Official reprint from UpToDate®
www.uptodate.com ©2016 UpToDate®

Stenotrophomonas maltophilia

Sarah S Lewis, MD
Aimee Zaas, MD, MHS
Section Editor
Daniel J Sexton, MD
Deputy Editor
Allyson Bloom, MD


Stenotrophomonas maltophilia is a multi-drug resistant gram-negative bacillus that is an opportunistic pathogen [1-4], particularly among hospitalized patients. Stenotrophomonas infections have been associated with high morbidity and mortality in severely immunocompromised and debilitated individuals.  


Stenotrophomonas (Xanthomonas) maltophilia is a ubiquitous, aerobic, non-fermentative, gram-negative bacillus that is closely related to the Pseudomonas species [5]. The name signifies "a unit feeding on few substrates," based on the Greek roots stenos (narrow), trophos (one who feeds), and monas (a unit). Maltophilia means "affinity for malt," based on the Greek roots maltum (malt) and philia (affinity).

S. maltophilia was first isolated in 1943 and, at the time, was named Bacterium bookeri. It was later classified within the genus Pseudomonas, then Xanthomonas, and then finally Stenotrophomonas in 1993 [4,6,7]. S. maltophilia is the only species of Stenotrophomonas known to infect humans [7], whereas its closest genetic relatives are plant pathogens [7,8]. It is frequently isolated from soil, water, animals, plant matter, and hospital equipment [4,9-21].

S. maltophilia has inherent ability to adhere to foreign materials and form a biofilm, rendering protection from host defenses as well as antimicrobial agents [18,19,22-26]. Factors contributing to this behavior include its positively charged surface and fimbrial adhesions [7,22-24,26-28]. In addition, Stenotrophomonas has intrinsic or acquired resistance mechanisms to a number of antibiotic classes, including beta-lactams, aminoglycosides, carbapenems, and fluoroquinolones. Resistance to beta-lactams is conferred by two inducible beta-lactamases, a zinc-containing penicillinase (L1) and a cephalosporinase (L2) [21,29-32]. An aminoglycoside acetyl-transferase confers resistance to aminoglycoside antibiotics [33-39]. Temperature-dependent changes in the outer membrane lipopolysaccharide (LPS) structure have been associated with added resistance to aminoglycoside antibiotics [18,40-43]. In addition, many strains of S. maltophilia possess efflux pumps, which confer further resistance to multiple antibacterial classes [33,44-47].


Stenotrophomonas infections have been associated with high morbidity and mortality in severely immunocompromised and debilitated individuals. Risk factors associated with Stenotrophomonas infection include admission to an intensive care unit, HIV infection, malignancy, cystic fibrosis, neutropenia, mechanical ventilation, central venous catheters, recent surgery, trauma, and previous therapy with broad-spectrum antibiotics [1,2,4,20,21,48-51].


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Apr 2016. | This topic last updated: Jan 28, 2014.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2016 UpToDate, Inc.
  1. Paez JI, Tengan FM, Barone AA, et al. Factors associated with mortality in patients with bloodstream infection and pneumonia due to Stenotrophomonas maltophilia. Eur J Clin Microbiol Infect Dis 2008; 27:901.
  2. Kwa AL, Low JG, Lim TP, et al. Independent predictors for mortality in patients with positive Stenotrophomonas maltophilia cultures. Ann Acad Med Singapore 2008; 37:826.
  3. Lai CH, Chi CY, Chen HP, et al. Clinical characteristics and prognostic factors of patients with Stenotrophomonas maltophilia bacteremia. J Microbiol Immunol Infect 2004; 37:350.
  4. Denton M, Kerr KG. Microbiological and clinical aspects of infection associated with Stenotrophomonas maltophilia. Clin Microbiol Rev 1998; 11:57.
  5. Calza L, Manfredi R, Chiodo F. Stenotrophomonas (Xanthomonas) maltophilia as an emerging opportunistic pathogen in association with HIV infection: a 10-year surveillance study. Infection 2003; 31:155.
  6. Giligan P, Lum G, Vandamme PAR, Whittier S. Burkholderia, Stenotrophomonas, Ralstonia, Brevundimonas, Comamonas, Delftia, Pandoraea, and Acidovorax. In: Manual of Clinical Microbiology, 8th, Murray PR (Ed), ASM, Washington 2003.
  7. Looney WJ, Narita M, Mühlemann K. Stenotrophomonas maltophilia: an emerging opportunist human pathogen. Lancet Infect Dis 2009; 9:312.
  8. Crossman LC, Gould VC, Dow JM, et al. The complete genome, comparative and functional analysis of Stenotrophomonas maltophilia reveals an organism heavily shielded by drug resistance determinants. Genome Biol 2008; 9:R74.
  9. Elsner HA, Dührsen U, Hollwitz B, et al. Fatal pulmonary hemorrhage in patients with acute leukemia and fulminant pneumonia caused by Stenotrophomonas maltophilia. Ann Hematol 1997; 74:155.
  10. Ganadu M, Mura GL, Campus AM, et al. Relapsing pyrogenic reactions due to Xanthomonas maltophilia in a dialysis patient with a long-term central venous catheter. Nephrol Dial Transplant 1996; 11:197.
  11. Girijaratnakumari T, Raja A, Ramani R, et al. Meningitis due to Xanthomonas maltophilia. J Postgrad Med 1993; 39:153.
  12. Lo WT, Wang CC, Lee CM, Chu ML. Successful treatment of multi-resistant Stenotrophomonas maltophilia meningitis with ciprofloxacin in a pre-term infant. Eur J Pediatr 2002; 161:680.
  13. Papadakis KA, Vartivarian SE, Vassilaki ME, Anaissie EJ. Stenotrophomonas maltophilia: an unusual cause of biliary sepsis. Clin Infect Dis 1995; 21:1032.
  14. Papadakis KA, Vartivarian SE, Vassilaki ME, Anaissie EJ. Septic prepatellar bursitis caused by Stenotrophomonas (Xanthomonas) maltophilia. Clin Infect Dis 1996; 22:388.
  15. Smeets JG, Löwe SH, Veraart JC. Cutaneous infections with Stenotrophomonas maltophilia in patients using immunosuppressive medication. J Eur Acad Dermatol Venereol 2007; 21:1298.
  16. Gilardi GL. Infrequently encountered Pseudomonas species causing infection in humans. Ann Intern Med 1972; 77:211.
  17. Khardori N, Elting L, Wong E, et al. Nosocomial infections due to Xanthomonas maltophilia (Pseudomonas maltophilia) in patients with cancer. Rev Infect Dis 1990; 12:997.
  18. Nicodemo AC, Paez JI. Antimicrobial therapy for Stenotrophomonas maltophilia infections. Eur J Clin Microbiol Infect Dis 2007; 26:229.
  19. Gilardi GL. Pseudomonas maltophilia infections in man. Am J Clin Pathol 1969; 51:58.
  20. Elting LS, Khardori N, Bodey GP, Fainstein V. Nosocomial infection caused by Xanthomonas maltophilia: a case-control study of predisposing factors. Infect Control Hosp Epidemiol 1990; 11:134.
  21. Falagas ME, Kastoris AC, Vouloumanou EK, et al. Attributable mortality of Stenotrophomonas maltophilia infections: a systematic review of the literature. Future Microbiol 2009; 4:1103.
  22. Bottone EJ, Reitano M, Janda JM, et al. Pseudomonas maltophilia exoenzyme activity as correlate in pathogenesis of ecthyma gangrenosum. J Clin Microbiol 1986; 24:995.
  23. Jucker BA, Harms H, Zehnder AJ. Adhesion of the positively charged bacterium Stenotrophomonas (Xanthomonas) maltophilia 70401 to glass and Teflon. J Bacteriol 1996; 178:5472.
  24. de Oliveira-Garcia D, Dall'Agnol M, Rosales M, et al. Fimbriae and adherence of Stenotrophomonas maltophilia to epithelial cells and to abiotic surfaces. Cell Microbiol 2003; 5:625.
  25. Di Bonaventura G, Spedicato I, D'Antonio D, et al. Biofilm formation by Stenotrophomonas maltophilia: modulation by quinolones, trimethoprim-sulfamethoxazole, and ceftazidime. Antimicrob Agents Chemother 2004; 48:151.
  26. Martínez JL, Baquero F. Interactions among strategies associated with bacterial infection: pathogenicity, epidemicity, and antibiotic resistance. Clin Microbiol Rev 2002; 15:647.
  27. de Oliveira-Garcia D, Dall'Agnol M, Rosales M, et al. Characterization of flagella produced by clinical strains of Stenotrophomonas maltophilia. Emerg Infect Dis 2002; 8:918.
  28. Waters VJ, Gómez MI, Soong G, et al. Immunostimulatory properties of the emerging pathogen Stenotrophomonas maltophilia. Infect Immun 2007; 75:1698.
  29. Avison MB, Higgins CS, von Heldreich CJ, et al. Plasmid location and molecular heterogeneity of the L1 and L2 beta-lactamase genes of Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2001; 45:413.
  30. Crowder MW, Walsh TR, Banovic L, et al. Overexpression, purification, and characterization of the cloned metallo-beta-lactamase L1 from Stenotrophomonas maltophilia. Antimicrob Agents Chemother 1998; 42:921.
  31. Saino Y, Inoue M, Mitsuhashi S. Purification and properties of an inducible cephalosporinase from Pseudomonas maltophilia GN12873. Antimicrob Agents Chemother 1984; 25:362.
  32. Walsh TR, MacGowan AP, Bennett PM. Sequence analysis and enzyme kinetics of the L2 serine beta-lactamase from Stenotrophomonas maltophilia. Antimicrob Agents Chemother 1997; 41:1460.
  33. Falagas ME, Valkimadi PE, Huang YT, et al. Therapeutic options for Stenotrophomonas maltophilia infections beyond co-trimoxazole: a systemic review. JAC 2008; 62:889.
  34. Spencer RC. The emergence of epidemic, multiple-antibiotic-resistant Stenotrophomonas (Xanthomonas) maltophilia and Burkholderia (Pseudomonas) cepacia. J Hosp Infect 1995; 30 Suppl:453.
  35. Hancock RE. Resistance mechanisms in Pseudomonas aeruginosa and other nonfermentative gram-negative bacteria. Clin Infect Dis 1998; 27 Suppl 1:S93.
  36. Lambert T, Ploy MC, Denis F, Courvalin P. Characterization of the chromosomal aac(6')-Iz gene of Stenotrophomonas maltophilia. Antimicrob Agents Chemother 1999; 43:2366.
  37. Li XZ, Zhang L, McKay GA, Poole K. Role of the acetyltransferase AAC(6')-Iz modifying enzyme in aminoglycoside resistance in Stenotrophomonas maltophilia. J Antimicrob Chemother 2003; 51:803.
  38. Poole K. Outer membranes and efflux: the path to multidrug resistance in Gram-negative bacteria. Curr Pharm Biotechnol 2002; 3:77.
  39. Safdar A, Rolston KV. Stenotrophomonas maltophilia: changing spectrum of a serious bacterial pathogen in patients with cancer. Clin Infect Dis 2007; 45:1602.
  40. Wheat PF, Winstanley TG, Spencer RC. Effect of temperature on antimicrobial susceptibilities of Pseudomonas maltophilia. J Clin Pathol 1985; 38:1055.
  41. Rahmati-Bahram A, Magee JT, Jackson SK. Growth temperature-dependent variation of cell envelope lipids and antibiotic susceptibility in Stenotrophomonas (Xanthomonas) maltophilia. J Antimicrob Chemother 1995; 36:317.
  42. Rahmati-Bahram A, Magee JT, Jackson SK. Temperature-dependent aminoglycoside resistance in Stenotrophomonas (Xanthomonas) maltophilia; alterations in protein and lipopolysaccharide with growth temperature. J Antimicrob Chemother 1996; 37:665.
  43. Rahmati-Bahram A, Magee JT, Jackson SK. Effect of temperature on aminoglycoside binding sites in Stenotrophomonas maltophilia. J Antimicrob Chemother 1997; 39:19.
  44. Alonso A, Martínez JL. Cloning and characterization of SmeDEF, a novel multidrug efflux pump from Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2000; 44:3079.
  45. Alonso A, Martinez JL. Expression of multidrug efflux pump SmeDEF by clinical isolates of Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2001; 45:1879.
  46. Zhang L, Li XZ, Poole K. Fluoroquinolone susceptibilities of efflux-mediated multidrug-resistant Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Burkholderia cepacia. J Antimicrob Chemother 2001; 48:549.
  47. Alonso A, Sanchez P, Martínez JL. Stenotrophomonas maltophilia D457R contains a cluster of genes from gram-positive bacteria involved in antibiotic and heavy metal resistance. Antimicrob Agents Chemother 2000; 44:1778.
  48. Muder RR, Harris AP, Muller S, et al. Bacteremia due to Stenotrophomonas (Xanthomonas) maltophilia: a prospective, multicenter study of 91 episodes. Clin Infect Dis 1996; 22:508.
  49. del Toro MD, Rodríguez-Bano J, Herrero M, et al. Clinical epidemiology of Stenotrophomonas maltophilia colonization and infection: a multicenter study. Medicine (Baltimore) 2002; 81:228.
  50. Carmeli Y, Samore MH. Comparison of treatment with imipenem vs. ceftazidime as a predisposing factor for nosocomial acquisition of Stenotrophomonas maltophilia: a historical cohort study. Clin Infect Dis 1997; 24:1131.
  51. Paez JI, Costa SF. Risk factors associated with mortality of infections caused by Stenotrophomonas maltophilia: a systematic review. J Hosp Infect 2008; 70:101.
  52. Morrison AJ Jr, Hoffmann KK, Wenzel RP. Associated mortality and clinical characteristics of nosocomial Pseudomonas maltophilia in a university hospital. J Clin Microbiol 1986; 24:52.
  53. Al-Jasser AM. Stenotrophomonas maltophilia resistant to trimethoprim-sulfamethoxazole: an increasing problem. Ann Clin Microbiol Antimicrob 2006; 5:23.
  54. Victor MA, Arpi M, Bruun B, et al. Xanthomonas maltophilia bacteremia in immunocompromised hematological patients. Scand J Infect Dis 1994; 26:163.
  55. Barchitta M, Cipresso R, Giaquinta L, et al. Acquisition and spread of Acinetobacter baumannii and Stenotrophomonas maltophilia in intensive care patients. Int J Hyg Environ Health 2009; 212:330.
  56. Senol E, DesJardin J, Stark PC, et al. Attributable mortality of Stenotrophomonas maltophilia bacteremia. Clin Infect Dis 2002; 34:1653.
  57. Wang WS, Liu CP, Lee CM, Huang FY. Stenotrophomonas maltophilia bacteremia in adults: four years' experience in a medical center in northern Taiwan. J Microbiol Immunol Infect 2004; 37:359.
  58. Gales AC, Jones RN, Forward KR, et al. Emerging importance of multidrug-resistant Acinetobacter species and Stenotrophomonas maltophilia as pathogens in seriously ill patients: geographic patterns, epidemiological features, and trends in the SENTRY Antimicrobial Surveillance Program (1997-1999). Clin Infect Dis 2001; 32 Suppl 2:S104.
  59. Köseoğlu O, Sener B, Gülmez D, et al. Stenotrophomonas maltophilia as a nosocomial pathogen. New Microbiol 2004; 27:273.
  60. Micozzi A, Venditti M, Monaco M, et al. Bacteremia due to Stenotrophomonas maltophilia in patients with hematologic malignancies. Clin Infect Dis 2000; 31:705.
  61. Chen YF, Chung PC, Hsiao CH. Stenotrophomonas maltophilia keratitis and scleritis. Chang Gung Med J 2005; 28:142.
  62. Penland RL, Wilhelmus KR. Stenotrophomonas maltophilia ocular infections. Arch Ophthalmol 1996; 114:433.
  63. Pathmanathan A, Waterer GW. Significance of positive Stenotrophomonas maltophilia culture in acute respiratory tract infection. Eur Respir J 2005; 25:911.
  64. Teo WY, Chan MY, Lam CM, Chong CY. Skin manifestation of Stenotrophomonas maltophilia infection--a case report and review article. Ann Acad Med Singapore 2006; 35:897.
  65. Son YM, Na SY, Lee HY, et al. Ecthyma Gangrenosum: A Rare Cutaneous Manifestation Caused by Stenotrophomonas maltophilia in a Leukemic Patient. Ann Dermatol 2009; 21:389.
  66. Pankuch GA, Jacobs MR, Rittenhouse SF, Appelbaum PC. Susceptibilities of 123 strains of Xanthomonas maltophilia to eight beta-lactams (including beta-lactam-beta-lactamase inhibitor combinations) and ciprofloxacin tested by five methods. Antimicrob Agents Chemother 1994; 38:2317.
  67. Giamarellos-Bourboulis EJ, Karnesis L, Galani I, Giamarellou H. In vitro killing effect of moxifloxacin on clinical isolates of Stenotrophomonas maltophilia resistant to trimethoprim-sulfamethoxazole. Antimicrob Agents Chemother 2002; 46:3997.
  68. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing: Eighteenth informational supplement [Document M100-S18]. Wayne, PA 2008.
  69. Tsiodras S, Pittet D, Carmeli Y, et al. Clinical implications of stenotrophomonas maltophilia resistant to trimethoprim-sulfamethoxazole: a study of 69 patients at 2 university hospitals. Scand J Infect Dis 2000; 32:651.
  70. Vartivarian S, Anaissie E, Bodey G, et al. A changing pattern of susceptibility of Xanthomonas maltophilia to antimicrobial agents: implications for therapy. Antimicrob Agents Chemother 1994; 38:624.
  71. Smit WJ, Boquest AL, Geddes JE, Tosolini FA. The antibiotic susceptibilities of Xanthomonas maltophilia and their relation to clinical management. Pathology 1994; 26:321.
  72. Yilmaz M, Celik AF, Mert A. Successfully treated nosocomial Stenotrophomonas maltophilia bacteremia following desensitization to trimethoprim-sulfamethoxazole. J Infect Chemother 2007; 13:122.
  73. Sader HS, Jones RN. Antimicrobial susceptibility of uncommonly isolated non-enteric Gram-negative bacilli. Int J Antimicrob Agents 2005; 25:95.
  74. San Gabriel P, Zhou J, Tabibi S, et al. Antimicrobial susceptibility and synergy studies of Stenotrophomonas maltophilia isolates from patients with cystic fibrosis. Antimicrob Agents Chemother 2004; 48:168.
  75. Berg G, Roskot N, Smalla K. Genotypic and phenotypic relationships between clinical and environmental isolates of Stenotrophomonas maltophilia. J Clin Microbiol 1999; 37:3594.
  76. Maningo E, Watanakunakorn C. Xanthomonas maltophilia and Pseudomonas cepacia in lower respiratory tracts of patients in critical care units. J Infect 1995; 31:89.
  77. Gómez-Garcés JL, Aracil B, Gil Y, Burillo A. Susceptibility of 228 non-fermenting gram-negative rods to tigecycline and six other antimicrobial drugs. J Chemother 2009; 21:267.
  78. Gülmez D, Cakar A, Sener B, et al. Comparison of different antimicrobial susceptibility testing methods for Stenotrophomonas maltophilia and results of synergy testing. J Infect Chemother 2010; 16:322.
  79. Liaw SJ, Teng LJ, Hsueh PR, et al. In vitro activities of antimicrobial combinations against clinical isolates of Stenotrophomonas maltophilia. J Formos Med Assoc 2002; 101:495.
  80. Poulos CD, Matsumura SO, Willey BM, et al. In vitro activities of antimicrobial combinations against Stenotrophomonas (Xanthomonas) maltophilia. Antimicrob Agents Chemother 1995; 39:2220.