''Legionella micdadei'' is a

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

from the genus ''

Legionella ''Legionella'' is a genus of pathogenic gram-negative bacteria that includes the species '' L. pneumophila'', causing legionellosis (all illnesses caused by ''Legionella'') including a pneumonia-type illness called Legionnaires' disease and a mi ...

'', which stains

acid-fast Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sam ...

. It stains weakly, but loses this trait upon being grown in culture. ''Tatlockia micdadei'' is an alternative term for ''L. micdadei'', the Pittsburgh pneumonia agent and TATLOCK strain.McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc. It is named after Joseph E. McDade, who first isolated ''L. pneumophila''.

References

Legionellales {{Legionellales-stub