Chapter 6 Study and Book Flashcards
Explain how each of the following contributes to the virulence of bacteria:
a. production of endotoxin
b. spore formation
c. presence of a capsule
a. Endotoxins are released from the cell walls of dead gram-negative organisms and cause fever and shock.
b. Microbes survive unseen for a long time under adverse conditions, can be destructive, and can reproduce after entering the body.
c. The capsule protects the microbe from phagocytosis.
- Predict how each of the following could reduce host resistance to infection:
a. bone marrow damage
b. circulatory impairment
c. puncture wound
a. A deficit of WBCs reduces phagocytosis and immune response; a deficit of RBCs decreases oxygen and mitosis.
b. Circulatory impairment reduces the number of cells—WBCs, RBCs, and antibodies—to the area, slowing tissue repair.
c. A puncture wound is characterized by reduced oxygen and a risk of anaerobes causing infection because it is difficult to remove foreign material.
Explain two benefits of resident flora.
Resident flora deter invasion by other microbes, aid digestion, produce vitamin K, and maintain local pH (skin, vagina).
Differentiate infection from inflammation.
Infection results from microbial action; inflammation has many causes, such as ischemia, allergy, irritants, and thermal injury.
Describe three ways of reducing the transmission of a respiratory infection.
A respiratory infection’s chances of being transmitted are reduced by covering the mouth and nose when coughing, handwashing, properly disposing of tissues, protecting food, dishes, and people from contact with respiratory secretions, cleaning any contaminated surfaces and maintaining a well-ventilated room.
Explain each of the following:
a. why the clinical signs of infection are not present immediately after the microorganism enters the body
b. why infection can often be cured without drug treatment
c. why antibacterial agents might be prescribed for an infection
a. Invaders must take time to colonize and reproduce; sufficient microbes are needed to produce signs.
b. Reproduction is decreased as nutrient supply is diminished and wastes build up, altering pH and other parameters. Defenses are activated.
c. Antimicrobial agents may be prescribed to prevent secondary infections and, in cases involving virulent microbes, to dangerous sites such as the brain, and to immunosuppressed individuals or those with chronic disease.
Explain why it is important to take the complete course of antimicrobial medication prescribed.
The complete course of medication should be taken because if all microbes are not eradicated, infection may recur. In addition, microbes mutate after drug exposure and become drug-resistant.
Explain why viral infections are difficult to treat.
Viral infections are difficult to treat because they are more difficult to culture and identify, and viruses exist inside host cells. Moreover, antiviral drugs can reduce replication, but they do not destroy the virus.
State two local and two systemic signs of influenza.
Local signs of influenza are sore throat and a nonproductive cough. Systemic signs of influenza are fever, aching, and headache.
Explain why a new influenza vaccine is prepared each year and consists of several components.
Viral strains mutate and change antigens, resulting in loss of immunity; strains from three groups of the virus, A, B, and C, may cause infection.
