In vitro infectability of prosthetic mesh by methicillin-resistant Staphylococcus aureus

Although mesh use is important for effective herniorrhaphy in adults, prosthetic infections can cause serious morbidity. Bacterial adherence to the mesh is a known precursor to prosthetic infection. We compared the ability of common mesh prosthetics to resist bacterial adherence. The meshes studied included polypropylene (Marlex, expanded polytetrafluoroethylene (PTFE) with and without silver chlorhexidine coating (DualMesh Plus and Dualmesh) composite meshes (Composix E/X, Proceed, and Parietex Composite) and lightweight polypropylene meshes (TiMesh, Ultrapro, and Vypro). Fifteen samples of each mesh type were individually inoculated with a suspension of 10(8 )methicillin-resistant Staphylococcus aureus (MRSA) in tryptic soy broth. After incubation at 37 degrees C for 1 h, the mesh pieces were then removed and serially washed. The colony-forming units (CFU) of MRSA present in the initial inoculum, at the end of the 1-h warm-water bath (broth count), and the pooled washes (wash count), were determined using serial dilutions and spot plating. The bacteria not accounted for in the broth or wash counts were considered adhered to the mesh. Samples of each mesh type were also analyzed using scanning electron microscopy (SEM). Data are presented as the mean percentage adherence with ANOVA and Tukey's test used to determine significance (P<0.05). The DualMesh Plus mesh had no detectable MRSA in the broth or the pooled wash samples. Dualmesh had less adherence compared with Marlex, Proceed, and Vypro (P<0.05). Conversely, Vypro had a statistically higher adherence (96%, P<0.05) as compared to TiMesh, Ultrapro, Composix E/X, and Parietex Composite. SEM confirmed bacterial adherence to all the mesh types except DualMesh Plus. The ability of a biomaterial to resist infection has an important clinical significance. DualMesh Plus, due to its antimicrobial coating, is the only mesh type of the nine tested that demonstrated a bactericidal property. Standard PTFE (Dualmesh) also had less bacterial adherence. Vypro demonstrated an increase in bacterial adherence; this was possibly due to the multifilament polyglactin 910 weaved within the prolene component of the mesh.