Abstract
Coagulase-negative staphylococci (CoNS) have been increasing in importance as a cause of native valve endocarditis (NVE). Most cases of NVE caused by CoNS are attributable to Staphylococcus epidermidis. NVE caused by CoNS acquired in a nosocomial setting may differ from cases acquired in the community in several ways. It may be associated with hemodialysis, the presence of a long-term indwelling central catheter or pacemaker, or a recent invasive procedure; nosocomial cases may have a higher rate of methicillin resistance among CoNS isolates, and so be more likely to be treated with vancomycin. Unfortunately, NVE caused by methicillin-resistant CoNS has been associated with significantly higher rates of persistent bacteremia and in-hospital mortality than methicillin-susceptible isolates. The poor outcomes in these cases point to the need for alternative therapies with potent activity against methicillin-resistant CoNS. In our medical center, a 76-year-old man presented with native-valve endocarditis and positive blood cultures for methicillin-resistant Staphylococcus epidermidis (MRSE). During each of three 6-week courses of treatment with vancomycin, blood cultures were negative, but they once again became positive for MRSE when vancomycin was discontinued. The minimum inhibitory concentration of the MRSE isolates for vancomycin remained stable at 2 μg/mL. Eventually, treatment with daptomycin was initiated (500 mg [7 mg/kg]) 3 times/week for 6 weeks. Over the following year, no positive cultures for MRSE were detected.
Highlights
Coagulase-negative staphylococci (CoNS) have been increasing in importance as a cause of native valve endocarditis (NVE) [1,2,3]
In the International Collaboration of Endocarditis-Prospective Cohort Study (ICE-PCS) cohort, which included 1635 patients from 61 centers in 28 countries with definite NVE and no history of injection drug use, the mortality rate for NVE caused by CoNS was comparable to that for NVE caused by Staphylococcus aureus and significantly higher than that for NVE caused by viridans group streptococci [4]
In a randomized clinical trial, daptomycin was as effective as a control regimen in patients with bacteremia caused by S. aureus, including the subset with right-sided endocarditis [16] and those with methicillin-resistant strains [17]
Summary
Coagulase-negative staphylococci (CoNS) have been increasing in importance as a cause of native valve endocarditis (NVE) [1,2,3]. In a randomized clinical trial, daptomycin was as effective as a control regimen (low-dose gentamicin plus either an antistaphylococcal penicillin or vancomycin) in patients with bacteremia caused by S. aureus, including the subset with right-sided endocarditis [16] and those with methicillin-resistant strains [17]. This report describes a case of NVE caused by MRSE that was treated successfully with daptomycin after the patient failed multiple courses of vancomycin. Four blood cultures obtained between January 18 and February 8, while the patient was receiving vancomycin and rifampin, were negative. Further treatment course The patient was admitted on July 27 with fever, chills, and rigor He was diagnosed with a central-line infection caused by Enterobacter cloacae and received lock therapy with IV ciprofloxacin 400 mg daily through his dialysis catheter for 2 weeks. The patient has remained stable and continues to do well at 18 months after discontinuing daptomycin
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