[A molecular and epidemiology study in patients with ventilator-associated pneumonia].

OBJECTIVE

To evaluate causative agents in patients with ventilator-associated (VA) pneumonia epidemiologically, then to provide useful suggestion for diagnosis and treatment of VA pneumonia.

METHOD

Prospectively, a protected specimens brush was used to obtain the secretion of lower respiratory tract of 65 patients, who had been receiving mechanical ventilation or tracheostomy for more than 72 hours. At the same time, other samples were collected from the relevant places, including pharyngeal and gastric juice of patients as well as other persons, ward's air. The secretion obtained were cultured with a quantitative method. Then all bacteria isolated were studied with the analysis of pattern of plasmids and chromosomal restriction endonuclease.

RESULT

It was showed that the route of infection of the Gram-negative bacilli in VA pneumonia (19 cases) was intrinsic, a retrograde colonization from patient's stomach, that was the pattern of clonization from stomach to pharynx, then into lower respiratory tract, and the Gram-positive staphylococcus spread mainly through the ward's air, then directly into lower respiratory tract, or extrinsic (20 cases).

CONCLUSION

The Gram-positive staphylococcus is also major disease-producing germs in VA pneumonia, and the infection routes of G+ and G- bacteria might be different.