Bacteria from patient's dental plaque causes ventilator-associated pneumonia

BUFFALO, N.Y. -- Patients admitted to a hospital's intensive care unit (ICU) already are seriously ill, so the last thing they need is a new infection. Unfortunately, statistics show that as many as 25 percent of all patients admitted to the ICU and placed on ventilators develop pneumonia, which can be fatal.

Ventilator-associated pneumonia is a major cause of infection in the hospital, and studies have shown that this infection can add $40,000 to costs and double the length of stay of the patient in the hospital.

Ironically, it turns out that the patient’s own dental plaque is a major source of germs that cause ventilator-associated pneumonia.

In results to be presented today (March 23, 2007) at the International Association of Dental Research (IADR), researchers from the University at Buffalo School of Dental Medicine show that the same bacteria identified in dental plaque of patients when they were admitted to the ICU and placed on ventilators were found later in the lungs from those who subsequently developed pneumonia.

"Our study shows that a strong relationship exists between oral and respiratory pathogens in patients with ventilator-associated pneumonia," said Paul Heo, D.D.S., a doctoral student in the UB dental school’s Department of Oral Biology and first author on the study.

"We are saying that if the patients’ mouths and teeth aren’t cleaned while they are in the hospital, they may easily develop lung disease."

The presentation is part of a three-year longitudinal, double-blind study funded by the National Institute of Dental and Craniofacial Research and headed by Frank A. Scannapieco, D.D.S., Ph.D., professor and chair of the Department of Oral Biology.

The trial aims to determine if swabbing ventilated ICU patients’ mouths with a bactericide protects them from developing pneumonia.

In this component, Heo and colleagues concentrated on three strains of suspected pathogens that are responsible for most hospital-acquired pneumonia: Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Samples of plaque from teeth and of secretions from the trachea were obtained from ICU patients on the day of admission and every third day thereafter, up to 21 days. Bronchial alveolar lavage samples also were collected from those suspected of having developed pneumonia.

Samples from nine patients who were found to have the pathogens of interest in their plaque and were suspected of having pneumonia were selected for analysis. Protein and DNA profiles of pathogens in plaque and in bronchial alveolar lavage samples were identified using a process called pulsed-field gel electrophoresis.

Results showed that genetic profiles of bacteria from tracheal and bronchial samples of the nine patients with pneumonia were identical to profiles of bacteria from their dental plaque.

"These results suggest that the teeth likely serve as an important reservoir of infection in these patients," said Heo. "To prevent opportunistic, hospital-acquired disease, taking care of teeth and gums while hospitalized might be especially important."