1.3.1 Avoiding a false negative result

What factors might lead to no bacterial growth in the presence of a bacterial infection (false negative result)?

Answer

Dead, damaged or low bacterial numbers in the specimen may result in no bacterial growth even if the animal from which the specimen was collected had a bacterial infection.

Examples of situations which can lead to dead or damaged bacteria are:

  • specimens collected from animals recently treated with antimicrobials
  • specimens collected/transported in preservatives or disinfectants
  • frozen specimens.

Examples of specimens that are likely to have small bacterial numbers are:

  • pus from old abscesses
  • specimens consisting of a few drops of fluid and swabs.

1.3 Selecting specimens for submission

1.3.2 Avoiding a false positive result