Necrotising pneumonia caused by Lactococcus lactis cremoris

Lactococcus lactis cremoris is a facultative anaerobic, gram-positive coccus whose natural host is bovine livestock. It may form part of the normal human bacterial flora found in the oropharynx, the gastrointestinal tract and the vagina. This bacterium is essential in the food industry, where it is used in milk fermentation to obtain cheese, yoghurt, etc. Exposure to unpasteurised dairy products has thus been recognised as a risk factor for infection by this organism. It is generally considered to be non-pathogenic, although it appears that pathogenicity may be emerging. We present an atypical case of necrotising pneumonia caused by L. lactis cremoris.