Surveillance of Methicillin-Resistant Staphylococcus aureus: Cluster Analysis for Minimum Inhibitory Concentration Typing Using Spreadsheet Software

• Published in: Japanese Journal of Infection Prevention and Control Vol. 27; no. 5; pp. 323 - 328
• Main Authors: YOSHIDA, Junichi, ASANO, Ikuyo, KIKUCHI, Tetsuya, MATSUBARA, Nobuo, UENO, Takako, HIRATA, Noriko, YAMASHITA, Akihisa, ISHIMARU, Toshiyuki
• Format: Journal Article
• Language: English; Japanese
• Published: Japanese Society for Infection Prevention and Control 2012
• Subjects: Computer programs; methicillin-resistant Staphylococcus aureus (MRSA); minimum inhibitory concentrations (MIC); Staphylococcus aureus; surveillance
• ISSN: 1882-532X; 1883-2407
• DOI: 10.4058/jsei.27.323

We have reported an accuracy of 73% using cluster analysis on drug sensitivity using the SPSSTM (Method S) compared to genotyping for methicillin-resistant Staphylococcus aureus (MRSA). Here we studied the efficacy of cluster analysis using ExcelTM with free additional software (Method E) on multi-drug susceptibility compared to Method S. Subjects were MRSA strains first isolated in an individual. Cluster analysis was performed in (1) 71 strains using the same 11 drugs used in our previous study, (2) 70 strains using 15 drugs for the 2011 series, and (3) 70 strains using 13 drugs for the 2005 series suspected of cross infection. (1) Method E typed completely as did Method S. (2) Method E showed sensitivity, specificity, and accuracy of 97.6%, 92.9%, and 95.7% compared to Method S. (3) Method S typed four strains in one cluster separately from those of hospital personnel, indicating cross propagation rather than transmission via the staff. Hand-to-hand infection control was enforced with success. Method E showed identical typing with Method S. Methods E and S allowed typing in about three days. Therefore, typing using Method E may have advantages in analyzing MRSA cross infection, enabling rapid intervention.