Evaluation of selection media for the detection of borderline MRSA |
| |
Authors: | Keiko Yamada Kazuhisa Inuzuka Norio Tatsumi Ikuyo Sanzen Teruko Ohkura Akira Okamoto Tadao Hasegawa Michio Ohta |
| |
Institution: | (1) Department of Bacteriology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan;(2) Department of Microbiology, Anjo Kosei Hospital, Anjo, Japan;(3) Department of Bacteriology, School of Medicine, Nagoya City University, Nagoya, Japan;(4) MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya, Japan;(5) Department of Fundamental Nursing II, College of Nursing, Aichi Medical University, Nagakute, Aichi, Japan; |
| |
Abstract: | Recently, hospital-associated as well as community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains showing a low level of resistance to oxacillin have emerged worldwide, and as a result, a highly sensitive
method to detect MRSA has become more important. To prevent MRSA being overlooked, some selection agar media have recently
been developed. We evaluated six commercially available selection agar media in regard to the detection of 35 borderline MRSA
(BOMRSA) strains which were mecA-positive but showed low resistance to oxacillin. The MIC values of oxacillin differed between the broth dilution method and
the agar dilution method, and 11 of the 35 BOMRSA strains were judged as sensitive by the broth dilution method and 14 of
the 35 strains were judged as sensitive by the agar dilution method. Thirty-two of the 35 strains were also judged as sensitive
by an oxacillin disk diffusion test. Moreover, there was no consistent pattern of resistance to the tested beta-lactams among
the BOMRSA strains. Some commercially available selection media designed for the detection of MRSA contain a beta-lactam antibiotic;
oxacillin, ceftizoxime, or cefoxitin, and we evaluated media containing each of these agents. The detection sensitivities
of cefoxitin-based agar media, such as CHROMagar MRSA and MRSA ID, for BOMRSA were 100% at 24-h culture. On the other hand,
the media containing oxacillin or ceftizoxime gave lower results at 24 h, suggesting that, possibly, BOMRSA strains may not
to be able to grow on these media. These results suggest that cefoxitin-based agar media should be recommended for the first-round
screening of BOMRSA. |
| |
Keywords: | Methicillin-resistant Screening Cefoxitin |
本文献已被 ScienceDirect SpringerLink 等数据库收录! |
|