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Micro Ch. 18 Flashcards

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1
Q

how does keratin work as a skin defense?

A

gives the cells their ability to withstand damage and abrasion; prevents most microorganisms from penetrating into sensitive deeper tissues

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2
Q

how does sloughing of the skin work as a skin defense?

A

millions of cells from the stratum corneum slough off every day, taking attached microorganisms with them; entire epidermis is replaced every 25-45 days

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3
Q

how does sebum work as a skin defense?

A

has a low pH, making the skin inhospitable to most microorganisms; oily due to its high concentration of lipids; breakdown of lipids leads to toxic by-products that inhibit the growth of microorganisms not adapted to the skin environment

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4
Q

how does sweat work as a skin defense?

A

inhibitory to microorganisms because of its low pH and high salt concentration; contains lysozyme, an enzyme that specifically breaks down peptidoglycan

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5
Q

what areas of the skin are vulnerable to infection?

A

moist areas and skin folds; hair follicles and glandular ducts

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6
Q

name at least three bacteria that are normal microbiota of the skin

A

a. Staphylococcus epidermidis
b. Propionibacterium acnes
c. Staphylococcus aureus

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7
Q

how does the eye prevent and stop infection?

A

mucus in conjunctiva and tears; lysozyme and lactoferrin in tears; the flow of tears prevent attachment

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8
Q

name some outer anatomical regions of the eye

A

eyelid, pupil, sclera, and iris (pg 539, figure 18.15)

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9
Q

name some inner anatomical regions of the eye

A

sclera, iris, lens, cornea, anterior chamber, posterior chamber, conjunctiva, retina, optic nerve, and vitreous chamber (pg 539, figure 18.15)

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10
Q

what infections do MRSA cause?

A

sores or boils; sometimes more serious skin infections or infect surgical wounds, the bloodstream, the lungs, or the urinary tract.

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11
Q

how is MRSA different from other Staphylococcus aureus?

A

It is resistant to some antibiotics (methicillin, amoxicillin, penicillin, and oxacillin).

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12
Q

how is MRSA treated?

A

Clindamycin, Tetracyclines (Doxycycline and Minocycline), Trimethoprim and Sulfamethaxozole, Rifampin, and Linezolid

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13
Q

what is gangrene?

A

caused by Clostridium perfringens, a gram positive endospore forming bacterium; anaerobic and requires anaerobic conditions to manufacture and release the exotoxins that mediate the damage in the disease.

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14
Q

what is anaerobic cellulitis?

A

the bacteria spread within damaged necrotic muscle tissue, producing toxins and gas as the infection proceeds; remains localized and does not spread to healthy tissue

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15
Q

what is true myonecrosis?

A

more destructive; toxins produced in large muscles; cause local necrosis at these sites; damaged tissue serves as a focus for continued bacterial growth, toxin formation, and gas production

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16
Q

what is the etiological agent of gas gangrene?

A

Clostridium perfringens

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17
Q

what conditions must be present in order for gas gangrene to develop?

A

anaerobic conditions

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18
Q

how is gas gangrene treated?

A

cleansing and surgical repair, debridement, surgery and large doses of antibiotics, hyperbaric oxygen therapy, and amputation

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19
Q

what is the etiological agent of small pox?

A

the variola virus

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20
Q

what are the typical signs and symptoms of a small pox infection?

A

fever and malaise, followed by a rash that starts at the pharynx and spreads to the face and extremities; begins as macular rash

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21
Q

how was small pox eradicated?

A

vaccine based on the vaccinia virus

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22
Q

what is the organism responsible for trachoma?

A

Chlamydia trachomatis

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23
Q

how is trachoma transmitted?

A

contaminated fingers, fomites, fleas, and a hot, dry climate

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24
Q

name the vector for trachoma.

A

Indirect contact, mechanical vector

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25
name the etiological agent, transmission, pathogenesis, and treatment of acne
Propionibacterium acnes; not considered transmissible; linked to the amount of sebaceous fluid produced in the skin; tx’d with topical agents to enhance the sloughing of skin cells, either topical or oral abx, and for severe acne, isotretinoin may be prescribed
26
name the etiological agent, transmission, pathogenesis, and treatment of impetigo
Staphylococcus aureus or Streptococcus pyogenes; highly contagious; transmitted direct contact, fomites, and mechanical vectors; S. aureus impetigo are exotoxins called exfoliative toxins A and B; S. pyogenes impetigo anchors itself to surfaces using a variety of adhesive elements on its surface (M protein), and possesses hyaluronidase; tx’d with topical mupirocin (Bactroban) or retapamulin, or with oral abx dicloxacillin, cephalexin, or trimethoprim-sulfamethoxazole
27
name the etiological agent, transmission, pathogenesis, and treatment of chickenpox
human herpesvirus 3; highly contagious, droplet contact, inhalation or aerosolized lesion fluid; incubation period of 10-20 days; usually lasts 4-7 days; contagious until lesions have crusted over; no tx necessary unless secondary infection occurs, in which case, abx are rx’d
28
name the etiological agent, transmission, pathogenesis, and treatment of measles
Morbillivirus; transmitted by respiratory droplents; virus implants in the respiratory mucosa and infects the tracheal and bronchial cells; travels to the lymphatic system; multiples and then enters the bloodstream; Viremia carries the virus to the skin and to various organs
29
name the etiological agent, transmission, pathogenesis, and treatment of rubella
Rubivirus; via contact with respiratory secretions or urine; mildly communicable; highly dangerous to fetus; postnatal rubella is generally benign and requires only symptomatic tx; no specific tx is available for the congenital manifestations
30
name the etiological agent, transmission, pathogenesis, and treatment of Scarlet fever
result of a respiratory infection with Streptococcus pyogenes; transmitted via droplet or direct contact; occasionally follows a streptococcal skin infection; can produce a distinctive red rash on the skin; tx’d with penicillin or clindamycin
31
name the etiological agent, transmission, pathogenesis, and treatment of warts
caused by HPV-1; transmitted through direct contact, autoinoculation, and indirectly; tx’d by home remedies, including nonprescription salicylic acid preparations, drugs, and/or cryosurgery; warts can grow back
32
name the etiological agent, transmission, pathogenesis, and treatment of ringworm
about 39 species in the genera Trichophyton, Microsporum, and Epidermophyton;direct and indirect contact with other humans or with infected animals; the dermatophytes have the ability to invade and digest keratin; tx’d with topical antifungal agents
33
name the etiological agent, transmission, pathogenesis, and treatment of conjunctivitis
Neisseria gonorrhoeae or Chlamydia trachomatis (neonatal), and Staphylococcus aureus, Streptococcus pneumonia, Haemophilus influenzae, and Moraxella; transmitted vertically from a genital tract infection, or autoinoculation from a genital infection or from sexual activity; tx’d with erythromycin (topically and orally), ceftriaxone, ciprofloxacin eye drops, erythromycin, gentamicin; prophylactic abx
34
name the important anatomical features of the skin
epidermis, stratum basale, dermis, sebaceous glands, sweat glands, hair follicles, superficial fascia, subcutaneous fat, nerves, veins, arteries, deep fascia, and muscle
35
list the types of the normal biota presently known to occupy the skin
Staphylococcus eptidermidis, Propionibacterium acnes, and staphylococcus aureus
36
which infectious skin conditions are transmitted to the respiratory tract through droplet contact?
`scalded skin syndrome, chickenpox, smallpox, measles, rubella, fifth disease, scarlet fever
37
which skin conditions call for vaccination?
chickenpox, smallpox, measles, rubella
38
what are the normal biota in the eye?
Staphylococcus edidermidis, Micrococcus, Streptococcus, and Corynebacterium species
39
what is the possible causative agent for conjunctivitis?
Chlamydia tractomatis or Neisseria gonorrhoeae (neonatal); S. pneumoniae, S. aureus, Haemophilus influenza, Moraxella, Neisseria gonorrhoeae, Chlamydia trachomatis (bacterial); Adenoviruses (viral)
40
what is the possible causative agent for keratitis?
Herpes simplex virus
41
what is the possible causative agent for river blindness?
Wolbachia, Onchocerca volvulus
42
why are there distinct differential diagnoses for neonatal and non-neonatal conjunctivitis?
neonatal conjunctivitis is usually transmitted vertically from a genital tract infection in the mother and can lead to serious eye damage if not treated promptly
43
an example of an effective treatment for a cutaneous mycosis like tinea pedis would be
miconazole
44
what is the antimicrobial enzyme found in sweat, tears, and saliva that can specifically break down peptidoglycan?
lysozyme
45
what is probably the most important defense factor for the skin?
antimicrobial peptides
46
name the organisms most commonly associated with cellulitis
Staphylococcus aureus and Streptococcus pyogenes
47
due to a highly successful vaccination program, the WHO has managed the worldwide eradication of what naturally occurring disease?
smallpox
48
what are warts caused by?
papillomavirus
49
herpesviruses can cause what diseases?
chickenpox, shingles, roseola, and keratitis
50
dermatophytes are fungi that infect the epidermal tissue by invading and attacking what skin defense?
keratin
51
poor contact lens hygiene is likely to cause
Acanthamoeba keratitis
52
what enzyme is associated with pathogenic strands of Staphylococcus aureus?
coagulase
53
how can fifth disease be treated and prevented?
there is no treatment or prevention
54
what makes up the integument?
skin, hair, nails, and sweat and oil glands
55
describe and give an example of a bulla
large wide vesicle; blister, gas blisters in gangrene
56
describe and give an example of a cyst
raised, encapsulated lesion, usually solid or semisolid when palpated; severe acne
57
describe and give an example of a macule
flat, well-demarcated lesion characterized mainly by color change; freckle, tinea versicolor
58
describe and give an example of a maculopapular rash
flat to slightly raised colored bump; measles, rubella, fifth disease, roseola
59
describe and give an example of a papule
small, elevated, solid bump; warts, cutaneous leishmaniasis
60
describe and give an example of petechiae
small purpura; meningococcal bloodstream infection
61
describe and give an example of plaque
elevated, flat-topped lesion larger than 1 cm; psoriasis
62
describe and give an example of purpura
reddish-purple discoloration due to blood in small areas of tissue; does not blanch when pressed; meningococcal bloodstream infection
63
describe and give an example of a pustule
small, elevated lesion filled with purulent fluid; acne, smallpox, mucocutaneous leishmaniasis, cutaneous anthrax
64
describe and give an example of a scale
flaky portions of skin separated from deeper skin layers; ringworm of the body and scalp, athletes foot
65
describe and give an example of a vesicle
elevated lesion with clear fluid; chickenpox
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