Ch. 17 - Skin and Eye Infections

Norman-McKay- Microbiology: Basic and Clinical Principles 2nd Edition

Norman-McKay2nd EditionMicrobiology: Basic and Clinical PrinciplesISBN: 9780137661619Not the one you use?Change textbook

Norman-McKay 2nd Edition

Ch. 17 - Skin and Eye Infections

Problem 13

Chapter 17, Problem 13

Acanthamoeba protozoa species are associated with:
a. keratitis.
b. conjunctivitis.
c. river blindness.
d. trachoma.
e. all of the above.

Verified step by step guidance

Step 1: Understand the organism in question. Acanthamoeba is a genus of free-living amoebae found in various environments such as soil, water, and air. It is known to cause infections in humans, particularly affecting the eyes and central nervous system.

Step 2: Review the diseases listed in the options and their common causative agents: keratitis (often caused by Acanthamoeba), conjunctivitis (commonly caused by bacteria or viruses), river blindness (caused by the parasitic worm Onchocerca volvulus), and trachoma (caused by Chlamydia trachomatis).

Step 3: Identify which disease(s) are specifically associated with Acanthamoeba. Acanthamoeba is well-known for causing keratitis, especially in contact lens users, due to its ability to invade the cornea.

Step 4: Evaluate the other options to confirm if Acanthamoeba is linked to them. Since conjunctivitis, river blindness, and trachoma have different primary causative agents, Acanthamoeba is not typically associated with these conditions.

Step 5: Conclude that the correct association is with keratitis, and therefore, the answer corresponds to option a.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acanthamoeba and Its Pathogenicity

Acanthamoeba is a genus of free-living amoebae found in soil and water. Some species are opportunistic pathogens causing infections in humans, particularly affecting the eyes and central nervous system. Understanding its pathogenic potential is key to linking it with specific diseases.

Keratitis Caused by Acanthamoeba

Acanthamoeba keratitis is a serious eye infection affecting the cornea, often linked to contact lens use or exposure to contaminated water. It causes pain, redness, and potential vision loss, making it a hallmark disease associated with Acanthamoeba species.

Differentiation from Other Eye Infections

Conjunctivitis, river blindness, and trachoma are caused by different pathogens: viruses/bacteria, Onchocerca volvulus, and Chlamydia trachomatis respectively. Recognizing these distinctions helps correctly associate Acanthamoeba specifically with keratitis.

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Differential Staining

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Textbook Question

Conjunctivitis is caused by the following agent types (select ALL that apply):

a. bacteria.

b. viruses.

c. protozoa.

d. fungi.

e. helminths.

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Textbook Question

Select the false statement about trachoma:

a. The causative agent is bacterial.

b. It is the leading cause of infectious blindness in the United States.

c. It is transmitted by unhygienic items, such as flies, fingers, and fomites.

d. Uncomplicated cases can be resolved with antibiotics.

e. Severe cases require surgery.

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Textbook Question

Select the false statement about cutaneous candidiasis:

a. The most common causative species is Candida albicans.

b. Candida albicans can be part of normal microbiota.

c. Usage of antibiotics can increase the chance of cutaneous candidiasis.

d. Changes in pH can permit overgrowth.

e. The causative agents are naturally found as mold filaments.

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Textbook Question

A frantic mother comes into your clinic because her two-year-old child has had a very high fever for two days now, with mild diarrhea and coldlike symptoms. As you consider the differential list, which is the most likely causative agent if the fever breaks and is replaced with a rash by tomorrow?

a. Human parvovirus B19

b. Hand, foot, and mouth disease

c. Roseola

d. Rubella

e. Measles

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Textbook Question

Your diabetic patient has a foot wound that has developed into serious necrosis and the recommended treatment has been sessions in the hyperbaric oxygen chamber. You are explaining to him what has contributed to this condition, including the causative agent, which is:

a. Bacillus anthracis.

b. Clostridium perfringens.

c. Corynebacteria diphtheriae.

d. Streptococcus pyogenes.

e. Pseudomonas aeroginosa.

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Textbook Question

Which best describes conjunctivitis (select ALL that apply)?

a. Itchy eyes

b. Scarred cornea

c. Red eyes