OBJECTIVE: To propose a standardized protocol for the evaluation of Legionella contamination in air. DESIGN: A bathroom having a Legionella contamination in water >1,000 cfu/l was selected in 10 different healthcare facilities. Air contamination was assessed by active (Surface Air System, SAS) and passive (Index of Microbial Air, IMA) sampling for 8 hours, about 1 m away from the floor and 50 cm from the tap water. Two hundred liters of air were sampled by SAS every 12 min, after flushing water for 2 min. The IMA value was calculated as the mean value of colony forming units/16 plates exposed during sampling (2 plates/hour). Water contamination was evaluated at T0, after 4 and 8 hours, according to the standard methods. RESULTS: Air contamination by Legionella was found in three healthcare facilities (one with active and two with passive sampling), showing a concomitant tap water contamination (median=40,000; range 1,100-43,000 cfu/l). The remaining seven hospitals isolated Legionella spp. exclusively from water samples (median=8,000; range 1,200-70,000 cfu/l). CONCLUSIONS: Our data suggest that environmental Legionella contamination cannot be assessed only through the air sampling, even in the presence of an important water contamination.
Legionella spp. contamination in indoor air: preliminary results of an Italian multicenter study / Montagna Maria, Teresa; De Giglio, Osvalda; Napoli, Christian; Cannova, Lucia; Cristina Maria, Luisa; Deriu Maria, Grazia; Delia Santi, Antonino; Giuliano, Ada; Guida, Marco; Lagana, Pasqualina; Liguori, Giorgio; Mura, Ida; Pennino, Francesca; Rossini, Angelo; Tardivo, Stefano; Torre, Ida; Torregrossa Maria, Valeria; Villafrate Maria, Rosaria; Albertini, Roberto; Pasquarella, Cesira. - In: EPIDEMIOLOGIA E PREVENZIONE. - ISSN 1120-9763. - 38:6(2014), pp. 62-65.
Legionella spp. contamination in indoor air: preliminary results of an Italian multicenter study
GUIDA, MARCO;PENNINO, FRANCESCA;TORRE, IDA;
2014
Abstract
OBJECTIVE: To propose a standardized protocol for the evaluation of Legionella contamination in air. DESIGN: A bathroom having a Legionella contamination in water >1,000 cfu/l was selected in 10 different healthcare facilities. Air contamination was assessed by active (Surface Air System, SAS) and passive (Index of Microbial Air, IMA) sampling for 8 hours, about 1 m away from the floor and 50 cm from the tap water. Two hundred liters of air were sampled by SAS every 12 min, after flushing water for 2 min. The IMA value was calculated as the mean value of colony forming units/16 plates exposed during sampling (2 plates/hour). Water contamination was evaluated at T0, after 4 and 8 hours, according to the standard methods. RESULTS: Air contamination by Legionella was found in three healthcare facilities (one with active and two with passive sampling), showing a concomitant tap water contamination (median=40,000; range 1,100-43,000 cfu/l). The remaining seven hospitals isolated Legionella spp. exclusively from water samples (median=8,000; range 1,200-70,000 cfu/l). CONCLUSIONS: Our data suggest that environmental Legionella contamination cannot be assessed only through the air sampling, even in the presence of an important water contamination.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
