871 - Assessment of the Wide-resistant Pseudomonas aeruginosa Outbreak at a University Hospital in Brazil: Have We Lost This War?!

Background: Resistance profile analysis in Pseudomonas aeruginosa isolates is extremely important to prevent its transmission and to detect outbreaks. Broadly resistant strains (BR) have a high mortality rate in invasive infections. By analyzing the clinical and microbiological characteristics of these infections, one can define more effective actions in a nosocomial outbreak setting in a university hospital in Brazil.

Methods: From January to September 2019, 13 patients from the oncohematology services and intensive care unit (ICU) followed by the stewardship program of a public university hospital in Brazil had Pseudomonas aeruginosa (PsA) BR infection. Resistant multidrug (MDR) was defined as resistant to three or more antimicrobial classes. Extensively resistant (XDR) was sensitive to a maximum of two antimicrobial classes. Resistant pandrug (PDR) has been defined as resistant to all antimicrobial classes. Bacterial samples were identified by the automated VITEK®2 system (BioMérieux). The resistance pattern was defined based on the CLSI-M100 2019 criteria. Colistin sensitivity was assessed by the colistin drop test (Pasteran et al., 2018). The modified carbapenemic inactivation method (mCIM) was performed by disk diffusion.

Results: The 13 strains of PsA were isolated from 84.6% (11/13) blood cultures and 15.4% (2/13) tracheal aspirates, being 76.9% (10/13) from the oncohematology unit and 23.1% (3/13) of the ICU. The resistance profile was 23.1% (3/13) strains PsA MDR, 61.5% (8/13) PsA XDR and 15.4% (2/13) strains resistant to all classes (PsA PDR). 69.2% (9/13) of the strains were mCIM positive, in which the therapeutic option was ceftazidime/avibactam in combination with polymyxin. Regarding the sites of infection and use of devices, 53.8% (7/13) of the patients developed the infection after the use of central venous catheter and/or mechanical ventilation. The mortality rate was 76.9% (10/13).

Conclusion: The investigation of the outbreak of Pseudomonas aeruginosa highlights the importance of infectious surveillance of this pathogen with this resistance profile, to better understand the causalities, minimize its damage and reduce potential recurrence of new outbreaks.