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Clinical Microbiology > (exam 2) ch 21 Microbial diseases of the skin and eyes > Flashcards

(exam 2) ch 21 Microbial diseases of the skin and eyes Flashcards

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1
Q

what are the two primary parts?

A

1) Epidermis 2) Dermis

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2
Q

what is the epidermis?

A

Outermost portion contains rows of dead cells; thin outer portion of skin; composed of layers of epithelial cells

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3
Q

keratin?

A

waterproofing protein coating outer layer of epidermis

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4
Q

what is the dermis?

A

inner, thick portion of skin; composed mainly of connective tissue

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5
Q

what are three passageways for microbes?

A

1) hair follicles 2) sweat gland ducts 3) oil gland ducts

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6
Q

what is sebum?

A

secreted by oil glands contains fatty acids that inhibit pathogens (but, Some microbes can use sebum for growth)

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7
Q

what are mucous membranes (mucosa) ?

A

Sheets of tightly packed epithelial cells attached to an extracellular matrix (Cells secrete mucus and some cells have cilia) - often folded to maximize surface area

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8
Q

what is exanthem?

A

skin rash arising from a disease

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9
Q

what is enanthem?

A

rash on mucous membranes arising from a disease

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10
Q

what are vesicles?

A

small, fluid-filled lesions; less than 1 cm

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11
Q

what is bullae?

A

vesicles larger than 1 cm in diameter

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12
Q

what are macules?

A

flat, reddened lesions; less than 1 cm

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13
Q

what are papules?

A

raised lesions

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14
Q

what are pustules?

A

raised lesions with pus

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15
Q

what two genera typically cause bacterial skin diseases?

A

Staphylococcus and Streptococcus frequently cause skin infections

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16
Q

what is Staphylococci?

A

spherical gram-positive bacteria; form irregular clusters

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17
Q

how are Staphylococcal skin infections clinically divided into two groups?

A

dependent on coagulase production

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18
Q

what is coagulase?

A

enzyme that clots fibrin in the blood

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19
Q

what is Staphylococcus epidermidis?

A

~90% of normal skin microbiota (Opportunistic pathogen); Healthcare-associated pathogen; Produces biofilm on catheters; Coagulase-negative

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20
Q

what is Staphylococcus aureus?

A

Carried in the nasal passages; Golden-yellow colonies (protects them from sunlight); Most pathogenic strains are coagulase-positive and these strains may also produce additional toxins; MRSA strains are antibiotic-resistant.

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21
Q

Staphylococcus aureus is often transported via Autoinoculation which means?

A

Infection caused by the spread of bacteria from one part of the body to another

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22
Q

what are two main types of Staphylococcus aureus infections?

A
  1. Hair follicle infections
  2. Impetigo
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23
Q

what is Folliculitis?

A

(Staphylococcus aureus- hair follicle infection) infections of hair follicles (often pimples)

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24
Q

what is a sty?

A

(Staphylococcus aureus – hair follicle infections) folliculitis of an eyelash

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25
Q

what is Furuncle (boil)?

A

(Staphylococcus aureus – hair follicle infections) more serious hair follicle infection; contains abscesses = which are localized region of pus surrounded by inflamed tissue (Difficult to treat; antibiotics don’t penetrate well)

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26
Q

what is a carbuncle?

A

hard, round inflammation of deep skin tissue; Caused from a spreading furuncle; Often causes general illness and fever

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27
Q

what is impetigo and what are the two types?

A

crusting sores; usually affects children (2-5yr); Highly contagious and spread by autoinoculation and direct contact. Two types, Nonbullous and Bullous

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28
Q

what is Nonbullous impetigo?

A

(Staphylococcus aureus - Impetigo) Most common; consists of isolated pustules; Typically heal w/o treatment

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29
Q

what is Bullous impetigo?

A

(Staphylococcus aureus - Impetigo) Caused by a toxin; Causes scalded skin syndrome; It is exfoliation/Separation of skin layers

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30
Q

what is Pemphigus neonatorum?

A

impetigo of a newborn

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31
Q

what is Scalded skin syndrome?

A

characteristic in late stages of toxic shock syndrome (TSS); TSS is often caused by S. aureus; Fever, vomiting, shock, and organ failure caused by toxic shock syndrome toxin 1 (TSST-1) in the bloodstream

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32
Q

what are Streptococcal Skin Infections?

A

Gram-positive cocci in chains; Produce hemolysins that lyse red blood cells (Alpha-, beta-, and gamma-hemolytic streptococci)

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33
Q

what are Beta-hemolytic streptococci ?

A

Often cause disease and are differentiated into groups A through T based on antigenic cell wall carbohydrates

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34
Q

what are antigens?

A

foreign substance that causes an immune response

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35
Q

what are Group A streptococci (GAS)?

A

(most important group of Beta-hemolytic streptococci ) Almost exclusively Streptococcus pyogenes and among most common human pathogens; Divided into more than 80 immunological types (based on antigenic properties of M proteins and the M protein for GAS is external to cell wall on fimbriae)

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36
Q

what are the four virulence factors of Group A streptococci (GAS)?

A

1) Streptolysins: lyse RBCs
2) M proteins: allow adherence and immune system avoidance
3) Hyaluronidase: dissolves connective tissue
4) Streptokinases: dissolve blood clots

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37
Q

what is Erysipelas?

A

(Streptococcal skin infections) caused by S. pyogenes that infects the dermal layer of the skin; presentation includes reddish skin patches with raised margins; usually on face (infection may progress to local tissue destruction and sepsis)

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38
Q

what is Necrotizing fasciitis?

A

(Streptococcal skin infection) known as “Flesh-eating” disease; Causes rapid tissue destruction; S. pyogenes toxins act as superantigens (which cause extreme immune response)

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39
Q

what is Streptococcal toxic shock syndrome?

A

(Streptococcal skin infection) Similar to staphylococcal TSS; But here, M proteins shed from bacteria act as toxin

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40
Q

what is Pseudomonas aeruginosa?

A

(Bacterial - Pseudomonads infection) it is a Gram-negative, aerobic rod that produces exo- and endotoxins for pathogenicity; Widespread growth in moist environments; Forms dense biofilms and are resistant to many antibiotics and disinfectants

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41
Q

what is Pseudomonas dermatitis?

A

(type of Pseudomonas aeruginosa) it is a self-limiting rash acquired in swimming pools

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42
Q

what is Otitis externa?

A

(a type of Pseudomonas aeruginosa) known as “Swimmer’s ear”

43
Q

what is Pseudomonas aeruginosa in assosiation with HAIs? Which two types of patients are most at risk for this infection?

A

opportunistic pathogen; Because there are biofilms on indwelling medical devices; and it is especially dangerous for Cystic fibrosis patients and Burn patients

44
Q

what is a “tell tell” sign or characteristic of P. aeruginosa infection on a plate?

A

Pyocyanin – which is a bacterial pigment; blue-green pus characteristic of P. aeruginosa infection

45
Q

what is the most common bacterial skin disease in humans?

A

Acne; Typically skin cells shed from hair follicles; Acne occurs when cells combine with sebum causing blockages

46
Q

what are Whiteheads (comedos)?

A

sebum/cell accumulation

47
Q

what are Blackheads (comedones) ?

A

blockage protrudes through skin

48
Q

what affects sebum formation?

A

Sebum formation is affected by hormones, not diet

49
Q

what are three forms of acne?

  • Comedonal (mild)
  • Inflammatory (moderate)
  • Nodular cystic (severe)
A

1) Comedonal (mild)
2) Inflammatory (moderate)
3) Nodular cystic (severe)

50
Q

what is Comedonal (mild) acne?

A

This type of acne is not usually associated with bacterial infection and is easily treated with topical formations

51
Q

what is Inflammatory (moderate) acne?

A

Caused by Cutibacterium acnes (formerly Propionibacterium acnes); Metabolizes sebum (fatty acids produce an inflammatory response); Treated with antibiotics and benzoyl peroxide

52
Q

what Nodular cystic (severe) acne?

A

Characterized by nodules or cysts; it is inflamed lesions with pus deep in the skin; Can result in scarring of face and upper body and is usually treated with drug treatment – isotretinoin

53
Q

what are warts / papillomas?

A

(viral disease) small skin growths caused by papillomavirus; transmitted via contact; incubation period of several weeks; treated with cryotherapy, electrodesiccation, or salicylic acid

54
Q

what is smallpox / variola virus?

A

(viral disease) Caused by Variola virus; Two forms of the disease (two virus variants), Variola major has 20–60% mortality and Variola minor has <1% mortality. Respiratory transmission, moves into the bloodstream, and infects the skin. Lesions become pustular after ~10 days

55
Q

what is monkeypox virus?

A

Related to smallpox, Endemic to small animals in Africa it can jump from animals to humans. Prevention by the smallpox vaccination

56
Q

Is smallpox still around?

A

No, it is eradicated from the human population by vaccination; There is no animal reservoir and the last case estimated was in 1977

57
Q

what is chickenpox / varicella?

A

Herpesvirus varicella-zoster (human alphaherpesvirus 3); Respiratory transmission with localized skin infection after ~2 weeks; Typically mild disease overall and causes pus-filled vesicles

58
Q

What is Reye’s syndrome?

A

Severe complications of chickenpox; vomiting and brain dysfunction; can affect children and teenagers; and aspirin use increases risk

59
Q

what is unique about chickenpox / varicella that leads to infection later in life?

A

After primary infection, virus becomes latent in dorsal root ganglion (near spine) so later (up to decades) the virus can reactivate, move along nerves, and cause a new skin infection. Often due to stress or lowered immunity.

60
Q

what is shingles / herpes zoster?

A

(virus that infects year after inital infection with chickenpox) Follows the distribution of affected cutaneous sensory nerves; Typically limited to one side of the body and usually near waist; Disease state differs due to partial immunity; Unvaccinated children exposed to shingles get chickenpox. Typically occurs once and in older adults

61
Q

what is postherpetic neuralgia?

A

persistent burning and/or stinging nerve pain after shingles

62
Q

is chickenpox (varicella) and Shingles (Herpes Zoster) still around today?

A

yes, there was a vaccine developed in 1995; it is a live, attenuated virus and is 97% effective but wanes over time. A breakthrough varicella – infection occurs after vaccination which consits typically of mild disease with rash. There is a boster vaccine for adults over 60

63
Q

what is Herpes Simplex?

A

Human alphaherpesvirus 1 (HSV-1) and 2 (HSV-2); •Ninety percent of the U.S. population is infected with HSV-1; •Usually develop as cold sores or fever blisters.

64
Q

what is HSV-1?

A

(Herpes Simplex) 90% of population and asymptomatic; HSV-1 remains latent in trigeminal nerve ganglia and outbreaks are triggered by the sun, stress, or hormonal changes

65
Q

what is HSV-2?

A

(types of Herpes Simplex) Remains latent in sacral nerve ganglia near the spine

66
Q

what is Herpes gladiatorum?

A

(HSV-2) vesicles on the skin (common in wrestlers)

67
Q

what is Herpetic whitlow?

A

(type of HSV-2) vesicles on the fingers (seen amoung healthcare workers)

68
Q

what is Herpes encephalitis?

A

(type of HSV-2) virus spreads to the brain

69
Q

how are herpes simplex (specifcally HSV-1 and HSV-2)?

A

Treated with acyclovir

70
Q

what is Measles (Rubeola)

A

caused by Measles morbillivirus; Respiratory transmission and is extremely contagious; Causes cold-like symptoms, macular rash; Koplik’s spots (diagnostic indicator); Particularly dangerous in infants and elderly

71
Q

what are Koplik’s spots and what disease do these spots indicate?

A

Red spots on the oral mucosa opposite the molars; it is a diagnostic indicator for Measles (Rubeola)

72
Q

what is Subacute sclerosing panencephalitis?

A

Rare; occurs 1 to 10 years after measles recovery; causes severe neurological symptoms and death

73
Q

Are Measles (Rubeola) still around today?

A

Yes, but it is prevented by the MMR (measles, mumps, rubella) vaccine which is 95% effective; Children under 1 year old cannot receive the vaccine and it is not reccomended for pregnant people.

74
Q

what is Rubella (German Measles)?

A

caused by Rubella virus; Milder than measles; Macular rash and light fever. Respiratory transmission with a 2- to 3-week incubation

75
Q

what is Congenital rubella syndrome?

A

Fetal damage due to Congenital rubella syndrome which can cause deafness, heart defects, mental retardation in 35% of cases and 15% mortality within first year of life

76
Q

what prevents both Rubella (German measles) and Congenital rubella syndrome?

A

Prevented by the MMR vaccine which is not recommended for pregnant women

77
Q

what is Fifth disease (erythema infectiosum)?

A

(viral disease) caused by parvovirus B19; mild flulike symptoms; “slapped-cheek” facial rash

78
Q

what is Roseola?

A

(viral diease) Human herpesviruses 6 and 7; causes high fever; body rash; recovery usually is within 1 to 2 days

79
Q

what is Hand-foot-and-mouth disease?

A

(viral disease) caused by enteroviruses; It is spread via mucous or saliva; Causes fever and sore throat; rash on the hands, feet, mouth, and tongue

80
Q

what is Mycosis?

A

fungal infection of the body

81
Q

what is cutaneous mycoses?

A

Colonize the hair, nails, and outer epidermis and metabolize keratin

82
Q

what are dermatomycoses?

A

Informally known as tineas or ringworm; there are four different kinds and treatment is usually topical drugs (miconazole and clotrimazole)

83
Q

what is Tinea capitis?

A

(type of dermatomycoses) scalp ringworm

84
Q

what is Tinea cruris?

A

(type of dermatomycoses) jock itch

85
Q

what is Tinea pedis?

A

(type of Dermatomycoses) athlete’s foot

86
Q

what is Tinea unguium?

A

(type of Dermatomycoses) ringworm of nails

87
Q

what is Subcutaneous Mycoses?

A

(fungal disease) More serious than cutaneous mycoses; can penetrate the stratum corneum and is usually caused by fungi that inhabit the soil.

88
Q

what is Sporotrichosis?

A

related to Subcutaneous Mycoses; it is when it enters a wound; forms a small ulcer; Treated with potassium iodide

89
Q

what is Candidiasis?

A

(fungal disease) Overgrowth of Candida albicans (yeast) - Forms pseudohyphae, making it resistant to phagocytosis; Occurs in the skin and mucous membranes of the genitourinary tract and mouth. Results when antibiotics suppress competing bacteria or a change occurs in the mucosal pH

90
Q

What is thrush?

A

C. albicans infection of the oral cavity

91
Q

what do we know about fulminating disease in the immunosuppressed?

A

Appears suddenly and severely

92
Q

what is Scabies?

A

(Parasitic Infestation of the Skin) Caused by Sarcoptes scabiei mites; Burrow into skin to lay eggs causes intense local itching; Causes inflammatory skin lesions; can cause secondary infections from scratching; Transmitted via intimate contact; Treatment with permethrin (topical)

93
Q

What is Pediculosis (Lice)? Feed on blood from the host; Itching due to sensitization from saliva; They lay eggs (nits) on the hair and attach to the shafts; Treatment with topical insecticides (permethrin or pyrethrin)

A
94
Q

what is Pediculus humanus capitis?

A

(parasitic disease) head louse?

95
Q

what is P. h. corporis?

A

(parasitic diseases) body louse

96
Q

what is the Conjunctiva?

A

Epithelial cells covering the eye that are considered a continuation of the skin or mucosa; covers outer surface of the eye and lines the eyelid; it is a mucous membrane

97
Q

what is Conjunctivitis?

A

(microbial disease of the eye) aka. red eye or pinkeye; it is inflammation of the conjunctiva; commonly caused by (Haemophilus influenza, Pseudomonads, or Adenoviruses); Associated with unsanitary contact lenses

98
Q

what is Ophthalmia Neonatorum?

A

(bacterial disease of the eye) Caused by Neisseria gonorrhoeae; Transmitted to a newborn’s eyes during passage through the birth canal; Large amount of pus forms and ulceration of corneas results- Untreated cases may lead to blindness! Prevented by treating a newborn’s eyes with antibiotics

99
Q

what is Inclusion Conjunctivitis (chlamydial conjunctivitis)?

A

(bacterial diseases) Caused by Chlamydia trachomatis (Serotypes D-K); less servere; Transmitted to newborn’s during birth; spread through unchlorinated pool water; Treated with tetracycline

100
Q

What is Trachoma?

A

(Bacterial diseases) Caused by Chlamydia trachomatis (Serotypes A-C); Transmitted via hand contact; Disease progression = Repeated infection causes conjunctivitis leading to trichiasis (in-turning of eyelashes)- Eyelashes abrade and scar cornea leading to blindness. This is the leading cause of blindness worldwide; Oral azithromycin are used in treatment.

101
Q

what is Keratitis? and what is the cause in US compared to the cause in Africa and Asia?

A

Inflammation of the cornea - Bacterial (United States) and Fungal (Africa and Asia)

102
Q

what is Herpetic keratitis?

A

(infectious disease) Caused by herpes simplex virus 1 (HSV-1); Infects cornea and may cause blindness; Treated with trifluridine

103
Q

what is Acanthamoeba keratitis?

A

(infectious disease of the eye) Mild inflammation followed by severe pain; Ameba transmitted via water and soil; Associated with unsanitary contact lenses; Treatment with 2% chlorhexidine and propamidine isethionate eye drops or topical neomycin. May require a corneal transplant.

Clinical Microbiology (17 decks)

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