title: Infection and colonization by Stenotrophomonas maltophilia: antimicrobial susceptibility and clinical background of strains isolated at a tertiary care centre in Hungary.
abstract: BACKGROUND
  Stenotrophomonas maltophilia is an important opportunistic, mainly nosocomial pathogen that emerged in the last decades worldwide. Due to its inherent extended antibiotic resistance, therapeutic options are strongly limited. New resistance mechanisms in S. maltophilia make antibiotic therapy even more difficult. The aim of our study was to investigate the antimicrobial resistance of S. maltophilia isolates collected in our laboratory and to reveal related clinical background.
  
  
  METHODS
  Consecutive non-duplicate S. maltophilia isolates (n = 160) were collected in a three-year period. Conventional methods, automated identification system and MALDI-TOF MS was used for identification, ERIC-PCR for genetic relationship analysis and broth microdilution method to determine the susceptibility for trimethoprim/sulfamethoxazole (SXT), ciprofloxacin, levofloxacin, moxifloxacin, colistin, doxycycline and tigecycline. Clinical final reports were used retrospectively to collect clinical information.
  
  
  RESULTS
  ERIC-PCR revealed large heterogeneity. Trimethoprim/sulfamethoxazole, moxifloxacin and levofloxacin were found to be the most effective agents with MIC50/MIC90 0.5/1, 0.25/1, 1/2 mg/l, respectively. Seventy percent of patients with S. maltophilia infection were treated in intensive care units. All-cause mortality rate was 45%. Nearly 70% of the isolates were collected from polymicrobial infections/colonizations.
  
  
  CONCLUSIONS
  Trimethoprim/sulfamethoxazole is the most potent antibiotic agent against S. maltophilia. In case of SXT hypersensitivity, intolerance or resistance, fluoroquinolones are alternative therapeutic options. Missing clinical breakpoints, consensus antibiotic susceptibility testing guidelines and clinical trials make the interpretation of antibiotic susceptibility testing results difficult. The indirect pathogenicity of S. maltophilia in polymicrobial infections or colonizations has to be taken into consideration.
authors.affiliation: Diagnostic Laboratory of Clinical Microbiology, Institute of Laboratory Medicine, Semmelweis University, Budapest, Hungary. juhasz.emese@med.semmelweis-univ.hu.
authors.forename: Emese
authors.initials: E
authors.lastname: Juhász
authors.affiliation: Institute of Medical Microbiology, Semmelweis University, Budapest, Hungary. orwell984@gmail.com.
authors.forename: Gergely
authors.initials: G
authors.lastname: Krizsán
authors.affiliation: Hungarian Defence Forces, Military Medical Centre, Budapest, Hungary. lgvirology@gmail.com.
authors.forename: György
authors.initials: G
authors.lastname: Lengyel
authors.affiliation: Hungarian Defence Forces, Military Medical Centre, Budapest, Hungary. grosz.gabor@gmail.com.
authors.forename: Gábor
authors.initials: G
authors.lastname: Grósz
authors.affiliation: Diagnostic Laboratory of Clinical Microbiology, Institute of Laboratory Medicine, Semmelweis University, Budapest, Hungary. pongraczjulia@yahoo.com.
authors.forename: Júlia
authors.initials: J
authors.lastname: Pongrácz
authors.affiliation: Diagnostic Laboratory of Clinical Microbiology, Institute of Laboratory Medicine, Semmelweis University, Budapest, Hungary. kristof.katalin@med.semmelweis-univ.hu.
authors.forename: Katalin
authors.initials: K
authors.lastname: Kristóf
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D060085:Coinfection / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality; D024881:Drug Resistance, Bacterial; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology* / Q000401:mortality; D006801:Humans; D006814:Hungary; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D020615:Stenotrophomonas maltophilia / Q000187:drug effects* / Q000302:isolation & purification*; D016019:Survival Analysis; D062606:Tertiary Care Centers; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents