Sampling of Aspergillus spores in air.

Nosocomially acquired aspergillosis typically occurs in the setting of treatment for leukaemia or other haematological malignancy. As Aspergillus species can be readily found in the environment, it has been widely believed that aspergillosis occurs as a consequence of exogenous acquisition of the fungus. Stringent environmental controls in transplant units have included high-efficiency air filtration, positive-pressure ventilation and frequent room air changes. Although there have been several well-documented examples of aspergillosis outbreaks as a result of hospital demolition and reconstruction, it has not always been possible to demonstrate elevated spore counts in clinical areas during building work. The sampling of air for Aspergillus is very problematic. Careful attention must be given to the design of air sampler, sampling protocols and an understanding of air sampling data. This review outlines many of the physical and environmental parameters that influence meaningful air sampling and recommends a simple procedure that has been tried and tested in many aspergillosis outbreaks.

New perspectives in the diagnosis of systemic fungal infections.

Profound and prolonged neutropenia following chemotherapy is a major risk factor for systemic fungal infections. Mortality associated with disseminated fungal infection is high, and treatment with conventional amphotericin B is complicated by renal toxicity. Candida and Aspergillus are among the major pathogens in these patients. Many patients remaining neutropenic over a prolonged period of time will receive empirical antifungal therapy. The clinical and laboratory diagnoses of these infections are neither sensitive nor specific and are generally limited in the early detection of invasive fungal infection. However, several new approaches to diagnosis are being developed, which should be translated into routine practice, based on a greater understanding of the pathogenesis of systemic fungal infection and virulence determinants of fungal pathogens. These include antigen detection and polymerase chain reaction. Patients with presumed fungal infection require more intense and accurate monitoring for signs of disseminated infection. Early diagnosis may guide appropriate treatment and prevent mortality. Continued development of commercial tests should help achieve the objective of definitive diagnostic tests for systemic fungal infections.

Diagnosis and prevention of fungal infection in the immunocompromized patient.

Profound and prolonged neutropenia following chemotherapy is a major risk factor for systemic fungal infections. Mortality associated with disseminated fungal infection is high and treatment with conventional amphotericin B is complicated by renal toxicity. Candida and Aspergillus are among the major pathogens in this patient population. Many patients remaining neutropenic over a prolonged period of time will receive empirical antifungal therapy. The clinical and laboratory diagnosis of these infections are neither sensitive nor specific and are generally limited in the early detection of invasive fungal infection. However, several new approaches to diagnosis are being developed which should be translated into routine practice. These include antigen detection and PCR. It is still unclear how effective the various measures that are currently being used are in preventing serious fungal infection. Refinements in the prophylactic use of fluconazole, itraconazole and aerosolized amphoteric in B, and the introduction of new formulations of existing antifungals may reduce the incidence of systemic fungal infections in some patient groups. Patients with presumed fungal infection require more intense and accurate monitoring for signs of disseminated infection. Early diagnosis may guide appropriate treatment and prevent mortality.