Multi-drug resistant bacteria: Impact on patient's prognosis in the intensive care unit

Multi-Drug Resistant (MDR) bacteria are bacteria resistant to at least one antibiotic molecule belonging to more than three different classes among the classes usually active on this specie. Among MDR bacteria, the most incident in daily clinical practice are ESBL-producing Enterobacteriaceae (ESBL-E). Approximately 10% of French people are colonised with ESBL-E in the gastrointestinal tract, and ESBL-E are responsible for 8% of the infections treated in the intensive care unit (ICU). Digestive colonisation with ESBL-E increases the risk of ESBL-E infection by approximately 25 to 50 times. However, the incidence of ICU-acquired ESBL-E infection in colonised patients remains relatively low, in the range of 10-15%, depending on the ESBL-producing bacterial species, its inoculum, the site of infection, and the patient's co-morbidities. Digestive colonisation with ESBL-E is a risk factor for increased ICU length-of-stay, whereas in the most recent studies, ESBL-E-related infection is associated with approximately 1.5-fold excess mortality. The characterisation of the actual impact of ESBL-E infection needs to be refined by further studies that will take into account confounding prognostic factors, including at least the efficacy of the empirical antibiotic therapy administered. Because of the relatively low incidence of ESBL-E infection in colonised patients, and to preserve the efficacy of these molecules, the prescription of carbapenems should be reserved for ICU patients colonised with ESBL-E suffering from severe infection in empirical situations, and for patients infected with ESBL-E without any validated therapeutic alternative (cefoxitin, temocillin, piperacillin/tazobactam, etc.) in documented situations. New diagnostic methods for rapid detection of bacterial resistance will undoubtedly make it possible in the near future to reduce the length of the period of diagnostic uncertainty, and to treat patients in a personalised manner by making better use of carbapenems.