Reversion of methicillin-resistant Staphylococcus aureus skin infections to methicillin-susceptible isolates.
OBJECTIVE
The rise of methicillin-resistant Staphylococcus aureus (MRSA) infections in the outpatient setting has led to a growing trend of empirical antibiotic treatment for MRSA. The limited oral antibiotics available and the growing resistance to these antibiotics make this a controversial practice.


OBJECTIVE
To determine the frequency of patients with MRSA skin and soft-tissue infections (SSTIs) reverting to methicillin-susceptible Staphylococcus aureus (MSSA) positivity.


METHODS
Retrospective medical record review of inpatients and outpatients from our university hospital and clinics between January 1, 2000, and December 31, 2010.


METHODS
Patients in our institutional microbiological database were included if they had a MRSA-positive SSTI and subsequent culture-proven S aureus SSTI more than 1 month later. No sociodemographic restrictions were applied. A sample of at least 200 patients meeting the above criteria was desired. The database was sorted by ascending medical record number, with the first 1681 patients' medical records reviewed. Of these, 215 patients met our criteria.


METHODS
Whether a patient remained MRSA positive in subsequent SSTIs or reverted to MSSA-positive infections.


RESULTS
Of the total 215 patients, 64 (29.8%) had at least 1 incident of MSSA reversion, and 55 (25.6%) reverted to MSSA infections for the remainder of the study. We assessed various factors that might increase or decrease the likelihood of reversion. The presence of an invasive device was the only factor to demonstrate a statistically significant risk (relative risk, 1.20; 95% CI, 1.02-1.41; P = .03) toward remaining MRSA positive in subsequent infections.


CONCLUSIONS
Patients with MRSA SSTIs demonstrated the ability to revert to subsequent MSSA SSTIs with a significant frequency. Further study regarding MRSA risk factors and their effects on subsequent infections would be valuable in guiding empirical treatment. Reculturing new infections in previously MRSA-positive patients is a prudent management strategy as we recognize that susceptibilities of the S aureus organisms change.
Department of Dermatology, Oregon Health & Science University, Portland2now with the Department of Dermatology, University of Texas Medical Branch, Galveston.
Anisha B
AB
Patel
Emma
E
Hill
Eric L
EL
Simpson
Jon M
JM
Hanifin
D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016208:Databases, Factual; D004864:Equipment and Supplies / Q000382:microbiology; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013207:Staphylococcal Skin Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents