MUPIROCIN TREATMENT OF STAPHYLOCOCCUS-AUREUS NASAL CARRIAGE AND PREVENTION OF INFECTION IN INTENSIVE-CARE UNITS - A MULTICENTER CONTROLLED-STUDY

Objective: To examine the efficacy of nasal mupirocine ointment for eradication of S. aureus nasal carriage and prevention of acquired infections due to S. aureus in patients hospitalised in intensive care units (ICU) with high endemic rate of MRSA. Design: Open sequential trial with two periods of 18 and 16 weeks, with one untreated group compared to a subsequent treated group. Setting: Five medical or polyvalent ICUs in university or university-affiliated hospitals. Patients: Consecutive patients with ICU stay of over two days and simplified acute severity score of >6. Intervention: Nasal swabs were obtained on admission and every four days for the first 2 weeks of ICU stay. During the second period, patients with S. aureus nasal carriage were treated with mupirocin for 5 days. Measurements and main results: S. aureus nasal carriage was detected in 225/546 (41%) patients followed during the first period, including 152 (28%) on admission and 95 (17.4%) secondarily; S. aureus infection occurred in 57 (10.4%) patients, associated in 33 (6%) with secondarily acquired nasal carriage. During the treatment period, nasal carriage was detected in 159/463 patients (34.4%, p=0.03), including 107 (23%) on admission and 59 (12.8%, p=0.04) secondarily. Mupirocin treatment resulted in eradication of nasal carriage in 78/95 evaluable patients treated; S. aureus infections however occurred in 35 (7.6%, p=0.12) patients, including 25 (5.4%) with secondarily acquired infection and nasal carriage. Methicillin-resistant strains (MRSA) accounted for 56% and 49% of all S. aureus isolates in the two periods, respectively, including 32% and 33% of isolates recovered from screening samples on admission and 88% and 76% of isolates (p<0.001) recovered after 4 days in the ICU. Six strains recovered during the second period had low-level resistance to mupirocin. Conclusions: In intensive care units where MRSA is highly endemic, screening for nasal carriers and their subsequent treatment with mupirocin results in limited reduction of infection rates despite marked efficacy on nasal carriage, and carries the risk of emergence of resistance to the topical agent.