Contaminants vs actual causative organism

The term contaminant refers to an external microorganism introduced in a sample subjected to laboratory analysis while the actual causative organism refers to the microorganism causing the disease which led to sample collection.

Due to nonproper handling of the sample/specimen, external microorganisms may be introduced into the sample and cause wrong laboratory analytical results. When a sample is contaminated by another sample is referred to as cross-contamination.

Potential sources of laboratory sample contamination:

• Sample environment
• Sample container
• Sampling Tools
• Contamination from other laboratory samples
• Contamination from substandard reagents
• Contamination from analyst
• Contamination arising from Visitors’ entry

Sample contamination leads to erroneous laboratory results which leads to wrong clinical decisions. In this situation, the interpreting clinician may prescribe an antimicrobial agent against the contaminant germ while the causative germ is not identified. This will cause unnecessary exposure of the antimicrobial agent to human body bacteria which will lead to further antimicrobial resistance development.

Sample contamination also leads to poor patient outcomes as there may be delayed diagnoses, inappropriate investigations undertaken, longer hospital stays or inappropriate treatment decisions based on erroneous results.