There are two limitations of PCR assay:false-positive and false-negative results.
The ability of PCR to generate many copies of a sequence from minute quantities of template DNA necessitates that extreme care be taken to avoid the generation of false-positives.
Although false positives can result from sample -to -sample contamination ,a more serious source is the carry-over of DNA from a previous amplification reaction of the same target.To avoid such false -positives ,specific precautions to control contamination must be taken .
To avoid false-negatives ,it is important to control the presence of inhibitory compounds in blood samples,such as haeme compounds,anticoagulants and large amounts of total DNA .
In PCR for Brucella spp.,no standardization regarding sample preparation ,target sequence,PCR and detection methods has been established so far.
My suggestion is that samples with a +ve blood culture but negative PCR ,should be considered as false PCR negative ;samples with a -ve blood culture but +ve PCR ,should be considered as false blood culture negative ,if there are clinical and serological findings to support the presence of brucellosis; samples with a -ve blood culture and negative PCR ,but with clinical and serological findings to support the presence of brucellosis should be considered as false blood culture negative and false PCR negative.
So, best results can be obtained by combining culture
and PCR ...
The ability of PCR to generate many copies of a sequence from minute quantities of template DNA necessitates that extreme care be taken to avoid the generation of false-positives.
Although false positives can result from sample -to -sample contamination ,a more serious source is the carry-over of DNA from a previous amplification reaction of the same target.To avoid such false -positives ,specific precautions to control contamination must be taken .
To avoid false-negatives ,it is important to control the presence of inhibitory compounds in blood samples,such as haeme compounds,anticoagulants and large amounts of total DNA .
In PCR for Brucella spp.,no standardization regarding sample preparation ,target sequence,PCR and detection methods has been established so far.
My suggestion is that samples with a +ve blood culture but negative PCR ,should be considered as false PCR negative ;samples with a -ve blood culture but +ve PCR ,should be considered as false blood culture negative ,if there are clinical and serological findings to support the presence of brucellosis; samples with a -ve blood culture and negative PCR ,but with clinical and serological findings to support the presence of brucellosis should be considered as false blood culture negative and false PCR negative.
So, best results can be obtained by combining culture
and PCR ...
பாய் .
Bhai when we find the agglutination test positive with a dilution of 1 in 80 we go for higher and more efficient tests like culture and PCR. If we have negative results for PCR and Culture and act on the basis of agglutination test, how are we going to convince the owner. They will ask if we consider the agglutination test as the final result(it costs only 25 riyal per sample) why did you make me spend(400 riyals for PCR and 400 riyals for CULTURE)more.
பதிலளிநீக்குThere is no test(without false negative/false positive) which will say this camel has Brucella oraganism, without such a confirmatory test how can we tell the owner to kill/cull the animal. I want to hear from other chennai stars also.
karaiyan.
Hey folks - let me get some more research on this from in house and get back to you. As far as I know PCR has been very conclusive for many of my studies. However I am also aware of false positives and false negatives with the test.
பதிலளிநீக்குGujili