Background and Goal of Study:Postoperative pneumonia (POP) is associated with an increase on morbimortality and length of hospital stay. Multicentre studies suggest that multi-drug resistant pathogens (MDR) could be present in respiratory samples in POP early after hospital admission (48h) even in patients without risk factors. This fact could imply a change on the antibiotic empiric strategy in order to improve outcomes.
The aim of the study is to assess microbiological features of POP in a surgical intensive care unit (SICU) and determine if risk factors for MDR germs (RFMDR) are still able to predict their isolation.
Materials and Methods:We retrospectively analysed data from POP diagnosed during the admission in the SICU (January/10-November/17). Variables analysed: demographic data, microbiological respiratory cultures, time onset POP (early: ≤4 days vs late: >4 days) and RFMDR: ≥5 days of hospitalization prior to the occurrence of POP, antimicrobial therapy in the preceding 90 days, hospitalization for ≥ 2 days in the preceding 90 days.
Results and Discussion:195 patients with an average age of 70 (18-93) years old had at least one episode of POP, 83% ASA III-IV and 95% were intubated in the operating room. A total of 267 episodes of POP were recorded and pathogens were isolated in 70% of cases (206 isolations). MDR (12% ESBL,14% MDR Ps.aeruginosa and 4% MRSA) were isolated in 31% of episodes. In 92% of cases, MDR isolation could be predicted by RFMDR. Most sensitive pathogens were isolated on early SICU admission and microbiological distribution is shown on the picture. Interestingly Ps.aeruginosa and Haemophilus spp. were the most frecuent germs in this group (24%). This germs are not usually present on community pneumonia.
Conclusions: On a tertiary SICU, no matter time on admission, MDR pathogens isolation are still predictable by RFMDR. Taking into account our local flora, empiric coverage of early POP in patients without RFMDR should include Ps. Aeruginosa and Gram-negative bacteria (Enterobacterias, Klebsiella spp.), that are not commonly isolated in community pneumonia.

07 / Microbiological characteristics of nosocomial pneumonia in surgical patients: one size doesn't fit all.