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Introduction:The spread of multidrug-resistant Pseudomonas aeruginosa in Brazilian hospitals has greatly impacted upon the morbidity and mortality of individuals in intensive care units. Given the lack of information regarding the dynamics of multidrug resistance in northern Brazil, we analyzed the clinical and microbiological features of nosocomial infections caused by P. aeruginosa. Methods: Between January 2010 and March 2012, we conducted a retrospective cohort study of P. aeruginosa isolates from 54 patients who were hospitalized in intensive care units. The clinical and epidemiologic variables were analyzed, including the patients' demographic data and comorbidities, and the lengths of the intensive care unit stays, the classification of the infections as nosocomial, the use of invasive procedures, antimicrobial therapy, and the patients' outcomes. We undertook susceptibility tests, molecular detection of the metallo-β-lactamase genes, and genotypic analyses of the isolates using the repetitive element-polymerase chain reaction. Results: Multidrug resistance occurred most frequently among isolates from adults who had been hospitalized for an average of 87.1 days. The use of mechanical ventilation and urinary catheters were risk factors for infection. The four isolates that harbored the blaSPM-1-like gene showed >95% genetic similarity. Conclusions: This study's findings show that P. aeruginosa has a high death rate, and that inadequate treatment and invasive procedures are risk factors for infection. This is the first report describing the detection of the blaSPM-1-like gene in northern Brazil. These results highlight the need for better monitoring and a greater understanding of nosocomial infections and their public health impacts.

Pseudomonas aeruginosa is the leading cause of nosocomial infections with high mortality rates owing to the limited therapeutic options for multidrug-resistant Pseudomonas aeruginosa (MDRPA) and metallo-beta-lactamase (MBL)-producing strains. Herein, we present a meta-analysis exploring the association between MDRPA and São Paulo MBL-1 (SPM-1)-producing strains vs. mortality. Online databases were screened to identify studies published between 2006 and 2016. A total of 15 studies, comprising 3,201 cases of P. aeruginosa infection, were included. Our results demonstrated a higher mortality rate among patients infected with MDRPA (44.6%, 363/813) than those with non-MDRPA infection (24.8%, 593/2,388) [odds ratio (OR) 2.39, 95% confidence interval (CI) 1.70-3.36, p <0.00001]. The risk of mortality in patients with non-SPM-1 strains was four times higher than that observed in the patients of the SPM-1 group; however, no statistically significant difference was observed (p = 0.43). In conclusion, the results of our study demonstrated that patients infected with MDRPA had a significantly higher mortality rate than that of patients infected with non-MDRPA strains, especially patients with bloodstream infection (BSI), immunosuppression, and inadequate antimicrobial therapy. The absence of studies on the molecular aspects of blaSPM-1 and its association with mortality limited the analysis; therefore, our results should be interpreted with caution. Our findings also highlight the need for more studies on the molecular aspects of resistance and the peculiarities of different nosocomial settings.

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