Step I Culture vs. PCR testing

[LuckiestOne]

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Is there a concept behind determining whether or not we should use PCR or culture in determining the cause of the disease?

I understand that obviously if the organism or pathogen is not culturable then it would not be useful, but I was wondering if there are other important reasons behind using PCR rather than cultures to confirm the diagnosis.

Thanks!

 

[thehundredthone]

Other than speed of diagnosis, especially in slow growing organisms, I would think PCR is actually less effective than a culture. PCR will pick up DNA whether from a living or dead organism, so it may not reflect active infection other than (probably) in viral infections.

 

[LuckiestOne]

Other than speed of diagnosis, especially in slow growing organisms, I would think PCR is actually less effective than a culture. PCR will pick up DNA whether from a living or dead organism, so it may not reflect active infection other than (probably) in viral infections.

Thank you for your response. Is it possible to culture virus?

 

[thehundredthone]

Some, yes. But it's not usually done for diagnostic purposes. With viruses, serology is usually the way to go.

E.g. the rabies virus can be cultured in chick embryos cells and monkey kidney (Vero) cells. But the utility is for vaccination purposes.

 

[Chirurg]

Other than speed of diagnosis, especially in slow growing organisms, I would think PCR is actually less effective than a culture. PCR will pick up DNA whether from a living or dead organism, so it may not reflect active infection other than (probably) in viral infections.

plus cultures will give you sensitivities to antibiotics, PCR won't.

 

[LuckiestOne]

There was a question about testing for HSV caused encephalopathy and the answer was PCR rather than culture... is this because HSV is unculturable? How do we know which virus is culturable?

 

[Chirurg]

There was a question about testing for HSV caused encephalopathy and the answer was PCR rather than culture... is this because HSV is unculturable? How do we know which virus is culturable?

on the steps, no virus is culturable. diagnosis is made via PCR or clinical Sx/Sx.