Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Boards 23' > Infectious Disease > Flashcards

Infectious Disease Flashcards

1
Q

Prokaryotes

A

no membrane bound organelle; no nucleus so nuclear material is free inside of cell; bacteria are prokaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Eukaryotes

A

membrane bound organelle that contain a nucleus; these include plant and animal cells, protozoa and fungi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Bacteria

A

single cell organism where the cell wall is a key component - helps differentiate gram (+) and gram (-) bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Gram (+) bacteria characteristics

A

thicker cells wall organisms (up to 40 sheets of peptidoglycan - 50% of cell wall); the thicker layer retains the gram stain and makes them purple; contains lipoteichoic acids (LTA) that drive lots of immune infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gram (-) bacteria characteristics

A

thinner cell wall (very few sheets of peptidoglycan - 5-10% of cell wall) with an ADDED outer membrane that contains lipopolysaccharides (LPS) makes people VERY VERY sick (sicker than gram (+)); Periplasm (space between cell membrane and outer-membrane) contains B-lactamase (inactivates antibiotics)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Peptides are always attached to what molecule in the peptidoglycan structure?

A

N-acetylmuramic acid (NAM); not NAG; some antibiotics act on peptidoglycan - penicillin and cephalosporins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Unique cell wall bacteria

A
  1. Mycoplasma (can cause interstitial pneumonia) - no cell wall, does NOT gram stain; the membrane has sterols for extra stability
  2. Mycobacteria (TB or leprosy) - cell wall has mycolic acid so does NOT stain well, needs a special Ziehl-Neelsen stain
  3. Chlamydia (STD and other infections) - lacks muramic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Cell membrane of bacteria

A

present in gram (+) and gram (-) bacteria; there is where electron transport (in humans takes place in mitochondria) and oxidative phosphorylation occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Lipopolysaccharide (LPS)

A

an ENDOTOXIN - only on gram (-) bacteria on their outer membrane; contains 3 components:

  1. polysaccharide
  2. Lipid A - HIGHLY toxic; triggers cytokine release (TNF and IL-1) - sepsis/septic shock
  3. O antigen - target for antibodies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Capsule

A

sticky gelatinous layer that both gram (+) and gram (-) bacteria can have that helps attach to host cells and also protects against phagocytosis; they are mostly made up of water and polysaccharides w/ ONE exception:

Bacillus anthraces (anthrax) - peptide capsule (d-glutamate); major virulence factor that allows for unimpeded growth; pts get REALLY sick!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Capsules and Immunology

A

B-cells secrete IgG and these bind/tag the capsule for phagocytosis; antibodies can also activate complement - formation of MAC (cell death) and formation of C3b (opsonin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

pt population who are at risk of recurrent encapsulated bacterial infections

A

pt who have loss of antibodies or complement or have had their spleen removed or sickle cell anemia pts (asplenia) loss of splenic phagocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Capsular vaccines for encapsulated bacteria

A

Neisseria meningitides
Streptococcus pneumonia
Haemophilus influenza type b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Glycocalyx

A

similar to a capsule, but is a “sugar coat” made of polysaccharides; irregular, slimy fuzzy layer that is used to adhere to surfaces (mainly catheters); pts with a IV line or a folly placement watch for Strep epidermidis - skin flora! (creates biofilms)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Spores and why are they so resistant?

A

Coat:
outermost layer “keratin-like” protein that is impermeable to many chemicals and antibacterial agents

Core:
Innermost layer compress of peptidoglycan

Dipicolinic acid:
large amounts inside spore that helps with heat resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

5 major examples of spore forming bacteria

A
  1. Bacillus anthracis - potential weapon of bioterroism
  2. Bacillus cereus - food poisoning
  3. Clostridium perfringens - food poisoning
  4. Clostridium tetani - food poisoning
  5. Clostridium botulism - food poisoning
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Key bacteria with Pili and Fimbria

A

structurally similar to flagella; made of protein and is more like an appendage or arm of the bacteria; allow for adherence or attaches to another bacteria and allow for conjugation - antigenic variation

E. coli - UTIs/Pyelonephritis (adherence)
Neisseria Gonorrhea (antigenic variation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

bacterium that is a common cause of pneumonia and respiratory failure in CF pts

A

Pseudomonas aeruginosa; oxidase (+) gram (-) rod; bacteria frequently colonize and form biofilms that allow for the bacterium to evade the immune system via their glycocalyx

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Most cocci are gram (+) bugs, what are the gram (-) exceptions?

A

Neisseria (meningitis/gonorrhea) and Moraxella catarrhalis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

most rods are gram (-) bugs, what are the few gram (+) exceptions?

A

Corynebacterium (diphtheria)
Clostridium
Listeria
Bacillus (anthrax, cereus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Branching/Filamentous bacteria

A

resembles fungi
Actinomyces
Nocardia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Spirochetes

A

treponema (syphilis)
borrelia (Lyme disease)
leptospira (leptospirosis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

the one gram (+) vibrio (curved/coma shaped) bacterium?

A

Vibrio cholerae (cholera)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The two pleomorphic bacteria

A

can take any shape; also both are intracellular pathogens
Rickettsia
Chlamydia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

gram stain steps

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

bacterium that do not stain well

A
  1. Treponema (syphilis) to thin to see
  2. Mycobacteria (TB) - mycelia acid in cell wall
  3. Mycoplasma (interstitial pneumonia) - no cell wall (Eaton’s agar)
  4. Intracellular bacteria (need to be a cell to grow)
    -Rickettsia
    -Chlamydia
    -Legionella
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Giemsa Stain

A

useful stain to get inside of cells

Protozoa: Plasmodium and Trypanosomes

Intracellular: Chlamydia, Rickettsia and Borrelia (sometimes intracellular)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Ziehl-Neelsen Stain

A

“acid-fast” stain - contains carbolfuchsin

Used to detach mycobacterium (TB) and can be used for Nocardia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Silver Stain is a special stain for which 3 organisms?

A
  1. Pneumocystis pneumonia (HIV/AIDs pt) - causes fungal infection and diffuse interstitial pneumonia
  2. Legionella - contaminated water (nursing homes) and causes pneumonia
  3. H. pylori (gastric ulcers)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

India Ink

A

it is a negative stain that stains the background and NOT the bug, so unstained organisms stand out. Used primarily for cryptococcus neoformans which is a fungi that exists as a yeast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Bug that produces as golden/yellow pigment?

A

Staph aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Bug that produces as blue-green pigment?

A

Pseudomonas aeruginosa (pyocyanin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Bug that produces a red pigment?

A

Serratia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Bug that produces colonies that have a yellow-orange appearance?

A

Actinomyces - filamentous bacteria that “comets” together - known as “sulfur granules”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Thayer-Martin is a selective media that only grow which bug?

A

Neisseria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Only which type of bacteria grow on a Eosin Methylene Blue agar?

A

selective because only gram (-) bacteria; also a differential agar because lactose fermenters grow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Fastidious bacteria

A

organisms that require special nutrients to grow:

H. influenza - chocolate agar
Legionella - buffered charcoal yeast extract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Chocolate Agar

A

a variant of blood agar used for H. influenza - contains red blood cells that are lysed; contain NAD (factor V) and hemming (factor X)

Note: H. influenza will grow on a blood agar if Staph aureus is present (because is beta hemolytic and completely lysis the blood)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Bordet-Gengou Agar

A

potato agar (high starch) special for Bordetella pertussis - whooping cough (extremely rare due to vaccinations)

40
Q

Loeffler’s Media/Tellurite Plate

A

selective for Corynebacterium diphtheriae; produces gray-black colored colonies

41
Q

Eaton’s Agar

A

culture for mycoplasma pneumonia; no cell wall so poorly visualized w/ gram stain; requires cholesterol to grow; takes week to grow so rarely used in the modern era

42
Q

MacConkey is a selective media for what type of bugs?

A

selective gram - rods
differential for lactose fermenters

43
Q

sOrbital MacConkey Agar

A

detection for E. coli 0157:H7 strains (shiga-like toxin)

sOribital = 0157

44
Q

Buffered charcoal yeast extract is used to only identify which bug?

A

Legionella - very important to culture this bacteria b/c can cause outbreaks (contaminate water supplies - nursing homes)

45
Q

Sabouraud’s Agar

A

selective media for fungi

46
Q

Obligate anaerobes

A

do NOT need O2 to generate ATP; lack catalase or superoxide dismutase (no need); normal in GI (about 99%/100x more than aerobes); don’t typically cause diseases; disease when mucosal surfaces break down; often present in abscesses; use fermentation and produces CO2 and H2 (gases and foul smelling)

AminOglycosides are ineffective (require O2 to work)

47
Q

Obligate aerobes

A

NEED O2 to generate ATP; under high O2 contents - need superoxide dismutase/catalase to protect against damage of free radicals that form

Pseudomonas aeruginosa
Mycobacterium (TB) - loves lungs b/c loves oxygen
Nocardia (opportunistic infection)

48
Q

Abdominal abscesses/perforations

A

contain many gram (-) anaerobic bacterium; most common bug is Bacteroides fragilis

tx - Metronidazole (anaerobic med for below the diaphragm) and a gram (-) agent

Diverticulitis/Appendicitis

49
Q

Aspiration pneumonia

A

when mouth anaerobes enter the lungs; commonly Peptostreptococcus, Fusobacterium and Prevotella

tx - Clindamycin (anaerobic medication for above the diaphragm)

50
Q

anaerobic medication for below the diaphragm

A

Metronidazole and a gram (-) agent
Diverticulitis/Appendicitis

51
Q

anaerobic medication for above the diaphragm

A

Clindamycin

52
Q

Facultative Anaerobes

A

can live w/o O2 but will use it if available; perform respiration and fermentation

many bacteria fall into this category

53
Q

Obligate Intracellular bacteria

A

cannot synthesize their own ATP (chlamydia) or depend on host ATP (rickettsia)

Rickettsia - Rocky Mountain spotted fever - diagnoses clinically or w/ serology test

Chlamydia - diagnosis w/ DNA testing

54
Q

Virulence Factor Protein A

A

key virulence factor for staph aureus; part of the peptidoglycan cell wall; inhibits phagocytosis and complement activation

54
Q

Virulence Factor Protein A

A

key virulence factor for staph aureus; part of the peptidoglycan cell wall; inhibits phagocytosis and complement activation

55
Q

IgA Protease is a virulence for which 3 bugs?

A

enzyme that cleaves IgA and allows for colonization of mucosal surfaces

Strep pneumonia
H. influenza
Neisseria (gonorrheae/meningitidis)

56
Q

M protein is an important virulence for which organism?

A

surface molecule for group A strep (pyogenes) - causes strep throat and rheumatic fever

prevents phagocytosis by binding factor H

57
Q

Endotoxin receptor on macrophages

A

CD14

endotoxin/LPS on gram (-) activates the CD14 receptor on macrophages and releases IL-1 causing fever

58
Q

Staphylococcus aureus

A

gram (+) cocci, catalase (+), coagulase (+) B-hemolytic cocci; mannitol salt agar - ferments mannitol (yellow)

Protein A virulence factor - prevents phagocytosis

Diseases:
-pneumonia - patchy infiltrates (usually secondary infection after a viral infection)
-septic arthritis (most common cause)
-acute bacterial endocarditis (IV drug user - RA tricuspid)
-osteomyelitis (most common cause)
-Scalded Skin Syndrome (toxin that causes a bad sunscreen)
-Toxic Shock Syndrome (superag TSST)
- Fast (1-8 hrs) onset food poison (preformed toxin - vomiting - meats and mayonnaise left out too long)
-MRSA (altered penicillin-binding proteins PBP) tx w/ vancomycin

Tx w/ Nafcillin (Naph for Staph)

59
Q

Disease caused by Staphylococcus aureus

A

-pneumonia - patchy infiltrates (usually secondary infection after a viral infection)
-septic arthritis (most common cause)
-acute bacterial endocarditis (IV drug user; RA tricuspid)
-osteomyelitis (most common cause)
-Scalded Skin Syndrome (toxin that causes something like a bad sunscreen)
-Toxic Shock Syndrome (superag TSST; tampons left in too long)
- Fast (1-8 hrs) onset food poison (preformed toxin - vomiting - meats and mayonnaise left out too long)
-MRSA (altered penicillin-binding proteins PBP) tx w/ vancomycin

Tx w/ Nafcillin (Naph for Staph)

60
Q

Staphylococcus epidermidis

A

gram (+), catalase (+), coagulase (-)

normal skin flora - can easily contaminate when blood is drawn;
enemy of orthopedic surgeons - causes a lot of prosthetic joint infection; catheter-assocaited infections; endocarditis of artificial heart valves; creates biofilms via glycolyx

tx w/ vancomycin
Novobiocin sensitive on agars

61
Q

Staphylococcus saprophyticus

A

gram (+), catalase (+), coagulase (-)

Diseases:
-honeymoon cystitis; UTI occurs in associated with sexual activity (not a STD)
-acute bacterial prostatitis

Novobiocin resistant on agars

62
Q

Streptococcus pyogenes

A

Group A Strep (Bacitracin sensitive)
encapsulated - hyaluronic acid; B- hemolytic

Infections:
-impetigo - pyogenic honey crusted skin infection (also caused by staph aureus)
-strep throat (pharyngitis)
-cellulitis and erysipelas

Strep pyogenes Exotoxins (SPEs):
-Scarlet fever (3 main symptoms):
1. Red and swollen tongue (strawberry tongue)
2. Pharyngitis (strept throat)
3. Wide spread rash that spares the face

-Toxic Shock Like Syndrome (TLS) - superag syndrome similar to staph auereus

-Necrotizing fasciitis “flesh eating bacteria”

Serious complications:
1. Rheumatic Fever
2. Post-Strep Glomerulonephritis

63
Q

Strep pyogenes Exotoxins (SPEs) infections

A

-Scarlet fever (3 main symptoms:
1. Red and swollen tongue (strawberry tongue)
2. Pharyngitis (strept throat)
3. Wide spread rash that spares the face

-Toxic Shock Like Syndrome (TLS) - superag syndrome similar to staph auereus

-Necrotizing fasciitis “flesh eating bacteria”

64
Q

Rheumatic Fever

A

Serious complication of Strep pyogenes infections; pharyngitis precipitates RF; type II hypersensitivity reaction

M protein virulence factor (anti-phagocytic and strong humoral response); molecular mimicry in mitral valve causing mitral stenosis

JONES criteria - joints, heart probs, nodules (elbows and knees), erythema marginatum (rash w/ nice borders), Sydenham’s chorea (rapid involvement movements

commonly tested concepts:
-ONLY occurs after pharyngitis (unlike PSG)
-early tx can prevent Rh (unlike PSG)

tx w/ penicillin

65
Q

Post-Strep Glomerulonephritis

A

Serious complication of Strep pyogenes infections (about 2 weeks post infection); pharyngitis precipitates kidney injury; type III hypersensitivity reaction

2 weeks after dark brown “cola cola” urine and facial puffiness from edema

virulence factor of streptolysin O

commonly tested concepts:
-can occur after pharyngitis OR impetigo (unlike Rh)
-cannot be prevented w/ early tx

tx w/ penicillin

66
Q

Scarlet fever (3 main symptoms)

A

caused by Strep pyogenes Exotoxins (SPEs); symptoms:
1. Red and swollen tongue (strawberry tongue)
2. Pharyngitis (strept throat)
3. Wide spread rash that spares the face

67
Q

Streptococcus Agalactiae

A

Group B Strep (Bacitracin resistant)
Hippurate (+), CAMP test (+), B hemolytic
Poly A capsule

causes meningitis in neonates (#1 cause)
sepsis in neonates
pneumonia

transmitted via vaginal canal during delivery - all moms need to be swapped at 35 weeks; if (+) tx mom w/ intrapartum penicillin

68
Q

Streptococcus pneumoniae

A

1 cause of community acquired pneumonia (rust color sputum; lobar pneumonia)

encapsulated gram (+) lancet-shaped diplococci; alpha hemolytic (partial); optochin sensitive; bile soluble

sickle cell and asplenic pt are at risk

Meningitis
Otitis media
Pneumonia
Sinusitis

Virulence factors:
IgA protease - cleaves IgA

tx w/ macrolides or ceftriaxone (3rd gen)
vaccines: 23 valent adult vaccine (IgM response) and a 7 valent children vaccine (IgG response)

69
Q

Streptococcus viridans

A

gram (+) diplococci; alpha hemolytic (partial); optochin resistant; bile resistant

commonly associated with dental caries - subacute endocarditis that affects damaged heart valves (mitral)

adheres to platelets (dextrans - glue that helps them stick to platelets)

70
Q

Enterococcus

A

Enterococcus faecium (more dangerous) & faecalis (more common); intestinal tract bacterium; can grow in 6.5% NaCl; bile resistant; 3 infections (Do U Heart Trees?)

UTIs
Endocarditis
Biliary tree infections

VRE (vancomycin resistant enterococcus)
tx w/ Linezolid or Tigecycline

71
Q

Streptococcus gallolyticus

A

Group D Strep (aka Strep Bovis)

encapsulated gram (+) cocci (chains or pairs); gamma hemolytic (no hemolysis); bile-soluble; creates a biofilm - heart valves; normal GL tract flora

Clinical relevance:
Endocarditis
STRONG association with colorectal cancer (obtain a colonoscopy)

tx w/ 3rd gen cephalosporins or vancomycin or penicillin

72
Q

Bacillus anthracis

A

gram (+) bacillus obligate aerobe that has the unique feature is looking like rods and chains; **encapsulated (protein - Poly D glutamate) - black eschar - black cutaneous lesions; **spore-forming

Toxins:
1. Edema Factor (EF) - AC analog that increases cAMP
2. Lethal Factor (LF) - endotoxin that acts as a protease that cleaves MAP kinase (controls cell growth) - leading to impeded growth

Pulmonary anthrax - spores in sheep’s wool

tx: 1st choice - fluoroquinolone 2nd choice - doxycycline

73
Q

Bacillus cereus

A

gram (+) bacillus; associated with food poisoning of **reheating fried rice

tx: 1st choice - fluoroquinolone 2nd choice - doxycycline

74
Q

Pulmonary anthrax

A

inhalation of Bacillus anthracis spores; watch for people who handle sheep/wool; presents w/ non specific pulmonary symptoms (dry cough) but can rapidly progress to pulmonary hemorrhage; CXR widened mediastinum - 100% fatal

tx; 1st choice - fluoroquinolone 2nd choice - doxycycline

75
Q

Clostridium tetani

A

gram (+) bacillus; spore-forming obligate anaerobe - the cause of tetanus

often found in soil - puncture wounds causes by **rusty nails or barged wire (construction worker or child playing near a construction zone) neuromuscular symptoms:

-spastic paralysis
-risus saronicus “an evil grin” or lock jaw symptoms
-opisthotonus “exaggerated arching of back”

Mechanism:
spores are in flesh - releases Tetanus toxin - travels retrograde (periphery to spinal cord) - cleaves SNARE proteins and prevents exocytosis at the NMJ synapse inhibiting GABA and Glycine (from Renshaw cells) - uncontrolled firing with no inhibition leading to spastic paralysis

Vaccine - toxoid vaccine

76
Q

Mechanism of Clostridium tetani

A

puncture wounds causes by **rusty nails or barged wire (construction worker or child playing near a construction zone) - spores are in flesh - releases Tetanus toxin - travels retrograde (periphery to spinal cord) - cleaves SNARE proteins and prevents exocytosis at the NMJ synapse inhibiting GABA and Glycine (from Renshaw cells) - uncontrolled firing with no inhibition leading to spastic paralysis

77
Q

Clostridium botulinum

A

gram (+) bacillus - the cause of botulism

improper of canning of food (spores) - cook canned food thoroughly; won’t say canned food - more like a family and everyone is the home is experiencing very similar neural symptoms:

  • descending flaccid paralysis
    -diplopia and ptosis

Mechanism:
ingestion of preformed toxin - travels to the peripheral nervous system through the gut - cleaves the SNARE proteins of motor neurons that release Ach

Babies:
“floppy baby syndrome” - HONEY!! (ingestion of spores)

78
Q

Mechanism of Clostridium botulinum

A

gram (+) bacillus - the cause of botulism

ingestion of preformed toxin - travels to the peripheral nervous system through the gut - cleaves the SNARE proteins of motor neurons that release Ach

Babies:
“floppy baby syndrome” - HONEY!! (ingestion of spores)

79
Q

Clostridium perfringens

A

gram (+) bacillus causing infections associated w/ motorcycle vehicle accidents and military combat wounds - large amount of flesh is exposed to dirt - spore transmission

“double zone of hemolysis on blood agar”

Infections:
1. gas gangrene (produces gas under tissues) - alpha toxin or lecithinase
2. late/slow onset food poisoning - watery diarrhea (transient)

tx; IV penicillin G

80
Q

Clostridioides difficile (C. diff)

A

gram (+) bacillus obligate anaerobe spore forming - fecal/oral route (ingestion of spores) - typically hospital acquired - can be caused by antibiotic use (wipes out normal flora):

  • Clindamycin, Fluoroquinolone, Penicillin, Cephalosporins and PPI

Toxins MOA: disruption of tight jxns in colon - increased paracellular permeability - water goes into lumen and leads to foul smoking HIGH volume watery diarrhea - can see “pseudomembranous colitis” - fear complication of toxic megacolon

Diagnose w/ EIA for toxins or PCR for toxins

tx: oral vancomycin (poor systemic absorption) or oral fidaxomicin severe C. diff tx with IV metronidazole in addition; if these fail do a fecal microbiota transplant (restores normal gut microbiome)

81
Q

Corynebacterium diphtheria

A

the cause of diphtheria - transmitted by respiratory droplets

gram (+) non spore forming bacillus; “club shape in a “Y” or “V” formation w/ metachromatic granules; exotoxin - 2 subunits A (active) and B (binding subunit) - inhibits elongation factor 2 (EF-2) to inhibit protein synthesis (ribosylation) - leading to cell death “pseudomembrane formation”; presents with “bullneck” thickening of the neck due to lymphadenopathy; systemic effects on heart - arrhythmias and heart blocks; local paralysis (posterior oral pharynx)

Diagnosis: Tellurite agar or Loeffler’s medium for culturing the bacteria; Elek’s test let you know that is toxin strain

Toxoid vaccine given in the US - look for kids who emigrated who were not vaccinated

82
Q

Listeria monocytogenes

A

gram (+) bacillus most commonly infects pregnant woman; narrow zone of hemolysis when plated (Beta- hemolytic) motile and “tumbling motility”; ‘actin rockets’ use for movement inside the cell; able to survive and multiple in freezing temperatures - can contaminate food even if refrigerated (dairy products); pregnant women are discouraged from eating soft cheese; can cause meningitis in newborns and in adults over 60 yrs

Tx: ampillicin

83
Q

Actinomyces israelii

A

gram (+) filamentous rod; obligate anaerobe (contrast w/ nocardia obligate aerobe); normal flora of oral cavity - common w/ recent dental work - invades surrounding structures (jaw trauma)

Slow onset - starts off non-tender lump on jaw - leading to abscess -drainage sinus tracks - yellow pus w/ “yellow sulfur granules”

Tx: Penicillin G

84
Q

Nocardia asteroides

A

gram (+) filamentous rod; obligate aerobe (contrast w/ actinomycete obligate anaerobe); catalase (+) and urease (+); found primary in the soil (but does NOT form spores); weakly stains acid-fast (mycolic acids); mainly affects immunocomprised pts

Symptoms are pulmonary, CNS and cutaneous
-pneumonia w/ lung abscess formation (cavitation lesions)
-brain abscess formation
-cutaneous indurated lesions

tx: Sulfonamides

85
Q

The two gram (-) cocci?

A

Neisseria (meningitidis/gonorrhoeae)
Moraxella catarrhalis

86
Q

Neisseria overview

A
87
Q

Meningoencephalitis caused by Cryptococcus neoformans

A

occurs in immunocompromised pt; appears as budding yeasts w thick polysaccharide capsules which can be demonstrated using miciarmine or India ink staining

88
Q

Condylomata acuminata

A

anogenital warts present as pink- or skin-colored plaques and verrucous lesions on the genitalia, perineum or perianal skin; primarily caused by HPV 6,11; lesions are associated w increased risk for HIV infection; HIV testing is recommended

89
Q

walking pneumonia w organism that form COLD agglutinins

A

mycoplasma pneumoniae can result in the formation of cold agglutinins, which are IgM antibodies that bind RBCs and cause clumping at low body temperatures

90
Q

HIV-2

A

most cases of AIDS worldwide are caused by HIV-1, however, AIDS can also be caused by infection of HIV-2 which is endemic to West Africa; HIV-2 infection is associated w lower viral loads, less risk of transmission and slower progression to AIDS; the dx is often suspected when HIV tests are incongruent; confirmation can be made using HIV-1/HIV-2 assay

91
Q

acute diarrhea

A

EHEC is primarily contracted after eating undercooked ground beef; EHEC produces Shiga toxin, which causes hemorrhagic colitis and can lead to hemolytic-uremic syndrome (HUS); HUS is characterized by acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia; children under 10 yrs are at greater risk

92
Q

Mumps

A
93
Q

Vibrio vulnificus

A

a curved, gram (-), free-living bacterium that grows in marine environments; transmission primarily occurs due the consumption of raw seafood (oysters) or wound contamination; manifestations are often mild, but individuals w liver disease or iron overload are at very high risk of severe, fulminant infections (sepsis, necrotizing fasciitis)

94
Q

Angiostrongylus infection

A

Eosinophilic meningitis is often due to helminth infection (Angiostrongylus); peripheral eosinophilia is largely mediated by the release of IL-5 response to helminths, allergens, drugs or rheumatic disease

95
Q

cat scratch disease

A

caused by Bartonella henselae, a gram (-) coccobaciluus transmitted by cat scratch or bite; pts commonly present w tender lymphadenopathy proximal to the inoculation site; lymph node histopathology often shows necrotizing granulomas and stellate-shaped micro abscesses

Boards 23' (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions