Catecholamine inotrope resuscitation of antibiotic-damaged staphylococci and its blockade by specific receptor antagonists

The increasing use of antibiotic-coated catheters, such as those containing rifampin or minocycline, has led to a decrease in catheter colonizationby staphylococci but not to a decrease in the incidence of catheter-related blood-stream infection (BSI). Because catheters are used for the administration of catecholamine inotropes tomaintain cardiac function, we examined whether 2 commonly employed inotropes, dopamine and norepinephrine, could affect bacterial viability after exposure to rifampin and minocycline. Rifampin inhibition and minocycline inhi-bition of staphylococcal growth could be reversed by exposure to dopamine or norepinephrine as a result, in part, of catecholamine-mediated increasedprovisionof host-sequestered iron.The simultaneous additionof inotropes with an antibiotic didnot affect antibiotic susceptibility. Inotrope-induced growth inbacteria previously exposed to antibiotics was blocked by the inclusion in culturemedia of specific catecholamine-receptor antagonists. Con-sidered collectively, these results provide amechanistic basis for understanding how host-related factors, such as inotrope-based therapeutics, may influence the recovery of antibiotic-stressed bacteria in clinical settings. The ability of staphylococci to colonize indwellingmed-ical devices, such as central venous catheters (CVCs), is recognized as the most common source of infection en-countered in the intensive care setting [1]. The incidenc