Ch. 21 Microbial Diseases of the Skin and Eyes Flashcards

1
Q

eyes get their microbiota from…

A

the skin

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2
Q

normal microbiota of the skin (three general characteristics related to the environment they are in) (cross contact into eye)

A
  • halotolerant
  • acid tolerant
  • resistant to drying
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3
Q

types of microbes on the skin

A
  • gram-positive cocci
  • diptheroids (pleomorphic, rods)
  • — propionbacterium (metabolize sebum, produce acid)
  • — cornybacterium
  • yeasts
  • — malassezia (require oil for growth)
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4
Q

bacterial diseases of the skin

A
  • Staphylococcus
  • S. epidermidis (coagulase negtive)
  • — most common cause of infection in indwelling devices; creates biofilms
  • — not a problem on the skin, but wrong location - bad
  • S. aureus (coagulase positive)
  • — many virulence factors
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5
Q

examples of S. aureus skin diseases

A
  • MRSA (methicillin resistance)
  • toxic shock syndrome (TSST-1)
  • — produces toxins that decrease blood pressure
  • impetigo (scabs around mouth; v. contagious)
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6
Q

Bacterial diseases of the Skin

A
  • Staphylococcus
  • Streptococcus
  • Psuedomonas
  • Acne
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7
Q

Viral diseases of the skin

A
  • warts
  • smallpox (variola)
  • varicella-zoster virus
  • cold sores
  • measles
  • rubella
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8
Q

Staphylococcus diseases of the skin

A

S. aureus (coagulase positive; many virulence factors)

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9
Q

S. aureus causes…

A

Scalded skin syndrome (exotoxin; small children or late-stage TSS)

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10
Q

Streptococcus diseases

A

S. pyogenes:

  • beta-hemolytic
  • Group A Streptococcus (GAS)
  • has M protein (allows microorg to evade phagocytosis)
  • still sensitive to beta-lactam antibiotics
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11
Q

Diseases caused by S. pyogenes

A

Erysipelas (often after strep throat)
Necrotizing fasciitis (flesh eating disease)
Streptococcal TSS

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12
Q

Pseudomonas disease-causing organisms (pseudomonad)

A

P. aeruginosa

  • lophotrichous
  • green pigment on petri dish
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13
Q

Diseases caused by P. aeruginosa

A
Pseudomonads dermatitis ("swimmer's itch" rash)
Otitis externa (external ear canal infection)
Opportunistic pathogen (HAI 2nd and 3rd degree burn patients)
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14
Q

Acne

A
Comedal acne (mild)
Inflammatory acne (moderate)
Nodular cystic acne (severe)
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15
Q

How do propionibacterium cause acne

A

normally it metabolises fatty acids in sebum, creating an acidic environment and acting as a first line of defense.

excess skin shedding in hair follicles block the follicle, leading to accumulation of sebum and infection by propionibact.

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16
Q

Warts are caused by…

A

papillomavirus

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17
Q

smallpox is caused by …

A

Variola virus: variola major (over 20% mortality) and minor (less than 1% mortality)

eradicated, as it has no animal hosts

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18
Q

chickenpox is caused by…

A

varicella-zoster virus (human herpes virus 3 HHV-3)

19
Q

HHV-3 characteristics

A
  • DNA virus
  • transmitted via respiratory route
  • incubation about 3 wks
  • virus migrates up peripheral nerves to dorsal root ganglion; latent viral DNA
  • pock marks
  • mostly mild in children, very severe in young adults
20
Q

recurrence of HHV-3

A

shingles (herpes zoster)

  • viruses move down peripheral nerve
  • often occurs later in life
21
Q

Reye’s syndrome

A

occurs post-chickenpox
vomiting, lethargy, coma, and eventual death

mortality previously was 90%; now, 30%

22
Q

chickenpox can be prevented by…

A

attenuated vaccine

23
Q

cold sores are caused by…

A

Herpes simplex virus type 1

  • oral or respiratory route
  • virus can travel up trigeminal nerve to ganglion where it is latent
24
Q

other diseases caused by HSV-1

A
Herpes gladiatorum (wrestling mats; raised bumps)
Herpetic whitlow (medical professionals; from nasal or mucosal secretions)
25
Q

Measles (Rubeola; “hard measles”)

A
  • respiratory route
  • Koplik’s spots in the mouth are key marker
  • complications: M ear infection, pneumonia, encephalitis, secondary bacterial infections
  • virus remains in body for unknown amount of time; latent or persistent (?)
  • subacute sclerosing panencephalitis
26
Q

MMR stands for…

A

Measles, Mumps, Rubella

27
Q

Rubella…

A
  • “3 day measles”
  • respiratory route
  • incubate up to 3 wks
  • can be subclinical in kids and adults
  • main concern: congenital rubella syndrome
28
Q

congenital rubella syndrome

A

stillbirth, deafness, blindness, heart defects, mental retardation when mother is infected during first trimester

29
Q

fungal skin diseases AKA…

A
  • cutaneous mycoses
  • dermatomycoses
  • tineas
30
Q

what are tineas?

A
  • fungi that grow on keratin

- transmitted via fomites

31
Q

examples of cutaneous mycoses

A
  • ringworm (tinea barbae)
  • athletes foot (tinea pedis)
  • can occur on scalp
  • thrush (candidiasis; usually opportunistic infection)
32
Q

microbial diseases of the eye

A
  • conjunctivitis
  • ophthalmia neonatorum
  • inclusion conjunctivitis
  • trachoma
  • acanthomoeba keratitis
33
Q

conjunctivitis (pinkeye)

A

generalized term; bacterial, viral, or even allergic

  • bacterial: pus discharge mostly
  • transmitted via direct contact or fomites among children
  • adults – improperly disinfected contact lenses
34
Q

ophthalmia neonatorum

A
  • caused by N. gonorrhoeae (woman infected w gonorrhea during time of delivery)
  • may result in blindness
  • treatment at birth (originally silver nitrate eye drops; now use antibiotic eye drops)
35
Q

inclusion conjunctivitis

A
  • at birth; caused by Chlamydia trachomatis
  • often co-infected with N. gonorrhoeae
  • antibiotic eye drops: tetracycline or erythromycin
36
Q

Trachoma

A
  • C. trachomaatis
  • caused by different serotype than STI
  • single greatest cause of blindness by infectious disease (severe inflammation of eyelid, trichiasis, scratching cornea)
  • transmission: direct contact; fomites; mechanical vector transmission
37
Q

Acanthamoeba Keratitis

A
  • grows in fresh water (hot tubs, contact lenses)
  • early treatment is very successful
  • later infection = severe damage
38
Q

neglected tropical diseases…

A

are a group of 16 diseases contracted by more than a billion people per year

39
Q

Protozoan NTDs

A

African trypanosomiasis

Chagas disease

Leishmaniasis

40
Q

Helminthic NTDs

A

Cysticerocosis, Dracunculiasis, Echinococcosis, Fascioliasis, Lymphatic filariasis, Onchocerciasis, Schistosomiasis

41
Q

Bacterial NTDs

A

Trachoma, Leprosy, Buruli ulcer, Yaws

42
Q

Viral NTDs

A

Dengue, Rabies

43
Q

Strategies that can greatly reduce incidence of NTDs

A
  • preventive chemotherapy
  • innovative, intensified disease managment
  • veterinary care
  • vector control
  • improved sanitation and hygiene services