Nosocomial invasive aspergillosis (IA) is increasingly described in non-hematological patients located in areas with low efficiency air filters. The indication of surveillance of spore concentrations in areas without HEPA filters is a matter of debate.
Since 2002 cases of IA have been prospectively registered and control of airborne spores performed in HEPA filtered (H-areas) and in selected non-protected areas (non H-areas) with a MAS 100 air filter. In October 2015 six IA were detected (mean monthly cases during the last 13 years: 1.12) and the outbreak was recognized. Median concentration of spores in the previous six months and during the outbreak was compared. No relationship with any ongoing construction work was identified.
The outbreak included 18 cases (2 proven and 16 probable IA). Overall, 6 cases occurred in onco-hematological patients and 12 in non-hematological wards (66.6% liver disease, 58.3% corticosteroid-dependent conditions, 41.6% COPD and 25% HIV infection). Pulmonary aspergillosis (88.9%) and A. fumigatus predominated (77.8%). The mortality rate was 66.7%. As for air samples, 215 air samples were performed during the pre-outbreak 6 months and during the outbreak period. In onco-hematological wards the median airborne fungi conidia was 0 CFU/m3 before and during the outbreak (H-areas). By opposite, in non-H areas the airborne conidia levels raised from 2 [1-8] CFU/m3 before the outbreak to 42 [19-80.5] during the outbreak period (p< 0.01). All cases of NA in non-hematological patients occurred in the presence of abnormally high spore counts (>25 CFU/m3). The outbreak abated when a multidisciplinary approach involving clinicians, engineers and hospital managers was implemented. Although no clear origin of the outbreak was identified, the cleaning and careful review of the ventilation system was key.
Our study reveals that when the concentrations of hospital airborne conidia are increased, patients with liver insufficiency and corticosteroid therapy are at high risk of developing nosocomial aspergillosis. The periodic control of airborne spores concentration in areas where these patients are admitted could help to rapidly detect high risk situations .(This study was partially financed by PROMULGA Project. Instituto de Salud Carlos III. PI1002868).
T. Pelaez, None
J. Guinea, None
M. Valerio, None
E. Bouza, None