The potential for dissemination of Mycobacterium tuberculosis through the anesthesia breathing circuit.
BACKGROUND
Respiratory pathogens that pass through the anesthesia breathing system potentially can infect other patients. This study was designed to determine if bacteria can pass through contemporary anesthesia breathing systems and if the environment within the machine is hostile to these organisms.


METHODS
Staphylococcus aureus, Pseudomonas aeruginosa, and Mycobacterium tuberculosis were nebulized into the expiratory limb of an anesthesia breathing circuit and collected from the inspiratory and expiratory limbs in an impinger system that provided a quantitative determination of the number of organisms entering the circuit and the number that would reach the patient in the inspiratory gas. Bacteria were collected before, during, and after nebulization. A second experiment determined if a saturated solution of soda lime was bactericidal.


RESULTS
When the gas flow through the circuit was interrupted for < 1 h following the nebulization period, large numbers of microorganisms (1 x 10(3) to 1 x 10(5), around 100% of the nebulized organisms) were collected from the inspiratory gas. Soda lime itself was not bactericidal for any of the organisms tested, but solutions of this material with a pH of 12 were bactericidal.


CONCLUSIONS
Cross contamination between patients may occur unless the gas flow through the anesthesia breathing system is interrupted for > 1 h.
Langevin
P B
PB
Department of Anesthesiology, University of Florida College of Medicine, Gainesville, USA.
Rand
K H
KH
Layon
A J
AJ
D000336:Aerosols; D000391:Air Microbiology; D000764:Anesthesia, Closed-Circuit / Q000295:instrumentation*; D017610:Calcium Compounds; D004866:Equipment Contamination; D066298:In Vitro Techniques; D009169:Mycobacterium tuberculosis / Q000254:growth & development*; D010087:Oxides; D011550:Pseudomonas aeruginosa / Q000254:growth & development; D012972:Sodium Hydroxide; D013211:Staphylococcus aureus / Q000254:growth & development
D000336:Aerosols; D017610:Calcium Compounds; D010087:Oxides; C004569:soda lime; D012972:Sodium Hydroxide