Evaluation of Roche LightCycler kits for the detection of methicillin-resistant Staphylococcus aureus in patient screening broths

Abstract number: 902_p1019

Levi K.


To evaluate two LightCycler kits for the detection of methicillin-resistant Staphylococcus aureus from patient screening swabs in comparison with conventional culture methods.


Sets of patient screening swabs (n = 100) were incubated in an overnight enrichment broth containing oxacillin to eliminate methicillin-sensitive S. aureus. Samples were lysed with lysozyme/lysostaphin before amplification. Broths were also cultured on Oxacillin Resistance Screening Agar. Samples were initially tested with the LightCycler Staphylococcus kit. Differentiation of S. aureus from coagulase-negative staphylococci (CNS) was based on melting curve analysis of the amplified product. Samples positive for S. aureus were also tested for the methicillin resistance gene mecA with the LightCycler MRSA Detection kit.


The LightCycler Staphylococcus and MRSA Detection kits identified 29 MRSA-positive samples from overnight screening broths; MRSA colonies were isolated from 22 of these samples. All seven samples positive only by the LightCycler assays remained positive on repeat testing, and negative controls were consistently negative. Two of these seven samples were obtained from patients who had been MRSA-positive in the previous 6 months. One sample, which was MRSA-positive by culture and LightCycler-negative for S. aureus DNA, was LightCycler-positive on repeat testing. No S. aureus-positive, mecA-negative samples were detected, indicating that the selective broth inhibited the growth of methicillin-sensitive S. aureus. Two melting peaks, characteristic of S. aureus and CNS, were identified in 12 samples; MRSA was isolated from eight of these.


The LightCycler Staphylococcus and MRSA Detection kits were highly sensitive and may be particularly useful for rapidly investigating the possibility of MRSA carriage by health care workers or patients in a potential outbreak situation.


Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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