PCG + GM (2週) ± リファンピシン
●Treatment of prosthetic valve endocarditis (PVE) is more difficult than treatment of native valve endocarditis (NVE) and may require surgical replacement of the prostheses in addition to antibiotic therapy.
●Identification of the causative organism is critical to determine the most appropriate antimicrobial regimens.
●We recommend the same antimicrobial regimens for a specific pathogen causing PVE as is used for that organism when it causes native valve endocarditis (Grade 1B) but usually for longer duration. An exception is staphylococcal endocarditis; for this microorganism, we recommend treatment with three agents in combination, with one of these being rifampin (Grade 1B).
●We recommend treatment of PVE with an agent(s) that is bactericidal for the isolated microorganism for at least six weeks (Grade 1C).
●Treatment choices for staphylococcal PVE are the same regardless of whether the pathogen is coagulase-negative Staphylococcus or S. aureus. The primary consideration in choosing therapy hinges upon whether or not the organism is sensitive to methicillin.
●We recommend a treatment regimen for enterococcal PVE that includes the synergistic interaction of a cell wall active agent (penicillin, ampicillin, or vancomycin) and an aminoglycoside (gentamicin or streptomycin) if possible (Grade 1B). When these combinations are precluded by the resistance pattern of the organism or the patient's risk for aminoglycoside nephrotoxicity, the high-dose ceftriaxone-ampicillin is a reasonable alternative regimen.
Most viridans group streptococci are highly penicillin susceptible, defined in the United States as a minimum inhibitory concentration (MIC) ≤0.12 mcg/mL. Occasional strains are relatively resistant to penicillin (MIC >0.12 mcg/mL and <0.5 mcg/mL), and rare strains are fully resistant with a penicillin MIC ≥0.5 mcg/mL . The American Heart Association (AHA) guidelines use these MIC parameters to guide approach to treatment; the British Society for Antimicrobial Chemotherapy (BSAC) guidelines and the European Society of Cardiology (ESC) guidelines use different MIC parameters.
Combination therapy with a beta-lactam antibiotic and an aminoglycoside (if the isolate does not exhibit high-level resistance to the aminoglycoside) is the preferred regimen for streptococcal prosthetic valve endocarditis (PVE). In an effort to provide maximal therapy, combination beta-lactam-aminoglycoside therapy is used to achieve synergistic killing of the organism. This synergistic interaction is similar to that seen with combination therapy for enterococcal endocarditis.
Based on in vitro studies, clinical series, and experience of experts, the addition of gentamicin to penicillin may be beneficial for the therapy of PVE caused by penicillin-susceptible streptococci. In the absence of high-level gentamicin resistance, gentamicin (given as a single daily dose) may be given during the initial two weeks of treatment.
In the absence of high-level streptomycin resistance, streptomycin may be given in lieu of gentamicin to achieve the same effect, but gentamicin is more commonly used in clinical practice due to the wider availability of laboratory testing for gentamicin serum levels and because dosing regimens for gentamicin are more familiar to most clinicians than dosing regimens for streptomycin. For these reasons, we recommend gentamicin if the isolate is susceptible. Penicillin, a cephalosporin, or vancomycin can be used alone if aminoglycoside therapy is relatively contraindicated.
If the Streptococcus is relatively resistant to penicillin, the AHA recommends that the aminoglycoside be continued for the entire duration of therapy, if not precluded by nephrotoxicity. Although there is a theoretical benefit to a longer course of aminoglycoside therapy when treating PVE caused by these relatively resistant strains, there are not sufficient data upon which to base recommendations on duration of therapy or dosing frequency. We recommend that gentamicin be administered in three divided doses for two weeks when the isolate has a penicillin MIC >0.12 mcg/mL and for six weeks if the MIC is ≥0.5 mcg/mL or if PVE is caused by Abiotrophia defectiva, Granulicatella spp, or Gemella spp. We base these recommendations on limited data generated from native valve endocarditis treatment and the risk of enhanced aminoglycoside nephrotoxicity with longer courses of therapy. If the patient is intolerant of penicillin and ceftriaxone, vancomycin monotherapy can be used; concurrent gentamicin treatment is not advised because of the increased risk of nephrotoxicity when these two antimicrobials are administered concurrently.
Among patients who are allergic to penicillin, vancomycin is advised for those with immediate-type reactions (urticaria or anaphylaxis). Cefotaxime or ceftriaxone may be used in non–immediate type allergies.
Antibiotic therapy for PVE caused by penicillin-susceptible Streptococcus pneumoniae (in the absence of meningitis) or a Streptococcus belonging to serogroups A, B, C, F, and G consists of penicillin or ceftriaxone as recommended for penicillin-susceptible viridans streptococci. For serogroups B, C, F, and G, gentamicin may be administered for the initial two weeks. For treatment of PVE due to S. pneumoniae with penicillin resistant (MIC ≥0.12 mcg/mL) in the absence of meningitis, the regimens in the Table may be used. In the setting of PVE due to penicillin-resistant pneumococci complicated by meningitis, the regimen must be adjusted to ensure adequate antimicrobial penetration into the cerebrospinal fluid (with meningeal doses of ceftriaxone, vancomycin, or both).