Performance of CHROMagar Staph aureus and CHROMagar MRSA for Detection of Airborne Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus
Abstract:In recent decades, the rise of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) has become one of the most significant problems in public health. The CHROMagar medium, which allows for direct color-based identification of target pathogens, could potentially be used to rapidly monitor airborne S. aureus and MRSA. In this study, the recovery efficiency of CHROMagar Staph aureus (CSA) for collecting airborne MSSA was evaluated in a chamber study. Subsequently, the colony identification performance of bioaerosol samplers combined with CSA and CHROMagar MRSA (C-MRSA) was evaluated in a hospital setting. Our results demonstrated that the agar medium, the type of bioaerosol sampler used, and the relative humidity all affected the recovery of the collected MSSA sample. The sampling stress that influenced the recovery of MSSA on CSA did not differ from that used when measuring its recovery on the commonly used tryptic soy agar. The average sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the colony identification were 24%, 90%, 13%, and 95%, respectively, for CSA and 71%, 65%, 16%, and 96%, respectively, for C-MRSA. Both CSA and C-MRSA had low PPV and high NPV, suggesting that a nonmauve-colored colony that is recovered on CSA or C-MRSA by air sampling can be reported as negative; however, any mauve-colored colonies should be subjected to further identification processes. On the basis of these findings, and depending upon the methods used, using CHROMagar to detect airborne MSSA or MRSA may shorten the detection time from 24 to 48 h.
Document Type: Research Article
Affiliations: 1: Research Center for Environmental Changes, Academia SinicaTaipei, Taiwan 2: Department and Graduate Institute of Public Health,Tzu Chi University, Hualien, Taiwan 3: Department of Laboratory Medicine and Biotechnology,Tzu Chi University, Hualien, Taiwan
Publication date: March 1, 2012