EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin

R. Skov; A. Varga; E. Matuschek; J. Åhman; D. Bemis; B. Bengtsson; M. Sunde; R. Humphries; L. Westblade; L. Guardabassi; G. Kahlmeter

doi:10.1016/j.cmi.2019.05.002

EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin

R. Skov^*, A. Varga, E. Matuschek, J. Åhman, D. Bemis, B. Bengtsson, M. Sunde, R. Humphries, L. Westblade, L. Guardabassi, G. Kahlmeter

^*Corresponding author af dette arbejde

2 Citationer (Scopus)

Abstract

Objectives: Until recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommended the cefoxitin disc to screen for mecA-mediated β-lactam resistance in Staphylococcus pseudintermedius. A recent study indicated that cefoxitin was inferior to oxacillin in this respect. We have re-evaluated cefoxitin and oxacillin discs for screening for methicillin resistance in S. pseudintermedius. Methods: We included 224 animal and human S. pseudintermedius isolates from Europe (n = 108) and North America (n = 116), of which 109 were mecA-positive. Disc diffusion was performed per EUCAST recommendations using 30-μg cefoxitin and 1-μg oxacillin discs from three manufacturers and Mueller–Hinton agar from two manufacturers. Results: Cefoxitin inhibition zones ranged from 6 to 33 mm for mecA-positive S. pseudintermedius (MRSP) and from 29 to 41 mm for mecA-negative S. pseudintermedius (MSSP). The corresponding oxacillin zone intervals were 6–20 mm and 19–30 mm. For cefoxitin 16% (95% CI 14.8–18.0%) of the isolates were in the area where positive and negative results overlapped. For oxacillin the corresponding number was 2% (1.6–2.9%). For oxacillin a breakpoint of susceptible (S) ≥ 20 mm and resistant (R) <20 mm resulted in only 0.4% and 1.1% very major error and major error rates respectively. Conclusions: This investigation confirms that the 1-μg oxacillin disc predicts mecA-mediated methicillin resistance in S. pseudintermedius better than the 30-μg cefoxitin disc. For a 1-μg oxacillin disc we propose that 20 mm should be used as cut off for resistance, i.e. isolates with a zone diameter <20 mm are resistant to all β-lactam antibiotics except those with activity against methicillin-resistant staphylococci.

Originalsprog	Engelsk
Tidsskrift	Clinical Microbiology and Infection
ISSN	1198-743X
DOI	https://doi.org/10.1016/j.cmi.2019.05.002
Status	Udgivet - jan. 2020

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10.1016/j.cmi.2019.05.002

http://www.clinicalmicrobiologyandinfection.com/article/S1198743X19302150/pdf

Citationsformater

Skov, R., Varga, A., Matuschek, E., Åhman, J., Bemis, D., Bengtsson, B., Sunde, M., Humphries, R., Westblade, L., Guardabassi, L., & Kahlmeter, G. (2020). EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin. Clinical Microbiology and Infection. https://doi.org/10.1016/j.cmi.2019.05.002

Skov, R, Varga, A, Matuschek, E, Åhman, J, Bemis, D, Bengtsson, B, Sunde, M, Humphries, R, Westblade, L, Guardabassi, L & Kahlmeter, G 2020, 'EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin', Clinical Microbiology and Infection. https://doi.org/10.1016/j.cmi.2019.05.002

@article{c518753fc14447298fdc6b63cddbd362,

title = "EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin",

abstract = "Objectives: Until recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommended the cefoxitin disc to screen for mecA-mediated β-lactam resistance in Staphylococcus pseudintermedius. A recent study indicated that cefoxitin was inferior to oxacillin in this respect. We have re-evaluated cefoxitin and oxacillin discs for screening for methicillin resistance in S. pseudintermedius. Methods: We included 224 animal and human S. pseudintermedius isolates from Europe (n = 108) and North America (n = 116), of which 109 were mecA-positive. Disc diffusion was performed per EUCAST recommendations using 30-μg cefoxitin and 1-μg oxacillin discs from three manufacturers and Mueller–Hinton agar from two manufacturers. Results: Cefoxitin inhibition zones ranged from 6 to 33 mm for mecA-positive S. pseudintermedius (MRSP) and from 29 to 41 mm for mecA-negative S. pseudintermedius (MSSP). The corresponding oxacillin zone intervals were 6–20 mm and 19–30 mm. For cefoxitin 16% (95% CI 14.8–18.0%) of the isolates were in the area where positive and negative results overlapped. For oxacillin the corresponding number was 2% (1.6–2.9%). For oxacillin a breakpoint of susceptible (S) ≥ 20 mm and resistant (R) <20 mm resulted in only 0.4% and 1.1% very major error and major error rates respectively. Conclusions: This investigation confirms that the 1-μg oxacillin disc predicts mecA-mediated methicillin resistance in S. pseudintermedius better than the 30-μg cefoxitin disc. For a 1-μg oxacillin disc we propose that 20 mm should be used as cut off for resistance, i.e. isolates with a zone diameter <20 mm are resistant to all β-lactam antibiotics except those with activity against methicillin-resistant staphylococci.",

keywords = "Cefoxitin, mecA-positive S.pseudintermedius, Methicillin resistance, Oxacillin, Staphylococcus pseudintermedius, Susceptibility testing",

author = "R. Skov and A. Varga and E. Matuschek and J. {\AA}hman and D. Bemis and B. Bengtsson and M. Sunde and R. Humphries and L. Westblade and L. Guardabassi and G. Kahlmeter",

year = "2020",

month = jan,

doi = "10.1016/j.cmi.2019.05.002",

language = "English",

journal = "Clinical Microbiology and Infection",

issn = "1198-743X",

publisher = "Elsevier",

}

TY - JOUR

T1 - EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius

T2 - oxacillin versus cefoxitin

AU - Skov, R.

AU - Varga, A.

AU - Matuschek, E.

AU - Åhman, J.

AU - Bemis, D.

AU - Bengtsson, B.

AU - Sunde, M.

AU - Humphries, R.

AU - Westblade, L.

AU - Guardabassi, L.

AU - Kahlmeter, G.

PY - 2020/1

Y1 - 2020/1

N2 - Objectives: Until recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommended the cefoxitin disc to screen for mecA-mediated β-lactam resistance in Staphylococcus pseudintermedius. A recent study indicated that cefoxitin was inferior to oxacillin in this respect. We have re-evaluated cefoxitin and oxacillin discs for screening for methicillin resistance in S. pseudintermedius. Methods: We included 224 animal and human S. pseudintermedius isolates from Europe (n = 108) and North America (n = 116), of which 109 were mecA-positive. Disc diffusion was performed per EUCAST recommendations using 30-μg cefoxitin and 1-μg oxacillin discs from three manufacturers and Mueller–Hinton agar from two manufacturers. Results: Cefoxitin inhibition zones ranged from 6 to 33 mm for mecA-positive S. pseudintermedius (MRSP) and from 29 to 41 mm for mecA-negative S. pseudintermedius (MSSP). The corresponding oxacillin zone intervals were 6–20 mm and 19–30 mm. For cefoxitin 16% (95% CI 14.8–18.0%) of the isolates were in the area where positive and negative results overlapped. For oxacillin the corresponding number was 2% (1.6–2.9%). For oxacillin a breakpoint of susceptible (S) ≥ 20 mm and resistant (R) <20 mm resulted in only 0.4% and 1.1% very major error and major error rates respectively. Conclusions: This investigation confirms that the 1-μg oxacillin disc predicts mecA-mediated methicillin resistance in S. pseudintermedius better than the 30-μg cefoxitin disc. For a 1-μg oxacillin disc we propose that 20 mm should be used as cut off for resistance, i.e. isolates with a zone diameter <20 mm are resistant to all β-lactam antibiotics except those with activity against methicillin-resistant staphylococci.

AB - Objectives: Until recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommended the cefoxitin disc to screen for mecA-mediated β-lactam resistance in Staphylococcus pseudintermedius. A recent study indicated that cefoxitin was inferior to oxacillin in this respect. We have re-evaluated cefoxitin and oxacillin discs for screening for methicillin resistance in S. pseudintermedius. Methods: We included 224 animal and human S. pseudintermedius isolates from Europe (n = 108) and North America (n = 116), of which 109 were mecA-positive. Disc diffusion was performed per EUCAST recommendations using 30-μg cefoxitin and 1-μg oxacillin discs from three manufacturers and Mueller–Hinton agar from two manufacturers. Results: Cefoxitin inhibition zones ranged from 6 to 33 mm for mecA-positive S. pseudintermedius (MRSP) and from 29 to 41 mm for mecA-negative S. pseudintermedius (MSSP). The corresponding oxacillin zone intervals were 6–20 mm and 19–30 mm. For cefoxitin 16% (95% CI 14.8–18.0%) of the isolates were in the area where positive and negative results overlapped. For oxacillin the corresponding number was 2% (1.6–2.9%). For oxacillin a breakpoint of susceptible (S) ≥ 20 mm and resistant (R) <20 mm resulted in only 0.4% and 1.1% very major error and major error rates respectively. Conclusions: This investigation confirms that the 1-μg oxacillin disc predicts mecA-mediated methicillin resistance in S. pseudintermedius better than the 30-μg cefoxitin disc. For a 1-μg oxacillin disc we propose that 20 mm should be used as cut off for resistance, i.e. isolates with a zone diameter <20 mm are resistant to all β-lactam antibiotics except those with activity against methicillin-resistant staphylococci.

KW - Cefoxitin

KW - mecA-positive S.pseudintermedius

KW - Methicillin resistance

KW - Oxacillin

KW - Staphylococcus pseudintermedius

KW - Susceptibility testing

U2 - 10.1016/j.cmi.2019.05.002

DO - 10.1016/j.cmi.2019.05.002

M3 - Journal article

C2 - 31108230

AN - SCOPUS:85067203406

SN - 1198-743X

JO - Clinical Microbiology and Infection

JF - Clinical Microbiology and Infection

ER -

EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin

Abstract

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