Taxonomic note: a proposal for reviewing the interpretation of the CAMP reaction between Listeria monocytogenes and Rhodococcus equi

Int J Syst Bacteriol. 1996 Jul;46(3):832-4. doi: 10.1099/00207713-46-3-832.


The discrepancies between the current description of the CAMP test between Listeria monocytogenes and Rhodococcus equi in the latest edition of Bergey's Manual of Determinative Bacteriology (L. monocytogenes is described as CAMP test negative with R. equi) and routine findings (positive reactions are usually described in many laboratories) make it advisable to review the current interpretation of the CAMP test to avoid confusion among people working in microbiological laboratories. Overall, 98.4% of the L. monocytogenes strains examined in this study, regardless of their source or the intensity of their hemolytic activity, displayed a synergic hemolytic reaction (CAMP phenomenon) with R. equi, indicating that L. monocytogenes can generally be considered CAMP positive with R. equi. We propose that L. monocytogenes, together with Listeria ivanovii, should be considered CAMP test positive with R. equi (circular or racket and semicircular or shovel shapes, respectively).

MeSH terms

  • Hemolysis
  • Listeria monocytogenes / classification*
  • Rhodococcus equi / classification*