Overgrowth of Microbes Overgrowth of Microbes Specimens mailed to laboratories without refrigeration or preservatives are subject to overgrowth of microbes, whether contaminants or pathogens. Shown here is a dense mat of fungal hyphae which was seen in a sediment prep of a canine urine specimen which had been several days in transit. Since fungal infection of the urinary tract in dogs is quite uncommon, the odds are that this represents overgrowth of contaminants. Bacteria, whether pathogens or contaminants, also can multiply when analysis is delayed. This often clouds the interpretation of both sediment examination and culture results.
Refrigeration is perhaps the best all-around method for preserving a specimen.
Some laboratories also suggest specific transport media or swabs when sending a specimen for culture.