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jadecaribou502Lv1

28 Sep 2019

Many microbes are not pathogenic. Their infections do not result in disease states. This assumes and implies that the immune system is capable of controlling them. When these organisms cause disease, we refer to them as opportunistic pathogens. Pseudomonas aeruginosa is one such organism; it does not cause disease in healthy individuals, but it causes serious wound infections with fatal outcome in burn patients, and its is also very serious in cystic fibrosis patients. Explain why in these patients, the second line of defense fails to control this microbe, whereas it is very effective in healthy individuals.

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Bunny GreenfelderLv2

28 Sep 2019

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Related questions

1. All of the following characteristics of skin help make it a good defensive barrier against pathogenic microbes EXCEPT:

Springy elasticity

Saltiness due to production of sweat from sweat glands

Acidic pH due to oily compound (sebum) metabolism

Normal microflora of skin

Constant sloughing off of old dead epithelial skin cells

2. The majority of microorganisms comprising the normal microflora inhabiting the skin surface are:

Gram-positive fungi of the single-celled yeasts

Gram-positive bacteria of the Staphylococcus, Micrococcus, Corynebacterium, and Proprionibacterium genera

Gram-negative bacteria of the Enterobacteriaceae family

Gram-negative bacteria of the Neisseria, Pseudomonas, and Salmonella genera

All of the above

3. The pus-producing skin infection (pyoderma) can be caused by:

Staphylococci

Streptococci

Corynebacteria

A combination of staphylococci, streptococci, and corynebacteria

All of these

4. Which of the following is NOT a characteristic of impetigo?

Common in children

Can be caused by Staphylococcus aureus

Can be caused by Streptococcus pyogenes

Is highly contagious

Can be caused by pseudomonads

5. Which of the following is NOT true about acne?

It is most commonly the result of male sex hormones that stimulate increased sebaceous gland growth and secretion of sebum.

Propionibacterium acnes in particular can turn a mild case of acne into a severe case by causing increased and widespread inflammation, tissue destruction, and scarring.

Common treatments are frequent cleansing of the skin and topical ointments that reduce the risk of infection.

Low doses of oral antibiotics are often prescribed to prevent bacterial infections of lesions and are without side effects.

In most cases, acne disappears or decreases in severity on its own as the body adjusts to the hormonal changes of puberty and sebaceous gland function stabilizes.

6. Which of the following often cause nosocomial infections in burn patients?

Streptococcus pyogenes

Serratia marcescens

Pseudomonas aeruginosa

Staphylococcus aureus

b and c

7. Gas gangrene is most likely associated with infection with:

Staphylococcus aureus

Clostridium perfringenes

Streptococcus pneumoniae

Neisseria gonorrhoeae

Pseudomonas aeruginosa

8. The leading cause of preventable blindness in the world is caused by:

Chlamydia trachomatis

Haemophilus influenzae

Neisseria gonorrhoeae

Staphylococcus aureus

Streptococcus pneumoniae

9. Chickenpox is a disease of chickens and is caused by the poxvirus, cowpox is a disease of cattle, and smallpox is a human disease that commonly affects only children. True or false?

10. Antibiotic is used to treat the eyes of newborn infants when:

The mother has gonorrhea

The mother has genital herpes

Neisseria gonorrhoeae is isolated from the newborn's eyes

Always

The mother has a history of multiple sex partners

11. The virus used to immunize individuals against smallpox causes the disease:

Chickenpox

Measles

Cowpox

Molluscum contagiosum

Warts

12. Which of the following fungal diseases result from an opportunistic fungal infection?

Zygomycoses

Aspergillosis

Candidasis

All of the above

None of the above

13. Rheumatic fever is caused by which organism?

Corynebacterium diphtheriae

Staphylococcus epidermidis

Staphylococcus aureus

Escherichia coli

Streptococcus pyogenes

14. Which of the following components of the respiratory system is normally free of microorganisms?

Lungs

Nasal cavity

Pharynx

Trachea

Bronchi

15. Which of the following is true about diphtheria?

It is caused by strains of Corynebacterium diphtheriae infected with a prophage that carries an exotoxin-producing gene.

A pseudomembrane composed of Corynebacterium diphtheriae cells, damaged epithelial cells, fibrin, and blood cells forms that can block the airway and cause suffocation.

The exotoxin spreads throughout the body damaging multiple organ system by interfering with cellular protein synthesis.

It can be prevented with DTP (diphtheria, tetanus, and pertussis) vaccine and treated with both antitoxin and antibiotics.

All of the above are true.

coppertrout695

Highlight or bold the answer you select for multiple choice or type in your answer in the blank space provided.

1. Which of the following is not true of the nervous system?

Consists of central and peripheral systems

(b) Central nervous system is composed of brain and spinal cord

(d) Meninges are membranes that cover brain and spinal cord

(e) Normally free of microbes

2. Which of the following is a common cause of meningitis in nonimmunized young children?

(a) Streptococcus pneumoniae

(b) Escherichia coli

(d) Haemophilus influenzae

(e) None of the above

3. A complication of infection with this organism (Waterhouse-Friderichsen syndrome) can occur if the organism becomes widely distributed in the body, leading to endotoxin shock and death. The organism is:

(a) Haemophilus influenzae type A

(b) Neisseria meningitidis

(d) Streptococcus pneumoniae

(e) Listeria monocytogenes

4. Which of the following bacterial meningitis diseases currently is the most common type in the U.S., with increased incidences in infants and in the 15- to 24-year-old age group, and has three types or strains of the infectious microbe?

(a) Haemophilus meningitis

(b) Listeriosis

(d) Meningococcal meningitis

(e) a and c

5. Before development of a vaccine against this microbe, the disease it caused accounted for two-thirds of bacterial meningitis cases during the first year of life but is still the number one leading cause of mental retardation in patients who survive serious disease due to permanent central nervous system disorders. What is the microorganism?

(a) Haemophilus influenzae type B

(b) Haemophilus influenzae type A

(d) Streptococcus pneumoniae

(e) Listeria monocytogenes

6. Which of the following bacteria that may cause meningitis is Gram-positive and therefore does not cause endotoxin shock in infected individuals?

(a) Escherichia coli

(b) Neisseria meningitidis

(d) Haemophilus influenzae type B

(e) None of these

7. Avid swimmers and hot tub enthusiasts sometimes acquire an opportunistic infection caused by Naegleria fowleri that results in a meningoencephalitis. This organism is a (an):

(a) Protist

(b) Helminth

(d) Amoeba

(e) a and d

8. Which of the following in NOT true about listeriosis?

(a) Foodborne transmission is the most common source of infection.

(b) It is a leading cause of bacterial meningitis today.

(d) It is sometimes acquired as a zoonosis.

(e) Individuals with impaired immune systems are highly susceptible to this disease.

9. Viral meningitis is usually always fatal if untreated, unlike bacterial meningitis, which is always self-limiting and nonfatal. True or false?

10. Which of the following is acid-fast and causes Hansen's disease?

(a) Mycobacterium tuberculosis

(b) Clostridium tetani

(d) Haemophilus influenzae

(e) Mycobacterium leprae

11. An immunofluorescent antibody test (IFAT) has replaced the older test for the presence of inclusions in neurons (Negri bodies) for the detection of infections caused by:

(a) Neisseria meningitidis

(b) Enteroviruses

(d) Rabies virus

(e) Haemophilus influenza

12. The viruses that cause encephalitis are most likely to be:

(a) Togaviruses

(b) Enteroviruses

(d) Rabies virus

(e) Hepatitis viruses

13. What do the following viral encephalitis diseases have in common: eastern equine encephalitis, western equine encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis, West Nile fever?

(a) They are all caused by the same virus.

(b) They are have the horse as a common intermediate host.

(d) Birds are never involved in the life cycle of the viruses that cause these diseases.

(e) Both a and d.

14. The only bacterium known to damage peripheral nerves is:

(a) Naegleria fowleri

(b) Mycobacterium leprae

(d) Neisseria meningitidis

(e) Haemophilus influenzae

15. All of the following are true about Clostridium tetani, the causative agent of tetanus, EXCEPT:

(a) They are spore-forming rods.

(b) They are part of the normal bowel microflora of horses, cattle, and humans.

(d) Their toxin elicits muscle stiffness, spasms, and paralysis in the victim.

(e) They require oxygen to survive.

16. A vaccine that was developed in 1933 has proven effective in reducing the incidence of disease caused by:

(a) Clostridium botulinum

(b) Mycobacterium leprae

(d) Streptococcus pneumoniae

(e) Listeria monocytogenes

17. The most common form of disease caused by Clostridium botulinum is:

(a) Infant

(b) Wound

(d) Foodborne

(e) None of these

18. The endospores of this organism are the most heat-resistant known; it is:

(a) Clostridium tetani

(b) Clostridium botulinum

(d) Streptococcus thermicos

(e) Listeria monocytogenes

19. All of the following are true about Clostridium botulinum, the causative agent of botulism, EXCEPT:

(a) Their ability to form toxin depends on infection with a bacteriophage.

(b) They can produce one of eight different toxins, all of which cause human disease.

(d) Although their endospores are highly heat-resistant, their toxin can be inactivated by only a few minutes' boiling.

(e) All of the above are true.

20. All of the following are true about poliomyelitis EXCEPT:

(a) Most poliovirus infections are inapparent or mild and nonparalytic.

(b) Polio can be caused by three strains of picornaviruses.

(c) The Salk vaccine contains live, attenuated polioviruses while the Sabin vaccine contains formalin-inactivated polioviruses.

(d) Transmission is by the fecal-oral route and pharyngeal secretions.

(e) Poliomyelitis has afflicted man for thousands of years.

graydinosaur157

Review Questions for Chapter 5: Control of Microbial Growth

1. Consider the following statement: âThorough handwashing with soap and water is the most important step in stopping the spread of many infectious diseasesâ.

a. Explain this statement.

b. Following thorough handwashing with soap, are your hands sterile? Why or why not?

2. If pasteurization does not achieve sterilization, why is pasteurization used to treat food? Why not just heat the food instead?

3. Consider the use of salts and sugars to preserve food.

a. How do salts and sugars preserve foods?

b. Why are these considered physical rather than chemical methods of microbial control?

c. Name one food that is preserved with sugar and one preserved with salt.

d. How do you account for the occasional growth of Penicillium mold in jelly, which is 50% sucrose?

4. Consider dried fruit you can buy at the store (e.g., raisins, pineapples, figs, dates, etc.) Dried fruits date back thousands of years B.C.

a. Why is this such an effective method of preserving food? Suggest several possibilities.

b. Fruit is often dried by being placed outside in the open under the sun in conditions that are not exactly sanitized. Why is this practice generally very safe?

5. There is great concern over healthcare-associated infections.

a. Why are healthcare settings such a âgoodâ place to catch infectious diseases? List several reasons.

b. What are several effective approaches that healthcare settings can take to minimize the spread of infectious disease?

6. Flying on an airplane includes lots of individuals in close quarters for potentially long periods of time.

a. What technology do you think airplanes use to reduce the amount of microbes from the air?

b. Despite this control method, there have been a number of documented cases of individuals infected with tuberculosis infecting other passengers during a flight. Explain how you think this happened. Which patients are at highest risk for infection, and what does this tell you about the effectiveness of microbial control on an airplane?

7. The thermal death time for a suspension of Bacillus subtilis endospores is 20 minutes in dry heat and less than 10 minutes in an autoclave. Which type of heat is more effective? Why?

8. A large hospital washes burn patients in a stainless steel tub. After each patient, the tub is cleaned with a quat. It was noticed that 14 of 20 burn patients acquired Pseudomonas infections

after being bathed. Provide an explanation for this high rate of infection.

9. If youâre on a municipal water supply, the water coming out of your faucet is chlorinated at the water treatment plant.

a. Is the water coming out of your faucet sterile?

b. Does the water still contain chlorine?

c. What are advantages and disadvantages of chlorine compared with other approaches (e.g., UV treatment, treatment with ozone).

10. You are a member of Engineers Without Borders, and your local chapter has been asked by a rural village in Thailand to assist them with improving their water supply, which they suspect of making villagers sick. The village has piping infrastructure that delivers water through a series of pipes to each household. Upon your initial site assessment of the village, you and your team determine that the water has high turbidity (particulate material) as well as a high bacterial count.

a. Design a strategy for treating the water to make it safe to drink that still relies upon the distribution system. Note that you may make some reasonable assumptions about conditions in the village (e.g., availability of electricity if you wish).

b. Identify some possible limitations of your approach.

11. A low technology approach to treating water in rural locations is to fill clear plastic soda bottles with water and leave it out all day in the sun (e.g., up on a roof).

a. What two factors are most likely at work in controlling microbes in these conditions?

b. What impact does each factor have on the microbes? Be specific.