title: Antimicrobial susceptibility of hospital acquired Stenotrophomonas maltophilia isolate biofilms.
abstract: OBJECTIVE
  We sought to characterize the antibiotic susceptibility of strains of Stenotrophomonas maltophilia isolated from clinical samples, and the role of Stenotrophomonas maltophilia biofilm in antibiotic resistance.
  
  
  METHODS
  Fifty-one clinical Stenotrophomonas maltophilia isolates were obtained from patients with nosocomial infection in the surgical wards and ICUs of six general hospitals in Tianjin, China. In vitro models of Stenotrophomonas maltophilia biofilms were established and confirmed by scanning electron microscopy and fluorescence microscopy with silver staining. The minimal inhibitory concentrations and biofilm inhibitory concentrations of commonly used antibiotics were determined.
  
  
  RESULTS
  47 of 51 strains were resistant to three or more antibiotics. 42 of 51 strains formed Stenotrophomonas maltophilia biofilms in vitro. Stenotrophomonas maltophilia biofilm formation greatly reduced sensitivity to most tested antibiotics, but not to levofloxacin. However, in the presence of erythromycin scanning electron microscopy revealed that levofloxacin inhibited Stenotrophomonas maltophilia biofilm formation. Factorial ANOVA revealed that erythromycin enhanced susceptibility to levofloxacin, cefoperazone/sulbactam, and piperacillin (p<0.05), and an ΔE model revealed that levofloxacin and erythromycin acted synergistically in biofilms, suggesting specific use of combined macrolide therapy may represent an effective treatment for Stenotrophomonas maltophilia infection.
  
  
  CONCLUSIONS
  Antibiotics could act synergistically to combat the protection conferred to clinical isolates of Stenotrophomonas maltophilia by biofilms. Macrolide antibiotics may be effective where used in combination.
authors.affiliation: The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin, China. Electronic address: irene_sunsun@yahoo.com.
authors.forename: Erlin
authors.initials: E
authors.lastname: Sun
authors.affiliation: The Second Hospital of Tianjin Medical University, Department of Infectious Disease, Tianjin, China.
authors.forename: Gehong
authors.initials: G
authors.lastname: Liang
authors.affiliation: The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin, China.
authors.forename: Lining
authors.initials: L
authors.lastname: Wang
authors.affiliation: University of Pennsylvania, Department of Anatomy and Cell Biology, Philadelphia, PA, United States.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Wei
authors.affiliation: The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin, China.
authors.forename: Mingde
authors.initials: M
authors.lastname: Lei
authors.affiliation: The Second Hospital of Tianjin Medical University, Department of Infectious Disease, Tianjin, China.
authors.forename: Shiduo
authors.initials: S
authors.lastname: Song
authors.affiliation: The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin, China.
authors.forename: Ruifa
authors.initials: R
authors.lastname: Han
authors.affiliation: The Second Hospital of Tianjin Medical University, Department of Infectious Disease, Tianjin, China.
authors.forename: Yubao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: The Second Hospital of Tianjin Medical University, Department of Infectious Disease, Tianjin, China. Electronic address: qiweitianjin@yahoo.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Qi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000254:growth & development*; D003428:Cross Infection / Q000382:microbiology; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic resistance; Biofilm; Nosocomial; Stenotrophomonas maltophilia