Point Of Care Test Biology Essay


Different types of POCT tests are available according to the diseases that need to be tested. The bacterial vagina (BV) diagnosis is carried out by BVBlue tests. This is also a type of POCT for BV, primarily caused due to the characteristic changes in the bacterial colony of adult women's vagina. The BVBlue test detects the activity of sialidase in the vaginal fluid pattern. This test establishes a difference between the specificity, sensitivity and the PH. This test is speedy, giving results in just ten minutes and also saving the time normally wasted in the transport of the specimen and in the analysis of the quantity of gram stain. On the other hand the sialidase activity presence does not mean the elimination of the organism T.vagialis and yeast. One of the disadvantages is to women who are to refrain from douche or a sexual intercourse before the tests. They are to also abstain from using any sort of contraceptives at least 72 hours before the tests area done (Myziuk et al, 2003).

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Another type of POCT is the Clearview test, which is sued in the detection of the sexually transmitted disease Chlamydia. This test requires a urethral swab from the men and a cervical swab from the women. The strip type used is immune chromatographic. As compared to the test of nucleic acid amplification to the above mentioned test (Woolley and Pumphrey, 1999; Pate et al, 1998), the Chlamydia trachomatis is found to have a sensitivity of 50-75% and a specificity of 98-99% (Mabey and Peeling, 2002). Beside the above mentioned test, another option is the EIA test for Chlamydia which detects the Chlamydia through the detection of chlamydial lipopolysaccharide (LPS) with the monoclonal or polyclonal antibodies having it linked with an enzyme. The spectrophotometer used for this process has the ability for the conversion of a colourless liquid to a coloured one (Barnes, 1989; Kellogg, 1992; Stamm, 1988). The test takes approximately thirty minutes to complete (Fadiman and Goldman, 2003). The sensitivity although obtained is not much due to the positive or a negative reaction between the LPS and specimens of Chlamydia besides C.trachomatis (Barnes, 1989; Kellogg, 1992; Stamm, 1988). Therefore the sensitivity obtained can vary from about 64% to 94% with a high specificity (Thejls et al, 1994). The disadvantage is that the positive results have to be reaffirmed for surety (Dean et al, 1998).

Another well known disease is the influenza, caused by viruses A or B. It is also been known to be restricted to some patients, therefore researchers have been trying its diagnosis through rapid method. Various POCT are used which gives results in an hour or less than an hour. These testing kits utilize ''Zstat-Flu, Quick Vue, BD Directigen Flu A+B, Flu OIA Biostar''. In case of using Quick Vue kit for influenza detection from the nasopharyngeal swab, the sensitivity obtained was about 74.4% to 82.7% with specificity (Bellei et al, 2003). In addition this test doesn't have the ability to determine the type of virus whether it is virus A or B (Gavin and Thomson, 2004). The time utilized is almost thirty minutes (Mehlmann et al, 2007) , which is less in comparison to the time utilised in RT-PCR, which requires a few hours for its result. The molecular diagnosis determines the sensitivity of the tests (Atmar et al, 1996; Steininger et al, 2002; van Elden et al, 2002).

POCT has proven effective for the diagnosis of Plasmodium flaciparum malaria, as they provide fast results and are easy to do low costs for detecting P.falciparum. Paracheck-Pf kit is one of the types based on the HRP-2 protein detection of P.falciparum (Pieroni et al, 1998; Shiff et al, 1993. It requires one drop of blood (5µL) for the tests (van den Broek et al, 2006). Besides the above mentioned type, ICT-Pf/Pv is another type for detecting P.falciparum. The method mobilizes two sets of antibodies. One is specialised for the detection of a particular protein HRP-2 of P.falciparum while the other specifically identifies a commonly found antigen of P.falciparum and P.vivax (Tjitra et al, 1999). These two tests can be conducted at room temperature and take only fifteen minutes to complete. The only disadvantage is that the test cannot be read before the fifteen minutes as there is always a possibility of the obtaining incorrect results. The ICT-Pf/Pv on the other hand only requires five to ten minutes and its results remain unchanged over time. Both the kits however are similar in specificity which is up to 95% (Proux et al, 2001). These tests have however been able to prevent patients from taking anti malaria drugs without the presence of any obvious symptoms or before a certain diagnosis has been made as was the case in several countries (Reyburn et al, 2007).

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The most commonly known gastritis infections are the Helicobacter pylori which can be tested by the rapid test which detects the H.pylori antibody on the body fluids. A current development has been made where the rapid test can detect the specific antibody of H.pylori in a urine sample taken for testing of about (0.5mL). This is based on the on immunochromatographic method and is known as (RAPIRUN H.pylori Antibody). The kit can be handled by any person without any specific skill and can be completed in ten to twenty minutes to read the results (Fujisawa et al, 2001). The figure 1 below shows the test.

RAPIRUN H.pylori Antibody kit

C: control zone.

T: test zone.

S: sample window.C:\Users\Ranya\Documents\img096.jpg

Figure 1: This figure demonstrates the procedural steps and the possible obtained results in (RAPIRUN H.pylori Antibody) (Fujisawa et al, 2001).

This kit when compared to HM-CAP, HEL-p TES and GAP-G have a better sensitivity of about 100% and specificity of about 66.7%. Therefore the accuracy of the results is around 95.2%. The HM-CAP, HEL-p TES and GAP-G, which are primarily based on ELISA, take a longer time to complete than the rapid tests. (Fujisawa et al, 2001). The RAPIRUN rapid test kit is best known for its accuracy in the detection of the H.pylori in the diagnosis (Wong et al, 2002). On the other hand the 13C-urea breath test is a rather expensive method and difficult to accomplish. While another enzyme linked rapid test is the immune-absorbent method but it is highly dependent on the laboratory support (Vaira and Vakil, 2001).

The above mentioned methods are effective with their benefits and disadvantages. They have proven beneficial in the case of emergencies as they cut down on the time taken and release the patients from the agony of waiting for the results (Parvin et al, 1996). It minimizes delays which might be caused due to the time taken in transporting the samples from the GPs to the laboratories (Myziuk et al, 2003). The POCT devices are not dependent on laboratory equipments (Stϋrenburg and Junker, 2009). Therefore these kits can be useful in situations where the patients cannot access the GPs or the laboratories in the hospitals (Reinert, 2007). The kit is handy and is easily available. The tests only require a minute blood or urine sample and are cheaper than the other manual tests. On the contrary these kits are dependent on immune-chromatography methods, which are not easily done by unskilled people. These kits have a limited storage date and have a reduced turnaround time (Briedigkeit et al, 1999).

To conclude one might say that these tests can prove effective in case of an emergency or a sudden outbreak of infections and can be handy in the emergency department. Most unskilled staff can use these kits for the diagnosis eliminating the need to wait for doctors or nurses. The kit enables the unskilled people to gain an idea about the disease and therefore can determine the right treatment after the diagnosis. Therefore the POCT kits are useful for the people to have an accurate idea of the disease and hence the right treatment and the steps that should follow the treatment. But that doesn't mean that these people should go ahead without the consultation of a medical expert after they acquire results from any POCT. The above mentioned kits of BVBlue test for bacterial vagina, Clearview rapid test for Chlamydia, Quick Vue test for influenza and the other EIA test, Paracheck-Pf, ICT-Pf/Pv and RAPIRUN H.pylori Antibody have a sensitivity percentage of 50-100 and a specificity percentage of 66-99 which is similar to the manual tests. But these tests are more preferable due to the less time required as compared to other tests.