TY - JOUR

T1 - Phenotypic and genomic characteristics of oxacillin-susceptible mecA-positive Staphylococcus aureus, rapid selection of high-level resistance to beta-lactams

AU - Gostev, Vladimir

AU - Sabinova, Ksenia

AU - Sopova, Julia

AU - Kalinogorskaya, Olga

AU - Sulian, Ofeliia

AU - Chulkova, Polina

AU - Velizhanina, Maria

AU - Pavlova, Polina

AU - Danilov, Lavrentii

AU - Kraeva, Lyudmila

AU - Polev, Dmitrii

AU - Martens, Elvira

AU - Sidorenko, Sergey

PY - 2023/9/1

Y1 - 2023/9/1

N2 - The aim of this study is to describe the phenotypic and genetic properties of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) isolates and their beta-lactam resistant derivatives obtained after selection with oxacillin. A collection of hospital- (HA-) and community-acquired (CA-) MRSA was screened for oxacillin susceptibility. Antibiotic susceptibility testing, population analysis profile (PAP), mecA expression analysis, and whole genome sequencing (WGS) were performed for 60 mecA-positive OS-MRSA isolates. Twelve high-level beta-lactam resistant derivatives selected during PAP were also subjected to WGS. OS-MRSA were more prevalent among CA-MRSA (49/205, 24%) than among HA-MRSA (11/575, 2%). OS-MRSA isolates belonged to twelve sequence types (ST), with a predominance of ST22-t223-SCCmec IVc and ST59-t1950-SCCmec V lineages. OS-MRSA were characterized by mecA promoter mutations at − 33 (C→T) or − 7 (G→T/A) along with PBP2a substitutions (S225R or E246G). The basal and oxacillin-induced levels of mecA expression in OS-MRSA isolates were significantly lower than those in control ST8-HA-MRSA isolates. Most of the OS-MRSA isolates were heteroresistant to oxacillin. High-level beta-lactam resistant OS-MRSA derivatives selected with oxacillin carried mutations in mecA auxiliary factors: relA (metabolism of purines), tyrS, cysS (metabolism of tRNAs), aroK, cysE (metabolism of amino acids and glycolysis). Cefoxitin-based tests demonstrated high specificity for OS-MRSA detection. The highest positive predictive values (PPV > 0.95) were observed for broth microdilution, the VITEK® 2 automatic system, and chromogenic media. Susceptibility testing of CA-MRSA requires special attention due to the high prevalence of difficult-to-detect OS-MRSA among them. Mis-prescription of beta-lactams for the treatment of OS-MRSA may lead to selection of high-level resistance and treatment failures.

AB - The aim of this study is to describe the phenotypic and genetic properties of oxacillin-susceptible methicillin-resistant Staphylococcus aureus (OS-MRSA) isolates and their beta-lactam resistant derivatives obtained after selection with oxacillin. A collection of hospital- (HA-) and community-acquired (CA-) MRSA was screened for oxacillin susceptibility. Antibiotic susceptibility testing, population analysis profile (PAP), mecA expression analysis, and whole genome sequencing (WGS) were performed for 60 mecA-positive OS-MRSA isolates. Twelve high-level beta-lactam resistant derivatives selected during PAP were also subjected to WGS. OS-MRSA were more prevalent among CA-MRSA (49/205, 24%) than among HA-MRSA (11/575, 2%). OS-MRSA isolates belonged to twelve sequence types (ST), with a predominance of ST22-t223-SCCmec IVc and ST59-t1950-SCCmec V lineages. OS-MRSA were characterized by mecA promoter mutations at − 33 (C→T) or − 7 (G→T/A) along with PBP2a substitutions (S225R or E246G). The basal and oxacillin-induced levels of mecA expression in OS-MRSA isolates were significantly lower than those in control ST8-HA-MRSA isolates. Most of the OS-MRSA isolates were heteroresistant to oxacillin. High-level beta-lactam resistant OS-MRSA derivatives selected with oxacillin carried mutations in mecA auxiliary factors: relA (metabolism of purines), tyrS, cysS (metabolism of tRNAs), aroK, cysE (metabolism of amino acids and glycolysis). Cefoxitin-based tests demonstrated high specificity for OS-MRSA detection. The highest positive predictive values (PPV > 0.95) were observed for broth microdilution, the VITEK® 2 automatic system, and chromogenic media. Susceptibility testing of CA-MRSA requires special attention due to the high prevalence of difficult-to-detect OS-MRSA among them. Mis-prescription of beta-lactams for the treatment of OS-MRSA may lead to selection of high-level resistance and treatment failures.

KW - Antimicrobial resistance selection

KW - Cefoxitin

KW - MRSA

KW - OS-MRSA

KW - Oxacillin

KW - Penicillin–clavulanate

KW - Staphylococcus aureus

UR - https://www.mendeley.com/catalogue/ae772a6f-1ccd-32af-915c-bc9286d8ab4d/

U2 - https://doi.org/10.1007/s10096-023-04646-1

DO - https://doi.org/10.1007/s10096-023-04646-1

M3 - Article

VL - 42

SP - 1125

EP - 1133

JO - European Journal of Clinical Microbiology and Infectious Diseases

JF - European Journal of Clinical Microbiology and Infectious Diseases

SN - 0934-9723

IS - 9

ER -