Interpreting the Results

Laboratories will sometimes find many different organisms in cultures from swabs. The technicians must then judge which are likely to be the pathogens. They will ignore the rest.

Ensure that you use a veterinary laboratory. Otherwise veterinary pathogens may be ignored and organisms of little significance tested and reported.

Interpret the results on the basis of the clinical case. Are the results likely, meaningful or relevant.

Sensitivity tests may have been done on several organisms and some organisms may show wide and worrying antibiotic resistance. If these are considered non-pathogenic e.g. coagulase negative staphylococci, or secondary and of low virulence, e.g. Proteus, you may be justified in aiming your antibiotic therapy at the pathogen(s) which have been isolated e.g. Staphylococcus intermedius.

Beware of organisms showing unusual or unlikely resistance patterns. This may indicate a misidentification by the laboratory. e.g. Staphylococcus intermedius resistant to cephalexin and co-amoxyclav. This could be a non-pigmented S. aureus and might be a methicillin-resistant S. aureus (MRSA), requiring a very different approach.