title: Update on infections caused by Stenotrophomonas maltophilia with particular attention to resistance mechanisms and therapeutic options.
abstract: Stenotrophomonas maltophilia is a Gram-negative, biofilm-forming bacterium. Although generally regarded as an organism of low virulence, S. maltophilia is an emerging multi-drug resistant opportunistic pathogen in hospital and community settings, especially among immunocompromised hosts. Risk factors associated with S. maltophilia infection include underlying malignancy, cystic fibrosis, corticosteroid or immunosuppressant therapy, the presence of an indwelling central venous catheter and exposure to broad spectrum antibiotics. In this review, we provide a synthesis of information on current global trends in S. maltophilia pathogenicity as well as updated information on the molecular mechanisms contributing to its resistance to an array of antimicrobial agents. The prevalence of S. maltophilia infection in the general population increased from 0.8-1.4% during 1997-2003 to 1.3-1.68% during 2007-2012. The most important molecular mechanisms contributing to its resistance to antibiotics include β-lactamase production, the expression of Qnr genes, and the presence of class 1 integrons and efflux pumps. Trimethoprim/sulfamethoxazole (TMP/SMX) is the antimicrobial drug of choice. Although a few studies have reported increased resistance to TMP/SMX, the majority of studies worldwide show that S. maltophilia continues to be highly susceptible. Drugs with historically good susceptibility results include ceftazidime, ticarcillin-clavulanate, and fluoroquinolones; however, a number of studies show an alarming trend in resistance to those agents. Tetracyclines such as tigecycline, minocycline, and doxycycline are also effective agents and consistently display good activity against S. maltophilia in various geographic regions and across different time periods. Combination therapies, novel agents, and aerosolized forms of antimicrobial drugs are currently being tested for their ability to treat infections caused by this multi-drug resistant organism.
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Municipal HsiaoKang Hospital Kaohsiung, Taiwan ; Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University Kaohsiung, Taiwan.
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Chang
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University Kaohsiung, Taiwan ; School of Medicine, Graduate Institute of Medicine, Sepsis Research Center, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan.
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University Kaohsiung, Taiwan ; School of Medicine, Graduate Institute of Medicine, Sepsis Research Center, College of Medicine, Kaohsiung Medical University Kaohsiung, Taiwan ; Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University HsinChu, Taiwan.
authors.forename: Yen-Hsu
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Departments of Laboratory Medicine and Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine Taipei, Taiwan.
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
keywords: Stenotrophomonas maltophilia; prevalence; surveillance; susceptibility; treatment