Emergence of Thymidine-Dependent Staphylococcus aureus Small-Colony Variants in Cystic Fibrosis Patients in Southern Brazil
Autor: | Daniele Conte, Dilair Camargo de Souza, Ana Paula de Oliveira Tomaz, Nelson Augusto Rosário Filho, Jussara Kasuko Palmeiro, Carlos Antônio Riedi, Laura Lúcia Cogo, Libera Maria Dalla-Costa |
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Rok vydání: | 2021 |
Předmět: |
Male
0301 basic medicine Cystic Fibrosis Physiology medicine.disease_cause Cystic fibrosis SCVs Missense mutation Child Ecology Middle Aged Antimicrobial QR1-502 Anti-Bacterial Agents thymidine dependent Infectious Diseases Staphylococcus aureus Child Preschool Vancomycin Female auxotrophism Brazil Research Article MLST medicine.drug Adult Microbiology (medical) Adolescent 030106 microbiology Microbial Sensitivity Tests Biology Microbiology antimicrobial susceptibility Frameshift mutation Young Adult 03 medical and health sciences Bacterial Proteins Drug Resistance Bacterial Genetics medicine Humans Gene Aged General Immunology and Microbiology Infant Cell Biology medicine.disease thyA 030104 developmental biology Mutation Multilocus sequence typing Thymidine |
Zdroj: | Microbiology Spectrum, Vol 9, Iss 1 (2021) Microbiology Spectrum |
ISSN: | 2165-0497 |
Popis: | We characterized Staphylococcus aureus small-colony variant (SCV) strains isolated from cystic fibrosis (CF) patients in southern Brazil. Smaller colonies of S. aureus were isolated from respiratory samples collected consecutively from 225 CF patients from July 2013 to November 2016. Two phenotypic methods—the auxotrophic classification and a modified method of antimicrobial susceptibility testing—were employed. PCR was conducted to detect the mecA, ermA, ermB, ermC, msrA, and msrB resistance genes. Furthermore, DNA sequencing was performed to determine the mutations in the thyA gene, and multilocus sequence typing was used to identify the genetic relatedness. S. aureus strains were isolated from 186 patients (82%); suggestive colonies of SCVs were obtained in 16 patients (8.6%). The clones CC1 (ST1, ST188, and ST2383), CC5 (ST5 and ST221), and ST398 were identified. Among SCVs, antimicrobial susceptibility testing showed that 77.7% of the isolates were resistant to multiple drugs, and all of them were susceptible to vancomycin. mecA (2), ermA (1), ermB (1), ermC (3), and msrB (18) were distributed among the isolates. Phenotypically thymidine-dependent isolates had different mutations in the thyA gene, and frameshift mutations were frequently observed. Of note, revertants showed nonconservative or conservative missense mutations. SCVs are rarely identified in routine laboratory tests. IMPORTANCE Similar findings have not yet been reported in Brazil, emphasizing the importance of monitoring small-colony variants (SCVs). Altogether, our results highlight the need to improve detection methods and review antimicrobial therapy protocols in cystic fibrosis (CF) patients. |
Databáze: | OpenAIRE |
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