Co-infection of Pseudomonas aeruginosa and Stenotrophomonas maltophilia in hospitalised pneumonia patients has a synergic and significant impact on clinical outcomes.

Ventilator-acquired pneumonia and hospital community-acquired pneumonia are frequently caused by Gram-negative and -positive bacteria. We noted that pneumonia patients with co-infection of Pseudomonas aeruginosa and Stenotrophomonas maltophilia had a poor clinical outcome. To verify this, we retrospectively reviewed pneumonia cases at Hebei General Hospital from 2010 to 2015. These cases were grouped into four categories: (1) co-infection with P. aeruginosa and S. maltophilia, (2) infection with P. aeruginosa, (3) infection with S. maltophilia and (4) infection with none of the known pneumonia-causing pathogens. The numbers of cases in each group were 50, 40, 41 and 33, with mortality rates of 64.0%, 12.5%, 14.6% and 6.1%, respectively. The analysed results indicated that a co-infection of P. aeruginosa and S. maltophilia had a synergic impact on the mortality of pneumonia patients. Therefore, future research is needed to develop treatment strategies for the co-infected patients to reduce the rate of mortality.