Colonization of dental plaque: a source of nosocomial infections in intensive care unit patients

Abstract

Objective: To study the dental status and colonization of dental plaque by aerobic pathogens and their relation with nosocomial infections in intensive care unit (ICU) patients.

Design: A prospective study in a medical ICU of a university-affiliated hospital.

Patients: Consecutive patients admitted to the ICU during a 3-mo period.

Interventions: Dental status was assessed by the same investigator using a score adapted from the "Caries-Absent-Occluded" (CAO) index (referred to in the U.S. as DMFT [Decayed-Missing-Filled Teeth] index). The amount of dental plaque on premolars was assessed using a semiquantitative score. Quantitative cultures of dental plaque, nasal secretions, tracheal aspirates, and urine were done at admission (day 0) and every fifth day until death or discharge. An additional study was done in eight patients to serially compare dental plaque, salivary, and tracheal aspirate cultures during a 2-wk period.

Measurements and main results: Fifty-seven patients were included in the main study. Due to the variability in their ICU stay, 29 patients could be examined on day 0 only (group A), 15 patients on days 0 and 5 (group B), and 13 patients on days 0, 5, and 10 (group C). The mean dental CAO score was 16 +/- 8 and did not change during the ICU stay. The dental plaque score was < or =1 in 70% of patients on day 0; > or =2 in 50% of patients on day 5; and > or =2 in 90% of patients on day 10. Dental plaque cultures were positive at 10(3) colony-forming units/mL for aerobic pathogens in 23% of patients on day 0; 39% of patients on day 5; and 46% of patients on day 10. In groups B and C, mean dental plaque score and frequency of plaque colonization increased from days 0 to 5 and from days 5 to 10. A high bacterial concordance was found between dental plaque and tracheal aspirate cultures, and in the additional study, between salivary and dental plaque cultures. Twenty-one patients developed a nosocomial infection in the ICU. Dental plaque colonization on days 0 and 5 was significantly associated with the occurrence of nosocomial pneumonia and bacteremia (sensitivity 0.77; specificity 0.96; positive predictive value 0.87; negative predictive value 0.91; relative risk 9.6). In six cases of nosocomial infection, the pathogen isolated from dental plaque was the first identified source of nosocomial infection.

Conclusions: The amount of dental plaque increased during the ICU stay. Colonization of dental plaque was either present on admission or acquired in 40% of patients. A positive dental plaque culture was significantly associated with subsequent nosocomial infections. Dental plaque colonization by aerobic pathogens might be a specific source of nosocomial infection in ICU patients.