Colonization of dental plaque by respiratory pathogens in medical intensive care patients

Abstract

Objective: To assess the prevalence of oral colonization by respiratory pathogens in a group of ICU patients, with specific attention to dental plaque and the oral mucosa.

Design: Prospective, nonrandomized study with age-matched controls.

Settings: Medical ICU in a tertiary-care Veterans Affairs Medical Center and a dental school outpatient preventive dentistry clinic.

Patients: Nonconsecutive, unselected patients admitted to the medical ICU during a 2-month period; controls were age-matched patients seen for the first time in the preventive dentistry clinic.

Interventions: None.

Measurements: Oral hygienic status was assessed in both groups using a semiquantitative system. Quantitative cultures of dental plaque and buccal mucosa were done within 12 hrs of medical ICU admission and every third day thereafter until discharge/death from the medical ICU. In controls, cultures of plaque and buccal mucosa were done on the initial visit only. Severity of illness of medical ICU patients was quantitated using the Acute Physiology and Chronic Health Evaluation (APACHE II) system and McCabe-Jackson criteria.

Main results: Oral hygiene of medical ICU patients was poor. These patients had a mean plaque score (1.9 +/- 0.2) that was significantly greater than that same score seen in outpatients of the preventive dentistry clinic (1.4 +/- 0.1; p less than .005). Plaque and/or oral mucosa of 22 (65%) of 34 medical ICU patients were colonized by respiratory pathogens, in contrast to only four (16%) of 25 preventive dentistry clinic patients (p less than .005). The potential respiratory pathogens cultured from medical ICU patients included methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and ten genera of Gram-negative bacilli. Colonization by respiratory pathogens was statistically associated with concomitant antibiotic therapy within the medical ICU group of patients, but not with severity of illness. Although medical ICU patients tended to have more dental plaque than preventive dentistry clinic patients, there was no statistically significant association noted between the presence of dental plaque and respiratory pathogen colonization.

Conclusions: These findings suggest that bacteria commonly causing nosocomial pneumonia colonize the dental plaque and oral mucosa of intensive care patients. In many cases, this colonization occurs by large numbers of bacteria. Dental plaque may be an important reservoir of these pathogens in medical ICU patients. Efforts to improve oral hygiene in medical ICU patients could reduce plaque load and possibly reduce oropharyngeal colonization.