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Microbiology Flashcards

1
Q

Gram positive structure

A

Cell wall present; major surface antigen

Composition:

  • Peptidoglycan
  • Lipoteichoic acid–> TNF, IL-1 induction
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2
Q

Gram negative structure

A

No cell wall, only outer membrane
- Site of Endotoxin= LPS (lipopolysaccharide)= major surface antigen

Composition:

  • Lipid A–> activate macrophages–> increased TNF and IL-1
  • Antigen= O polysaccharide
  • Periplasm= space between cytoplasmic membrane and outer membrane; contains hydrolytic enzymes (beta-lactamases)
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3
Q

Spore structure

A

Resistant to dehydration, heat, chemicals
- Must autoclave (121 C for 15 min)

Composition:

  • Keratin-like coat
  • Dipicolinic acid core
  • Peptidoglycan

Seen in:

  • Soil: B. anthracis, Clostridium perfringens, c. tetani
  • Other: B. cereus, C. botulinum, Coxiella burnetti
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4
Q

Gram-positive cocci

A

Staphylococcus

Streptococcus

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5
Q

Gram-negative cocci

A

Neisseria

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6
Q

Gram-positive rod

A 
Clostridium
Corynebacterium
Bacillus
Listeria
Mycobacterium (high lipid= acid fast)
Gardenerella (gram variable)
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7
Q

Gram-negative rods

A

Almost everything else:

  1. Enterics:
    - E. Coli
    - Shigella
    - Yersinia
    - Klebsiella
    - Proteus
    - Enterobacter
    - Serratia
    - Vibrio
    - Campylobacter
    - Helicobacter (silver stain+)
    - Pseudomonas
    - Bacteroides
  2. Respiratory:
    - Haemophilus (pleomorphic)
    - Legionella (intracellular; silver stain +)
    - Bordetella
  3. Zoonotic
    - Francisella
    - Brucella
    - Pasteurella
    - Bartonella
    • resistant to Penicillin G (gram-negative outer membrane inhibits Pen G/Vanco from entering)
    • Susceptible to Ampicillin, amoxicillin
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8
Q

Spirochetes

A

Gram-negative (too thin)

  • Leptospira
  • Borrelia
  • Treponema
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9
Q

Pleomorphic bacteria

A

Giemsa-stain

  • Rickettsiae (intracellular)
  • Chlamydiae (intracellular, no muramic acid)
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10
Q

Bacteria with no cell wall

A

Mycoplasma= no staining

- Sterols with no wall

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11
Q

Giemsa-positive

A

Certain Bugs Really Try my Patience:

  • Chlamydia
  • Borrelia
  • Rickettsiae
  • Trypanosomes
  • Plasmodium
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12
Q

Carbol Fuschin stain (Ziehl-Neelsen)

A

Acid-fast organisms

  • Nocardia
  • Mycobacterium
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13
Q

India ink positive

A

Cryptococcus neoformans

- can also stain with mucicarmine

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14
Q

Exotoxin

A

Derived from gram + and gram -

  • Secreted from cell
  • Polypeptide
  • Located on plasmid/bacteriophage
  • Highly toxic
  • Antigenic= Induces antitoxins (titer antibodies)
  • Vaccine= toxoids
  • Destroyed at 60C (besides staph enterotoxin)

Seen in: Tetanus, botulism, diphtheria

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15
Q

Endotoxin

A

LPS= structural component of outer cell membrane in gram negative; released when lysed (NOT secreted)

Activates:

  1. Macrophages:
    - IL-1–> fever
    - TNF–> fever, hypotension
    - NO–> hypotension
  2. Complement
    - C3a–> hypotension, edema
    - C5a–> neutrophil chemotaxis
  3. Tissue factor
    - Coagulation cascade–> DIC
  • Located on Bacterial chromosome
  • Low toxicity
  • Causes: Fever, shock
  • Mode of action:Induces TNF and IL-l
  • Antigenic: Poorly antigenic
  • Vaccines= none
  • Stable at 100C for 1 hour

Seen in: meningococcemia, gram-negative sepsis

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16
Q

Obligate aerobes

A

Nagging Pests Must Breathe

  • Nocardia
  • Pseudomonas aeruginosa
  • Mycobacterium tuberculosis (apices of lung)
  • Bacillus
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17
Q

Obligate anaerobes

A

Can’t Breathe Air

  • Clostridium
  • Bacteroides
  • Actinomyces

Seen in GI tract, pathogenic anywhere else
** Can’t treat with aminoglycosides= need O2 to enter cell

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18
Q

Obligate intracellulars

A

Rickettsia

Chlamydia

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19
Q

Facultative intracellular

A

Now Listen Sally, Yer Friend Bruce Must Leave

  • Neisseria
  • Listeria
  • Salmonella
  • Yersinia Pestis
  • Francisella
  • Brucella
  • Mycobacterium
  • Legionella
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20
Q

Encapsulated bacteria

A

Positive Quellung reaction–> swelling

SHiNE SKiS

  • Streptococcus pneumoniae
  • Haemophilus infiuenzae type B
  • Neisseria meningitidis
  • Escherichia coli
  • Salmonella
  • Klebsiella pneumoniae
  • group B Strep.
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21
Q

Catalase-positive

A 
Degrades H2O2 before converted to microbicidal products by Myeloperoxidase (MPO)
PLACESS for your cats:
- Pseudomonas
- Listeria
- Aspergillus
- Candida
- E. Coli
- S. Aureus
- Serratia
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22
Q

Urease-positive

A

CHuck norris hates PUNKSS:

  • Cryptococcus
  • H. pylori
  • Proteus
  • Ureaplasma
  • Nocardia
  • Klebsiella
  • S. epidermidis
  • S. saprophyticus
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23
Q

IgA protease

A

Enzyme cleaving IgA–> colonize respiratory mucosa: SHiN

  • S. pneumoniae
  • H. influenza (B)
  • Neisseria

** These can all take up naked DNA from environment as well= Transformation

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24
Q

Protein A

A

S. Aureus

- Binds Fc region of Ig–> no opsonization/phagocytosis

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25
Q

M Protein

A

Group A strep

- Prevents phagocytosis

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26
Q

Pigment-producing bacteria

A

Actinomyces Israelii= yellow (Israel= yellow sand)

S. Aureus= yellow (pus/gold)

Pseudomonas aeruginosa= blue/green (pyocyanin)

Serratia marcescens= red (maraschino cherry)

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27
Q

Novobicin

A

Used to ID catalase-positive, coagulase-negative staphylococci

  • Staph Saprophyticus= resistant
  • Staph Epidermis= sensitive
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28
Q

Optochin

A

used to ID catalase-negative alpha-hemolytic streptococci:

  • Viridans= resistant
  • Penumoniae= sensitive
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29
Q

Bacitracin

A

Used to ID Catalse-negative, beta-hemolytic streptococci:

  • Agalactiae= resistant
  • Pyogenes= sensitive
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30
Q

Alpha-hemolytic bacteria

A

Partial hemolysis; green ring around colonies

  • Strep pneumo
  • Strep viridans
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31
Q

Beta-hemolytic bacteria

A

Complete hemolysis; clear ring around colonies:

  • Staph aureus
  • Strep pyogenes (group A)
  • Strep agalctiae (group B)
  • Listeria monocytogenes
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32
Q

Staphylococcus aureus

A

Gram positive cocci, Clustered
Catalase positive
Coagulase positive

Virulence factor= Protein A (binds Fc-IgG–> prevents phagocytosis)

Causes:

  1. Inflammatory disease: skin infections, organ abscesses, pneumonia
    - Acute bacterial endocarditis
    - Osteomyelitis
  2. Toxin-mediated disease:
    - Toxic shock syndrome (TSST-1)= superantigen, binds MHC II receptor–> T-cell activation–> IFN-gamma, IL-2 release
    - scalded skin (exfoliative toxin)
    - rapid-onset food poisoning (preformed enterotoxins)
    * * Activates T-cells (IL-2) and macrophages (IL-1, TNF)
  3. MRSA: resistant to beta-lactams (altered penicillin-binding protein)

Treatment:

  • Nafcillin (Naf for Staph- EXCEPT MRSA)
  • Vancomycin for MRSA

THINK:

  • Pus, empyema, abscess
  • Surgical wound
  • chronic granulomatous disease (Catalase-positive microbes)
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33
Q

Staphylococcus epidermidis

A

Gram positive cocci
Catalase positive
Coagulase negative
Novobicin sensitive (vs staph saprophyticus)

Infects prostehetic devices, IV catheters (biofilm)

  • Seen in normal skin flora
  • Contaminates blood cultures

Resistant to penicillins, tx with Vancomycin

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34
Q

Staphylococcus saprophyticus

A

Gram positive cocci
Catalase positive
Coagulase negative
Novobicin resistant (vs staph epidermidis)

Causes UTIs

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35
Q

Streptococcus pneumoniae

A 
Gram positive cocci; lancet shaped
Catalase negative
alpha-hemolytic
Capsule (+ quelling)
Optochin sensitive (vs strep Viridans)
IgA protease

Causes:

  • Meningitis
  • Otitis media
  • Pneumonia (rusty sputum)
  • Sinusitis
  • Sepsis, splenectomy in Sickle cell
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36
Q

Streptococcus viridans

A 
Gram positive cocci
Catalase negative
alpha-hemolytic
No capsule
Optochin resistant (vs strep pneumo)

Causes:

  • Dental caries (normal flora in mouth= strep mutans)
  • Subacute bacterial endocarditis (strep sanguis)
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37
Q

Strep pyogenes

A 
Group A strep
Gram positive cocci
Catalase negative
beta-hemolytic
Bacitracin sensitive (vs strep agalactiae)

M-protein (prevents opsonization–> blocking phagocytosis)

Exotoxin=

  1. streptolysin O
    - Protein degrades cell membrane (lyse RBCs)- test for ASO antibodies
  2. Exotoxin A: brings MHC II and T-cell receptors together–> release IFN-gamma, IL-2 release–> Toxic shock-like syndrome
  3. Streptokinase= plasminogen activator (blocks clotting)

Causes:

  1. Pyogenic:
    - Pharyngitis
    - Cellulitis
    - Impetigo (precedes glomerulonephritis, pharyngitis)
  2. Toxigenic:
    - Scarlet fever (spares face, strawberry tongue, throat)
    - Toxic shock-like syndrome
    - Necrotizing fasciitis
  3. Immunologic:
    - Rheumatic fever (polyarthritis, carditis, subcutaneous nodules, erythema marginatum, Sydenham’s chorea)
    - Acute glomerulonephritis
    - Post strep glomerulonephritis= deficiency of complement due to fixation in renal tubules
    • ASO titer to detect infection (antibodies to streptolysin O)
    • Host antibodies to M-protein–> rheumatic fever
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38
Q

Strep agalactiae

A 
Group B strep
Gram positive coci
Catalase negative
Beta hemolytic (Produces CAMP factor--> increased hemolysis)
Bacitracin resistant (vs strep pyogenes)
Hippurate test positive

Causes:

  • Illnesses mainly seen in babies (due to colonization of vaginal flora): Pneumonia, meningitis, sepsis
    • Screen women at 35-37 weeks
  • Prophylaxis with penicillin
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39
Q

Enterococci

A 
Group D strep
Gram positive cocci
Catalase negative
Non-hemolytic/variable hemolysis
Grows in Bile and 6.5% NaCl

Enterococci faecalis, faecium:

  • Penicillin G resistant
  • Cause UTI, biliary tract infections, subacute endocarditis
  • Vancomycin-resistant strains= nosocomial infection
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40
Q

Streptococcus bovis

A 
Group D strep
Gram positive cocci
Catalase negative
Non-hemolytic
Grows in Bile (no NaCl)

Colonizes gut
- Colon cancer patients: subacute endocarditis, bacteremia

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41
Q

Corynebacterium diphtheriae

A

Gram positive rod (club-shaped)

Black colonies in cystine-tellurite agar

Metachromatic (blue and red) granules
AB Exotoxin= (B=binds, A= active–> EF-2)
- B-prophage encoded–> inhibits protein synthesis (ADP-ribosylates elongation factor= EF-2)
- Test= Elek’s test

Causes:

  • Pseudomembranous pharyngitis (gray-white)
  • Lymphadenopathy
  • Myocarditis
  • Arrhythmias

** Toxoid vaccine= induces production of IgG against exotoxin B (toxin causes disease, not bacteria)

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42
Q

Clostridium tetani

A

Gram-positive rod
Spore-forming
Obligate anaerobe

Exotoxin= Tetanospasmin

  • Tetanus toxin–> cleaves neurotransmitter-releasing proteins (SNARE)
  • Blocks glycine, GABA release (inhibitory neurotransmitters) from Renshaw cells in spinal cord
  • Causes spastic paralysis, trismus (lockjaw), risus sardonicus)

Tx: passive vaccine

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43
Q

Clostridium botulinum

A

Gram-positive rod
Spore-forming
Obligate anaerobe

Exotoxin= botulinum toxin

  • Cleaves SNARE proteins (blocking neurotransmitter release)
  • Inhibits ACh release at NM junction–> flaccid paralysis
  • Adults= ingest preformed toxin
  • Babies= spores in honey–> floppy baby)

Tx: passive vaccine

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44
Q

Clostridium perfringens

A

Gram-positive rod
Spore-forming
Obligate anaerobe

Exotoxin= alpha toxin (lecithinase= phospholipase)

  • Phospholipase degrades tissue, cell membranes–>
  • Causes myonecrosis (gas gangrene)
  • Hemolysis
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45
Q

Clostridium difficile

A

Gram-positive rod
Spore-forming
Obligate anaerobe

Exotoxins:

  1. Toxin A = enterotoxin binding brushborder of gut)
  2. Toxin B = cytotoxin binding enterocytes–> pseudomembranous colitis
    - Secondary to antibiotics (clindamycin, ampicillin)

Treatment:

  • Metronidazole
  • Oral vancomycin
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46
Q

Bacillus anthracis

A

Gram-positive rod
* Polypeptide capsule (D-glutamate containing)
Spore-forming

Exotoxin= anthrax (Edema factor)

  • Mimics adenylate cyclase (increased cAMP)
  • Calmodulin-dependent adenylate cyclase–> increases cAMP in smooth muscle–> vasodilation (edema), suppressed neutrophil funciton)

Forms:

  • Cutaneous–> black eschar (painless ulcer)–> bacteremia, death)
  • Pulmonary–> flu-like symptoms–> fever, pulmonary hemorrhage, mediastinitis, shock (Woolsorter’s disease)
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47
Q

Bacillus cereus

A

Gram-positive rod
Spore-forming
Obligate aerobe

Enterotoxin= Cereulide

  • Food poisoning (enterotoxin in rice= “reheated rice syndrome)
  • Emesis: rice, pasta–> N/V in 1-5 hours
  • Diarrhea: GI pain, watery, non-bloody in 8-18 hours
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48
Q

Listeria Monocytogenes

A

Gram positive rod
Facultative intracellular
Catalase positive
Beta hemolytic

Forms “actin rockets”–> move cell to cell
- Tumbling motility

Ingested from unpasteurized milk/cheese, deli meats
Causes:
- Amnionitis
- Septicemia
- Spontaneous abortion
- Meningitis in immunocompromised
- Gastroenteritis in healthy (self-limited)

Vaginal transmission
Causes:
- Granulomatosis infantiseptica
- Neonatal meningitis

  • Tx= ampicillin
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49
Q

Actinomyces

A 
Long, branching filament (resembles fungi)
Gram-positive
Anaerobe
NOT acid-fast
Found in normal oral flora

Causes:

  • Oral/facial abscesses that drain–> sinus tracts
  • Yellow “sulfur granules”

Tx: Penicillin

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50
Q

Nocardia

A 
Long, branching filament (resembles fungi)
Gram-positive
Aerobe
Acid fast
Found in soil

Causes:

  • Pulmonary infections in immunocompromised
  • Cutaneous infections (post-trauma) in healthy

Tx: Sulfonamides

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51
Q

Mycobacterium tuberculosis

A

Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices)
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion

Primary TB:

  • Nonimmune host infected–> Ghon complex:
    1. Heals (fibrosis)–> immunity/hypersensitivity
    2. Progressive lung disease (immune compromised)
    3. Severe bacteremia–> Miliary TB
    4. Preallergic lymphatic/hematogenous dissemination–> dormant–> reactivate later in life

Secondary TB:

  • Partially immune hypersensitized host (adult) reinfected)
    1. Fibrocaseous cavitary lesion (upper lobes)
    2. Reactivates

Reactivated TB= Extrapulmonary TB

  • CNS (parenchymal TB/meningitis in base of brain)
  • Vertebral body (Pott’s disease)
  • Lymphadenitis
  • Renal
  • GI

Symptoms:
- Fever, night sweats, weight loss, hemoptysis

Tx:

  • Prophylaxis= Isoniazid (INH)
  • Therapy= Rifampin, Isoniazid, Pyrazinamide, Ethambutol (RIPE for tx)
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52
Q

Mycobacteria Kansasii

A

Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices)
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion

Pulmonary TB-like symptoms

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53
Q

Mycobacterium avium-intracellulare

A

Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices)
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion

Disseminated non-TB disease in AIDS, resistant to multiple drugs

** Prophylaxis with azithromycin (CD4+ < 50)
Tx: Azithromycin, Rifampin, Ethambutol, Streptomycin

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54
Q

Mycobacterium leprae

A

Gram-positive rod
Carbol-Fuschin (Ziehl-Neelsen) stain
Acid fast (lipid membrane)
Obligate aerobe (lung apices), likes cool temps
Facultative intracellular
* Cord factor in virulent strain–> TNF-alpha release, inhibited macrophage maturation
* Sulfatides (surface glycolipids) inhibit phagolysosomal fusion

Reservoir in USA= armadillos

Causes Leprosy. 2 forms:
1. Lepromatous= lethal
- Communicable
- Low cell-mediated immunity, humoral Th2 response only
Tx: Dapsone, rifampin, clofazimine (2-5 years)

  1. Tuberculoid= hypoesthetic hairless skin plaques (“glove and stocking” loss of sensation)
    Tx: Dapsone, Rifampin (6 months)
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55
Q

Lactose-fermenting enteric bacteria

A

Gram-negative rods
Grow pink colonies on MacConkey’s agar:

Fast fermenter= Lactose in KEE

  • Klebsiella
  • E. coli
  • Enterobacter

Slow fermenter=

  • Citrobacter
  • Serratia
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56
Q

Neisseria Gonococci

A

Gram-negative diplococci
Ferments Glucose (Gonococci)
Produces IgA proteases
Facultative intracellular

Grown on special agar: Thayer-Martin agar (or VPN agar)—an agar plate containing antibiotics (vancomycin, colistin, nystatin, and TMP-SMX)

  • NO vaccine available (rapid antigenic variation in pilus)
  • STD

Causes:

  • Septic arthritis
  • Neonatal conjunctivitis
  • PID
  • Fitz-Hugh-Curtis syndrome (adhesions due to PID; infection of liver capsule)

Tx: Ceftriaxone (+ azithromycin/doxycyclin for chlamydia coinfection)

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57
Q

Neisseria Meningococci

A 
Gram-negative diplococci
Ferments Maltose and glucose (MeninGococci)
Produces IgA proteases
Facultative intracellular
Encapsulated (polysaccharide capsule)

Grown on special agar: Thayer-Martin agar (or VPN agar)—an agar plate containing antibiotics (vancomycin, colistin, nystatin, and TMP-SMX)

  • Vaccine (none for Type B)
  • Found in respiratory, oral secretions

Causes:

  • Meningococcemia
  • Meningitis
  • Waterhouse-Friderichsen syndrom

Tx: Ceftriaxone, Pen G
** Rifampin, ciprofloxacin, ceftriaxone in close contacts

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58
Q

Haemophilus Influenza

A 
Gram negative 
Coccoid rods
Requires factor V and X to grow in culture (chocolate agar)
IgA protease
Encapsulated
  • Vaccine= type B capsular polysaccharide conjugated to diphtheria toxoid (2-18 months)
  • Nontypable strains cause mucosal infections (no vaccine available)

Causes:

  • Epiglottitis (cherry red)
  • Meningitis
  • Otitis media
  • Pneumonia

Tx: Ceftriaxone (meningitis)
* Rifampin prophylaxis in close contacts

THINK:
- Pediatric infection (epiglottitis)

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59
Q

Legionella pneumophilia

A

Gram-negative rod
Facultative intracellular
Silver stain
Grown on charcoal yeast extract with iron, cysteine

  • Aerosol transmission from water source
  • Detected in urine
  • Labs show hyponatremia

Causes:

  • Legionnaire’s disease= severe pneumonia, fever, GI, CNS symptoms
  • Pontiac fever= mild flu-like syndrome

Tx: Macrolide (protein synthesis), quinolone (topoisomerase II)

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60
Q

Pseudomonas aeruginosa

A 
Gram negative rod (enteric)
Obligate aerobe
Catalase positive 
Lactase NON-fermenting
Oxidase positive
Blue-green pigment, grape-like odor

Motile, oxidase positive

Produces:

  • Endotoxin (fever, shock)
  • Exotoxin A (inactivates EF-2)
  • Elastase (breaks down vessel walls)
Causes: PSEUDOmonas
- Pneumonia (chronic in CF pts due to biofilm)
- Sepsis
- External otitis
- UTI
- Drug use
- Osteomyelitis (diabetic/drug user)
\+ Hot tub foliculitis, wound/burn infections
\+ MEO in diabetics

Tx:
- Aminoglycoside + extended-spectrum penicillin (piperacillin, ticarcillin)

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61
Q

Enteroinvasive E. Coli (EIEC)

A

Gram-negative rod
Lactose fermenting

Virulence factors:

  • P fimbriae (cystitis/pyelonephritis)
  • K capsule (pneumonia, neonatal meningitis)
  • LPS endotoxin (septic shock)

Mechanism:
- Invades intestinal mucosa–> necrosis, inflammation

Manifestation: similar to Shigella

  • Invasive
  • Dysentery (blood, pus in stool)
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62
Q

Enterotoxigenic E. Coli (ETEC)

A

Gram-negative rod
Lactose fermenting

Virulence factors:

  • P fimbriae (cystitis/pyelonephritis)
  • K capsule (pneumonia, neonatal meningitis)
  • LPS endotoxin (septic shock)

Mechanism:

  • Labile toxin: overactivates adenylate cyclase–> increased cAMP–> Cl- secretion in gut–> H20 moves out of cells
  • Stable toxin: overactivates guanylate cyclase–> increased cGMP–> decreased resorption of NaCl /H20 in gut
  • NO inflammation/invasion

Manifestation: traveler’s diarrhea

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63
Q

Enteropathogenic E. Coli (EPEC)

A

Gram-negative rod
Lactose fermenting

Virulence factors:

  • P fimbriae (cystitis/pyelonephritis)
  • K capsule (pneumonia, neonatal meningitis)
  • LPS endotoxin (septic shock)

Mechanism:

  • Adheres to apical surface, flattens villi
  • Prevents absorption

Manifestation:
- Pediatric diarrhea

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64
Q

Enterohemorrhagic E. Coli (EHEC)

A

Gram-negative rod
Lactose fermenting

Virulence factors:

  • P fimbriae (cystitis/pyelonephritis)
  • K-1 capsule (pneumonia, neonatal meningitis)
  • LPS endotoxin (septic shock)

Mechanism:

  • O157:H7= most common–> Shiga-like toxin
  • Shiga-like toxin (SLT)= inactivates 60S ribosomal subunit by removing adenine from rRNA
  • Endothelial swelling, narrowed lumen–> hemolysis, reduced renal blood flow
  • Damaged endothelium–> thrombocytopenia

Cuases:

  • Dysentery (Shiga-like)
  • Hemolytic-uremic syndrome (HUS) due to cytokine release in response to SLT–> vascular damage–> capillary thrombus formation–> anemia, thrombocytopenia, acute renal failure, increased bleeding time
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65
Q

Klebsiella

A

Gram negative rod
Lactose fermenter
Polysaccharide capsule (mucoid colonies)

4As:

  • Aspiration pneumonia
  • Abscess (lungs/liver)
  • Alcoholics
  • diAbetics
  • can also cause nosocomial UTI: positive urease test
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66
Q

Salmonella

A 
Gram negative rod
Lactose non-fermenter
Oxidase negative
Facultative intracellular
Encapsulated
  • Flagellated
  • Hematogenous dissemination
  • Animal reservoir
  • Produce hydrogen sulfide
  • Invades intestinal mucosa–> monocytic response

Causes:

  • Bloody diarrhea
  • Non-typhoidal= appendicitis mimicker
  • Typhi= Typhoid fever (humans only): rose spots on abdomen, fever, headache, diarrhea
  • Osteomyelitis in sickle cell pts

Tx: Antibiotics prolong symptoms

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67
Q

Shigella

A

Gram negative rod
Lactose non-fermenter
Oxidase negative
Shiga toxin= inactivates 60S ribosomal subunit by removing adenine from rRNA

  • No flagella
  • Cell to cell transmission
  • Reservoir= humans/primates
  • Invades intestinal mucosa–> PMN infiltration
  • Shiga toxin–> Cytokine release–> HUS: due to cytokine release in response to Shige toxin–> vascular damage–> capillary thrombus formation–> anemia, thrombocytopenia, acute renal failure, increased bleeding time

Tx: antibiotics shortens excretion of organism in feces

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68
Q

Campylobacter jejuni

A

Gram negative comma-shaped
Oxidase positive
Grows at 42C

Transmitted through poultry, meat, unpasteurized milk

Causes:

  • Bloody diarrhea (esp. children)
  • Guillain-Barre syndrome, reactive arthritis
  • Mimics appendicitis
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69
Q

Vibrio cholerae

A

Gram negative comma-shaped
Oxidase positive
Grows in alkaline media

Mechanism:
- Cholera toxin Activates Gs of adenylate cyclase–> increased cAMP–> increased Cl- secretion, H20 efflux

Causes:
- Profuse rice-water diarrhea (common in developing countries)

Tx: rehydration

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70
Q

Yersinia enterocolitica

A

Gram negative rod
Facultative intracellular

Mechanism:
- Transmitted from pet feces, contaminated milk, pork

Causes:
- Mesenteric adentitis (Crohn’s, appendicitis mimicker)

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71
Q

H. Pylori

A

Curved Gram-negative rod
Silver stain
Urease positive (urease breath test)- alkaline environment created in stomach

Causes:

  • Gastritis
  • 90% duodenal ulcers
  • Increased peptic ulcer, gastric adenocarcinoma, B-cell lymphoma risk

Tx: triple therapy:

  • PPI
  • Clarithromycin
  • Amoxicillin/ Metronidazole
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72
Q

Spirochetes

A

Borrelia (BIG)= Wright/Giemsa stain
Leptospira
Treponema= dark field microscopy

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73
Q

Leptospira interrogans

A

Spirochete

Water contaminated with animal urine (triathletes in tropics)

Causes:

  • Flu-like symptoms
  • Jaundice
  • Photophobia with conjunctivitis
  • Weil’s disease= icterohemorrhagic leptospirosis: severe; jaundice, azotemia (liver, kidney dysfunction), fever, hemorrhage, anemia
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74
Q

Borrelia Burgdorferi

A

Spirochete (visualized with Wright/Giemsa stain)

Lyme disease:

  • Transmitted by Ixodes tick
  • Reservoir= wood mouse
  • Stages:
    1. Erythemia migrans (bull’s eye), flu-like
    2. Neurologic (Bell’s palsy), cardiac (AV node block)
    3. Musculoskeletal (chronic monoarthritis, migratory polyarthritis), neurological (encephalopathy, polyneuropathy), cutaneous
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75
Q

Treponema Pallidum

A

Spirochete

  • Visualized by dark-field microscopy
  • Screened with VDRL, confirmed with FTA-ABS

Syphillis:

  1. Primary: localized painless chancre (treponemes)
  2. Secondary: disseminated disease
    - Constitutional symptoms
    - Maculopapular rash
    - Condylomata lata (treponemes found on warty lesions)
  3. Tertiary:
    - Gummas (chronic granulomas)
    - Aortitis (vaso vasorum destruction)
    - Neurosyphilis (tabes dorsalis)
    - Argyll-Robertson pupil (non-reactive, accomodative)
    - Signs: broad-based ataxia, + Romberg, Charcot joint, stroke w/o HTN
    - Treponemes in spinal tap

Congenital syphilis:

  • Saber shins
  • Sadle nose
  • CNVII deafness
  • Hutchinson’s teeth
  • Mulberry molars
    • VDRL= nonspecific; can also indicate:
  • Viruses
  • Drugs
  • Rheumatic fever
  • Lupus, leprosy

Tx: Pen G
- Can lead to Jarisch-Herxheimer reaction (killed bacteria release pyrogens)- administer steroids, low dose antibiotics

76
Q

Bartonella

A

Cat scratch disease

- Can cause bacillary angiomatosis in immune compromised

77
Q

Borrelia Recurrentis

A

Recurrent fever

Source: Louse

78
Q

Brucella

A

Gram negative rod
Facultative intracellular

Causes: Undulent fever

Source: unpasturized dairy

79
Q

Chlamydia psittaci

A

Obligate intracellular organism (cannot make own ATP)

  • Giemsa positive
  • Pleomorphic

Elementary body= Enters cell via Endocytosis

Reticulate body= replicates in cell via fission (seen on tissue culture)
- Cytoplasmic inclusions on Giemsa, fluorescent antibody

Psittacosis (pneumonia)

Source: parrots, birds

Tx:

  • Azithromycin (one time)
  • Doxycycline
80
Q

Coxiella burnetii

A

Q fever

Source: aerosol of cattle, sheep amniotic fluid
- Survives in soil for years (spore)

Tx: Doxycycline

81
Q

Ehrlichia chaffeensis

A

Monocyte with morula (berry-like) inclusion in cytoplams

Ehrlichiosis

Source: lone star tick

Tx: Doxycycline

82
Q

Francisella tularensis

A

Tularemia

Source: ticks, rabbits, deer fly

83
Q

Pasteurella multocida

A

Cellulitis, osteomyelitis

Source: animal bite (cat, dog)

84
Q

Rickettsia prowazekii

A

Obligate intracellular
Need CoA and NAD+

Epidemic typhus (pro-WAr)
- Rash sparing palms and soles

Source: louse

Tx: Doxycycline

85
Q

Rickettsia Typhi

A

Obligate intracellular
Need CoA and NAD+

Endemic typhus

Source: fleas

Tx: Doxycycline

86
Q

Yersinia pestis

A

Facultative intracellular
Plague

Source: fleas (rats/prairie dogs= reservoir)

87
Q

Gardenerella vaginalis

A

Gram-variable pleomorphic rod
“Clue cells” on vaginal swab
KOH prep= fishy smell

Causes: Bacterial vaginitis

  • Non-painful, smelly
  • Not STD (associated with sexual activity)

Tx: Metronidazole

88
Q

Rickettsia Rickettsii

A

Obligate intracellular
Need CoA and NAD+

Causes:

  • Rocky Mountain Spotted Fever (Broad distribution)
  • Rash: wrists, ankles–> trunks, palms, soles
  • Headache, fever
89
Q

Anaplasma

A

Anaplasmosis:

Granulocytes with morula in cytoplasm

90
Q

Chlamydia trachomatis

A

Obligate intracellular organism (cannot make own ATP)

  • Giemsa positive
  • Pleomorphic

Elementary body= Enters cell via Endocytosis

Reticulate body= replicates in cell via fission (seen on tissue culture)
- Cytoplasmic inclusions on Giemsa, fluorescent antibody

Causes:
Reiter's syndrome:
- Reactive arthritis
- Conjunctivitis
- Nongonococcal urethritis
- PID

Serotypes:

  • A, B, C= chronic infection–> follicular conjuntivitis–> blindness (ABC= Africa, Blindness, Chronic infection)
  • D-K= Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis)
  • L1, L2, L3= lymphogranuloma

Tx:

  • Azithromycin (one time)
  • Doxycycline
91
Q

Mycoplasma pneumoniae

A

No cell wall (no stain)
- Sterol membrane (stability)

Atypical “walking” pneumonia

  • Insidious onset, H/A, nonproductive cough, diffuse interstital infiltrate
  • IgM titer–> agglutinate, lyse RBCs

Tx: macrolide, fluoroquinolone

92
Q

Bordetella pertussis

A

Pertussis toxin
- Overactivates adenylate cyclase–> increased cAMP (disables Gi)–> impairs microbial phagocytsosis

Causes:
- Whooping cough= cough on expiration, whoop on inspiration

93
Q

Histoplasmosis

A 
Dimorphic fungi (20C= cold mold, 37C= heat yeast)
- Can mimic TB with no person-person transmission

Location:

  • Mississippi, Ohio river valleys
  • Bird/bat droppings in CAVES

Causes: pneumonia
- Hilar adenopathy

Histo: Macrophage filled with histo (Histo hides in macrophages)

Tx:

  • Local= fluconazole, itraconazole
  • Systemic= Amphotericin B
94
Q

Blastomycosis

A 
Dimorphic fungi (20C= cold mold, 37C= heat yeast)
- Can mimic TB with no person-person transmission

Location:
- States East of Mississippi river, Central America

Causes: inflammatory, lung disease

  • Disseminates to skin, bone
  • Granulomatous nodules

Histo: broad-based budding (Blasto Buds)

Tx:

  • Local= fluconazole, itraconazole
  • Systemic= Amphotericin B
95
Q

Coccidioidomycosis

A 
Dimorphic fungi (20C= cold mold, 37C= heat SPHERULE)
- Can mimic TB with no person-person transmission

Location:
- SW USA, California (Valley fever)

Causes: pneumonia, meningitis

  • Disseminate to skin, bone
  • Increased cases after earthquakes

Histo: Spherule filled with endospores (larger than RBC)
- Coccidio crowds

Tx:

  • Local= fluconazole, itraconazole
  • Systemic= Amphotericin B
96
Q

Paracoccidioidomycosis

A 
Dimorphic fungi (20C= cold mold, 37C= heat yeast)
- Can mimic TB with no person-person transmission

Location: Latin America (Paracoccdio parasails with Captain’s wheel all the way to Latin America)

Histo:
- Budding yeast, captain’s wheel formation

Tx:

  • Local= fluconazole, itraconazole
  • Systemic= Amphotericin B
97
Q

Tinea Versicolor

A

Malassezia furfur

  • Lipid degradation–> acids–> malanocyte damage–> hypo/hyperpigmented areas
  • Seen in hot, humid weather

Histo:
- “spaghetti and meatball” on KOH

Tx:

  • Topical miconazole
  • Selenium sulfide (Selsun Blue)
98
Q

Candida albicans

A

Tx:

  • Topical azole for vaginal infection
  • Fluconazole/capsofungin for oral/esophageal
  • Fluconazole, ampho B, caspofungin for systemic tx
99
Q

Aspergillus Fumigatus

A

Invasive= immunocompromised, chronic granulomatous disease

Allergic broncopulmonary (ABPA)= Asthma, CF

Aspergillomas in lung cavities (post-TB)

** Produce aflatoxins= associated with Hepatocellular carcinoma

100
Q

Cryptococcus neoformans

A

Encapsulated (crypt) yeast

  • Found in soil, pigeon droppings
  • Inhaled, hematogenous dissemination to meninges

Culture:

  • Sabouraud’s agar
  • India Ink stain
  • Latex agglutination= polysaccharide capsular antigen

Can cause meningitis (“soap bubble lesions” in brain) in immune-compromised (AIDS patients with CD4+ < 50)

Tx:
- Amphotericin B + Flucytosine

101
Q

Pneuomcystis jirovecii

A

PCP= diffuse interstitial pneumonia

  • bilateral CXR
  • Dx= biopsy, lavage
  • Disc-shaped yeast on methenamine silver stain

Tx: TMP-SMZ, pentamidine, dapsone
- Prophylax with CD4+ < 200

102
Q

Sporothrix schenckii

A

Dimorphic
Cigar-shpaed budding yeast

“Rose-pickers” thumb= pustule, ulcer with nodules along lymphatic drainage

Tx: itraconazole, potassium iodide (plant a rose in the pot)

103
Q

Giardia Lamblia

A

Trophozoite

Giardiasis: bloating, flatulence, foul-smelling, fatty diarrhea

Transmission: cysts in water

Dx: stool: trophozoites, cysts

Tx: Metronidazole (GET on the Metro: G= giardia, E= entamoeba, T= Trichomonas)

104
Q

Entamoeba histolytica

A

Trophozoite

Amebiasis: bloody diarrhea (dysentery), liver abscess (anchovy paste exudate), RUQ pain (flask-shped ulcer if submucosal colon abscess ruptures)

Transmission: cysts in water

Dx: Serology, trophozoites (with phagocytosed RBCs) or cysts (multinucleated) in stool

Tx: Metronidazole (GET on the Metro: G= giardia, E= entamoeba, T= Trichomonas)
- Iodoquinol for asymptomatic carriers

105
Q

Cryptosporidium

A

AIDS patients: severe diarrhea
- Milder (watery diarrhea) in immunocompetent

Transmission: Cysts in water)

Dx: Cysts on acid-fast stain

Tx: Prevent (filter water)
- Nitazoxamide in immunocompetent

106
Q

Toxoplasma Gondii

A

HIV: brain abscess (ring-enhancing lesions)
Congenital: Triad= chorioretinitis, hydrocephalus, intracranial calcifications

Transmission: cysts in meat, cat feces

Dx: Serology, biopsy

Tx: Sulfadiazine, pyrimethamine

107
Q

Naegleria Fowleri

A

Rapidly fatal meningoencephalitis

Transmission: swimming in freshwater lakes, Netti pot (cribiform plate–> brain)

Dx: Amoebas in CSF

Tx: Amphotercin (maybe?)

108
Q

Trypanosoma brucei gambiense

A

West African Sleeping sickness:

  • Slowly progressive fevers, wasting, late neuro symptoms
  • Recurrent fevers: due to Variable Surface Glycoproteins (change with each generation–> immune system can’t keep up)

Transmission: Tsetse fly (painful bite)

Diagnosis: blood smear

Tx:
Blood borne= Suramin
CNS= Melarsoprol
“Sure is nice to go to sleep. Melatonin helps with sleep”

109
Q

Trypanosoma brucei rhodesiense

A

East African sleeping sickness:
- More severe, rapid progression (recurrent fevers–> neurological disease–> coma–> death)

Transmission: Tsetse fly (painful bite)

Diagnosis: blood smear

Tx:
Blood borne= Suramin
CNS= Melarsoprol

110
Q

Plasmodium vivax/ovale

A

Malaria: fever, H/A, anemia, splenomegaly

  • 48 hr cycle (fever on 1st, 3rd day)
  • Dormant form in liver

Transmission: Mosquito

Diagnosis: Blood smear

  • Trophozoite ring
  • RBC schizont with merozoites

Tx:

  • Chloroquine (blocks heme ploymerase)
  • Mefloquine for resistant strains
  • Life-threatening: IV quinidine (test for G6PD)
  • **Add primaquine (test for G6PD) to kill hypnozoites in liver
111
Q

Plasmodium falciparum

A

Malaria: fever, H/A, anemia, splenomegaly

  • Severe, irregular fever
  • Parasitized RBCs occlude brain capillaries–> cerebral malaria, kidneys, lungs

Transmission: Mosquito

Diagnosis: Blood smear

  • Trophozoite ring
  • RBC schizont with merozoites

Tx:

  • Chloroquine (blocks heme ploymerase)
  • Mefloquine for resistant strains
  • Life-threatening: IV quinidine (test for G6PD)
112
Q

Plasmodium malariae

A

Malaria: fever, H/A, anemia, splenomegaly
- 72 hour cycle of fever

Transmission: Mosquito

Diagnosis: Blood smear

  • Trophozoite ring
  • RBC schizont with merozoites

Tx:

  • Chloroquine (blocks heme ploymerase)
  • Mefloquine for resistant strains
  • Life-threatening: IV quinidine (test for G6PD)
113
Q

Babesia

A

Babesiosis: fever, hemolytic anemia

  • Seen in NE USA
  • Increased risk of severe disease in asplenia

Transmission: Ixodes tick

Diagnosis: blood smear (ring form, “Maltese cross), PCR

Tx: Atovaquone + azithromycin

114
Q

Trypanosoma cruzi

A

Chagas’ disease: dilated cardiomyopathy, megacolon, megaesophagus

Transmission: Reduviid bug (“kissing bug”)- painless bite–> feces enter wound

Diagnosis: Blood smear

Tx: Nifurtimox

115
Q

Leishmania donovani

A

Visceral leishmaniasis: spiking fevers, hepatosplenomegaly, pancytopenia

Transmission: sandfly

Diagnosis: macrophages with amastigotes

Tx: sodium stibogluconate

116
Q

Trichomonas Vaginalis

A

Vaginitis: foul-smelling, greenish discharge
- Itching, burning

Transmission: sexual (must have host- no cyst form)

Diagnosis: Trophozoites (motile) on wet mount
- Strawberry cervix

Tx: Metronidazole (patient and partner) (GET on the Metro: G= giardia, E= entamoeba, T= Trichomonas)

117
Q

Enterobius Vermicularis

A

Pinworm
Intestinal infection–> anal pruritis (“Scotch tape test”)

Transmission: food contaminated with eggs

Tx: Bendazoles, pyrantel pamoate (“Bendy” worms)

118
Q

Ascaris Lumbricoides

A

Giant roundworm
Intestinal infection

Transmission: Fecal-oral; see eggs under microscope

Tx: Bendazoles, pyrantel pamoate

119
Q

Strongyloides stercoralis

A

Intestinal infection: N/V, diarrhea, anemia

Transmission: larvae in soil penetrate skin

Tx: Albendazole, ivermectin

120
Q

Ancylostoma duodenale, Necator Americanus

A

Old world, new world hookworm
Intestinal infection–> anemia (suck blood) (microcytic anemia)

Transmission: larvae penetrate skin

Treatment: Bendazoles, pyrantel pamoate

121
Q

Dranunculus medinensis

A

Skin inflammation, ulceration

Transmission: drinking water

Tx: slow extraction of worm

122
Q

Onchocerca volvulus

A

“River blindness”: microfilariae migrate to eye–> die–> inflammatory response–> opacity

  • Hanging groin
  • Lymphadenopathy
  • Allergic reactions

Transmission: Female black fly

Tx: Ivermectin (Iver for River blindness)

123
Q

Loa Loa

A

Swelling in skin, pain and edema in eye (worm in conjunctiva)

Transmission: female deer fly (horse, mango fly)

Treatment: Diethycarbamazine

124
Q

Wucheria bancrofti

A

Blocks lymphatic drainage–> elephantiasis (~1 year after bite)

Transmission: female mosquitoes (night)

Tx: Diethylcarbamazine

125
Q

Toxocara canis

A

Visceral larval migrans: granulomas in viscera (including CNS)–> death from respiratory failure, cardiac arrhythmias, brain damage

Transmission: food contaminated with eggs (carried by cats, dogs)

Tx: Albendazole, mebendazole

126
Q

Taenia Solium

A

Cestode (tapeworm)
1. Ingestion of larvae in undercooked pork–> Intestinal infection

Tx: Praziquantel

  1. Ingestion of eggs (fecal-oral)–> Cysticercosis, neurocysticercosis

Tx: Praziquantel, bendazoles for neurocysticercosis

127
Q

Diphyllobothrium latum

A

Cestode (tapeworm)
Vitamin B12 deficiency (tapeworm competes for B12 in intestine)–> anemia

Transmission: Ingestion of larvae from raw freshwater fish

Treatment: Praziquantel

128
Q

Echinococcus granulosus

A

Cestode (tapeworm)
Ingestion of eggs (dog feces)

Cysts in liver (anaphylyaxis if released–> pretreat with ethanol injection before removing)

Tx: Bendazoles

129
Q

Schistosoma

A

Trematode

  • Liver and spleen granulomas, fibrosis, inflammation
    • S. haematobium–> SCC of bladder
    • S. Mansoni–> portal HTN

Transmission: Snails= host–> cercariae penetrate skin

Tx: praziquantel

130
Q

Clonorchis sinensis

A

Trematode= Chinese liver fluke

  • Biliary tract inflammation–> pigmented gallstones
  • Associated with cholangiocarcinoma

Transmission: undercooked fish

Tx: Praziquantel

131
Q

Paragonimus Westermani

A

Trematode
- Lung inflammation; secondary bacterial infection–> hemoptysis

Transmission: undercooked crab meat

Tx: Praziquantel

132
Q

Live, attenuated vaccines

A 
Smallpox
Yellow fever
Chicken pox (VZV)
Sabin's polio virus
MMR (only one can be given to HIV+ patients without immune deficiency)
Influenza (flumist nasal spray)
133
Q

Killed vaccines

A

Rabies
Influenza
Salk Polio
HAV

134
Q

Recombinant vaccine

A

HBV: antigen= recombinant HBsAg
HPV: 6, 11, 16, 18

135
Q

RNA viral genomes

A
  • All are ssRNA except Reoviridae
  • All replicate in cytoplasm except Retrovirus (diploid ssRNA), influenza

+ ssRNA:
I went to a RETRO(virus) TOGA(virus) party, where I drank FLAVored(flavivirus) CORONA(virus) and ate Hippy(hepevirus) CALIfornia (calcivirus) PICkles (picornavirus)

136
Q

DNA viruses

A

All dsDNA, linear, icosahedral, replicate in nucleus:

Hepadna (circular, incomplete)
Herpes
Adeno
Pox (complex, has DNA-dependent RNA polymerase--> replicates in cytoplasm)
Parvo (ssDNA)
Papilloma (circular, supercoiled)
Polyoma (circular, supercoiled)
137
Q

Herpesviruses

A

Enveloped
dsDNA, linear

HSV1= oral, Spontaneous temporal lobe encephalitis, keratoconjunctivitis
HSV2= genital
HSV3= VZV= chickenpox
HSV4= EBV= mono, Burkitt's, Hodgkin's, nasopharyngeal carcinoma
HSV5= CMV= AIDS retinitis, congenital defects (latent in mononuclear cells= "owl's eyes")
HSV6= roseola
HHV7= roseola (less common)
HHV8= Kaposi's sarcoma

Diagnosis:

  1. PCR (#1)
  2. Tzanck test= smear of opened vesicle (used for HSV1, 2, VZV)
    - See intranuclear Cowdry A inclusions
  3. Monospot (EBV): heterophile antibodies on agglutination of sheep/horse RBCs
    - Atypical lymphocytes= reactive cytotoxic T cells
138
Q

Hepadnavirus

A

Enveloped
dsDNA, partial circular

Hep B:

  • Acute or chronic (incubation= months)
  • Vaccine= recombinant (HBsAg)
  • Contains reverse transcriptase (NOT retrovirus)= DNA-dependent DNA polymerase
  • Uses host RNA polymerase–> viral proteins

Transmission: Parenteral, sexual, maternal-fetal

Serology:

  • HBsAg= infected (acute/chronic)
  • Anti-HBs= immunity (vaccine/recovered)
  • HBcAg= antigen to core (infected)
  • Anti-HBc= positive during infection (IgM= acute/recent, IgG= prior/chronic)
  • HBeAg= Active (acute/chronic)
  • Anti-HBe= Window, chronic (low infectivity, recovery)
    • Risk of HCC
    • ALT > AST (vs alcoholics: AST > ALT
139
Q

Adenovirus

A

Non-enveloped
dsDNA, linear

Pharyngitis, hemorrhagic cystitis
Pneumonia
Conjunctivitis

140
Q

Parvovirus

A

Non-enveloped
ssDNA, linear negative (smallest DNA virus)

B19= “slapped cheeks” (erythema infectiosum), 5th disease

  • In SC pts–> aplastic crisis
  • In uteros–> hydrops fetalis
  • Adults: RBC aplasia, RA symptoms
141
Q

Papillomavirus

A

Non-enveloped
dsDNA, circular

HPV:
1, 2, 6, 11= warts
16, 18= CIN, cervical cancer
** Recombinant vaccine

Diagnosis:
- Koilocytes on Papanicolaou smear (pap smear)

142
Q

Polyomavirus

A

Non-enveloped
dsDNA, circular

  • JC virus= PML in HIV
  • BK virus= transplant patients, kidney targeted (Bad Kidney)
143
Q

Poxvirus

A

Enveloped
dsDNA, linear (largest DNA virus)

Smallpox= germ warfare
Vaccinia= cowpox
Molluscum contagiosum= flesh-dome lesion with central dimple

144
Q

Reovirus

A

Nonenveloped
dsRNA, linear
Icosahedral

Coltavirus= colorado tick fever (arbovirus)

Rotavirus:
- villus destruction, atrophy–> decreased Na absorption, loss of K+

145
Q

Picornavirus

A

Non-enveloped
ssRNA+, linear
Icosahedral

PERCH:
Poliovirus
Echovirus (aseptic meningitis)
Rhinovirus (common cold)
Coxsackievirus (aseptic meningitis, herpangina, hand foot mouth disease, myocarditis)
HAV (acute Hep A virus): asymptomatic, acute, alone (no carriers)

** All but Rhino (acid-labile) are fecal-oral enteroviruses

146
Q

Hepevirus

A

Non-enveloped
ssRNA+, linear
Icosahedral

Hep E

  • Transmission= fecal-oral (waterborne epidemics)
  • No carrier state, short incubation, no HCC
  • Enteric, Expectant mothers (bad), Epidemic
147
Q

Calcivirus

A

Non-enveloped
ssRNA+, linear
Icosahedral

Norovirus

148
Q

Flavivirus

A

Enveloped
ssRNA+, linear
Icosahedral

Hep C:

  • Transmission= blood, IVDU, post-transfusion
  • Long incubation
  • HCC risk
  • Chronic, Cirrhosis, Carcinoma, Carrier

Yellow fever (arbovirus): fever, black vomit, jaundice

Dengue (arbovirus)

St. Louis Encephalitis (arbovirus)

West Nile (arbovirus)

149
Q

Togavirus

A

Enveloped
ssRNA+, linear
Icosahedral

Rubella (German measles)

  • Postauricular lymphadenopathy, arthralgias, truncal rash (head–> trunk)
  • Mild in children, serious congenital disease

Eastern Equine Encephalitis (arbovirus)
Western Equine Encephalitis (Arbovirus)

150
Q

Retrovirus

A

Enveloped
ssRNA+, linear
Icosahedral (HTLV–> T-cell leukemia)
Complex conical (HIV–> AIDS)

** contain reverse transcriptase

HIV:

  • envelope proteins acquired by budding from host plasma membrane= ENV
  • Env glycosylation–> gp160–> cleaved in ER/golgi–> gp120, gp41
    1. gp120= docking glycoprotein*;
  • attach to host CD4+ cell (early= CCR5, late= CXCR4)
  • attach to CCR5/CD4 on host macrophages
  • CCR5 mutation–> immunity (homo), slow course (hetero)
    2. gp41= transmembrane protein*; fusion and entry
    3. p17= matrix protein
    4. p24= capsid protein: GAG
    5. reverse transcriptase: POL

Diagnosis:

  1. ELISA= rule out (high false-positive)
  2. Western Blot= rule in (high false-negative)
  3. PCR for viral load
  4. CD4+ count (< 200= AIDS) or CD4/CD8 < 1.5
151
Q

Coronaviruses

A

Enveloped
ssRNA+, linear
Helical

Corona= common cold, SARS

152
Q

Orthomyxoviruses

A

Enveloped
ssRNA- , linear, 8 segmented
Helical

Influenza:

  • Hemagglutin= viral entry
  • Neuraminidase= progeny virion release
  • Genetic shift/antigenic shift= pandemics (high frequency recombination) ex: swine and human virus recombine
  • Genetic drift= epidemics (minor, random mutation)
153
Q

Paramyxovirus

A

Enveloped
ssRNA-, nonsegmented
Helical

Parainfluenza (croup)

RSV (bronchiolitis in babies, Rx= Ribavirin)

Measles:

  • Cough–> conjunctivitis-> spots–> Maculopapular rash: head to toe
  • Koplik spots (buccal mucosa)
  • Delayed encephalitis (SSPE)
  • Giant cell pneumonia (immune suppressed)

Mumps: (makes your parotids and testes as big as POM poms)

  • Parotitis
  • Orchitits
  • Meningitis
    • surface F (fusion) protein= respiratory epithelial cells fuse–> multinucleated cells
  • Use Palivizumab (MAB against F) to prevent RSV in premies)
154
Q

Rhabdovirus

A

Enveloped
ssRNA-, linear
Helical

RABIES!:

  • Bullet-shaped
  • Negri bodies= cytoplasmic inclusions in neurons (Purkinje of Cerebellum)
  • Post-exposure prophylaxis= Wound cleansing + Rabies Ig
  • Bite–> nerve axons–> CNS–> salivary glands
155
Q

Filovirus

A

Enveloped
ssRNA-, linear
Helical

Ebola/Marburg hemorrhagic fever

156
Q

Arenaviruses

A

Enveloped
ssRNA-, circular segments
Helical

Lymphocytic Choriomeningitis Virus (LCMV)
Lassa Fever encephalitis (mouse-borne)

157
Q

Bunyaviruses

A

Enveloped
ssRNA-, circular segmets
Helical

California encephalitis (Arbovirus)
Sandfly/Rift valley fever (Arbovirus)
Crimean-Congo hemorrhagic fever (Arbovirus)
Hantavirus–> hemorrhagic fever, pneumonia

158
Q

Delta virus

A

Enveloped
ssRNA-, cricular

Hep D:
Defective (needs HBV for coinfection)
- Transmission: parenteral, sexual, maternal-fetal
- Short superinfection, long coinfection

159
Q

Negative stranded viruses

A 
Must transcribe negative strand to positive:
Always Bring Polymerase Or Fail Replication
- Arenavirus
- Bunyavirus
- Paramyxovirus
- Orthomyxovirus
- Filovirus
- Rhabdovirus
160
Q

Segmented viruses

A

RNA viruses: BOAR

  • Bunyaviruses
  • Orthomyxoviruses
  • Arenaviruses
  • Reoviruses
161
Q

Systemic symptoms of HIV infection

A

Histoplasma capsulatum (pulm symptoms only in immune competent): low grade fever, hepatosplenomegaly, tongue ulcer

  • CD4 < 100
  • Oval yeast cells in macrophages
162
Q

Dermatologic symptoms of HIV infection

A

C. albicans (thrush): cottage-cheese lesions

  • oral: CD4 < 400
  • esophageal: CD4< 100
  • Pseudohyphae

Bartonella henselae: superficial vascular proliferation
- Neutrophilic inflammation

163
Q

GI symptoms of HIV

A

Cryptosporidium: chronic watery diarrhea

  • CD4 < 200
  • Acid-fast cysts in stool
164
Q

Neurologic symptoms of HIV

A

JC virus: encephalopathy
- CD4 < 200

Toxoplasma: abscesses
- CD4 < 100

Cryptococcus neoformans: Meningitis
- CD4 < 50

CMV: Retinitis
- CD4 < 50

Dementia due to HIV

165
Q

Oncologic processes in HIV

A

HHV8: Kaposi’s sarcoma
- Lymphocytic inflammation

EBV:

  1. hairy leukoplakia (tongue);
  2. non-Hodgkin’s lymphoma (large cell)- seen on Waldeyer’s ring
  3. CNS lymphoma (focal or multiple)

HPV: Squamous cell carcinoma (anus, cervix)

166
Q

Respiratory processes in HIV

A

CMV: Interstitial pneumonia
- Owl’s eye intranuclear inclusions

Aspergillus: invasive
- pleuritic pain, hemoptysis, infiltrate on imaging

Pneumocystis jirovecii: Pneumonia
- CD4 < 200

Mycobacterium aviium intracellulare: TB-like

  • CD4 < 50
  • Prophylax with azithromycin
167
Q

CD4 < 200

A
  1. Pneumocystis jirovecii: Pneumonia
  2. JC virus: encephalopathy
  3. Cryptosporidium: chronic watery diarrhea
168
Q

CD4 < 100

A
  1. C. albicans (esophageal thrush): cottage-cheese lesions
  2. Toxoplasma: abscesses
  3. Histoplasma capsulatum (pulm symptoms only in immune competent): low grade fever, hepatosplenomegaly, tongue ulcer
169
Q

CD4 < 50

A
  1. CMV: Retinitis

2. Cryptococcus neoformans: Meningitis

170
Q

Prion diseases

A

PrPc= normal cellular prion protein
PrPsc= Beta-pleated form; transmissible
- Accumulation–> spongiform encephalopathy (dementia, ataxia, death)

Creutzfeld-Jacob= sporadic, rapidly progressive dementia

Gerstmann-Straussler-Scheinker= inherited

Acquired= Kuru, New Variant CJD

171
Q

Normal flora in body

A

Skin= staph epidermidis
Nose= staph epidermidis, colonized by s. aureus
Oropharynx= viridans group strep
Dental plaque= strep mutans
Colon= Bacteroides fragilis > e. coli
Vagina= lactobacillus; colonized by e. coli and group B strep

172
Q

Bugs causing food poisoning

A

Vibrio parahaemolyticus, vulnificus= contaminated seafood (wounds for vulnificus)
Bacillus cereus= reheated rice
S. aureus= meats, mayonnaise, custard; preformed toxin
Clostridium perfringens= reheated meat
C. botulinum= improperly canned food
E. coli= undercooked meat (O157:H7)
Salmonella= poultry, meat, eggs

173
Q

Bloody diarrhea

A 
Campylobacter
Salmonella 
Shigella
EHEC
EIEC
Yersinia enterocolitica
Entamoeba histolytica
174
Q

Watery diarrhea

A 
ETEC (Stable and Labile toxins)
Vibrio
C. Diff (can also have blood)
C. perferingens
Protozoa (giardia, crypto)
Noro, Rotavirus
175
Q

Common causes of pneumonia neonates

A

Group B strep

E. coli

176
Q

Common causes of pneumonia: children

A 
RSV/ viruses
Mycoplasma
Chlamydia trachomatis
C. pneumoniae
Streptococcus pneumonia

“Runts May Cough Chunky Sputum”

177
Q

Common causes of pneumonia: adults 18-40

A

Mycoplasma
C. pneumoniae
S. pneumoniae

178
Q

Common causes of pneumonia: adults 40-65

A 
S. pneumoniae
H. influenzae
Anaerobes
Viruses
Mycoplasma
179
Q

Common causes of pneumonia: elderly

A 
S. pneumoniae
Influenza
Anaerobes
H. influenzae
Gram-negative rods
180
Q

Common causes of meningitis: newborns

A

Group B strep
E. coli
Listeria

181
Q

Common causes of meningitis: children (6 months-6 years)

A

Strep pneumo
N. meningitidis
H. flu type B
Enteroviruses

182
Q

Common causes of meningitis in 6-60 year olds

A

S. pneumo
N. meningitidis
Enteroviruses
HSV

183
Q

Common causes of meningitis in 60+ years

A

S. pneumo
Gram-negative rods
listeria

184
Q

Meningitis: CSF findings

A

Bacterial= normal pressure, PMNs, increased protein, decreased sugar

Fungal/TB= normal pressure, Lymphocytes, increased protein, decreased sugar

Viral= normal pressure, lymphocytes, normal/elevated protein, normal sugar

185
Q

UTI findings

A

Predisposition:

  • Women (10x more common)
  • Males= congenital defects in infants, vesicoureteral reflux
  • Elderly males= enlarged prostate

Diagnostics:

  • Bacterial UTI= positive leukocyte esterase
  • Gram-negative UTI= positive nitrite test

Causes:

  1. E. coli
  2. Staph saprophyticus
  3. Klebsiella pneumoniae (urease positive)
    - Serratia marascens= nosocomial, drug resistant
    - Enterobacter cloacae= nosocomial, drug resistant
    - Proteus mirabilis= motile, “swarm” in agar; urease positive–> struvite stones
    - Pseudomonas= nosocomial, drug resistant
186
Q

ToRCHeS

A

Toxoplasma:
- triad: chorioretinitis, hydrocephalus, intracranial calcifications

Rubella:
- triad: Septal defects/PDA/pulmonary artery hypoplasia or stenosis, cataracts, deafness (+/- “blueberry” rash)

CMV:
- Hearing loss, seizures, petechial rash, “blueberry” rash

HIV:
- Recurrent infections, chronic diarrhea

Herpes Simplex Virus 2:
- Encephalitis, herpetic lesions

Syphillis:
- Stillbirth, hydrops fetalis, facial abnormalities (Hutchinson’s teeth, saddle nose, short maxilla), saber shins, deafness (CNVIII)

Step 1 Subjects (26 decks)

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