Pseudomonas aeruginosa carriage, colonization, and infection in ICU patients

Objective: We evaluated whether Pseudomonas aeruginosa associated nosocomial infections in our ICU originate mainly from patients’ endogenous flora or from exogenous cross-transmission. Design and setting: A 6-month prospective surveillance survey was performed according to standardized protocols at the interdisciplinary ICU of the Azienda Ospedaliera Cannizzaro.Patients: The study analyzed 121 patients and focused on three different states: carriage upon admission, colonization of sterile sites, and infections during ICU stay. Results: We identified 138 P. aeruginosa isolates from 45 patients. The cumulative incidence of P. aeruginosa sustained colonization in the ICU was 29.9/100 patients, and the incidence density was 16.2/1,000 patient-days. The cumulative incidence of P. aeruginosa sustained infections in the ICU was 36.7/100 patients, and the incidence density was 19.9/1,000 patient-days. The most frequent infection type was ventilator-associated pneumonia. PFGE analysis of P. aeruginosa isolates led to the identification ofa major clone represented by 60.8% of isolates involving 45.9% of patients. The impact of cross transmission, i.e., the preventable proportion of P. aeruginosa acquisition, was estimated to be at least 59.5% of all colonization or infection episodes. Acquisition of multidrug-resistant P. aeruginosa was significantly associated with cross transmission.Conclusions: Our results suggest that the ICU personnel and environment served as reservoirs for cross-transmission and emphasize the importance of exogenous acquisition of multidrug-resistant P. aeruginosa, of reduction in antibiotic pressure, and prompt enforcement of infection control measures.Notes: Intensive Care Medicine is the official journal of The European Society of Intensive Care Medicine and The European Society of Paediatric and Neonatal Intensive Care. The article by Agodi et al. (first Author and corresponding Author) is an original paper reporting progress and results in the epidemiology and prevention of Pseudomonas aeruginosa infections in the Intensive Care Unit (ICU), that are a constant concern worldwide. Colonization with this organism often precedes infection and its prevention is, therefore, extremely important. The paper by Agodi et al. has been cited 27 times, and the most recent citation by Boyer et al. 2011 has highlighted the importance of exogenous colonization during hospitalization underlining the relevance, the international value and the novelty of the paper, addressing the relevant issue of the surveillance of the epidemiological routes and way of transmission as well as the role of assessing clonality by the means of golden standard molecular methods. Molecular epidemiology techniques have given an insight into P. aeruginosa acquisition by demonstrating that the same pulsotypes may spread from the environment to patients. Preliminary results of this paper were presented in part at the 16th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID). Furthermore, due to the international value, the excellance of the paper and of her published research on this field, Antonella Agodi has been invited by Prof. Frank Columbus, President and Editor-in-Chief of Nova Science Publishers, Inc., to give her contibution in the book entitled “Cross Infections: Types, Causes and Prevention”, writing a chapter entitled “Assessment of Patient-To-Patient Transmission of Healthcare-Associated Infections: Integrating Laboratory Data with Patient-Based Surveillance” (Agodi A, Barchitta M. Assessment of Patient-To-Patient Transmission of Healthcare-Associated Infections: Integrating Laboratory Data with Patient-Based Surveillance. In Cross Infections: Types, Causes and Prevention. Hauppauge, NY: Nova Science Publishers, Inc. 2009).