Antibody-coated bacteria test

A method to detect upper UTI is the antibody-coated bacteria test, an immunofluorescent method that detects bacteria coated with immunoglobulin in freshly voided urine. 

The antibody-coated bacteria test is another microscopic procedure that has been applied to tracheal aspirates from intubated patients. The results from one study were similar to those reported for sputa from patients not receiving ventilation, with low sensitivity in detection of pneumonia (48%-73%) but excellent specificity (98%-100%) (46). In another study, however, specificity was only 56% when compared to quantitative PSB cultures (47). It has also been suggested that a positive antibody-coated test (1) may precede a subsequent infection, (2) may be positive when quantitative culture results are low because of prior antimicrobial treatment or poor specimen handling or processing, and (3) may show antibiotic effectiveness by conversion to a negative test after treatment. 

Suppose that a microfabricated cantilever beam is to be used as a sensor for detecting the presence of a certain bacterium in a hquid solution see Figure 1.31. Following its fabrication, the beam is first coated with an antibody that is specific to the particular bacterium of interest and its free vibration characteristics are determined. The beam is then dipped into the solution to be tested. If the bacteria of interest are present, they will attach themselves to the surface of the beam, attracted by the antibody. The beam is then removed from the solution and its free vibration characteristics are re-examined. Estimate the influence of an added mass due to the attached bacterium cells, say rib cells each of mass mb, on the fundamental natural frequency of the beam. (The effectiveness of this approach for detection of bacteria has been demonstrated by Ilic et al. (2000).)... 

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