INFECTION-CONTROL IN CRITICALLY ILL PATIENTS - EFFECTS OF SELECTIVE DECONTAMINATION OF THE DIGESTIVE-TRACT

The use of selective decontamination of the digestive tract (SDD) to c ontrol infection in the intensive care unit (ICU) is reviewed. There a re three basic patterns of infection in the ICU: primary endogenous, s econdary endogenous, and exogenous. In exogenous infection, no microbi al carriage precedes colonization and infection. In endogenous infecti on, infection is preceded by oropharyngeal or GI carriage. A primary e ndogenous infection is caused by an organism carried by the patient on admission to the ICU, whereas a secondary endogenous infection is cau sed by organisms acquired in the ICU. The traditional approach to infe ction control in the ICU has included frequent hand washing, limiting the use of agents for prophylaxis of stress-ulcer bleeding, and limiti ng the use of injectable antimicrobials to the treatment of infection in order to prevent resistance. The recognition that hand washing only partially reduces endogenous infection led to the use of nonabsorbabl e antimicrobials to abolish oropharyngeal and gastrointestinal carriag e of potentially pathogenic microorganisms. In addition, the use of an injectable antimicrobial during the first four days in the ICU to con trol primary endogenous infection was considered not to lead to resist ance as long as it was combined with nonabsorbable antimicrobials. Of 41 fully reported clinical trials of SDD, 33 showed a significant redu ction of infectious morbidity among patients who received SDD. Of the 32 trials in which carriage of potential pathogens was a measured endp oint, 31 showed a reduction in carriage. Of the 24 studies in which re sistance was an endpoint, 22 showed no increase in resistance associat ed with SDD. Only 10 of 35 trials that examined death showed a signifi cant decrease in mortality. SDD, used in conjunction with traditional infection-control measures, diminishes microbial carriage and infectio us morbidity in the ICU without increasing antimicrobial resistance.