CLINICAL MEDICINE

Detailed explanation-1: -Most bacteria are not pathogenic. Those that are contain specific virulence genes that mediate interactions with the host, eliciting particular responses from the host cells that promote the replication and spread of the pathogen.

Detailed explanation-2: -Some microorganisms are harmless and even helpful. A microorganism is only considered a pathogen if it causes disease. Harmless viruses, bacteria, fungi, protozoa, and parasites are simply called microorganisms.

Detailed explanation-3: -The correct answer for this question is D. It is not true that all organisms cause disease in humans.

Detailed explanation-4: -Microbes that cause disease are called pathogens. It is important to remember that: A pathogen is a micro-organism that has the potential to cause disease. An infection is the invasion and multiplication of pathogenic microbes in an individual or population.

Detailed explanation-5: -Not all bacteria cause infections. Those that can are called pathogenic bacteria. Your body can be more prone to bacterial infections when your immune system is compromised by a virus. The disease state caused by a virus enables normally harmless bacteria to become pathogenic.