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Identification of mecA-related oxacillin resistance in staphylococci by the E test and the broth microdilution method

Petersson, A C; Miörner, Håkan LU and Kamme, C (1996) In Journal of Antimicrobial Chemotherapy 37(3). p.445-456
Abstract
A set of 165 strains of different staphylococcal species, 67 Staphylococcus aureus, 71 novobiocin-sensitive coagulase-negative staphylococci (CNS) and 27 novobiocin-resistant CNS was used. The oxacillin and methicillin MICs were recorded after 24 and 42 h of incubation at 35 degrees C and at 30 degrees C. Significantly higher MICs were recorded at 30 degrees C compared with 35 degrees C. While a poor discrimination between mecA-positive and mecA-negative strains was obtained with methicillin, the oxacillin MICs enabled identification of resistant strains under certain conditions. The distribution of MICs differed between the three groups of species. Separation of uninduced mecA-positive (> or = 4.0 mg oxacillin/L) and mecA-negative... (More)
A set of 165 strains of different staphylococcal species, 67 Staphylococcus aureus, 71 novobiocin-sensitive coagulase-negative staphylococci (CNS) and 27 novobiocin-resistant CNS was used. The oxacillin and methicillin MICs were recorded after 24 and 42 h of incubation at 35 degrees C and at 30 degrees C. Significantly higher MICs were recorded at 30 degrees C compared with 35 degrees C. While a poor discrimination between mecA-positive and mecA-negative strains was obtained with methicillin, the oxacillin MICs enabled identification of resistant strains under certain conditions. The distribution of MICs differed between the three groups of species. Separation of uninduced mecA-positive (> or = 4.0 mg oxacillin/L) and mecA-negative (< or = 2.0 mg oxacillin/L) strains of S. aureus was only achieved with the E test and after 42 h of incubation. Oxacillin-induction yielded higher MICs for mecA-positive strains of S. aureus, and a separation from mecA-negative strains was achieved with the E test after 24 h and with the broth microdilution method after 42 h. Separation of mecA-positive and mecA-negative strains of novobiocin-sensitive CNS required agar supplemented with 5% blood, incubation of MIC trays and E test for 42 h, and species-specific oxacillin MIC breakpoints (S < or = 0.5 mg/L and R > or = 1.0 mg/L). The mecA-positive and mecA-negative strains of novobiocin-resistant CNS were clearly separated after 24 h of incubation by either method. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Antimicrobial Chemotherapy
volume
37
issue
3
pages
445 - 456
publisher
Oxford University Press
external identifiers
  • pmid:9182101
ISSN
1460-2091
DOI
10.1093/jac/37.3.445
language
English
LU publication?
yes
id
5d7baf48-6615-4f23-9d2f-d988ba3e1310 (old id 1110408)
date added to LUP
2008-07-29 09:20:33
date last changed
2016-04-15 19:06:46
@article{5d7baf48-6615-4f23-9d2f-d988ba3e1310,
  abstract     = {A set of 165 strains of different staphylococcal species, 67 Staphylococcus aureus, 71 novobiocin-sensitive coagulase-negative staphylococci (CNS) and 27 novobiocin-resistant CNS was used. The oxacillin and methicillin MICs were recorded after 24 and 42 h of incubation at 35 degrees C and at 30 degrees C. Significantly higher MICs were recorded at 30 degrees C compared with 35 degrees C. While a poor discrimination between mecA-positive and mecA-negative strains was obtained with methicillin, the oxacillin MICs enabled identification of resistant strains under certain conditions. The distribution of MICs differed between the three groups of species. Separation of uninduced mecA-positive (&gt; or = 4.0 mg oxacillin/L) and mecA-negative (&lt; or = 2.0 mg oxacillin/L) strains of S. aureus was only achieved with the E test and after 42 h of incubation. Oxacillin-induction yielded higher MICs for mecA-positive strains of S. aureus, and a separation from mecA-negative strains was achieved with the E test after 24 h and with the broth microdilution method after 42 h. Separation of mecA-positive and mecA-negative strains of novobiocin-sensitive CNS required agar supplemented with 5% blood, incubation of MIC trays and E test for 42 h, and species-specific oxacillin MIC breakpoints (S &lt; or = 0.5 mg/L and R &gt; or = 1.0 mg/L). The mecA-positive and mecA-negative strains of novobiocin-resistant CNS were clearly separated after 24 h of incubation by either method.},
  author       = {Petersson, A C and Miörner, Håkan and Kamme, C},
  issn         = {1460-2091},
  language     = {eng},
  number       = {3},
  pages        = {445--456},
  publisher    = {Oxford University Press},
  series       = {Journal of Antimicrobial Chemotherapy},
  title        = {Identification of mecA-related oxacillin resistance in staphylococci by the E test and the broth microdilution method},
  url          = {http://dx.doi.org/10.1093/jac/37.3.445},
  volume       = {37},
  year         = {1996},
}