The extreme sensitivity of the firefly luciferase ATP assay could be applied in detection of bacteriuria. The methods available to determine the presence and quantity of microorganisms in a urine specimen can be divided into those that are growth dependent and those that are non-growth dependent. Growth dependent methods require dilution, inoculation and incubation on to a suitable medium and an incubation period of 18-24 hours. This will result in an enumeration as well as the identification of the microbes present. Nongrowth dependent methods, in contrast, do not require cultivation of the organism, but rather provide a direct enumeration of the bacterial population present.
In a typical microbiology laboratory as many as 70% or more of urine specimens may not contain significant populations of bacteria. In such a setting, bacteriuria screening tests are very useful in eliminating these samples from further analysis.
This study was carried out to investigate the application of a firefly luciferase ATP assay intended for rapid detection of bacteriuria in clinical specimen.
The results were as follows:
1. The somatic ATP was effectively eliminated by pretreatment of NRS/Apyrase (p=0.001<0.05).
2. The limit of sensitivity of the luciferase ATP assay was 10-13 M ATP, the lineality
and correlation were y = 33.46 + 0.93x and r=0.997 (p<0.05), respectively.
3. The linearity was seen at 105 CFU/ml of urine. The lineality and the correlation
were y=49.06+2.32x and r=0.980 (p<0.05) in 105 -106 CFU/ml, and
y = 3.30 + 0.73x, and r = 0.976 (p<0.05) in 105_ 1.5 x 108 CFU/ml, respectively.
4. In luciferase ATP assay, sensitivity, specificity and positive predictive value were
90.9%, 61.3%, 34.5%, respectively, otherwise negative predictive value was 95.0%.
In conclusion, luciferase ATP assay provided a useful method for rapid detection of bacteriuria.
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