The pitfalls of transthoracic echocardiography. A case of eustachian valve endocarditis.

A case of infective endocarditis involving the vestigial eustachian valve is presented and the available English medical literature is reviewed. Only 5 prior cases have been reported: 4 of those required transesophageal echocardiography for diagnosis, and the other was found at autopsy. This clinical entity is routinely missed on transthoracic echocardiography. Injection drug use is a common predisposing factor, and Staphylococcus aureus is the most commonly identified organism. This report broadens the differential diagnosis of endovascular infections in injection drug users and highlights the importance of transesophageal echocardiography for diagnosis in selected patients.

Extracolonic manifestations of Clostridium difficile infections. Presentation of 2 cases and review of the literature.

Clostridium difficile is most commonly associated with colonic infection. It may, however, also cause disease in a variety of other organ systems. Small bowel involvement is often associated with previous surgical procedures on the small intestine and is associated with a significant mortality rate (4 of 7 patients). When associated with bacteremia, the infection is, as expected, frequently polymicrobial in association with usual colonic flora. The mortality rate among patients with C. difficile bacteremia is 2 of 10 reported patients. Visceral abscess formation involves mainly the spleen, with 1 reported case of pancreatic abscess formation. Frequently these abscesses are only recognized weeks to months after the onset of diarrhea or other colonic symptoms. C. difficile-related reactive arthritis is frequently polyarticular in nature and is not related to the patient's underlying HLA-B27 status. Fever is not universally present. The most commonly involved joints are the knee and wrist (involved in 18 of 36 cases). Reactive arthritis begins an average of 11.3 days after the onset of diarrhea and is a prolonged illness, taking an average of 68 days to resolve. Other entities, such as cellulitis, necrotizing fasciitis, osteomyelitis, and prosthetic device infections, can also occur. Localized skin and bone infections frequently follow traumatic injury, implying the implantation of either environmental or the patient's own C. difficile spores with the subsequent development of clinical infection. It is noteworthy that except for cases involving the small intestine and reactive arthritis, most of the cases of extracolonic C. difficile disease do not appear to be strongly related to previous antibiotic exposure. The reason for this is unclear. We hope that clinicians will become more aware of these extracolonic manifestations of infection, so that they may be recognized and treated promptly and appropriately. Such early diagnosis may also serve to prevent extensive and perhaps unnecessary patient evaluations, thus improving resource utilization and shortening length of hospital stay.

Right-side endocarditis in injection drug users: review of proposed mechanisms of pathogenesis.

Infective endocarditis of the right-side heart valves occurs commonly in injection drug users. Although a variety of hypotheses have been put forward to explain this clinical observation, no single hypothesis is adequate. In this article, basic scientific, clinical, and microbiological data on this topic are presented. It is apparent that no clear unifying mechanism emerges to explain the well-documented clinical predilection for the infection of the right-side heart valves in this population. Further investigation of this topic utilizing large international clinical registries may help to clarify matters further.

Maintaining and enhancing vaccine immunogenicity.

This contribution highlights factors involved with maintaining and enhancing antigen delivery or immunogenicity. Areas discussed include the cold chain, adjuvants, recombinant vectors for antigen delivery, routes for antigen delivery, and edible plant vaccines. It is doubtless that the technological understanding that underlies these advances is about to revolutionize vaccinology in the near future.

Space-occupying and life-threatening infections of the head, neck, and thorax.

Infections of the deep structures of the head and neck are polymicrobial, rapidly progressive, and frequently life-threatening. The bacteriology, clinical presentation, and the need for multidisciplinary management of these infections are stressed. In addition, this article discusses selected head and neck infections of immunocompromised hosts and postexposure prophylaxis for serious infections of the pharynx.

Fragmentation hemolysis: an unusual indication for valve replacement in native valve infective endocarditis.

Intravascular mechanical fragmentation of erythrocytes is an uncommon occurrence in native valve infective endocarditis. We report a case of fragmentation hemolysis in a patient with tricuspid valve endocarditis due to Staphylococcus aureus. She received transfusion of multiple units of packed red blood cells and ultimately required surgical removal of the affected valve to control the hemolytic process. We believe this to be only the fifth such reported case and the first in which surgical therapy was necessary to control the hemolytic process.

Comparative killing kinetics of methicillin-resistant Staphylococcus aureus by bacitracin or mupirocin.

The in vitro activities of bacitracin and mupirocin were compared for seven different strains of methicillin-resistant Staphylococcus aureus. Six of seven strains showed bacitracin minimum inhibitory concentrations (MICs) of 0.5 to 1.0 units/mL, and all seven had mupirocin MICs of 0.5 to 2 micrograms/mL. Time-kill studies revealed 2.6- to 4.5-log reduction in 24 hours with strains susceptible to bacitracin (4 units/mL) and 0 to 2.2 reduction with mupirocin (16 micrograms/mL). Bacitracin should be considered further for in vivo studies because of enhanced bacteriocidal effect and lower cost.

Diagnosis of probable cocaine-induced cerebral vasculitis by magnetic resonance angiography.

Cocaine-induced cerebral vasculitis is a serious but uncommon clinical entity. We present a case of probable cocaine-induced vasculitis that was unusual in that it was suggested by magnetic resonance angiography. The patient was a 42-year-old woman, who used cocaine both intravenously and intranasally, who was admitted with the acute onset of an illness that resembled bacterial meningitis. Results of the initial standard evaluation were negative, and a diagnosis of cerebral vasculitis was ultimately suggested by magnetic resonance angiography. We believe this to be the first reported case of the diagnosis of cocaine-induced cerebral vasculitis to be suggested by magnetic resonance angiography.

Tracing the spread of methicillin-resistant Staphylococcus aureus by Southern blot hybridization using gene-specific probes of mec and Tn554.

In a community hospital in Brooklyn, New York, over a 3-year period, 79 methicillin-resistant Staphylococcus aureus (MRSA) isolates from five different case clusters were subtyped by Southern blot hybridization with two previously characterized gene probes, mec and Tn554. Together, the genotyping enabled the hospital infection control team to differentiate simultaneous MRSA clusters in the surgical intensive care unit (type I:A) and the open heart unit (type II:J), document the spread of one strain (type I:A) between roommates, identify an endemic strain (type II:J) from cardiac monitors and medical personnel, and identify an unrelated outbreak strain (type II:NH) in the labor and delivery unit. On the basis of this investigation it is clear that the routine DNA fingerprinting of MRSA in health care facilities, to monitor their spread and identify cases of nosocomial infections, is an important infection control measure.

Immune-based therapeutics: scientific rationale and the promising approaches to the treatment of the human immunodeficiency virus-infected individual.

The primary approach to therapy for infection with human immunodeficiency virus (HIV) continues to be centered around antiretroviral agents that have conferred significant clinical benefits. The considerable degree of immunologic dysfunction in HIV infection, however, has led to intense interest in methods of immune stimulation and reconstitution. Immunomodulatory intervention in HIV infection is highly controversial. Over the years a number of immunomodulatory agents--many with only a poor rationale for their clinical use--have been evaluated. In this review we concentrate on immunomodulatory approaches that are currently being investigated. We group these interventions, reviewing the rationale and clinical data for each category: passive immunity (administration of immunoglobulins and use of apheresis), thymic hormone treatment, cytokine treatment (administration of interleukins, tumor necrosis factor, and interferons), adoptive cellular immunity, and therapeutic vaccination. At present, the only interventions supported by data from well-controlled studies are the parenteral administration of interferon alpha to patients with HIV-associated Kaposi's sarcoma and the administration of pooled immunoglobulin (to decrease the rate of bacterial infections) to children who cannot take trimethoprim-sulfamethoxazole. However, several other approaches under development show promise in reversing some of the immune deficits of HIV infection. Clinical evaluation of these approaches should yield valuable insights into the immunopathogenesis of HIV infection, and these insights should facilitate the formulation of new modalities of treatment.

Emergence of unusual opportunistic pathogens in AIDS: a review.

Opportunistic infections are a major cause of morbidity and death among patients infected with the human immunodeficiency virus (HIV), particularly late in the disease, when immunosuppression is severe. Some pathogens, such as Pneumocystis carinii and Toxoplasma gondii, are extremely common in this population and are readily recognized by clinicians caring for these patients. However, many other organisms occasionally cause conditions that clinically mimic the more commonly encountered pathogens. Clinicians must be alert to the threat posed by these less frequently occurring organisms and of the broader differential diagnosis that must be considered for infections in patients with HIV infection.

Streptococcal toxic shock syndrome due to noninvasive pharyngitis.

Serious infections due to group A beta-hemolytic streptococcus (GABHS) have been reported with increasing frequency in recent years. We report a case of toxic shock syndrome (TSS) due to GABHS pharyngitis in an otherwise healthy 14-year-old boy. The organism was found to produce toxin A. To our knowledge, this is the second reported case of streptococcal TSS associated with the production of toxin A that is not associated with an invasive disease and the first case associated with a documented rise in the level of antibody to the streptococcal toxin itself. Clinicians must be especially vigilant for this entity in patients who have streptococcal pharyngitis because early recognition and institution of aggressive supportive therapy can be lifesaving.