasiveness and ability to be transmitted to humans.