Colonisation à bactéries multirésistantes en service de médecine physique et réadaptation

The Persistence of Staphylococcus aureus in Pressure Ulcers: A Colonising Role

Decubitus pressure ulcers (PU) are a major complication of immobilised patients. Staphylococcus aureus is one of the most frequently detected microorganisms in PU samples; however, its persistence and role in the evolution of these wounds is unknown. In this study, we analysed S. aureus strains isolated from PU biopsies at inclusion and day 28. Eleven S. aureus (21.1%) were detected in 52 patients at inclusion. Only six PUs (11.5%) continued to harbour this bacterium at day 28. Using a whole genome sequencing approach (Miseq®, Illumina), we confirmed that these six S. aureus samples isolated at D28 were the same strain as that isolated at inclusion, with less than 83 bp difference. Phenotypical studies evaluating the growth profiles (Infinite M Mano, Tecan®) and biofilm formation (Biofilm Ring Test®) did not detect any significant difference in the fitness of the pairs of S. aureus. However, using the Caenorhabditis elegans killing assay, a clear decrease of virulence was observed between strains isolated at D28 compared with those isolated at inclusion, regardless of the clinical evolution of the PU. Moreover, all strains at inclusion were less virulent than a control S. aureus strain, i.e., NSA739. An analysis of polymicrobial communities of PU (by metabarcoding approach), in which S. aureus persisted, demonstrated no impact of Staphylococcus genus on PU evolution. Our study suggested that S. aureus presented a colonising profile on PU with no influence on wound evolution.

Bacterial Colonization in COPD Patients Admitted to a Rehabilitation Respiratory Unit and Impact on Length of Stay: A Real-Life Study

Bacterial colonization is a well-known phenomenon in acute care, but scant information is available regarding the rehabilitation setting. We retrospectively analyzed, in COPD patients admitted to a Respiratory Rehabilitative unit in 2010, the number of cultures requested, of positive cultures, and of cultures showing multiple drug resistant (MDR) organisms. We also compared hospital admissions (HA) with versus without positive cultures and with versus without MDR and investigated which baseline variables may predict length of stay (LOS) > 30 days. Of 286 COPD admissions (involving 269 patients, age 71 ± 11 years, males 66%), culture samples were requested in 62 (22%). The rate of colonization and of MDR organisms was 61 and 39%, respectively. Patients with a positive culture had a worse clinical condition and disability, and were more frequently tracheostomized, on invasive mechanical ventilation (MV) and admitted from/discharged to acute care. Patients with MDR cultures showed a lower exercise tolerance. Factors predicting LOS > 30 days were the presence of comorbidities, invasive MV, age > 65 years, and lower functional status, but not a positive culture or MDR presence. To our knowledge, this is the first real-life Italian study investigating the epidemiology of colonization and the association between colonization and LOS in a respiratory rehabilitation setting. Further investigation is necessary to clarify the relationship between colonization burden and patients' baseline clinical status and outcomes.