Prospective study of nosocomial colonization and infection due to Pseudomonas aeruginosa in mechanically ventilated patients.
OBJECTIVE
To investigate the respective contribution of endogenous and exogenous transmission of Pseudomonas aeruginosa in the colonization of lungs in the mechanically ventilated patient, to estimate the role of P. aeruginosa colonization in the occurrence of severe infections, and to extrapolate appropriate control measures for the prevention of P. aeruginosa ventilator-associated pneumonia.


METHODS
Prospective study of the presence of P. aeruginosa (in stomach fluid, throat specimens, stool, and sputum) on admission, twice a week throughout the patient's stay, and in their environment. O-serotyping, pulsed-field gel electrophoresis, and arbitrarily-primed polymerase chain reaction were used to characterize the strains.


METHODS
The two intensive care units (ICUs 1 and 2) of a university hospital.


METHODS
During a 6-month period, 59 patients were included (21 in ICU 1 and 38 in ICU 2).


RESULTS
P. aeruginosa was isolated in 26 patients, including ten pneumonia cases and seven colonizations on admission. The incidence of acquired colonization was statistically different between the two ICUs: 5.5 and 20.5 per 1000 days of mechanical ventilation, in ICUs 1 and 2, respectively. Endogenous acquisition was the main origin of P. aeruginosa colonization (21 of 26 patients) and the upper respiratory tract was the main bacterial reservoir in broncho-pulmonary colonization and infection. However, during the 6-month period of the study, a multidrug-resistant strain of P. aeruginosa O:11, isolated in the sink of the room of 12 patients, was found responsible for two colonizations (1 digestive, 1 throat/lungs) and one pneumonia. As a whole, from 26 cases of colonization/infection with P. aeruginosa, 5 were related to an exogenous contamination (environmental reservoir in 4 patients and cross-contamination in one patient).


CONCLUSIONS
These results emphasize the need for applying various infection control measures to prevent colonization of patients with P. aeruginosa, including strategies to limit the potential of sinks from acting as a source or reservoir for this bacterium.
Berthelot
P
P
Infectious Diseases Unit, Hospital Bellevue, 42055 Saint-Etienne, France.
Grattard
F
F
Mahul
P
P
Pain
P
P
Jospé
R
R
Venet
C
C
Carricajo
A
A
Aubert
G
G
Ros
A
A
Dumont
A
A
Lucht
F
F
Zéni
F
F
Auboyer
C
C
Bertrand
J C
JC
Pozzetto
B
B
D000368:Aged; D000704:Analysis of Variance; D015169:Colony Count, Microbial; D003428:Cross Infection / Q000209:etiology* / Q000517:prevention & control / Q000635:transmission*; D004197:Disease Reservoirs; D018562:Disease Transmission, Infectious / Q000517:prevention & control / Q000706:statistics & numerical data*; D016521:Electrophoresis, Gel, Pulsed-Field; D004866:Equipment Contamination / Q000517:prevention & control / Q000706:statistics & numerical data; D005260:Female; D005602:France; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D017053:Infection Control; D007362:Intensive Care Units; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000209:etiology* / Q000517:prevention & control / Q000635:transmission*; D011550:Pseudomonas aeruginosa; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods; D012307:Risk Factors; D012703:Serotyping; D013997:Time Factors