Revised interpretation of oxacillin MICs for Staphylococcus epidermidis based on mecA detection

McDonald, Christine; Maher, William E.; Fass, Robert J.

doi:10.1128/aac.39.4.982

Cited by 53 publications

(46 citation statements)

References 19 publications

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“…Essential agreement between the oxacillin MICs in the two methods was recorded for four of the remaining seven strains, which all had to be classified as resistant ( Table 2). The 10 (7.2%) mecA-negative S. epidermidis strains for which the oxacillin MICs were Ն0.5 g/ml, out of a total of 139 S. epidermidis strains, represent a proportion similar to that in another study, which found 2 of 37 (5.4%) S. epidermidis strains for which the oxacillin MICs were Ն0.5 g/ml (30). For epidemiological reasons, study populations vary in their species compositions and strains differ in their phenotypic expression of methicillin resistance.…”

Section: Discussionmentioning

confidence: 55%

“…Alternatively, detection of PBP2a as a marker of methicillin resistance has shown promising results with CoNS and is therefore also recommended (1, 15-17, 25, 33, 44, 48). In contrast, phenotypic detection of methicillin resistance in CoNS is difficult due to the heterogeneous expression of mecA (6,30,40,47). Commonly used tests rely on modified culture conditions to enhance the expression of resistance and take up to 48 h for reliable results (30,40,47).…”

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confidence: 99%

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Evaluation of the BD PHOENIX Automated Microbiology System for Detection of Methicillin Resistance in Coagulase-Negative Staphylococci

et al. 2004

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The new BD PHOENIX automated microbiology system (Becton Dickinson Diagnostic Systems, Sparks, Md.) is designed for automated rapid antimicrobial susceptibility testing and identification of clinically relevant bacteria. In our study, the accuracy and speed of the BD PHOENIX oxacillin MIC determination for detecting methicillin resistance was evaluated for 200 clinical isolates of coagulase-negative staphylococci (CoNS). Compared to mecA PCR, the BD PHOENIX system detected methicillin resistance with a sensitivity of 99.2%. According to the actual NCCLS oxacillin MIC breakpoint of >0.5 g/ml, the specificity was only 64.9%, attributable to false-positive results in 26 mecA-negative strains, including 16 non-Staphylococcus epidermidis strains. Alternative oxacillin breakpoints of >1, >2, and >4 g/ml resulted in increased specificities of 83.8, 94.6, and 100% and high sensitivities of 99.2, 99.2, and 96.7%, respectively. Similarly, NCCLS broth microdilution oxacillin MICs exhibited a sensitivity of 100% but a low degree of specificity. However, the previous oxacillin MIC breakpoint of >4 g/ml performed with a sensitivity of 98.4% and a specificity of 98.7%. BD PHOENIX oxacillin MIC results were available after 9 h for 40.5% of the examined CoNS strains and were completed after 17 h. Our results revealed the high reliability of the BD PHOENIX system as a phenotypic method for detection of resistance to oxacillin in mecA-positive CoNS. However, for the improvement of specificity, reevaluation of the optimal oxacillin MIC breakpoint for CoNS appears to be necessary.

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Section: Discussionmentioning

confidence: 55%

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confidence: 99%

Evaluation of the BD PHOENIX Automated Microbiology System for Detection of Methicillin Resistance in Coagulase-Negative Staphylococci

et al. 2004

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“…Some results were difficult to read because of faint growth at 24 hrs. This was not reported by the studies that showed a high degree of correlation between the disc test and the presence of mecA (McDonald et al, 1995). Currently, multiple antibiotic resistant S. aureus strains constitute a major healthcare problem, since they are the etiologic agent of several nosocomical and skin infection.…”

Section: Analysis Of Meca Genementioning

confidence: 51%

Antimicrobial Potential of Plant Seed Extracts against Multidrug Resistant Methicillin Resistant Staphylococcus aureus (MDR-MRSA)

Karthy¹,

Ranjitha²,

Mohankumar³

2009

IJB

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Based on ethnopharmacological information, four different varieties of seeds were obtained from authentic seed suppliers. Ethanol, methanol, acetone, chloroform and petroleum ether seed extracts were assessed for antibacterial activity against wound isolates of Multi Drug Resistant -Methicillin Resistant Staphylococcus aureus (MDR-MRSA). Ethanol, methanol and acetone extracts of Moringa oleifera, Elettaria cardamomum and Tamarindus indica seeds showed more effective anti MRSA activity than Artocarpus heterophyllus. In addition Moringa oleifera seed extracts may have the potential to restore the effectiveness of -lactam antibiotics against MRSA.

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“…Recently, several investigators have reported disagreement between the oxacillin MICs for CoNS and the presence or absence of mecA (11,12,17,21). Accordingly, the National Committee for Clinical Laboratory Standards (NCCLS) (15,16) has modified the oxacillin interpretive criteria for this organism, applying an MIC breakpoint of Յ0.25 g/ml for susceptibility for suspectibility and an MIC breakpoint of Ն0.5 g/ml for resistance (16).…”

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confidence: 99%

Comparison of the Vitek Gram-Positive Susceptibility 106 Card, the MRSA-Screen Latex Agglutination Test, and mecA Analysis for Detecting Oxacillin Resistance in a Geographically Diverse Collection of Clinical Isolates of Coagulase-Negative Staphylococci

et al. 2001

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The Vitek automated susceptibility testing system with a modified gram-positive susceptibility (GPS) 106 card (bioMerieux Vitek, Inc., Hazelwood. Mo.) and a rapid slide latex agglutination test (MRSA-Screen test; Denka Seiken Co., Ltd., Tokyo, Japan) were evaluated for their abilities to detect oxacillin resistance in coagulase-negative staphylococci (CoNS). The reference broth microdilution method and the detection of the mecA gene by PCR ("gold standard" reference result) were used to compare the results obtained with the commercial products. A total of 123 clinical isolates consisting of eight species were selected from U.S. surveillance collections. Among the mecA-positive isolates (95 strains), 30 isolates were initially negative on the MRSA-Screen test read at 3 min. When the agglutination reaction was extended for 10 min, 26 of the 30 isolates became positive. For a different four isolates, the oxacillin MIC was <0.25 g/ml on the Vitek GPS 106 card. Among the mecA-negative isolates (28 strains), for two Staphylococcus warneri, two S. lugdunensis, and two S. saprophyticus strains MICs were >0.5 g/ml by the reference broth microdilution method. Four of these isolates were also categorized as resistant with the Vitek GPS 106 card and two isolates were positive by the MRSA-Screen test. Overall, the MRSA-Screen test, GPS 106 card, and reference broth microdilution method had sensitivities of 95.7 (result at 10 min), 95.7, and 100%, respectively, and specificities of 92.8, 85.7, and 78.5%, respectively. Although the MRSA-Screen test required a slight procedural modification, both commercial methods achieved a sensitivity and specificity at detecting oxacillin resistance in CoNS at a level that was acceptable for clinical laboratory use.

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Revised interpretation of oxacillin MICs for Staphylococcus epidermidis based on mecA detection

Cited by 53 publications

References 19 publications

Evaluation of the BD PHOENIX Automated Microbiology System for Detection of Methicillin Resistance in Coagulase-Negative Staphylococci

Evaluation of the BD PHOENIX Automated Microbiology System for Detection of Methicillin Resistance in Coagulase-Negative Staphylococci

Antimicrobial Potential of Plant Seed Extracts against Multidrug Resistant Methicillin Resistant Staphylococcus aureus (MDR-MRSA)

Comparison of the Vitek Gram-Positive Susceptibility 106 Card, the MRSA-Screen Latex Agglutination Test, and mecA Analysis for Detecting Oxacillin Resistance in a Geographically Diverse Collection of Clinical Isolates of Coagulase-Negative Staphylococci

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