Laboratory evaluation of a filter for the control of cross-infection during pulmonary function testing.
Nosocomial transmission of respiratory pathogens is a possible complication of lung function testing. The use of a filter, placed between the patient and the spirometer equipment may be one way of preventing such nosocomial spread. This paper reports the laboratory evaluation of the efficiency of such a filter at removing bacteria from exhaled breath. Volunteers exhaled 100 normal breaths or four forced exhalations through a filter on to a blood agar plate. Bacterial counts on the agar plate were compared with recoverable bacterial counts from the filter. Total challenge from the forced exhalations ranged from 161-84,200 colony forming units. The calculated efficiency of 10 volunteers was 99.9%. For the normal breaths the challenge ranged from 0-262,000 colony forming units. There was no growth on any of the blood-agar plates. These filters appear to be highly efficient at removing exhaled bacteria.
Public Health Laboratory, Chester, UK.
Y L
YL
Kirk
K
K
Kendall
H A
HA
Ashworth
P R
PR
Hunter
D001419:Bacteria / Q000302:isolation & purification*; D015169:Colony Count, Microbial; D003428:Cross Infection / Q000517:prevention & control*; D005069:Evaluation Studies as Topic; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D012129:Respiratory Function Tests / Q000295:instrumentation*