Role of different routes of tracheal colonization in the development of pneumonia in patients receiving mechanical ventilation.
OBJECTIVE
To evaluate the importance of the different pathogenic pathways involved in the development of ventilator-associated pneumonia (VAP).


METHODS
Prospective study.


METHODS
An 18-bed medical and surgical ICU.


METHODS
One hundred twenty-three patients receiving mechanical ventilation (MV).


METHODS
Tracheal, pharyngeal, and gastric samples were obtained simultaneously every 24 h. In cases where VAP was suspected clinically, bronchoscopy with protected specimen brush and BAL were performed. Semiquantitative cultures of pharyngeal samples and quantitative cultures for the remaining samples were obtained.


RESULTS
Tracheal colonization at some time during MV was observed in 110 patients (89%). Eighty patients had initial colonization, 34 patients had primary colonization, and 50 patients had secondary colonization. Nineteen patients had VAP, and 25 organisms were isolated. For none of these organisms was the stomach the initial site of colonization. Gram-positive organisms colonized mainly in the trachea during the first 24 h of MV (p<0.001). On the contrary, enteric Gram-negative bacilli (p<0.001) and yeasts (p<0.002) colonized the trachea secondarily. Previous endotracheal intubation (p<0.005) and acute renal failure before admission to the ICU (p<0.001) were associated with colonization by Pseudomonas aeruginosa; prior antibiotics were associated with colonization by Acinetobacter baumanii (p<0.05) and yeasts (p<0.006); and cranial trauma was associated with Staphylococcus aureus colonization (p<0.035).


CONCLUSIONS
Although the stomach can be a source of organisms that colonize the tracheobronchial tree, it is a much less common source of the bacteria that cause VAP. The pattern of colonization and risk factors may be different according to the type of organisms involved.
Cardeñosa Cendrero
J A
JA
Servicio de Medicina Intensiva, Hospital Ntra Sra del Pino, Las Palmas de Gran Canaria, Spain.
Solé-Violán
J
J
Bordes Benítez
A
A
Noguera Catalán
J
J
Arroyo Fernández
J
J
Saavedra Santana
P
P
Rodríguez de Castro
F
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009960:Oropharynx / Q000382:microbiology; D011014:Pneumonia / Q000209:etiology / Q000628:therapy*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000009:adverse effects*; D014132:Trachea / Q000382:microbiology*