Stenotrophomonas maltophilia is a multidrug-resistant bacterium that is difficult to treat in hospitals worldwide, leading to high mortality. Published data describing the use of monotherapy or combination therapy and which one is better is still unclear. We aimed to investigate the efficacy of monotherapy and combination therapy in the treatment of S. maltophilia infections. We performed a systematic review of combination therapy and additionally a systematic review and meta-analysis to determine the effects of monotherapy versus combination therapy on mortality in S. maltophilia infections. Electronic databases: Cochrane Library, PubMed, Embase, ClinicalTrials.gov, Scopus, and OpenGrey were accessed. Of the 5030 articles identified, 17 studies were included for a systematic review of combination therapy, of which 4 cohort studies were finally included for meta-analysis. We found there is a trend of favorable outcomes with respect to mortality in the use of combination therapy to treat complex or severe S. maltopholia infections. A meta-analysis of monotherapy showed a statistical significance in the decreasing rate of mortality in hospital-acquired pneumonia (hazard ratio 1.42; 95% confidence interval, 1.04–1.94) compared to combination therapy, but not significant in bacteremia (hazard ratio 0.76; 95% confidence interval, 0.18–3.18). Further studies should continue to explore this association.

Background: Stenotrophomonas maltophilia is a multidrug-resistant bacteria that is difficult to treat in hospitals around the world. It has become a public health issue, as well as being linked to a high mortality rate. Several studies have shown a variety of treatment and clinical outcomes; however, the efficacy of combination therapy remains limited. Therefore, the purpose of this study is to investigate the effect of monotherapy and combination therapy for S. maltophilia infections on mortality outcome.Methods: We performed a systematic review and meta-analysis of combination therapy versus monotherapy in the treatment of S. maltophilia infections on mortality as a clinical outcome. Electronic databases, including Cochrane Library, PubMed, EMBASE, ClinicalTrials.gov, Scopus, and OpenGrey, were systematically searched from the inception of the database until September 3, 2021. Results: Of which 6,524 articles identified, a total of 13 studies and 2 cohort studies were included for systematic review of combination therapy and meta-analysis, respectively. The systematic review of combination antimicrobial therapy had been showed clinically desirable outcome on mortality in S. maltopholia infection, especially in complex or severe infection. In the fixed-effects meta-analysis of the cohort study, monotherapy was surprisingly shown to have statistically significant effects on the decreased risk of mortality (hazard ratio 1.42; 95% confidence interval, 1.04-1.94). Conclusions: Our results found that the combination antimicrobial therapy had been showed clinically desirable outcome on mortality in S. maltopholia infection and monotherapy has a trend toward improved better outcome than combination therapy on mortality for the treatment of S. maltophilia infections. A longitudinal study that further explores this association is warranted. Trial registration: This study was registered with the trial registration number ID: 210843 under the international prospective register of systematic reviews (PROSPERO: www.crd.york.ac.uk/PROSPERO).