Improved Detection of mecA-Mediated β-Lactam Resistance in Staphylococcus lugdunensis Using a New Oxacillin Salt Agar Screen

Copyright © 2021 Ho, Law, Liu, Lau, Tong, Chow, Wu, Tse, Cheng and Que..

Oxacillin resistance mediated by mecA in Staphylococcus lugdunensis is emerging in some geographic areas. We evaluated cefoxitin disk diffusion (DD) and a new oxacillin agar (supplemented with 2 μg/ml oxacillin and 2% sodium chloride) screen for the detection of mecA-mediated resistance in S. lugdunensis. A total of 300 consecutive, non-duplicated clinical S. lugdunensis isolates from diverse sources in Hong Kong in 2019 were tested. The categorical agreement and errors obtained between cefoxitin DD test, oxacillin agar screen and mecA PCR were analyzed. Isolates with discordant results were further tested by MIC, penicillin binding protein 2a (PBP2a) assays, population analysis and molecular typing. PCR showed that 62 isolates were mecA-positive and 238 isolates were mecA-negative. For cefoxitin DD results interpreted using S. aureus/S. lugdunensis breakpoints, the categorical agreement (CA) for two brands of Muller-Hinton agars, MH-II (Becton Dickinson) and MH-E (bioMérieux) were both 96.0%; MEs were both 0%; and VMEs were 19.4 and 12.9%, respectively. The new oxacillin agar reliably differentiated mecA-positive and mecA-negative isolates (100% CA) without any ME or VME results. The 8 isolates with false susceptibility in the cefoxitin DD testing had cefoxitin and oxacillin MICs in the susceptible range. The isolates showed heterogeneous oxacillin resistance with resistant subpopulations at low frequencies. All had positive PBP2a results and were typed as sequence type 27/SCCmec V. The findings highlight the inability of cefoxitin DD and MIC tests for reliable detection of some mecA-positive S. lugdunensis isolates.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:12

Enthalten in:

Frontiers in microbiology - 12(2021) vom: 23., Seite 704552

Sprache:

Englisch

Beteiligte Personen:

Ho, Pak-Leung [VerfasserIn]
Law, Ying-Hang [VerfasserIn]
Liu, Melissa Chun-Jiao [VerfasserIn]
Lau, Andes [VerfasserIn]
Tong, Man-Ki [VerfasserIn]
Chow, Kin-Hung [VerfasserIn]
Wu, Alan Ka-Lun [VerfasserIn]
Tse, Cindy Wing-Sze [VerfasserIn]
Cheng, Vincent Chi-Chung [VerfasserIn]
Que, Tak-Lun [VerfasserIn]

Links:

Volltext

Themen:

Cefoxitin
Journal Article
Methicillin resistance and mecA gene
Oxacillin agar screening method
Staphylococcus lugdunensis
Susceptibility test comparison

Anmerkungen:

Date Revised 24.08.2021

published: Electronic-eCollection

Citation Status PubMed-not-MEDLINE

doi:

10.3389/fmicb.2021.704552

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM329652230