Legionella steelei sp. nov., isolated from human respiratory specimens in California, USA, and South Australia

Int J Syst Evol Microbiol. 2012 Aug;62(Pt 8):1766-1771. doi: 10.1099/ijs.0.035709-0. Epub 2011 Sep 23.


Legionella-like bacteria were isolated from the respiratory tract of two patients in California, USA, and South Australia, but were not thought to cause disease. These bacteria, strains F2632 and IMVS-3376(T), were found to have identical Legionella macrophage infectivity potentiator (mip) gene sequences and were therefore further characterized to determine their genetic and phenotypic relatedness and properties. Both of these Gram-negative-staining bacterial strains grew on buffered charcoal yeast extract medium, were cysteine auxotrophs and made a characteristic diffusible bright yellow fluorescent pigment, with one strain making a late appearing colony-bound blue-white fluorescent pigment. The optimal in vitro growth temperature was 35 °C, with very poor growth at 37 °C in broth or on solid media. There was no growth in human A549 cells at either 35 or 37 °C, but excellent growth in Acanthamoeba castellani at 30 °C and poorer growth at 35 °C. Phylogenetic analysis of these bacteria was performed by sequence analysis of 16S rRNA, mip, ribonuclease P, ribosomal polymerase B and zinc metalloprotease genes. These studies confirmed that the new strains represented a single novel species of the genus Legionella for which the name Legionella steelei sp. nov. is proposed. The type strain is IMVS-3376(T) ( = IMVS 3113(T) = ATCC BAA-2169(T)).

MeSH terms

  • Adult
  • California
  • Cell Line
  • DNA, Bacterial / genetics
  • Genotype
  • Humans
  • Legionella / classification*
  • Legionella / genetics
  • Legionella / isolation & purification*
  • Male
  • Molecular Sequence Data
  • Phylogeny*
  • Pigmentation
  • RNA, Ribosomal, 16S / genetics
  • Respiratory System / microbiology*
  • Sequence Analysis, DNA
  • South Australia
  • Temperature


  • DNA, Bacterial
  • RNA, Ribosomal, 16S

Associated data

  • GENBANK/HQ398202
  • GENBANK/HQ398203
  • GENBANK/HQ398204
  • GENBANK/HQ398205
  • GENBANK/HQ398206