Background:
Commonly used incubation period of urine culture is overnight at first and then additional 24 hours incubation in case that there is a discrepancy between the clinical presentation and the direct Gram stain or culture results. But, a recent
study
show that incubation for a minimum of 24 hours is neceassary for the detection of uropathogens and that 2 days incubation is necessary for the detection of funguria. So we compared the recovery of organisms after overnight and additional 24 hours
of
incubation.
Methods:
All urine specimens were inoculated with a 0.001-mL calibrted loop onto 5% blood agar plate and MacConkey agar plate, and both plates were incubated at 35℃. All plates were examined after for overnight and additional 1 day, and isolates
present
more than 10E4 colonies per mL were identified by standard procedures.
Results:
A total of 20 (13.4%) of the 149 isolates were detected only after day 2 of incubation. The proportion of isolation rate of these slowly growing organisms were gram-positive cocci 20% (7/35), nonfermentative gram-negative bacilli 14.3%
(4/28),
Enterobacteriaceae 6.8% (4/59), and fungi 5.3% (1/19), And among the 20 patients, 45% were positive Gram stain, 50% were previous antibiotic user, and 70% were symptomatic patients
Conclusions:
We conclude that overnight incubation is reliable if prolonged incubation is selectively performed when specimens are obtained from patients no antibiotics or symptomatic patients and when culture results do not correlate with Gram stain
findings
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