Reviews of infectious diseases最新文献

Herpes simplex virus (HSV) types 1 and 2 cause a variety of severe manifestations in humans. A major characteristic of HSVs is their ability to establish latent infection in sensory ganglia, where these viruses are shielded from the immune system and are impervious to the action of antiviral drugs known to date. Ideally, HSV-induced clinical syndromes should be prevented by vaccination, but two major problems arise. First, although many antiviral vaccines have successfully prevented disease, none have prevented infection. Once the virus infects cells at the portal of entry of the infection, it can establish latent infection in sensory neurons that innervate the cell. Second, while HSV disease primarily affects adults greater than 18 years of age, mass immunization in the United States is effectively carried out in the interval between nursery school and high school, and yet the vaccines must confer protection for a long time after vaccination. The central issues involved in the development of an anti-HSV vaccine include what type of vaccine should be developed, what we should expect from an HSV vaccine, and how we should monitor the effectiveness of the vaccine.

Fifteen cancer patients have developed catheter-related infections caused by the Mycobacterium fortuitum complex (M. fortuitum and Mycobacterium chelonae) at M. D. Anderson Cancer Center since 1978. Eleven patients had bacteremia and four had catheter site infections. Nine infections were caused by M. fortuitum and six by M. chelonae. All four bacteremic patients whose catheters were initially removed and who were treated with antibiotics recovered, whereas for all of the seven bacteremic patients whose catheters remained in place, the infection relapsed or treatment failed. Six (86%) of the latter group ultimately responded to additional antibiotic therapy when the catheter was removed. Successful treatment of local catheter infections was accomplished by catheter removal alone or in combination with antibiotic therapy. Fourteen additional cases have been reported, and eight (57%) of these patients also had underlying cancer. Patients with septicemia or an infection at the catheter insertion site responded to catheter removal and appropriate antibiotics. Patients with infection in the catheter tunnel (tunnel infection) responded only after surgical excision of the tissue surrounding the infected tunnel. M. fortuitum complex is a cause of catheter-related bacteremia in patients with cancer. Appropriate treatment consists of antibiotic therapy and catheter removal. Tunnel infections usually also require surgical excision.

The multiple effects of estrogens on infectious processes are only beginning to be understood. The existence of such effects is suggested by gender-related differences in the incidence and severity of some infections and by the association of certain infections with predictable hormonal changes. Current information indicates that estrogens may depress cell-mediated immunity, impair the activity of natural killer cells, and suppress some aspects of neutrophil function. Estrogens potentiate the production of systemic antibody, but local antibody responses may be impaired. Direct effects of estrogens on microorganisms have thus far been best studied in fungi; these hormones may either stimulate or suppress fungal virulence, depending on the species involved. Recent research also suggests responsiveness to estrogens in a wider variety of microorganisms. Studies in cell culture, animals, and humans indicate that pregnancy, estrogen supplementation, and menstrual stage can affect the acquisition and severity of certain bacterial, parasitic, and viral infections. This interaction depends on multiple attributes of both the microbe and the host in a given setting and thus may lead to disparate outcomes; however, there appears to be a predisposition to increased infectious morbidity in certain high-estrogen states. In view of the widespread use of estrogen supplementation, the clinical impact of estrogens on the incidence and outcome of infection needs to be better defined.

Three cases of metronidazole-induced acute pancreatitis have been reported recently in three women who were being treated for nonspecific vaginitis. We report the fourth such case in a 63-year-old woman with long-standing Crohn's disease who developed acute pancreatitis that was temporally associated with the initiation of metronidazole therapy for a rectovaginal fistula. No other risk factors for pancreatitis were identified except for possibly Crohn's disease itself. We review the literature with regard to metronidazole-induced acute pancreatitis and suggest a possible mechanism. Metronidazole should be considered as a possible cause of acute pancreatitis, and its use should be discontinued if no other risk factor is found.

The polymerase chain reaction was used for the detection of Clostridium difficile, the etiologic agent of antibiotic-associated colitis. An upstream primer identical to a coding region (segment I) of the C. difficile 16S rRNA gene and a downstream primer complementary to a highly conserved region of eubacterial 16S rRNA served to amplify a targeted 270-base-pair fragment of genomic DNA. This technique allowed the detection of as few as 10 C. difficile organisms among 10(6) Escherichia coli bacteria. This level of sensitivity represents a 100-fold increase over that of conventional anaerobic culture. C. difficile was detected in DNA extracted directly from the stools of 23 patients with antibiotic-associated colitis and from those of four patients with diarrhea whose stools had been negative for C. difficile when assessed in a cytotoxicity assay. No amplification products were found in the stools of asymptomatic patients. When detected in stools of symptomatic patients, amplification products of C. difficile were confirmed by Southern blotting with a nonradioactive, horseradish peroxidase-catalyzed, chemiluminescent probing system in which biotin-labeled oligonucleotides were used. This system discriminates between C. difficile and similar organisms, such as Clostridium sordellii and Clostridium bifermentans. The combination of the polymerase chain reaction with enzyme-linked probing results in a faster and more sensitive assay for C. difficile than standard culture.

Splenic tuberculosis is an uncommonly considered diagnosis in clinical practice. We report splenic tuberculosis in three patients with AIDS who were admitted to the hospital because of fever and constitutional syndrome. In all of the patients, abdominal sonography and abdominal computed tomography revealed multiple hypoechoic and hypodense lesions, respectively. In two patients needle aspiration of the spleen with sonographic control was the diagnostic procedure. In the third patient the diagnosis was confirmed after splenectomy. In AIDS patients tuberculosis must be included in the differential diagnosis of hypoechoic and hypodense lesions by means of sonography and computed tomography, respectively, especially in those patients with active tuberculosis.

Clinical data from 10 episodes of disseminated infection with Fusarium among eight recipients of bone marrow transplants and from 31 cases reported previously in the literature were analyzed in an effort to characterize the natural history of this rare infection and its response to therapy. The characteristic signs of fusarial infection--disseminated skin nodules, fungemia, and multiple-organ involvement--are results of its propensity for early spread. From a review of the literature and our own experience, it appears that recovery of phagocytic mechanisms (the primary immunologic defenses against Fusarium) in the form of rising neutrophil counts is mandatory for clinical resolution. Even after a graft begins to function adequately, Fusarium may not be completely eradicated, as evidenced by the high incidence of recurrence among patients with subsequent neutropenic episodes. Fusarium is highly resistant to conventional antifungal drugs in vitro, but its progression may be slowed by intensive antifungal therapy until the recovery of adequate neutrophil levels.

Vaccinia virus recombinants expressing antigens from herpes simplex virus (HSV) have been tested as potential live virus vaccines for prevention of HSV infection. We describe three vaccinia virus/HSV recombinants. The first expresses the HSV-1 glycoprotein D (vaccinia/gD), the second expresses the HSV-1 glycoprotein B (vaccinia/gB), and the third expresses both the HSV-1 glycoprotein D and the influenza A hemagglutinin (vaccinia/HSVgD/influenza). Mice immunized with vaccinia/gD or vaccinia/gB developed antibodies capable of neutralizing HSV in vitro and were protected against both lethal and latent infection with HSV. Protection against HSV challenge persisted for greater than 1 year in mice immunized with vaccinia/gD. The immune response to HSV in mice immunized with vaccinia/gD could be increased by a booster vaccination with vaccinia/gD. However, the immune response to HSV was decreased in animals immunized with a vaccinia recombinant that expressed non-HSV genes before vaccination with vaccinia/gD. In separate experiments, a bivalent vaccinia recombinant, vaccinia/HSVgD/influenza, was constructed and was found to be comparable to the vaccinia/gD single recombinant in immunogenicity and protective efficacy against lethal HSV challenge. We conclude that vaccinia/HSV recombinants can provide protection against HSV infection in mice and that these recombinants may provide an alternative approach in the development of a live virus vaccine against HSV.