Because MDRAB survives for long periods on environmental surfaces and may promote cross-transmission, we investigated the efficiency of ϕAB2 in reducing A. baumannii M3237 contamination on surfaces. We observed the ϕAB2 concentration required to reduce A. baumannii M3237 contamination was lower for liquid suspensions than hard surfaces. The mean survival rate ratio of

A. baumannii M3237 between surface and liquid suspension ranged from 2–10,151 depending on the phage concentration. As ϕAB2 does not diffuse as freely on a hard surface as in a suspension, a higher concentration of ϕAB2 was required VX-809 supplier for surface decontamination of MDRAB compared with in solution. The ability of phages to persist on a surface for extended periods is limited by many factors, such as desiccation [37], which may explain the loss of ϕAB2 infectivity after 2 months

storage on a glass surface. Because ϕAB2 cannot survive for long periods on a hard surface, the phage detergent must be frequently re-applied XL184 to surfaces to provide persistent bactericidal or MDRAB activity. Previous biocontrol studies suggested that high phage numbers should be used without relying on phage amplification [22, 23]. Although ϕAB2 has a larger burst size than other phages [23, 35], it is important to determine the optimal phage concentration that will allow efficient phage attachment and amplification for the quantity of MDRAB present. Experiments on environmental ICU samples have identified A. baumannii on 39% of the sampled surfaces with

a mean A. baumannii DNA concentration of 19,696 copies [39]. Based on the results of our surface evaluation, we recommend that a phage concentration of at least 107 PFU/cm2 be applied to surfaces in ICUs. This approach may not be suitable for the treatment of large surfaces, but may be useful for small biomedical devices. Abuladze et al. suggested a glass matrix is easier Sulfite dehydrogenase to decontaminate than gypsum [26]. Thus, the phage decontamination efficiency for different surfaces such as gypsum, plastic, Teflon, or other polymers may vary, and requires further investigation. In addition to phage concentration, the incubation time is also critical for surface applications. When a high phage concentration (108 PFU/slide) was used to treat a surface contaminated with bacteria at a concentration of 105 CFU/slide, an incubation time of 5 min resulted in a 96% reduction of A. baumannii M3237 numbers. This incubation time was caused a 94% reduction in the number of Escherichia coli O157:H7 [26] under the same test conditions. MDRAB can be transmitted via the hands of health-care personnel. However, frequent or improper hand washing can cause skin to lose moisture or become irritated, reducing the hand washing rate despite intensive hand washing educational programs.