The Cardiobacteriaceae are a family of

Pseudomonadota Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. Currently, they are considered the predominant phylum within the domain of bacteria. They are naturally found as pathogenic and free-living (non- parasitic) ...

, given their own order. They are

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

and rod-shaped, with diameters around 0.5 to 1.7 μm and lengths from 1–6 μm.George M. Garrity: ''Bergey's Manual of Systematic Bacteriology'' 2. Auflage. Springer, New York, 2005, Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria

References

Gammaproteobacteria {{gammaproteobacteria-stub