Phenotypic and Genotypic Characterization of Macrolide, Lincosamide and Streptogramin B Resistance among Clinical Methicillin-Resistant Isolates in Chile.
Mario Quezada-Aguiluz, Alejandro Aguayo-Reyes, Cinthia Carrasco, Daniela Mejías, Pamela Saavedra, Sergio Mella-Montecinos, Andrés Opazo-Capurro, Helia Bello-Toledo, José M Munita, Juan C Hormazábal, Gerardo González-Rocha
Author Information
Mario Quezada-Aguiluz: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile.
Alejandro Aguayo-Reyes: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile.
Cinthia Carrasco: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile.
Daniela Mejías: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile.
Pamela Saavedra: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile.
Sergio Mella-Montecinos: Departamento de Medicina Interna, Facultad de Medicina, Universidad de Concepción, Concepción 4070386, Chile.
Andrés Opazo-Capurro: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile. ORCID
Helia Bello-Toledo: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile. ORCID
José M Munita: Millennium Initiative for Collaborative Research on Bacterial Resistance (MICROB-R), Santiago 3580000, Chile. ORCID
Juan C Hormazábal: Subdepartamento de Enfermedades Infecciosas, Instituto de Salud Pública de Chile, Santiago 7780050, Chile.
Gerardo González-Rocha: Laboratorio de Investigación en Agentes Antibacterianos, Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción 4070386, Chile. ORCID
Macrolides, lincosamides, and type B streptogramins (MLSB) are important therapeutic options to treat methicillin-resistant Staphylococcus aureus (MRSA) infections; however, resistance to these antibiotics has been emerging. In Chile, data on the MLSB resistance phenotypes are scarce in both community-(CA) and hospital-acquired (HA) MRSA isolates. Antimicrobial susceptibility to MLSB was determined for sixty-eight non-repetitive isolates of each HA-(32) and CA-MRSA (36). Detection of SCCmec elements, ermA, ermB, ermC, and msrA genes was performed by PCR. The predominant clones were SCCmec I-ST5 (HA-MRSA) and type IVc-ST8 (CA-MRSA). Most of the HA-MRSA isolates (97%) showed resistance to clindamycin, erythromycin, azithromycin, and clarithromycin. Among CA-MRSA isolates, 28% were resistant to erythromycin, azithromycin, and 25% to clarithromycin. All isolates were susceptible to linezolid, vancomycin, daptomycin and trimethoprim/sulfamethoxazole, and over 97% to rifampicin. The ermA gene was amplified in 88% of HA-MRSA and 17% of CA-MRSA isolates (p < 0.001). The ermC gene was detected in 6% of HA-SARM and none of CA-SARM isolates, whereas the msrA gene was only amplified in 22% of CA-MRSA (p < 0.005). Our results demonstrate the prevalence of the cMLSB resistance phenotype in all HA-MRSA isolates in Chile, with the ermA being the predominant gene identified among these isolates.
