Characterization of Staphylococcus epidermidis 1457 and an isogenic PIA-negative/HA-negative mutant in a rat CVC-associated infection model

S. epidermdis (SE) is the preeminent cause of intravascular catheter-associated infection. The hemagglutinin (HA) and polysaccharide intercellular adhesin (PIA) are polysaccharides that appear to play an important role in the ability of SE to adhere to biomaterials and form macrocolonies. We developed a novel in-vivo model in which subcutaneously tunneled central venous catheters (CVC) were implanted in 11 male Sprague-Daley rats. The catheters were infected by injection of 10⁴ CFU of either SE 1457 or PIA(-)/HA(-) mutant M10. 7 days following IV challenge, the rats were sacrificed and the catheters removed aseptically. SE adhering to the CVC were quantitated and quantitative cultures were performed on the blood, heart, lungs, liver, and kidneys. Mean number of SE recovered from the various sites are as follows: catheter blood heart lung liver kidney 1457 130 488 10967 3320 10553 356 M10 0 20 576 1515 1643 93 SE 1457 showed a significantly greater propensity to cause CVC-associated infection as compared to the PIA (-) / HA (-) mutant (66% vs 20%). We conclude that PIA and HA are important in the pathogenesis of CVC-associated infection.