Module 8

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Microbiology
Chapters 19, 20
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1

Folliculitis

  1. What?- follicle infection; called pimple, sty (eyelid), furuncle (boil), or carbuncle (fused furuncles)
  2. Who?- Staph aureus (likely) or S. epidermidis
  3. Diagnosis?- isolate gram+ staph from pus
2

SSSS (Staph. Scalded Skin Syndrome)

  1. What?- exfoliative toxins; no permanent scarring
  2. Who?- S. aureus
  3. Diagnosis?- sloughing epidermis characteristic; pus in blisters are bacteria-free
3

Impetigo (pyoderma)

  1. What?- red patches, pus filled vesicles, itchy, honey-colored sticky crust
  2. Who?- Usually S. aureus , sometime Streptococcus pyogenes (Group A Streptococcus)
  3. Diagnosis?- vesicles; bacteria in pus, morphology = culprit
4

Necrotizing Fasciitis

  1. What?- flesh-eating bacteria
  2. Who?- Strep. pyogenes . Exotoxin A, streptolysin S
  3. Diagnosis?- symptoms non-specific; extreme pain not proportional to injury
5

Acne

  1. What?- infected follicle; whitehead, blackhead, pustule (cystic acne)
  2. Who?- Propionibacterium acnes (85%), some S. aureus
  3. Diagnosis?- visual, widespread, not isolated like a pimple
6

Cat scratch disease

  1. What?- scratch/bite causes fever, prolonged malaise, swelling at infection site and nearby lymph nodes for several months
  2. Who?- Bartonella (gram-neg, so endotoxin)
  3. Diagnosis?- indirect fluorescent antibody test against antigen
7

Pseudomonas infection

  1. What?- opportunistic, issue with burn victims, rarely breaches external barriers, but can infect anywhere in body
  2. Who?- Pseudomonas aeruginosa (gram-neg bacillus)
  3. Diagnosis?- difficult, pyocyanin discoloring (green) indicative
8

Rocky Mountain Spotted Fever

  1. What?- a non-itchy spotted fever rickettsioses from tick vector, subcutaneous hemorrhages in 50% of patients
  2. Who?- Rickettsia rickettsii (aerobic gram-neg, itracellular)
  3. Diagnosis?- serological tests
9

Cutaneous Anthrax

  1. What?- itching before painless, swollen, black, crusty ulcer called eschar; animal handlers beware
  2. Who?- Bacillus anthracis endospores;
  3. Diagnosis?- eschar, patient history
10

Gas gangrene

  1. What?- infected skin blackens, has gas bubbles
  2. Who?- Endospore forming Clostridium perfringens
  3. Diagnosis?- appearance diagnostic; associated with diabetes
11

Poxviruses

  1. What?- smallpox, cowpox, monkeypox (NOT chickenpox)
  2. Who?- Orthopoxvirus (variola virus); dsDNA; enveloped
  3. Diagnosis?- lesion stages (macule, papule, vesicle, pustule, crust, scar)
12

Herpes infections

  1. What?- fever blisters, cold sores, genital herpes
  2. Who?- HSV-1 and -2 (HHV also); dsDNA; enveloped; latent in ganglia
  3. Diagnosis?- lesions; immunoassay
13

Warts

  1. What?- benign epithelial growths on skin or mucous membranes
  2. Who?- Papilloma viruses
  3. Diagnosis?- observation
14

Chickenpox and shingles

  1. What?- lesions (spread in chickenpox; localized along nerve in shingles)
  2. Who?- Varicella-Zoster virus; enveloped dsDNA; latent in ganglia
  3. Diagnosis?- lesions
15

Rubella

  1. What?- minor rash in children; major birth defects in unborn babies
  2. Who?- Rubella virus ( Rubivirus ), enveloped ssRNA(+)
  3. Diagnosis?- rash and serological testing
16

Measles (Rubeola)

  1. What?- serious; Koplik's spots in mouth mucous membrane
  2. Who?- Measles virus ( Morbillivirus ); enveloped ssRNA(-) virus
  3. Diagnosis?- Koplik’s spots
17

Mycoses

  1. What?- Fungal infections; dermatophytoses; Ringworm or Tinea
  2. Who?- Microsporum, Trichophyton, and Epidermophyton
  3. Diagnosis?- Clinical observation
18

Leishmaniasis

  1. What?- parasitic; cutaneous, mucocutaneous, and visceral
  2. Who?- Leishmania (via female sand flies) infect macrophages
  3. Diagnosis?- microscopic ID of protozoan
19

Scabies

  1. What?- itchy, pimple-like furrows under skin, especially itchy at night
  2. Who?- the arachnid Sarcoptes scabiei
  3. Diagnosis?- characteristic burrows and finding eggs/fecal matter on skin
20

Bacterial Meningitis- Three types

What?- severe headache, nausea, vomiting, high fever with meningeal inflammation; encephalitis; stiff neck

Neisseria meningitidis (Meningococcal meningitis)- Nonmotile g(-) cocci, capsule, LOS endotoxin. Intracellular (in phagocytes).

Strep. pneumoniae- g(+) cocci; intracellular in host cells that cross blood-brain barrier

Listeria monocytogenes - g(+) coccobacillus; uses LLO to escape phagosomes, uses host cytosolic actin to make comet-tails to move and push into neighboring cells. Actively crosses blood-brain barrier

Diagnosis?- symptoms and culturing from cerebral spinal fluid (CSF)

21

Leprosy

  1. What?-
    1. Tuberculoid- Non-progressive. Nerve damage/lost sensation. Good T-cell response
    2. Lepromatous- Progressive tissue damage. Weak T-cell response
  2. Who?- Mycobacterium leprae : high G-C g(+) bacillus
  3. Diagnosis?- via signs/symptoms; confirm acid-fast bacilli in samples
22

Botulism

  1. What?- deadliest toxin. Weak, dizzy, voluntary muscle paralysis, death.
  2. Who?- Clostridium botulinum - endospore, g+ bacillus. Prevents motor neurons from releasing acetylcholine vesicles into synaptic cleft
  3. Diagnosis?- culture or toxin detection
23

Tetanus

  1. What?- tightening jaw, neck muscles, sweating, spasms; death due to not being able to exhale
  2. Who?- Clostridium tetani - tetanospasmin prevents release of inhibitory neurotransmitter to muscles, so they can’t unclench.(Opposite of botulism)
  3. Diagnosis?- characteristic muscle contractions, often too late by then
24

Viral meningitis

  1. What?- fever, headache, confusion; milder than bacterial or fungal meningitis; most common meningitis
  2. Who?- Enterovirus - naked ssRNA(+), lytic; named after portal of entry, not disease they cause
  3. Diagnosis?- signs/symptoms w/o bacteria in CSF
25

Poliomyelitis

  1. What?-almost 90% asymptomatic; minor; nonparalytic; paralytic
  2. Who?- Poliovirus (an Enterovirus)- naked (+)ssRNA; destroys motor neurons in brainstem that connect to upper spinal cord
  3. Diagnosis?- look for virus in throat and feces
26

Rabies

  1. What?- seizures, hallucinations, paralysis, hydrophobia
  2. Who?- Rabies virus- ssRNA(-), bullet-shaped envelope
  3. Diagnosis?- via unique neurological symptoms and Ab in blood; post-mortem detection of Negri-brodies (viral aggregates) in brain cells
27

Arboviral encephalitis

  1. What?- arthropod-borne viruses; mild unless cross blood-brain barrier: high fever, weakness, nausea, headache, confusion, coma.
  2. Who?- Togaviruses, Flaviviruses. Ex: West nile encephalitis
  3. Diagnosis?- via signs/symptoms and antibodies to different arboviruses
28

Cryptococcal meningitis

  1. What?- Fungal, similar to bacterial/viral meningitis
  2. Who?- Cryptococcus neoformans- spherical single-celled
  3. Diagnosis?- fungal antigens in CSF
29

African Sleeping Sickness

  1. What?- lesion at bite; in blood causing lymph node swelling, fever, and headaches; invade CNS causing meningoencephalitis; cyclical parasitemia in blood every 7-10 days
  2. Who?- Trypanosoma brucei via tsetse fly
  3. Diagnosis?- observe trypanosomes in blood, lymph, or CSF
30

vCJD

  1. What?- prion disease
  2. Who?- prion proteins
  3. Diagnosis?- signs/symptoms, but often confused with dementia