Follow-up cultures for MRSA after eradication therapy: are three culture-sets enough?

Objectives: We compared the standard procedure of three MRSA follow-up culture sets to six to determine the number of recurrences detected between the third and sixth follow-up culture-set, and studied possible risk factors for MRSA recurrence.
Methods: A retrospective carrier cohort (2005-2010) was studied. Data was collected on MRSA culture-sets, follow-up, risk factors and outcome (recurrences during follow-up). We compared outcome between three and six follow-up MRSA culture sets, between HCWs and patients groups for complicated or uncomplicated carriers, and between nose-throat carriers and other carriers.
Results: Of 406 MRSA carriers, 179 had received eradication therapy and had a negative first follow-up MRSA culture-set. Between the third and sixth follow-up culture-set 54% (35/65) of total recurrences occurred. Over 88% of all recurrences were detected within two months. Combined nose and throat carriage OR 25.5 (1.6-419.1)) and intravascular lines (OR 13.6 (1.2-156.2)) were risk factors for early recurrence.
Conclusions: We recommend five culture-sets till one year after successful eradication therapy with a distinction between those at risk for early recurrence and HCWs who require frequent culturing in the beginning and those not at risk for early recurrence. This recommendation is a balance between the need for swift detection of MRSA recurrence and the patients' burden.
(Copyright © 2015 The British Infection Association. Published by Elsevier Ltd. All rights reserved.)