Evaluation of Two Chromogenic Agar Media for Recovery and Identification of Staphylococcus aureus Small-Colony Variants

• Published in: Journal of Clinical Microbiology Vol. 43; no. 4; pp. 1956 - 1959
• Main Authors: Kipp, Frank, Kahl, Barbara C, Becker, Karsten, Baron, Ellen J, Proctor, Richard A, Peters, Georg, von Eiff, Christof
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.04.2005
• Subjects: Agar; Bacterial Typing Techniques; Bacteriological Techniques; Bacteriology; Biological and medical sciences; Chromogenic Compounds - metabolism; Culture Media; Fundamental and applied biological sciences. Psychology; Humans; Infectious diseases; Medical sciences; Microbiology; Miscellaneous; Phenotype; Staphylococcal Infections - diagnosis; Staphylococcal Infections - microbiology; Staphylococcus aureus; Staphylococcus aureus - classification; Staphylococcus aureus - growth & development; Staphylococcus aureus - isolation & purification; Bacteria; Micrococcales; Micrococcaceae; Identification; Microbiology; Staphylococcus aureus
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.43.4.1956-1959.2005

To identify the most rapid and reliable technique for recovery and identification of Staphylococcus aureus small-colony variants (SCVs), the colonial appearance of 106 isolates representing SCVs and the normal phenotype were evaluated on two newly described chromogenic agar media. Although almost all of the SCVs grew on the chromogenic agar media, they did not exhibit a change of color. In comparison with conventional media, S. aureus ID agar (SAID; bioMérieux, La Balme Les Grottes, France) showed the most reliable results, with 49 of 53 SCVs tested growing either as an SCV colony or with a normal phenotype after only 24 h of incubation. Growth of SCVs was often not detected before 72 h of incubation on some of the media tested. In conclusion, the most accurate and rapid method to detect both the species S. aureus and the SCV phenotype is to inoculate specimens onto both Columbia blood agar and SAID.