PCR Microbial Screening

Overview

PCR-based microbial screening uses nucleic-acid amplification to detect microbial genetic material. It is a contamination-screening approach, distinct from culture-based counts and from the identity, purity, or quantity of the intended substance.

What PCR detects

The polymerase chain reaction (PCR) copies specific stretches of DNA (or, via a preliminary step, RNA) many times over, so that even small amounts of a target sequence become detectable. In a microbial-screening context, PCR is directed at genetic sequences characteristic of microorganisms, allowing their genetic material to be detected.

How it differs from culture-based tests

Culture-based methods such as bioburden estimate viable organisms by growing them. PCR instead detects genetic material, which can be present whether or not organisms are currently viable. The two approaches therefore answer related but different questions, and a screening result should be read for exactly what its method measures.

What a screening result describes

A PCR microbial-screening result speaks to whether targeted microbial genetic material was detected, within the method’s scope. It does not describe the identity, purity, or amount of the intended substance, and it is not the same measurement as endotoxin testing or a viable-count bioburden.

What this test can and cannot establish

Key terminology

PCR

Polymerase chain reaction — a technique that amplifies specific nucleic-acid sequences so they can be detected.

Nucleic acid

DNA or RNA; the genetic material PCR targets.

Screening

A test designed to flag the possible presence of something for further consideration.