Author + information
- Vivian H. Chu, MD, MHS∗ ()
- ↵∗Reprint requests and correspondence:
Dr. Vivian H. Chu, Duke University Medical Center, Box 102359, Hanes 177, Durham, North Carolina 27710.
Infective endocarditis (IE) often poses challenges of the diagnostic and/or treatment variety. Take, for instance, the case of a 24-year-old man with congenital heart disease who is diagnosed with Bartonella henselae IE. Patient: “What’s the next step, doc?” Physician: “You will have a peripherally inserted central catheter in your arm through which you will receive intravenous antibiotics for 6 weeks. This will be followed by at least 3 to 6 months of oral antibiotics, potentially longer. These antibiotics may cause diarrhea. You will need to have your pacemaker removed and then replaced. If your heart valve falters, you will need to have open heart surgery to replace your heart valve.” And now for the really bad news: “You have to give away your cat…sorry.”
In this issue of the Journal, Delahaye et al. (1) report the results of a single-center study examining portals of entry (POEs) in IE. In this study, a total of 318 patients hospitalized for IE between 2005 and 2011 were systematically evaluated by a dentist, ear, nose, and throat specialist, urologist (women were evaluated by a gynecologist), and, if indicated on examination, a dermatologist. Brain and body radiological scans were systematically performed. A gastrointestinal (GI) evaluation, including colonoscopy and gastroscopy, was performed if the infecting pathogen was a GI microorganism and/or if the patient was ≥50 years of age or at high risk for colorectal cancer. POEs were identified in 74% of the patients. The largest group of POEs were cutaneous (40%), followed by oral or dental (29%) and GI (23%). Furthermore, the investigators found that one-third of patients had additional POEs that could serve as sources for new IE episodes. This study grapples with the issue of source identification in patients with IE, a ubiquitous concern that has been sparsely addressed in published medical research.
The identification of POEs and subsequent eradication of sources of infection is particularly important in IE because having IE in the first place puts one at risk for subsequent IE. In the published research, the lifetime risk for a repeat episode of IE ranges from 2% to 30% (2,3). In a large multicenter cohort of patients with IE, history of IE was an independent predictor of repeat IE (4), highlighting the importance of obtaining timely source control in patients with IE.
Prevention of Infective Endocarditis: Can We Do More?
The discussion surrounding IE prevention has evolved over time and, in the United States and Europe, focuses primarily on the use of antibiotic prophylaxis before dental procedures in high-risk patients (5,6). Patients with histories of IE fall into the high-risk category, making them eligible for antibiotic prophylaxis. Are we done here? According to 1 study, the intensity of bacteremia required to cause IE in an animal model was at least 4 orders of magnitude greater than the intensity of bacteremia after tooth extraction in humans (7). In another study, the cumulative exposure to bacteremia after tooth brushing was 107 times greater than a single tooth extraction (8). These and other studies suggest that the risk for bacteremia and subsequent IE from everyday activities is much higher than that from the occasional dental procedure (9). Importantly, specific indexes of oral hygiene (i.e., plaque, calculus, and gingival bleeding) have been correlated with risk for bacteremia (10). In the present study, 22% of patients had dental POEs. A thoughtful discussion of which patients, when, and with what particular antimicrobial agents (given present-day patterns of antibiotic resistance) antibiotic prophylaxis should be geared toward is beyond the scope of this editorial. Nevertheless, not only dentists but also physicians should routinely advocate something as simple as maintenance of good oral hygiene.
Efforts to decrease intravascular catheter-related infections via evidence-based infection control measures, such as the use of chlorhexidine, education in sterile techniques, and avoidance of femoral site location, have led to a decline in these infections over the past decade (11), but intravascular catheters are still a major POE for infection. In this study, 18% of cutaneous POEs were related to vascular access. Appropriate management of intravascular catheters in the setting of bacteremia (12) is essential for source control.
Another major problem to consider with cutaneous POEs is intravenous drug use. In this cohort, intravenous drug use accounted for 22% of cutaneous POEs. Particularly in the United States, where the rate of heroin abuse has skyrocketed to surprising levels (13), intravenous drug use–related cutaneous POEs may become a growing problem. Preventing additional episodes of IE is a special challenge in this population. Effective approaches to treatment must incorporate drug rehabilitation and social services; however, these approaches still need to be defined.
Strengthening the Correlation Between Infective Endocarditis and Gastrointestinal Pathology: Knowing What to Look For—and Finding It
The link between Streptococcus bovis and colon cancer was first described in 1951 (14). Previously categorized as a Lancefield group D streptococcus, an enterococcus, or simply as “S. bovis group,” these bacteria have since been differentiated by deoxyribonucleic acid sequencing as S. gallolyticus and S. infantarius. In the present study, 14% of patients with a GI POEs were also diagnosed with colorectal adenocarcinoma. The present study joins a host of other studies that support the association between bacteremia or IE due to these pathogens and GI pathology: mostly colon cancer (15–18) but also adenomatous polyps (19), diverticulosis (16), and biliary lesions (16,18). Taken together, the evidence highlights the importance of distinguishing S. bovis group microorganisms from the general bale of viridans group streptococci and searching for a culprit GI source.
Delahaye et al.’s study on POE in IE is limited in generalizability by its single-center nature. In addition, it relies on the most logical, but not necessarily proven, POE and does not elaborate on the possibility of multiple POEs. However, from a practical and clinical perspective, it is good to know that a systematic search will likely yield an answer. The take-home message is that we can add an element of prevention to the treatment plan for a potentially devastating disease.
Interestingly, only 1 case of cat scratch disease and IE due to Bartonella henselae was diagnosed in this cohort, and we don’t know what happened to the cat. With the diagnosis of IE, the cat’s out of the bag—but let’s try to prevent it from happening again.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Dr. Chu has reported that she has no relationships relevant to the contents of this paper to disclose.
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