Transthoracic echocardiography (TTE): sufficiently sensitive screening test for native valve infective endocarditis (IE).

We recently reviewed our experience with paired transthoracic echocardiogram (TTE) and transesophageal echocardiogram (TEE) studies for the diagnosis of native valve infective endocarditis. In patients with normal heart valves, we demonstrated that a normal TTE effectively rules out infective endocarditis and a TTE is unnecessary. In patients with abnormal heart valves, a TEE did not enhance the diagnostic yield in most patients (12/15). We reviewed 87 paired TTEs and TEEs, that is, TEE with a preceding TTE performed for the evaluation of native valve IE. Of 87 paired echocardiograms, 72 of 87 had normal TTEs and TEEs, with no evidence of a vegetation indicative of infective endocarditis. A total of 15 of 87 TTEs had thickened/calcified valves without a definite vegetation. Of these, only 3 of 15 were subsequently shown to have a vegetation indicative of endocarditis by TEE. In patients with possible native valve infective endocarditis, before blood culture results are known, a negative TTE was sufficiently specific to rule out native valve infective endocarditis. Our data showed that the negative predictive value of a normal TTE in the evaluation of possible native valve endocarditis is 90% or greater. In those with some valve abnormality (ie, thickened/calcified heart valves), subsequent TTE did not materially increase vegetation detection.

Fever of unknown origin (FUO) caused by miliary tuberculosis: diagnostic significance of morning temperature spikes.

Miliary or disseminated Mycobacterium tuberculosis continues to be a difficult diagnostic challenge. The clinical signs and symptoms of miliary tuberculosis (TB) depend on the extent and severity of both pulmonary and extrapulmonary organ involvement. When miliary TB presents as a fever of unknown origin (FUO), the diagnosis of miliary TB can be particularly perplexing. Because only 10% to 20% of patients have a history of antecedent TB, the diagnosis of miliary TB often goes unsuspected until suggested by miliary calcifications on the chest x-ray. High-resolution computed tomography of the chest has enhanced the diagnosis of miliary TB. In patients with miliary TB, acid-fast smear positivity for acid-fast bacilli is low in sputum, urine, and cerebrospinal fluid. Traditionally, miliary TB has been diagnosed by demonstrating granulomas in liver or bone marrow specimens. Transbronchial biopsy may be used when liver and bone marrow biopsies are negative. We present a case of FUO due to miliary TB with miliary calcifications on the chest x-ray but with negative liver and bone marrow biopsies. The clinical diagnosis of miliary TB was further enhanced by finding daily morning temperature spikes characteristic of miliary TB. Morning temperature spikes are associated with only 2 other entities, that is, typhoid fever and periarteritis nodosa, which are unlikely to be confused clinically with miliary TB. Although fever curves/patterns are diagnostically unhelpful in many febrile conditions, characteristic fever curves/patterns are most useful in the most diagnostically difficult cases with obceure fevers, particularly FUOs. Clinicians should take care to analyze the fever curves/patterns in such patients, which may provide an important clue to the diagnosis and prompt specific diagnostic testing.

Lack of value of repeat stool testing for Clostridium difficile toxin.

Twenty years ago, Clostridium difficile was first established as a cause of pseudomembranous colitis and antibiotic-associated diarrhea.C. difficile diarrhea is a widely recognized problem in the inpatient setting, with potentially significant morbidity and mortality. Antibiotics, and some chemotherapy agents, can potentially cause C. difficile colitis/diarrhea. The most commonly implicated agents are ampicillin, clindamycin, and cephalosporins. Diarrhea during antibiotic therapy is common and may be caused by C. difficile. Testing for C. difficile differentiates diarrheas into C. difficile positive and C. difficile negative. C. difficile can be carried asymptomatically as normal gastrointestinal flora, and in adults who have received antibiotic therapy, carrier states can be as high as 46%. Hospitalized patients are often colonized with C. difficile. C. difficile produces 3 virulence factors: an enterotoxin (toxin A), a cytotoxin (toxin B), and a substance to inhibit bowel motility. Different tests can be used to detect these toxins. The most widely used test is the enzyme immunoassay (EIA) for toxin A, toxin B, or both. The EIA C. difficile toxin assay has sensitivity and specificity ranges of 50% to 90% and 70% to 95%, respectively. Diagnostically, C. difficile cell culture cytotoxin assay remains the gold standard with sensitivity and specificity of 93% and 89%, respectively. Because of lack of confidence of the EIA for C. difficile, some clinicians assume an initial negative result may represent a false-negative test, and repeat testing is often done. We evaluated the value of repeat stool testing for C. difficile toxin A and B by EIA in inpatients with nosocomial diarrhea on antibiotics.

Methicillin-resistant Staphylococcus aureus prosthetic aortic valve endocarditis with paravalvular abscess treated with daptomycin.

Prosthetic valves have been used extensively for severe cardiac valvular dysfunction for the past 3 decades. Prosthetic cardiac valves may be infected with organisms causing bacteremia, particularly gram-positive cocci. Staphylococcus epidermidis (coagulase negative staphylococci) and Staphylococcus aureus , both methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) strains, are the most frequent pathogens causing prosthetic valve endocarditis (PVE). Vancomycin has been the cornerstone of therapy for serious MRSA infections including bacteremia and endocarditis. Clinicians have noted that MRSA bacteremias treated with vancomycin often fail to clear even with prolonged therapy. Persistent or prolonged MRSA bacteremia unresponsive to vancomycin therapy has led to the treatment of these infections by other agents, that is, quinupristin, dalfopristin, linezolid, or daptomycin. These antibiotics have been found particularly useful in treating MRSA bacteremias unresponsive to vancomycin therapy. We report a case of a patient who presented with MRSA PVE complicated by perivalvular aortic abscess with persistent MRSA bacteremia unresponsive to vancomycin therapy. The patient's MRSA bacteremia was cleared with daptomycin therapy (6 mg/kg/d). Because the patient refused surgery, daptomycin therapy was continued in hopes of curing the endocarditis and sterilizing the perivalvular aortic abscess. Transesophageal echocardiogram revealed a decrease in abscess in the aortic perivalvular abscess after 1 week of daptomycin therapy. The patient made an uneventful recovery. The cure of PVE and perivalvular abscesses usually requires removal of the prosthetic device and abscess drainage. In this case, in which surgery was not an option, medical therapy of PVE and a decrease in size of the aortic perivalvular abscess were accomplished with daptomycin therapy. Daptomycin is an alternative to vancomycin therapy in patients with prolonged or persistent MRSA bacteremia secondary to endocarditis or abscess.