Virulence factors include all the following, except
exoenzymes.
endotoxins.
ribosomes.
exotoxins.
capsules.
The Correct Answer is C
A. Exoenzymes: Exoenzymes are enzymes secreted by pathogenic microorganisms that help them invade host tissues and obtain nutrients. They can break down host cell components such as proteins, lipids, or connective tissue, facilitating spread within the host. Because they enhance the ability of a pathogen to cause disease, they are considered virulence factors.
B. Endotoxins: Endotoxins are components of the outer membrane of Gram-negative bacteria, specifically lipopolysaccharides (LPS). When released during bacterial cell death or division, they trigger strong immune and inflammatory responses such as fever, shock, and hypotension. Their ability to damage host tissues and disrupt normal physiology makes them important virulence factors.
C. Ribosomes: Ribosomes are cellular structures responsible for protein synthesis in all living cells, including bacteria. They translate messenger RNA into proteins necessary for cellular survival and metabolism. Although essential for basic cellular function, ribosomes do not directly contribute to pathogenicity and therefore are not classified as virulence factors.
D. Exotoxins: Exotoxins are potent toxic proteins secreted by certain bacteria during growth and metabolism. They can damage host cells by disrupting normal cellular processes, such as nerve signaling or protein synthesis. Because they directly harm host tissues and contribute to disease severity, exotoxins are major virulence factors.
E. Capsules: Capsules are protective polysaccharide layers surrounding some bacterial cells. They help bacteria evade the host immune system by inhibiting phagocytosis and enhancing bacterial survival in host tissues. This protective function allows pathogens to persist and cause infection, making capsules significant virulence factors.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. degermation: Degermation, or degerming, is the mechanical removal of microbes from living surfaces such as skin using friction and antiseptics. It reduces microbial load but does not destroy all microorganisms or endospores and is not considered sterilization.
B. sanitization: Sanitization reduces microbial populations on inanimate objects to levels considered safe by public health standards. It lowers the risk of infection but does not eliminate all microorganisms, nor does it reliably destroy bacterial endospores.
C. sterilization: Sterilization is a process that destroys or removes all forms of microbial life, including vegetative cells, viruses, fungi, and particularly resistant bacterial endospores. Methods include autoclaving (steam under pressure), dry heat, chemical sterilants, and radiation. It is essential for surgical instruments and other items that must be completely free of microorganisms.
D. disinfection: Disinfection uses physical or chemical agents to eliminate most pathogenic microorganisms on inanimate objects but does not reliably destroy bacterial endospores. It is less comprehensive than sterilization and is suitable for surfaces or equipment that do not require sterility.
E. antisepsis: Antisepsis involves applying chemical agents to living tissues to reduce or inhibit microbial growth. It does not guarantee the destruction of all microorganisms or endospores and is intended primarily for infection control on skin and mucous membranes.
Correct Answer is A
Explanation
When a virus enters a host cell, it hijacks the host's cellular machinery to replicate itself. Viral genes direct the host cell to transcribe and translate viral proteins instead of its own normal proteins. This redirection alters the host’s metabolic and genetic activities, often shutting down regular cellular processes. The host cell becomes a “viral factory,” producing viral components that are then assembled into new virions. This process can damage or kill the host cell, depending on the type of virus and replication strategy, and is a defining characteristic of viral infections, distinguishing them from non-infectious intracellular activities.
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