title: Standardized broth microdilution antimicrobial susceptibility testing of Francisella tularensis subsp. holarctica strains from Europe and rare Francisella species.
abstract: OBJECTIVE
  Tularaemia is a widespread zoonosis in Europe caused by Francisella tularensis subsp. holarctica. Because of a lack of standardized CLSI-approved antibiotic susceptibility data from European Francisella strains, the antibiotic susceptibilities of a selection of F. tularensis subsp. holarctica isolates originating from Germany, Austria, France, Spain and other European countries were determined. Rarely isolated species and subspecies of Francisella such as Francisella philomiragia, F. tularensis subsp. novicida and F. tularensis subsp. mediasiatica as well as the type strain of Francisella hispaniensis were included in this study.
  
  
  METHODS
  MIC data were obtained using cation-adjusted Mueller-Hinton broth with a 2% growth supplement. The broth microdilution testing system comprised 14 antibiotics, including gentamicin, streptomycin, ciprofloxacin and tetracycline.
  
  
  RESULTS
  All of the 91 strains tested were susceptible to aminoglycosides, quinolones, tetracycline and chloramphenicol. The antimicrobial susceptibility of rare Francisellae was similar to the antibiotic profile of F. tularensis subsp. holarctica strains. For erythromycin, we detected two geographically distinct groups of F. tularensis subsp. holarctica isolates in western Europe. One group was resistant and the other one was susceptible. Both groups overlapped in a small region in Germany.
  
  
  CONCLUSIONS
  Being performed in accordance with CLSI criteria, this study provides reliable data on antibiotic susceptibility patterns of European Francisella isolates. The standardized methodology of this study can be used for testing of suspicious colonies from clinical specimens for therapeutic guidance. Based on the results, aminoglycosides or quinolones are recommended as first-choice antibiotics for the therapy of F. hispaniensis, F. philomiragia or F. tularensis subsp. novicida infections in immunocompromised patients.
authors: Bundeswehr Institute of Microbiology, Neuherbergstrasse 11, D-80937 Munich, Germany. enrico1georgi@bundeswehr.org
authors: Enrico
authors: E
authors: Georgi
authors: Erik
authors: E
authors: Schacht
authors: Holger C
authors: HC
authors: Scholz
authors: Wolf D
authors: WD
authors: Splettstoesser
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004783:Environmental Microbiology; D005060:Europe; D005603:Francisella / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods* / Q000592:standards*; D014406:Tularemia / Q000382:microbiology* / Q000662:veterinary*
chemical_list: D000900:Anti-Bacterial Agents