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The Challenge of Right-Sided Endocarditis
Abstract & Commentary
Synopsis: The challenges inherent in the management of pulmonic valve endocarditis mandate a high level of awareness in the clinician.
Source: Hamza N, et al. Isolated Pulmonic Valve Infective Endocarditis: A Persistent Challenge. Infection. 2004;32: 170-175.
Isolated pulmonic valve endocarditis is the topic of an interesting article from the Cleveland Department of Veterans Affairs Medical Center. Hamza and colleagues reported 3 of their own cases, involving men ages 47, 64, and 76, none of whom were intravenous drug addicts (IVDA). In 2 of the patients, Enterococcus faecalis was the causative pathogen, and in the other patient, a coagulase-negative staphylococcus was the pathogen. Transesophageal echocardiograms (TEE) were useful in proving involvement of the pulmonic valve. The 64-year-old patient, with a history of hypertension and chronic renal insufficiency, died. Initially, this patient was treated with intravenous vancomycin and gentamicin, but fever persisted and the E. faecalis isolated remained resistant to vancomycin, ampicillin, and gentamicin. Therapy with linezolid followed for 6 weeks, and subsequent blood cultures were negative. One week after completion of linezolid therapy, while in rehabilitation, the patient developed fever, hypotension, and acute respiratory failure and subsequently died.
Hamza et al reviewed 41 other cases of isolated pulmonic endocarditis. The most common pathogens were staphylococci, both Staphylococcus aureus and coagulase-negative staphylococci. A potpourri of other organisms included group B Streptococcus and Actinobacillus acitomycetemcomitans. Neisseria gonorrheae, known to attack the right side of the heart, was the cause in only 1 patient. About 40% of reviewed patients had no detected site of entry. One fourth were IVDA patients. About 15% were related to IV or dialysis catheters. Less than half of all patients had embolic phenomena, and only a handful died.
Only 2 patients had an Enterococcus as a causative pathogen, which highlights the new cases reported by Hamza et al. The occurrence of vancomycin-resistant E. faecalis pushed Hamza et al to use parenteral linezolid in 1 patient with apparent sterilization of the blood, although no postmortem exam was performed. The patient who had oxacillin-resistant CNS was also treated with an oral regimen of linezolid in combination with rifampicin which produced subsequent sterile blood cultures.
Comment by Joseph F. John JR, MD
Hamza et al, from the Cleveland VA, have uncovered 3 noteworthy cases of isolated pulmonic valve endocarditis, allowing them to produce for us a very useful review. The major points of their own cases and reviews include the uncommonness of the entity, the association with IVDA and catheter infection, the high prevalence of Staphylococci as the causative organisms, necessity for newer antimicrobial agents to combat multiresistant pathogens, improved diagnostic value of TEE, and finally, the emergence of Enterococci in 2 of the 3 reported cases in this article.
A high degree of suspicion truly helps to make this diagnosis. Basic physical examination proved useful; all 3 reported that the patients had murmurs suggestive of pulmonic valve involvement. That finding, plus positive blood cultures and a positive TEE, clinched the diagnosis. In the patient with CNS, a follow up TEE actually showed some resolution of the vegetation, suggesting the follow-up TEE may be helpful. In this patient, Hamza et al were also able to recover the CNS from a Permacath, thus suggesting a site of entry.
Hamza et al also discuss the interesting aspect of surgery. They decided against surgery in 2 of their patients, and note that medical management allowed stabilization of cardiac function. Finally, although the poorly bactericidal effect of linezolid did cause apparent failure in the 2 patients reported, other new agents now available, like daptomycin, have bactericidal mechanisms that may benefit such patients.
Joseph F. John, Jr., MD Chief, Medical Subspecialty Services, Ralph H. Johnson Veterans Administration Medical Center; Professor of Medicine, Medical University of South Carolina, Charleston, SC, is Co-Editor of Infectious Disease Alert.