Genomic analysis of oxacillin-susceptible mecA-positive Staphylococcus haemolyticus ST159 isolated from anovaginal colonization in Brazil

Oxacillin-susceptible methicillin-resistant Staphylococcus spp. (OS-MRS) is a known phenotype, mainly regarding S. aureus. It is considered a concerning pathogen due to its difficulty to be detected only with phenotypic methods, and reporting false susceptibility to beta-lactams could lead ineffecti...

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Main Authors: Andre Rio Tinto, Dr Natáli Costa, Dr Laura Oliveira, Prof. Sergio Fracalanzza, Prof. Lucia Teixeira, Dr. Penelope Marinho, Prof. Tatiana Pinto
Format: Article
Language:English
Published: Elsevier 2025-03-01
Series:International Journal of Infectious Diseases
Online Access:http://www.sciencedirect.com/science/article/pii/S1201971224006805
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Summary:Oxacillin-susceptible methicillin-resistant Staphylococcus spp. (OS-MRS) is a known phenotype, mainly regarding S. aureus. It is considered a concerning pathogen due to its difficulty to be detected only with phenotypic methods, and reporting false susceptibility to beta-lactams could lead ineffective treatment. During a surveillance study for detection of anovaginal colonization of methicillin-resistant Staphylococcus spp. (MRS) among pregnant population, between April 2021 and August 2022, 518 anovaginal specimens were streaked onto CHROMagarTM MRSA, and 331 strains were obtained. Phenotypic confirmation for methicillin resistance was performed using cefoxitin disc diffusion, according to CLSI, and 27 (8.2%) were susceptible. PCR detection for mecA was performed for all strains, and 11 (3.3%) phenotypic susceptible strains harbored the mecA gene, hence belonging to the OS-MRS phenotype. One OS-MR S. haemolyticus strain was randomly selected for whole genome sequencing, using Illumina. Genome analysis using CARD and ResFinder database confirmed the presence of the mecA gene, along with other resistance determinants: APH(3′)-IIIa, blaZ, mgrA, mphC, msrA, and sat4. Sequence alignment with reference sequences of all SCCmec types was performed using BLAST and indicated as best results 100% identity and only 55 and 52% query coverage with SCCmec types VI and IVc respectively. A novel ST159 was determined using PubMLST. This data corroborates the need for further understanding of OS-MRS epidemiology in our setting, and the importance of specific protocols for its detection.
ISSN:1201-9712