48 What are virulenoe factors? A) factors that enable a microorganism to be resi

Question

48 What are virulenoe factors? A) factors that enable a microorganism to be resistant to antimicrobial medications B) characteristics of a microorganism, such asits Gram stain morphology, type of media it grows on, and colony morphology Q the ste within a host in which a microorganism resides and causes disease D) characteristics of a microorganism that enable it to establish infection and cause disease the natural habitat of the microorganism or the souroe from which a host can become infected 49. Malaria is a human disease caused by the eukaryotic pathogen, Flasmodium faldparum This pathogen is transferred from one infected host to another by mosquitoes Mosquitoes can take up the pathogen when taking a blood meal from an infected individual. P. falaiparum multiplies in the mosquito, but does it no harm. The mosquito can then transfer the pathogen into another person through its bite. Which is the best use of terms to describe the role df humans and mosquitoes? A) humans are vectors -mosquitoes are the reservoir B) humans are the carrier- mosquitoes are the reservoir O humans are both the vector and the carrier --mosquitoes are the reservoir D) humans are the carrier mosquitoes are reservoir and the vector D humans are the reservoir - mosquitoes are the carrier and the vector 50. The following are different forms of virulence factors used by bacteria against phagocytoss Which of the following is not an anti-phagocytic factor? A) production of leukoadins B) endospore C secretion of a capsule D) ability to survive intracellularly E none of the above

Explanation / Answer

A) Virulence factors are D) characteristics of a microorganism that enable it to establish infection and cause disease. Saying more elaborately, these factors play the following pivotal roles during pathogenesis of a disease.

B) Humans are the reservoir and mosquitos are the carrier and the vector. Biological vector is a living organism that transmits an infectious agent from an infected animal to a human or another animal.

C) Leukocidin is a type of cytotoxin created by some types of bacteria (Staphylococcus) . It is a type of pore forming toxin. It helps bacteria invade the host tissue to which they are attached. This is not anti-phagocytic. Both the endospore and capsule have protective role in bacteria. Endospore is sometimes surrounded by a thin covering known as the exosporium, which overlies the spore coat. The spore coat, which acts like a sieve that excludes large toxic molecules like lysozyme, is resistant to many toxic molecules. Capsule is a sticky gelatinous covering of uncharged polysacharides or polypeptides which can also protect bacteria from phagocytic damage. The ability to survive intracellularly certainly confers bacteria the property to defend themselves in the face of phagocytic attacks by hydrolytic enzymes.  

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