New opportunistic infections--more opportunities

Performance of transport and selective media for swine Bordetella bronchiseptica recovery and it comparison to polymerase chain reaction detection

Three comparative assays were performed seeking to improve the sensitivity of the diagnosis of Bordetella bronchiseptica infection analyzing swine nasal swabs. An initial assay compared the recovery of B. bronchiseptica from swabs simultaneously inoculated with B. bronchiseptica and some interfering bacteria, immersed into three transport formulations (Amies with charcoal, trypticase soy broth and phosphate buffer according to Soerensen supplemented with 5% of bovine fetal serum) and submitted to different temperatures (10°C and 27°C) and periods of incubation (24, 72 and 120 hours). A subsequent assay compared three selective media (MacConkey agar, modified selective medium G20G and a ceftiofur medium) for their recovery capabilities from clinical specimens. One last assay compared the polymerase chain reaction to the three selective media. In the first assay, the recovery of B. bronchiseptica from transport systems was better at 27°C and the three formulations had good performances at this temperature, but the collection of qualitative and quantitative analysis indicated the advantage of Amies medium for nasal swabs transportation. The second assay indicated that MacConkey agar and modified G20G had similar results and were superior to the ceftiofur medium. In the final assay, polymerase chain reaction presented superior capability of B. bronchiseptica detection to culture procedures.

The role of complement in invasive fungal infections. Die Rolle des Komplements bei invasiven Pilzinfektionen

New therapeutic approaches enable organ transplantations and guarantee longer survival for AIDS patients or patients with haematological neoplasia. The price for these medical advances is immunosuppression and thus enhanced susceptibility to opportunistic fungal infections. As a consequence invasive fungal infections are on the march in modern medicine. Therapeutic limitations and difficulties strongly demand for a deeper understanding of the interaction between the various fungi and the hosts' innate and adaptive immune defence system. This understanding is the essential prerequisite for a potential therapeutic approach, which may support specifically the insufficient antifungal attack of the host. In the present article, we therefore review the current knowledge of the role of the complement system as a central part of innate immunity and as a fine tuner of adaptive immunity in the pathogenesis of invasive fungal infections, such as aspergillosis, candidosis, cryptococcosis, paracoccidioidomycosis, blastomycosis and histoplasmosis.

Disseminated Mycobacterium genavense infection in a FIV-positive cat

An 8-year-old FIV-positive Australian cat was presented with coughing, periocular alopecia, pyrexia and inappetence. Skin scrapings demonstrated Demodex cati mites. Antibiotics were administered and it was treated successfully for periocular demodectic mange, but the cat continued to exhibit respiratory signs and lose weight. Further investigation revealed an ascarid infection and active chronic inflammation of undetected cause affecting the lower airways. Repetitive treatment with pyrantel failed to eradicate the ascarid infection. The cat became cachectic and developed moist ulcerative dermatitis of the neck, severe non-regenerative anaemia, leucopenia and thrombocytopenia. Necropsy and histopathology revealed mycobacteriosis affecting skin, lungs, spleen, lymph nodes, liver and kidney. Attempted culture of frozen tissues at a mycobacteria reference laboratory was unsuccessful. Paraffin-embedded, formalin-fixed tissue was retrieved and examined using PCR to amplify part of the 16S rRNA gene. A diagnosis of disseminated Mycobacterium genavense infection was made based on the presence of acid fast bacteria in many tissues and partial sequence of the 16S rRNA gene. Although M genavense has been identified previously as a cause of disseminated disease in AIDS patients, this is the first report of infection in a cat. It was suspected that the demodecosis, recurrent ascarid infections and disseminated M genavense infection resulted from an immune deficiency syndrome consequent to longstanding FIV infection.

Bacterial persistence and expression of disease

A considerable body of experimental and clinical evidence supports the concept that difficult-to-culture and dormant bacteria are involved in latency of infection and that these persistent bacteria may be pathogenic. This review includes details on the diverse forms and functions of individual bacteria and attempts to make this information relevant to the care of patients. A series of experimental studies involving host-bacterium interactions illustrates the probability that most bacteria exposed to a deleterious host environment can assume a form quite different from that of a free-living bacterium. A hypothesis is offered for a kind of reproductive cycle of morphologically aberrant bacteria as a means to relate their diverse tissue forms to each other. Data on the basic biology of persistent bacteria are correlated with expression of disease and particularly the mechanisms of both latency and chronicity that typify certain infections. For example, in certain streptococcal and nocardial infections, it has been clearly established that wall-defective forms can be induced in a suitable host. These organisms can survive and persist in a latent state within the host, and they can cause pathologic responses compatible with disease. A series of cases illustrating idiopathic conditions in which cryptic bacteria have been implicated in the expression of disease is presented. These conditions include nephritis, rheumatic fever, aphthous stomatitis, idiopathic hematuria, Crohn's disease, and mycobacterial infections. By utilizing PCR, previously nonculturable bacilli have been identified in patients with Whipple's disease and bacillary angiomatosis. Koch's postulates may have to be redefined in terms of molecular data when dormant and nonculturable bacteria are implicated as causative agents of mysterious diseases.

Clinical parameters associated with recalcitrant oral candidosis in HIV infection: a preliminary study

Clinical resistance in oropharyngeal candidosis is an increasingly significant management problem in HIV-seropositive patients. This study was undertaken to identify predisposing risk factors including the isolation of particular species of Candida which may be associated with the development of clinical resistance. The effect of particular antifungal prescribing regimens was also assessed. Data were compiled by chart review of 2 groups, each of 10 HIV-seropositive CDC stage IV patients with recurrent oropharyngeal candidosis. All patients had swabs taken at intervals during treatment and all candida isolates were species typed. The patients in group 1 exhibited candida infections which did not respond clinically to standard therapeutic regimens. The second patient group did respond to standard oral antifungal therapies. An association was found between the frequent utilization of azoles, particularly fluconazole and the development of clinically resistant oral candidosis. The number of candida isolates grown from the initial swab was also significantly related to the development of resistance.

Oral Candida in HIV infection and AIDS: new perspectives/new approaches

Oral candidosis has become an increasingly important problem in HIV-infected individuals. At present, the small body of published literature on the characterization of the Candida strains and species found in HIV+ patients is full of confusion and contradictions. Some of these difficulties are the result of the methodological shortcomings of a number of the techniques that have been used. Examples of the problems that may be encountered on primary isolation and subculture are described and the drawbacks associated with the systems used to date for phenotyping Candida are quoted. While molecular characterization techniques would appear to offer a reliable and objective alternative, they too have their strengths and weaknesses. An attempt is made to summarize the progress that has been made recently in the detection and identification of Candida albicans and also the non-albicans species from HIV-infected individuals. What emerges is that the commensal Candida species that inhabit the oral cavities of HIV+ patients are subjected to a number of significant pressures that probably promote the selection of organisms with unusual phenotypes and genotypes. These Candida are more difficult to characterize and behave differently compared to their counterparts in HIV- individuals. It is clear that uncovering the factors that are important for the selection of treatment regimens and will be predictive of outcome will not be easy. Candida organisms are neither as benign nor as simple as once thought.

Rochalimaea henselae sp. nov., a cause of septicemia, bacillary angiomatosis, and parenchymal bacillary peliosis

Nine strains of Rochalimaea spp. that were isolated from patients over a period of 4.5 years were characterized for their enzyme activities, cellular fatty acid compositions, and DNA interrelatedness among Rochalimaea spp., Bartonella bacilliformis, and Afipia felis (cat scratch disease bacillus). All except one isolate, which was Rochalimaea quintana, were determined to belong to a newly proposed species, Rochalimaea henselae sp. nov. After recovery from clinical material, colonies required 5 to 15 days of incubation to become apparent. Cells were small, gram-negative, curved bacilli and displayed twitching motility. Enzyme specificities for amino acid and carbohydrate substrates showed that R. henselae could be distinguished from Rochalimaea vinsonii by L-arginyl-L-arginine and L-lysyl-L-alanine peptidases, but not all strains could be distinguished from R. quintana on the basis of peptidases or carbohydrate utilization. R. henselae also closely resembled R. quintana in cellular fatty acid composition, with both consisting mainly of C18:1, C18:0, and C16:0 fatty acids. However, the strains of R. henselae all contained C18:0 in amounts averaging greater than or equal to 22%, in contrast to R. quintana, which contained this cellular fatty acid in amounts averaging 16 and 18%. DNA hybridization confirmed the identification of one clinical isolate as R. quintana and showed a close interrelatedness (92 to 100%) among the other strains. Under optimal conditions for DNA reassociation, R. henselae showed approximately 70% relatedness to R. quintana and approximately 60% relatedness to R. vinsonii. Relatedness with DNA from B. baciliformis was 43%. R. henselae was unrelated to A. felis. R. henselae is the proposed species of a newly recognized member of the family Rickettsiaceae, which is a pathogen that may be encountered in immunocompromised or immunocompetent patients. Prolonged fever with bacteremia or vascular proliferative lesions are clinical manifestations of the agent.

Genetic characterization and transovarial transmission of a typhus-like rickettsia found in cat fleas

The identification of apparently fastidious microorganisms is often problematic. DNA from a rickettsia-like agent (called the ELB agent) present in cat fleas could be amplified by PCR with conserved primers derived from rickettsial 17-kDa common protein antigen and citrate synthase genes but not spotted fever group 190-kDa antigen gene. Alu I sites in both the 17-kDa and citrate synthase PCR products obtained with the rickettsia-like agent and Rickettsia typhi were different even though both agents reacted with monoclonal antibodies previously thought specific for R. typhi. The DNA sequence of a portion of the 17-kDa PCR product of the rickettsia-like agent differed significantly from all known rickettsial sequences and resembled the 17-kDa sequences of typhus more than spotted fever group rickettsiae. The rare stable transovarial maintenance of this rickettsia in cat fleas has important implications for the disease potential of cat fleas.