Persistence of Acinetobacter Baumannii Complex (ABC) and Methicillin-Resistant Staphylococcus Aureus (MRSA) in Hospital Rooms Despite 4 Rounds of Terminal Cleaning and Disinfection (C/D): Exploring a New Strategy

Background:

Persistence of multi-drug resistant ABC (MDRABC) and MRSA on inanimate surfaces in hospital rooms has been implicated as a potential source of nosocomial infection in hospitalized patients.  The optimal C/D method of rooms newly vacated by MDRABC+ (infected and/or colonized) patients is unclear.

Objective: To study the rate of persistently ABC+ or MRSA+ rooms (with 1 or more culture+ site) newly vacated by MDRABC+ patients following 4 rounds of C/D (4xC/D) and explore the impact of a new strategy, 1xC/D followed by HPV treatment (1XC/D+HPV), on the rate of persistently ABC+ or MRSA+ rooms in non-outbreak settings.

Methods: The setting was a 900-bed tertiary care hospital in St. Louis, MO. MDRABC (susceptible to 3 or less antibiotics)+ patients in the burn unit (BU) were considered "non-endemic", while those outside of the BU were categorized as "endemic" cases.  There were no known hospital outbreaks of MRSA during the observed periods.  Rooms newly vacated by MDRABC+ patients were routinely cultured by pre-moistened swabs for ABC and MRSA (irrespective of MRSA status of the prior room occupant) following 4xC/D with 0.5% hypochlorite solution during period A (Jan 9, 2006- Apr 3, 2008), and following 1xC/D+HPV during period B (Dec 15, 2008-Dec 17, 2009). 

Results: During period A, 312 (56[18%] in the BU) rooms newly vacated by MDRABC+ patients were cultured (5705 room sites, mean 18.3 sites/room, range 16-30 sites/room) following 4xC/D.  Either ABC or MRSA grew from ≥ 1 site of 83 (26.6%) rooms; 51 (16.4%) and 44 (14.1%) rooms with persistent ABC or MRSA+ site(s), respectively.  In the BU, the rate of persistently ABC+ rooms was not significantly different than those of other hospital rooms studied (21.4% vs 15.2%, respectively, P=0.3), but the rate of persistently MRSA+ rooms was significantly higher (28.6% vs 10.9%, O.R. 3.3, P=0.002).  During period B, 128 rooms vacated by MDRABC+ patients outside of the BU underwent 1xC/D+HPV treatment and cultured (20 sites/room); 6 (4.5%) rooms remained either ABC+ or MRSA+, 5 (3.9%) and 2 (1.5%) were persistently ABC+ or MRSA+, respectively.  Considering endemic MDRABC cases alone (BU rooms excluded),  rooms undergoing 1xC/D+HPV treatment were significantly less likely to remain ABC+ or MRSA+  compared to 4x C/D rooms (3.9% vs 15.5%, O.R. 0.22, and 1.5% vs 11.4%, O.R. 0.12, respectively, P<0.001 for both) .  All 4 ABC isolates from 1xCD+HPV rooms undergoing susceptibility testing were MDR; 3 were resistant to imipenem. 

Conclusions: Despite 4xC/D, a sizeable proportion of hospital rooms vacated by MDRABC+ patients remain contaminated with ABC and MRSA in non-endemic and endemic settings.   A new strategy involving 1xC/D followed by HPV treatment appears superior to 4xC/D in reducing the rate of persistently ABC and MRSA-contaminated hospital rooms in endemic settings.