| The spread of antibiotic resistant bacteria is a major public health concern, as they result in greater healthcare costs and increased morbidity and mortality rates. Methicillin resistant Staphylococcus aureus (MRSA) is one organism of particular concern, with the number of infections increasing in epidemic proportion. Bacterial surface contamination with MRSA is significant, as it may serve as a reservoir for transmission and have negative health implications. The purpose of this study was to evaluate survival of MRSA on five environmental surface materials; glass, wood, vinyl, plastic, and cloth. The effect of relative humidity (RH) and bovine serum albumin (BSA) were also examined. Surfaces of 5.1cm2 were inoculated with 3.0 x 108 -- 1.4 x 109 MRSA CFU/ml with and without 1% BSA. Surfaces were incubated at 35°C at 45--55% and 16% RH. Hard surfaces were swab sampled and cloth surfaces hand stomached and re-suspended in phosphate buffer (PB). Suspensions of 100microl were spread plated onto agar plates and incubated at 35°C for 24 hrs; resulting colonies were enumerated. Samples were taken immediately upon drying (time 0), 3 hrs, 24 hrs, 2 days, 3 days, 4 days, and 5 days. Results showed that there was a significant difference (p<.001) among the surfaces; MRSA survived on plastic and vinyl for the longest amount of time, and wood for the least amount of time. The overall greatest concentration of CFU/ml remained on cloth; however, the MRSA did not persist past 3 days. The addition of BSA enabled MRSA to survive significantly longer (p<.001). The amount of CFU/ml was significantly less (p=.002) on surfaces stored in 45--55% RH versus 16% RH. Information gathered from this study indicates that viable MRSA bacteria can remain on surfaces for days; likely serving as a reservoir for transmission. The best way to control the MRSA epidemic is to prevent transmission. |
