Interaction of granulocytopenia and construction activity as risk factors for nosocomial invasive filamentous fungal disease in patients with hematologic disorders

A Guide to Investigating Suspected Outbreaks of Mucormycosis in Healthcare

This report serves as a guide for investigating mucormycosis infections in healthcare. We describe lessons learned from previous outbreaks and offer methods and tools that can aid in these investigations. We also offer suggestions for conducting environmental assessments, implementing infection control measures, and initiating surveillance to ensure that interventions were effective. While not all investigations of mucormycosis infections will identify a single source, all can potentially lead to improvements in infection control.

Prophylaxis of invasive aspergillosis with voriconazole or caspofungin during building work in patients with acute leukemia

BACKGROUND

Invasive aspergillosis is a common life-threatening infection in patients with acute leukemia. The presence of building work near to hospital wards in which these patients are cared for is an important risk factor for the development of invasive aspergillosis. This study assessed the impact of voriconazole or caspofungin prophylaxis in patients undergoing induction chemotherapy for acute leukemia in a hematology unit exposed to building work.

DESIGN AND METHODS

This retrospective cohort study was carried out between June 2003 and January 2006 during which building work exposed patients to a persistently increased risk of invasive aspergillosis. This study compared the cumulative incidence of invasive aspergillosis in patients who did or did not receive primary antifungal prophylaxis. The diagnosis of invasive aspergillosis was based on the European Organization for Research and Treatment of Cancer/Mycosis Study Group criteria.

RESULTS

Two-hundred and fifty-seven patients (213 with acute myeloid leukemia, 44 with acute lymphocytic leukemia) were included. The mean age of the patients was 54 years and the mean duration of their neutropenia was 21 days. Eighty-eight received antifungal prophylaxis, most with voriconazole (n=74). The characteristics of the patients who did or did not receive prophylaxis were similar except that pulmonary antecedents (chronic bronchopulmonary disorders or active tobacco use) were more frequent in the prophylaxis group. Invasive aspergillosis was diagnosed in 21 patients (12%) in the non-prophylaxis group and four (4.5%) in the prophylaxis group (P=0.04). Pulmonary antecedents, neutropenia at diagnosis and acute myeloid leukemia with high-risk cytogenetics were positively correlated with invasive aspergillosis, whereas primary prophylaxis was negatively correlated. Survival was similar in both groups. No case of zygomycosis was observed. The 3-month mortality rate was 28% in patients with invasive aspergillosis.

CONCLUSIONS

This study suggests that antifungal prophylaxis with voriconazole could be useful in acute leukemia patients undergoing first remission-induction chemotherapy in settings in which there is a high-risk of invasive aspergillosis.

Nosocomial aspergillosis in outbreak settings

Nosocomial aspergillosis represents a serious threat for severely immunocompromised patients and numerous outbreaks of invasive aspergillosis have been described. This systematic review summarizes characteristics and mortality rates of infected patients, distribution of Aspergillus spp. in clinical specimens, concentrations of aspergillus spores in volumetric air samples, and outbreak sources. A web-based register of nosocomial epidemics (outbreak database), PubMed and reference lists of relevant articles were searched systematically for descriptions of aspergillus outbreaks in hospital settings. Fifty-three studies with a total of 458 patients were included. In 356 patients, the lower respiratory tract was the primary site of aspergillus infection. Species identified most often were Aspergillus fumigatus (154 patients) and Aspergillus flavus (101 patients). Haematological malignancies were the predominant underlying diseases (299 individuals). The overall fatality rate in these 299 patients (57.6%) was significantly greater than that in patients without severe immunodeficiency (39.4% of 38 individuals). Construction or demolition work was often (49.1%) considered to be the probable or possible source of the outbreak. Even concentrations of Aspergillus spp. below 1 colony-forming unit/m(3) were sufficient to cause infection in high-risk patients. Virtually all outbreaks of nosocomial aspergillosis are attributed to airborne sources, usually construction. Even small concentrations of spores have been associated with outbreaks, mainly due to A. fumigatus or A. flavus. Patients at risk should not be exposed to aspergilli.

Invasive aspergillosis: clusters and sources?

Clusters of invasive infection with Aspergillus fumigatus are known to be associated with building works but studying the epidemiology has been hampered by the lack of a reliable typing system. A combination of three typing systems; silver staining of sodium dodecyl sulphate-polyacrylamide gels, immunoblot fingerprinting, and random amplification of polymorphic DNA (RAPD) was applied to seven cases on a haematology unit. The results show three of the patients to have indistinguishable isolates, suggesting a common source. Detection and removal of such sources, although difficult, would be an effective way of controlling the infection.