There are several theories as to why bacterial biofilms are so resistant to antimicrobial therapy, which may exist in tandem with one another: i) the matrix impedes the penetration of antimicrobials into the biofilm, ii) many cells within the biofilm are not metabolically active and are thus resistance to many antimicrobials therapies, iii) biofilms are actively

resistant through the acquisition of resistance genes and/or the expression of efflux pumps, and iv) biofilms contain a subpopulation of cells that are not susceptible to antimicrobials (e.g. resistors) [4, 9]. As a result, the minimum inhibitory EPZ004777 in vitro concentration (MIC) of biofilm-embedded bacteria can be 10 to 1000 times higher than their planktonic counterparts, which often represents a dose that would be lethal to the host [10, 11]. Due to the potential impact of biofilms on the development and persistence of serious and life-threatening infections and the difficulty in eliminating them, understanding the mechanisms used to produce them in clinically relevant GSK1838705A mw bacteria along with the identification of potentially novel strategies to prevent or remove them is paramount. Staphylococcus pseudintermedius is a critically important, opportunistic, canine pathogen found in skin, soft tissue, and surgical site infections (SSIs)

[12]. Methicillin-resistant strains (MRSP) are of concern, because of their inherent resistance and ability to form biofilms [13, 14]. Overall, MRSP may be a good model of methicillin resistant biofilms that may have application to human methicillin resistant

infections [15]. In vitro studies of other staphylococcal strains have shown that biofilm-associated SSIs may be reduced through combinational antimicrobial therapy [16]. Clarithromycin (CLA), a semi-synthetic broad spectrum macrolide, has fairly potent in vitro and in vivo anti-biofilm activity against Gram-positive S. aureus alone and in combination with other antimicrobials, independent of its antimicrobial activity [16–18]. A recent study indicated that clarithromycin alone MycoClean Mycoplasma Removal Kit had little to no effect on biofilm formation by MRSP [19], yet a combinational therapy remained to be evaluated. Therefore, we elected to test such a therapy on MRSP biofilms. Fosfomycin (FOS) has been reported to destroy biofilm and increase penetration of other antimicrobials into the biofilms of both Gram-positive and Gram-negative bacteria [20–22]. This antimicrobial has been shown to interfere with the synthesis of peptidoglycan in the cell wall and enters susceptible bacteria by means to two different transport uptake selleck products systems: the L-α-glycerophosphate transport system (GlpT) and the hexose–phosphate uptake system (UhpT) [23].