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J Clin Microbiol. 1996 Aug; 34(8): 1995–2000.
PMCID: PMC229169

Characterization of two unusual clinically significant Francisella strains.


We have isolated two phenotypically distinct nonfastidious Francisella strains (Fx1 and Fx2) from the blood of compromised patients with pneumonia and compared them with eight other Francisella strains, including Francisella tularensis biovar tularensis, F. tularensis biovar novicida, and F. philomiragia. Our isolates grew well on sheep blood agar, chocolate agar, modified Thayer-Martin agar, and Trypticase soy agar. Fx1 and Fx2 were determined to be within the Francisella genus by cellular fatty acid analysis and by the utilization of glucose, production of H2S and catalase, and lack of motility, oxidase, nitrate reductase, and gelatinase. They were additionally shown to belong to the species F. tularensis by sequencing of two variable regions comprising approximately 500 nucleotides of the 16S rRNA gene. Also, RNA probe hybridization confirmed their belonging to the species F. tularensis. However, the new strains, which are not identical, are distinguished from other F. tularensis strains by growth characteristics, repetitive extragenic palindromic PCR fragment pattern, and some biochemical tests. Key biochemical differences included the findings that Fx1 was positive for beta-galactosidase and arabinose hydrolysis and that both strains were citrulline ureidase positive and glycerol negative. Commercial F. tularensis antiserum agglutinated stock F. tularensis strains but not Fx1, Fx2, F. tularensis biovar novicida, or F. philomiragia; serum from either patient failed to agglutinate or only weakly agglutinated commercial antigen but showed agglutination when tested against each patient's respective isolate. Fx1 and Fx2 produced beta-lactamase. Because of their good growth, negative serology, and biochemical profile, the organisms could be misidentified in the clinical laboratory if standard strategies or commercial identification systems are used.

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Selected References

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  • Bernard K, Tessier S, Winstanley J, Chang D, Borczyk A. Early recognition of atypical Francisella tularensis strains lacking a cysteine requirement. J Clin Microbiol. 1994 Feb;32(2):551–553. [PMC free article] [PubMed]
  • Clarridge JE, 3rd, Raich TJ, Pirwani D, Simon B, Tsai L, Rodriguez-Barradas MC, Regnery R, Zollo A, Jones DC, Rambo C. Strategy to detect and identify Bartonella species in routine clinical laboratory yields Bartonella henselae from human immunodeficiency virus-positive patient and unique Bartonella strain from his cat. J Clin Microbiol. 1995 Aug;33(8):2107–2113. [PMC free article] [PubMed]
  • Evans ME, Gregory DW, Schaffner W, McGee ZA. Tularemia: a 30-year experience with 88 cases. Medicine (Baltimore) 1985 Jul;64(4):251–269. [PubMed]
  • Forsman M, Sandström G, Jaurin B. Identification of Francisella species and discrimination of type A and type B strains of F. tularensis by 16S rRNA analysis. Appl Environ Microbiol. 1990 Apr;56(4):949–955. [PMC free article] [PubMed]
  • Forsman M, Sandström G, Sjöstedt A. Analysis of 16S ribosomal DNA sequences of Francisella strains and utilization for determination of the phylogeny of the genus and for identification of strains by PCR. Int J Syst Bacteriol. 1994 Jan;44(1):38–46. [PubMed]
  • Hill B, Sandström G, Schröder S, Franzén C, Tärnvik A. A case of tularemia meningitis in Sweden. Scand J Infect Dis. 1990;22(1):95–99. [PubMed]
  • Hoel T, Scheel O, Nordahl SH, Sandvik T. Water- and airborne Francisella tularensis biovar palaearctica isolated from human blood. Infection. 1991 Sep-Oct;19(5):348–350. [PubMed]
  • Hollis DG, Weaver RE, Steigerwalt AG, Wenger JD, Moss CW, Brenner DJ. Francisella philomiragia comb. nov. (formerly Yersinia philomiragia) and Francisella tularensis biogroup novicida (formerly Francisella novicida) associated with human disease. J Clin Microbiol. 1989 Jul;27(7):1601–1608. [PMC free article] [PubMed]
  • Jantzen E, Berdal BP, Omland T. Cellular fatty acid composition of Francisella tularensis. J Clin Microbiol. 1979 Dec;10(6):928–930. [PMC free article] [PubMed]
  • Long GW, Oprandy JJ, Narayanan RB, Fortier AH, Porter KR, Nacy CA. Detection of Francisella tularensis in blood by polymerase chain reaction. J Clin Microbiol. 1993 Jan;31(1):152–154. [PMC free article] [PubMed]
  • Mignani E, Palmieri F, Fontana M, Marigo S. Italian epidemic of waterborne tularaemia. Lancet. 1988 Dec 17;2(8625):1423–1423. [PubMed]
  • Ohara Y, Sato T, Fujita H, Ueno T, Homma M. Clinical manifestations of tularemia in Japan--analysis of 1,355 cases observed between 1924 and 1987. Infection. 1991 Jan-Feb;19(1):14–17. [PubMed]
  • Pavlovich NV, Tkacheva TI. Prirodnaia ustoichivost' Francisella tularensis k penitsillinu. Antibiot Khimioter. 1990 Aug;35(8):25–28. [PubMed]
  • Payne MP, Morton RJ. Effect of culture media and incubation temperature on growth of selected strains of Francisella tularensis. J Vet Diagn Invest. 1992 Jul;4(3):264–269. [PubMed]
  • Provenza JM, Klotz SA, Penn RL. Isolation of Francisella tularensis from blood. J Clin Microbiol. 1986 Sep;24(3):453–455. [PMC free article] [PubMed]
  • Reary BW, Klotz SA. Enhancing recovery of Francisella tularensis from blood. Diagn Microbiol Infect Dis. 1988 Oct;11(2):117–119. [PubMed]
  • Sandström G, Sjöstedt A, Forsman M, Pavlovich NV, Mishankin BN. Characterization and classification of strains of Francisella tularensis isolated in the central Asian focus of the Soviet Union and in Japan. J Clin Microbiol. 1992 Jan;30(1):172–175. [PMC free article] [PubMed]
  • Versalovic J, Koeuth T, Lupski JR. Distribution of repetitive DNA sequences in eubacteria and application to fingerprinting of bacterial genomes. Nucleic Acids Res. 1991 Dec 25;19(24):6823–6831. [PMC free article] [PubMed]
  • Wenger JD, Hollis DG, Weaver RE, Baker CN, Brown GR, Brenner DJ, Broome CV. Infection caused by Francisella philomiragia (formerly Yersinia philomiragia). A newly recognized human pathogen. Ann Intern Med. 1989 Jun 1;110(11):888–892. [PubMed]

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