Comparison of three chromogenic media and enrichment broth media for the detection of methicillin-resistant Staphylococcus aureus from mucocutaneous screening specimens : Comparison of MRSA chromogenic media.
This study compares the performance of three chromogenic culture agar plates, chromID MRSA, MRSA-Screen and MRSA-Select, by challenging with a collection of Staphylococcus aureus strains and screening samples obtained from hospitalised patients. All chromogenic media showed excellent sensitivity (>95%) and specificity after 18 h on the methicillin-resistant Staphylococcus aureus (MRSA) collection strains, but the specificity of MRSA-Screen decreased markedly after 42 h. Sixty-eight of 1,002 screening specimens yielded MRSA on at least one medium. The sensitivity of all media to detecting MRSA after 18 h was <50%, but this increased to 75% (chromID MRSA), 81% (MRSA-Screen) and 72% (MRSA-Select) after 42 h and 85% after enrichment and plating on the same media. The specificity at 18 h was excellent, but was significantly lower for MRSA-Screen after 42 h and enrichment. In conclusion, all media showed equivalent sensitivities after 18 h of incubation and performed better when enriched before inoculation. MRSA-Screen was more sensitive but less specific than the two other media after 42 h of incubation.
Laboratoire de Référence MRSA-Staphylocoques, Service de Microbiologie, Hôpital Erasme, Bruxelles, Belgium. claire.nonhoff@ulb.ac.be
C
C
Nonhoff
O
O
Denis
A
A
Brenner
P
P
Buidin
N
N
Legros
C
C
Thiroux
M
M
Dramaix
M J
MJ
Struelens
D002863:Chromogenic Compounds; D003470:Culture Media; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000254:growth & development* / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D009297:Nasal Mucosa / Q000382:microbiology; D010502:Perineum / Q000382:microbiology; D010614:Pharynx / Q000382:microbiology; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012867:Skin / Q000382:microbiology; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013997:Time Factors
D002863:Chromogenic Compounds; D003470:Culture Media