Necessity of Screening of both the Nose and the Throat To Detect Methicillin-Resistant Staphylococcus aureus Colonization in Patients upon Admission to an Intensive Care Unit

We read with great interest the article by Marshall and Spelman (1). Similar to findings from our study with mainly methicillin-susceptible Staphylococcus aureus (MSSA), they found the throat to be an important site of colonization by methicillin-resistant Staphylococcus aureus (MRSA) (2). Our findings from a setting with a low prevalence for MRSA (0.74% MRSA colonization; 37/5,041 individuals) are confirmed by this study of a setting with a high prevalence (19%; 224/1,181 individuals) for MRSA: the colonization patterns of MRSA and MSSA are very similar in these studies. However, our study results indicate that throat cultures increase sensitivity to the detection of carriers by 12.8%, compared to the additional 15.3% (28/183 patients) stated in the study by Marshall and Spelman (1), ignoring the patients who had only positive groin and axillary swabs. Therefore, we do not agree with the conclusions that “either throat or nose swabs are essential.” Both sites are important, and the costs of cultures of the nose and throat can be minimized by pooling the samples in the laboratory, which is applicable for both conventional cultures and PCR techniques. Screening of additional sites may increase the sensitivity in an intensive care setting but may not be feasible in a routine setting such as an emergency room (3).

In conclusion, screening of the nares only should be replaced by screening of the nares and the throat, in any setting. Pooling samples in the microbiology laboratory is a reasonable option to avoid additional expense.