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Medical Microbiology > Section 3- Bacteriology > Flashcards

Section 3- Bacteriology Flashcards

1
Q

Coagulase

A

Clumping factor enzyme made by bacteria
Virulence factor- helps bacteria wall itself off so immune cells cannot reach it
Takes fibrinogen (soluble) and along with thrombin, makes fibrin (insoluble) which helps blood clot
+ = s. aureus
Can test on a slide (surface coagulase) or in a tube (secreted coagulase)

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2
Q

Mannitol Salt Agar (MSA)

A

Selective
Mannitol sugar fermentation results in acid production and media turns yellow
+ = S. aureus
- = S. epidermidis, S. saprophyticus

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3
Q

Blood Agar

A

Standard medium
Almost everything grows on
NOT Neisseria gonorrhoeae

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4
Q

Sepsis

A

Signs= fever, elevated pulse, respiratory distress and kidney failure
Indicative of bacterial infection

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5
Q

Pleural effusion

A

Excess fluid between pleura layers

Evidence of infection

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6
Q

HAP

A

Hospital Acquired Pneumonia

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7
Q

Nosocomial pneumonia pathogens (7)

A 
Pseudomas aeruginosa
Klebsiella
Escherichia coli
Acinetobacter
Haemophilus influenzae
Staphylococcus aureus
Streptococcus pneumoniae
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8
Q

Alpha toxin

A

Hemolysin

Causes hemolysis of RBCs

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9
Q

MRSA

A 
Methicillin resistant S. aureus
Emerged as nosocomial infection in U.S. 
Community acquired
Current epidemic in U.S.
Necrotizing pneumonias
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10
Q

von Willebrand factor binding protein (vWbp)

A

Cell wall associated
Binds host vW factor
Facilitates adhesion in blood vessels

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11
Q

Protein A (SpA)

A

Cell wall associated
Binds to Fc region of IgG and binds to Fab region of BCR
Prevents immune cell recognition and complement activation

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12
Q

Leukocidins

A

Target WBCs to form pores

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13
Q

Hemolysins

A

Target RBCs to form pores

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14
Q

Toxic Shock Syndrome Toxin (TSST-1)

A

Superantigen
Causes TSS
Superantigens cross-link MHC class II molecules with TCRs, Polyclonal T cells activated, Massive pro inflammatory cytokine release, then toxic shock (cytokine storm) and organs fail

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15
Q

Staphylococcal Enterotoxin B (SEB)

A

Superantigen
Heat stable
Released when bacteria replicate in food and causes staphylococcal food poisoning

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16
Q

Epidermolytic/Exfoliative Toxins (ET-A and ET-B)

A

Cause scalded skin syndrome

Released by S. aureus during growth

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17
Q

Skin and Soft Tissue Infections (SSTIs)

A

Infection of hair follicles, spectrum
Can be superficial or deep
Folliculitis (surface)
Boil (into pore of hair)
Carbuncle (follicle infection)
Impetigo (young children, fluid filled blisters; bullous and nonbullous)
Stye (sebaceous gland of eyelashes infection)
Abscess (Collection of pus in a tissue in response to infection)
Cellulitis (rapid dissemination of bacteria under superficial skin layers; rash appearance)
Treated with surgical drainage (I&D-Incision and Drainage) if necessary and antibiotic therapy (not beta lactams)

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18
Q

Staphylococcal Scalded Skin Syndrome (SSSS)

A

Post infectious complication of soft tissue infections

Caused by exfoliative toxins

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19
Q

Staphylococcal food poisoning

A

Meat mixes (Mayonnaise), Cooked ham or sausage, Dairy
Bacteria replicate in food and release SEB
Vomiting, diarrhea, stomach cramps
Very quick onset and resolves on own

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20
Q

Toxic Shock Syndrome (TSS)

A

Very serious
Rare, life-threatening
Results from exposure to TSST-1
Most commonly associated with use of superabsorbent tampons, surgical dressings, and nasal packing
Symptoms= Hypotension, high fever, diffuse erythematous rash, desquamation of palms and feet, vomiting, diarrhea, liver damage, renal distress, Altered mental status, myalgia
Treat with Clindamycin** (kills bacteria and stops toxin production)

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21
Q

Catalase

A 
(+) = Staph, N. gonorrhoeae
(-) = Strep
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22
Q

M protein

A

Binds to factor H and prevents opsonization by complement

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23
Q

Capsule virulence

A

Blocks phagocytosis by neutrophils
Antigenic
Vaccine component sometimes

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24
Q

Lipoteichoic acid (LTA)

A

Helps with cell attachment

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25
Streptococcal pyrogenic exotoxins
Superantigens | Cytokine storm
26
Streptolysin S
Beta hemolysis
27
Hylurodinase, Streptokinase, Deoxyribonucleases
Assist with tissue invasion
28
Scarlet Fever
Caused by release of Streptococcal Pyrogenic Exotoxin A (SpeA) Perioral rash Strawberry tongue Usually children
29
Necrotizing Fasciitis
Severe infection of subcutaneous tissues and fascia Very rapid dissemination of bacteria Must debride dead, damaged, and infectious tissues May have to amputate Give large dose penicillin and/or clindamycin
30
Acute Rheumatic Fever (ARF)
Anti-M protein antibodies cross-react with epitopes on heart, joint, skin, and brain leading to tissue damage Type II Hypersensitivity Can lead to Carditis and congestive heart failure and also subcutaneous nodules (painless, not severe)
31
Acute Glomerulonephritis (AGN)
Antibody-antigen complexes deposit in glomerular membrane, which recruits complement and neutrophils Kidney failure Type III Hypersensitivity
32
Pneumolysin
Partial hemolysis (alpha)
33
Thayer Martin Agar
Contains vancomycin and colistin to control growth of other species Grows Neisseria gonorrhoeae and Neisseria meningitidis ONLY
34
Gonorrhea
Dysuria and urethral discharge | WBCs in discharge containing gram (-) diplococci
35
Type IV Pilus
Hair-like projections; allow bacteria to adhere to epithelial tissues in urinary tract Can be assembled or retracted for motility (grappling hook) Under antigenic variation to evade immune response
36
Lipo-oligosaccharide (LOS, Endotoxin)
Very similar to LPS Resistance to serum killing, complement can't bind Fever, cytokine storm Diffuse intravascular coagulopathy (DIC), rash, low BP, Organ damage
37
IgA protease
Cleaves mucosal IgA antibodies | Immune evasion
38
Epididymitis
Inflammation of testicles | Sterile if untreated
39
Disseminated Gonococcal infection (DGI)
Necrotic pustules on an erythmatous base | Anywhere on body
40
Meningitis symptoms
Still neck, severe headache, delirium, *****non-blanching petechial rash = hallmark
41
Waterhouse-Friderichsen Syndrome
Most severe form of meningococcemia Diffuse intravascular coagulopathy causes massive hemorrhage within adrenal glands Hormonal imbalance Almost always fatal
42
2 types of H. influenzae
Serotypable (capsule) vs. Non-typable (no capsule) *Serotype B is most important
43
Otitis media
Middle ear infection Caused by S. pneumoniae and H. influenzae Swelling of eustachian tubes prevents mucus drainage and provides bacterial breeding grounds Anatomical differences between kids and adults explain why infection rates increased for infants Pressure placed on tympanic membrane creates pain
44
Satellite test
Some bacteria can't grow on blood agar and need another way to get nutrients S. aureus plated and has B hemolysis to release nutrients Stimulates growth of bacteria that could not grow before only in the hemolytic zone EX: H. influenzae
45
Pertactin and hemagglutinin
Adhesins | Promote attachment to cilia in lungs
46
Adenylate cyclase toxin and pertussis toxin (PTx)
Alter intracellular CAMP concentrations
47
Tracheal cytotoxin
Suppresses cilia activity and promotes coughing fits
48
Acellular Pertussis vaccine
Contains all virulence factors
49
3 stages of Pertussis
1) Catarrhal (low fever and mild, occassional cough) 2) Paroxysmal (severe paroxysmal cough (whoop), vomiting, exhaustion, paroxysmal attacks, death) 3) Convalescent (gradual recovery) Death often due to secondary pneumonia infection
50
Bordet- Gengou Agar and Regan-Lowe medium
Selective for Bordatella species (pertussis)
51
DaPT vaccine
Diphtheria, acellular Pertussis, and Tetanus vaccine | Booster required as a teenager
52
MacConkey Agar
Selective for gram (-) ONLY Gram (+) will not grow Contains lactose, bile, and crystal violet
53
Medusa-head colonies
Comma-shaped protrusions from colony edge under magnification Bacillus anthracis
54
Bacillus anthracis Tissue vs BAP culture
Tissue- short chains in capsules | BAP- long chains with endospores
55
Anthrax spores
Infectious form Sporulation requires poor nutrient conditions and exposure to oxygen Very resistant to heat, cold, pH, dessication, and chemicals Can survive for decades Taken up by host and germinate
56
Anthrax toxin
``` 3 components Lethal factor ( inactivates key signaling proteins and leads to cell death) Edema factor (generates cyclic nucleotides to increase vascular permeability and edema) Protective antigen (mediates entry of LF and EF into cell) ```
57
Cutaneous anthrax
Spores enter skin through wound Papule to vesicle to necrotic ulcer (eschar) Infection typically more contained to entry site Low fatality rate
58
Inhalational anthrax
**Meningitis is a complication of INHALATIONAL ANTHRAX Need a lot of spores to be infected Spores rapidly engulged by macrophages in alveoli and transported to lymph nodes Spores can germinate, lyse macrophages, and rapidly replicate in lymph node Release of toxin results in mediastinal widening and pleural effusion Bacteria enters bloodstream and causes toxemia and septic shock High fatality
59
Gastrointestinal anthrax
Consumption of undercooked contaminated meat Bloody diarrhea, abdominal pain, toxemia and sepsis High fatality rate Not documented in U.S.
60
Life cycle of Listeria
Bacteria actively invade intestinal epithelium Become trapped in endocytic vacuole Use Listeriolysin O (LLO) to escape from endocytic vacuole--pores made Rapidly divide in cytoplasm Form comet tails Propel into cell wall and pentrate adjacent cell Trapped in vacuole and escape again Cycle repeats
61
Diphtheria toxin (DTx)***
Only virulence factor for C. dipheriae Single gene Inactivates elongation factor 2 Prevents protein synthesis which leads to cell death
62
Tinsdale Agar
Selective and differential | C. diphtheriae is black with brown halo
63
Enterobacteriaceae family
``` Small gram (-) rods Require selective media 4 major features: 1. Ferment glucose 2. Reduce nitrates to nitrites 3. Oxidase (-) 4. Motile (except Klebsiella and Shigella) ```
64
4 major groups of Shigella
**S. dysenteriae (SD1) S. flexneri S. boydii S. sonnei
65
Dysentery
Diarrhea with blood and mucus in stool
66
Hemolytic Uremic Syndrome (HUS)
Lysis of RBCs Thrombocytopenia Renal failure Treat with Ciprofloxacin
67
Reiter's Syndrome
Conjunctivitis, urethritis, and arthritis | Only in people with HLA-B27 type
68
Shiga toxin (STx)
Produced by S. dysenteriae only Cleaves adenine residue from rRNA subunit which inhibits protein synthesis Damages endothelial cells lining blood vessels--leads to HUS and kidney failure
69
E coli serotypes
``` MANY H antigen (flagella) O antigen (LPS) K antigen (capsule) ```
70
Pathogenic E. coli
``` Divided into 6 pathovars ETEC EPEC EHEC EIEC EAEC UPEC ```
71
Pyuria
WBCs in urine
72
UPEC
Uropathogenic E. coli Major cause of lower and upper UTIs in US *****Expression of multiple pili (Type I pilus allows colonization of bladder) (P-type pilus allows colonization of ureters and kidneys)
73
ETEC
Enterotoxigenic E. coli Traveler's diarrhea and childhood diarrhea (contaminated water) Adhere to intestinal mucosa by fimbriae Produce enterotoxins (heat-labile and heat-stable toxins) Toxins cause water and electrolyte loss and rapid dehydration Large volume watery diarrhea Must rehydrate
74
EPEC
Enteropathogenic E. coli Persistent diarrheal disease in cihldren High infant mortality in developing countries Causes attaching and effacing lesions (loss of microvilli) Large volume watery diarrhea
75
EHEC
Enterohemorrhagic E. coli Can cause hemorrhagic colitis, HUS (produces Shiga toxin) Bloody diarrhea Can be found in undercooked hamburger because cattle can be colonizers (O157:H7 serotype)
76
If large volume watery diarrhea, suspect which two E. coli?
ETEC or EPEC
77
If bloody stools suspect which 4 bacteria?
EHEC Shigella EIEC (maybe) EAEC (maybe)
78
Guillain Barre Syndrome
Peripheral neuropathy Affects nerves in feet causing debilitating paralysis and neuro complications (spreads up) Usually effects are temporary as nerves regenerate Patients develop antibodies that are similar to self and attack nerve cells
79
Pathogenesis of H. pylori
Invade mucus layer with polar flagella to reach underlying gastric epithelial cells Release mucinase to degrade mucin layer Release VacA to disrupt epithelial cell layer and T cell functions Lamina propria exposed to stomach acid and cells death occurs Peptic ulcer forms
80
Halotolerant
Can grow at high salt concentrations
81
Pathogenesis of Vibrio cholerae
Adhere to mucosal cell layer Cholera toxin upregulates activity of CFTR chloride ion channel, leads to Cl- efflux and ionic imbalance Leads to profuse, watery diarrhea Little to no abdominal pain or vomiting
82
Legionnaire's disease
Immunocompromised, smokers, Chronic lung disease patients Myalgia, headache, fever, chills, dry cough that leads to productive cough Chest pain, vomiting, diarrhea, confusion, delirium Septic shock high mortality

Medical Microbiology (5 decks)

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