We appreciate the thoughtful comments and remarks of Dr Kaw regarding our article in the ARCHIVES. Indeed, MRSA nasal colonization leads to autoinfection at higher rates than does colonization with MSSA. However, this observation is most probably confounded by differences in severity of underlying disease between patients colonized with MRSA and MSSA. In addition, patients with more serious disease severity are more often exposed to different classes of antibiotics. This selective antibiotic pressure promotes colonization with MRSA to a greater degree than does MSSA.1 Consequently, as there is a larger load of S aureus colonization, the likelihood of autoinfection increases.
Blot SI, Vandewoude KH, Hoste EA, Colardyn FA. Is MRSA More Pathogenic in Critically Ill Patients?—Reply. Arch Intern Med. 2003;163(6):740. doi:10.1001/archinte.163.6.739