You suspect your patient to be suffering from a bacterial disease, however the number of bacteria in the patient's body is very less. Which method can help you detect these pathogens in the laboratory ?

Options

A. Hybridoma technology
B. PCR
C. Somatic hybridization
D. DNA fingerprinting

Answer

To detect bacterial pathogens in a patient with a low bacterial load, the most effective method is the Polymerase Chain Reaction (PCR). Here's a step-by-step explanation of how PCR can be used in this context:

### Step-by-Step Solution:

1. **Sample Collection**: Begin by collecting a sample from the patient. This could be blood, urine, or any other relevant biological fluid where the bacteria might be present.

2. **Understanding the Problem**: Recognize that conventional methods (like blood or urine analysis) may not be effective due to the low number of bacteria in the sample. This necessitates a method that can amplify the genetic material of the bacteria.

3. **Polymerase Chain Reaction (PCR)**: Use PCR, a technique specifically designed to amplify DNA. This method can detect even a single copy of bacterial DNA by creating millions of copies, making it easier to identify the presence of the pathogen.

4. **Denaturation**: In the first step of PCR, heat the sample to a high temperature (around 82-92°C). This process separates the two strands of the DNA, resulting in single-stranded DNA.

5. **Annealing**: After denaturation, the temperature is lowered to allow short sequences of nucleotides known as primers to bind to the specific regions of the single-stranded DNA. These primers are designed to match the sequences of the target bacterial DNA.

6. **Extension**: The temperature is then raised again, and a heat-stable enzyme called Taq polymerase (derived from the bacterium Thermus aquaticus) is used to synthesize new DNA strands. This enzyme extends the primers, creating new copies of the target DNA.

7. **Repetition of Cycles**: The process of denaturation, annealing, and extension is repeated for multiple cycles (typically 25-35 cycles). Each cycle doubles the amount of target DNA, leading to exponential amplification.

8. **Detection**: After sufficient amplification, the resulting DNA can be analyzed using various methods (like gel electrophoresis) to confirm the presence of the bacterial DNA, thus indicating an infection.

### Conclusion:
The Polymerase Chain Reaction (PCR) is the most suitable method for detecting bacterial pathogens in a patient with a low bacterial load, as it allows for the amplification of the bacterial DNA, making it detectable.

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