title: Impact of antibiotics on the gut microbiota of critically ill patients.
abstract: We evaluated the relationship between the intestinal microbiota composition and clinical outcome in a group of 15 high-risk patients admitted for acute infection and/or surgical/accidental trauma who were treated with systemic antibiotics according to standard intensive care unit (ICU) protocols. There was a high mortality rate amongst these patients, each of whom had a considerable organ failure score at admission, respiratory assistance during the most of their ICU stay and a long length of stay. All of these individuals received sedation and enteral nutrition, and the majority also received insulin, vasoactive drugs and some stress-ulcer prophylaxis agents. The intestinal microbiota composition was assessed using denaturing gradient gel electrophoresis (DGGE), a molecular biology tool used to characterize bacterial ecosystems. As all of the patient subjects were in good health prior to their acute illness and admission to the ICU, the first faecal samples obtained from this group showed a DGGE banding pattern that was similar to that of healthy subjects. After 1 week of critical illness, coupled with intensive care treatment, including antibiotics, a very definite alteration in the overall microbiota composition was evident, as revealed by a reduction in the number of DGGE bands. Further pronounced changes to the DGGE banding profiles could be observed in patients remaining in the ICU for 2 weeks. Moreover, a dominant band, identified by sequencing as highly related to Enterococcus, was detected in the DGGE profile of some of our patient subjects. We also performed real-time PCR and obtained results that were in agreement with our qualitative evaluations using DGGE. The degree of organ failure and ICU mortality was significantly higher in patients for whom a high reduction in microbiota biodiversity was coupled with a massive presence of enterococci. A statistically significant link between these two ecological traits and the use of clindamycin was also found.
authors.affiliation: Istituto di Anestesiologia e Rianimazione, Università degli Studi, Polo San Paolo, via Di Rudinì 8, I-20142 Milano, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Iapichino
authors.affiliation: Centro Ricerche Biotecnologiche, Università Cattolica del Sacro Cuore, Via Milano 24, 26100 Cremona, Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Callegari
authors.affiliation: Istituto di Anestesiologia e Rianimazione, Università degli Studi, Polo San Paolo, via Di Rudinì 8, I-20142 Milano, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Marzorati
authors.affiliation: Istituto di Anestesiologia e Rianimazione, Università degli Studi, Polo San Paolo, via Di Rudinì 8, I-20142 Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Cigada
authors.affiliation: Istituto di Anestesiologia e Rianimazione, Università degli Studi, Polo San Paolo, via Di Rudinì 8, I-20142 Milano, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Corbella
authors.affiliation: Centro Ricerche Biotecnologiche, Università Cattolica del Sacro Cuore, Via Milano 24, 26100 Cremona, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Ferrari
authors.affiliation: Istituto di Microbiologia, Università Cattolica del Sacro Cuore, Via E. Parmense 84, 29100 Piacenza, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Morelli
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016638:Critical Illness; D004586:Electrophoresis; D016983:Enterococcus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D007422:Intestines / Q000382:microbiology*; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008967:Molecular Biology; D016133:Polymerase Chain Reaction
chemical_list: D000900:Anti-Bacterial Agents