Another important advantage with lower urinary
tract disease is the relative ease of collecting culture specimens. Aseptically collected catheterized
samples should be used for culture, and submitted
in a sterile container. Urine swabs should be
avoided because of the much smaller volume of
material for culture and the fact they do not allow
for quantitative culture. Semi-quantitative culture
is useful to determine the clinical relevance
of results, as contamination can occur even with
catheterized samples. Growth from a catheterized
sample of >1000 colony forming units (CFU/ml) is
considered abnormal, while a suspicious growth is
500–1000 CFU/ml. For free-flow samples, >40 000
CFU/ml is considered abnormal with 20–40 000
CFU/ml suspicious (21).