[Bacterial colonization and home mechanical ventilation: prevalence and risk factors].
OBJECTIVE
To investigate the prevalence of bacterial contamination of ventilators and colonization of patients, the bacteria implicated, and predisposing factors in noninvasive home ventilation.


METHODS
Forty patients on a home noninvasive ventilation program (mean [SD] age: 63.1 [12] years; time on ventilation: 30.7 [25] months; daily use: 8.1 [2] hours) were enrolled in this descriptive cross-sectional study. Microbiological samples for semiquantitative cultures were swabbed from the ventilator (mask and tubing) and the nostrils. A questionnaire was completed on the underlying disease, time on the ventilation program, type of ventilator, presence of a humidifier, and attention to ventilator cleanliness and maintenance. We defined "colonization" as the presence of microorganisms in the nostrils without evidence of a host immune response, and "contamination" as the presence of surface microorganisms (on tubing or the nasal mask).


RESULTS
Potentially pathogenic bacteria were isolated from 6 ventilators (15%) and the nasal swabs of 10 patients (25%). Staphylococcus aureus was the most frequently isolated one (in 5 ventilators and 6 patients--contamination coinciding with colonization in 3 cases). Other potentially pathogenic bacteria isolated were Proteus species (from the nostrils of 2 patients) and an unidentified gram-negative bacillus from the ventilator. On analysis by underlying disease, 60% of the patients with obesity had been colonized. No other findings of note were obtained for other diseases. Contamination and colonization correlated with attention to cleanliness and maintenance of the ventilator but not with type of ventilator, time on the ventilation program, or use of a humidifier.


CONCLUSIONS
Home mechanical ventilators are a potential source of nasal colonization. The most frequently encountered microorganism was S. aureus. The degree of ventilator cleaning and disinfection seems to affect contamination; thus it is necessary to impress on patients the need for adequate maintenance of their ventilators.
Sección de Soporte Ventilatorio y Trastornos del Sueño, Servicio de Neumología, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
J M
JM
Rodríguez González-Moro
G
G
Andrade Vivero
J
J
de Miguel Díez
S
S
López Martín
C
C
Sánchez
J L
JL
Izquierdo Alonso
P
P
de Lucas Ramos
D000328:Adult; D000368:Aged; D001419:Bacteria / Q000302:isolation & purification*; D003430:Cross-Sectional Studies; D004866:Equipment Contamination; D005260:Female; D006699:Home Care Services; D006801:Humans; D008297:Male; D008875:Middle Aged; D009666:Nose / Q000382:microbiology*; D015995:Prevalence; D012121:Respiration, Artificial; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D012122:Ventilators, Mechanical / Q000382:microbiology*