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106 Cards in this Set
- Front
- Back
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What are the gram + bacilli (rods)?
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Clostirdium (anaerobe), Corynebacterium, Listeria, Bacillus
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What is the first test to distinguish gram + cocci and what are the organisms that fall into each category?
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Catalase test
Catalase + organisms: staphylococcus (clusters) Catalase - organisms: Streptococcus (chains) |
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What is the test used to further differentiate between Gram +, Catalase + organisms and which organisms fall into each category?
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Coagulase test
coagulase + organisms: S. aureus coagulase - organisms: S. epidermidis, S. saprophyticus |
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What is the test used to further differentiate between Gram +, catalase +, coagulase - organisms and which organisms fall into each category?
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Novobiocin test
novobiocin sensitive: S. epidermidis novobiocin resistant: S. saprophyticus |
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What is the test used to further differentiate gram + cocci, that are catalase -, which organisms fall into each category?
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Type of hemolysis on blood agar
alpha hemolysis (partial hemolysis: green): S.pneumoniae, Viridans streptococci (S. mutans) beta hemolysis (complete hemolysis: clear): Group A (S.pyogenes), Group B (S. agalactiae) Gamma hemolysis (no hemolysis): enterococcus (E. faecalis), peptostreptoccus (anaerobe) *entercoccus is either alpha or gamma hemolytic |
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How do you differentiate between S. pneumoniae and Viridans streptococci?
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Presence of a capsule, Optochin test, and bile solubility
S. pneumoniae has a capsule (+ quelling), optochin sensitive, and bile soluble Viridans streptococci (S. mutans) does not have a capsule, optochin resistant, and not bile soluble) |
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How do you differentiate between the Beta hemolytic bacteria?
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Bacitracin sensitivity test
Group A (S. pyogenes): bacitracin sensitive Group B (S. agalactiae): bacitracin resistant |
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What is the organism that is a gram + cocci, catalase +, and coagulase +?
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S. aureus
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What is the organism that is gram + cocci, catalase +, coagulase -, and novobiocin sensitive?
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S. epidermidis (can contaminate catheters, b/c of slime mold they form)
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What is the organism that is gram + cocci, catalse +, coagulase -, and novobiocin resistant?
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S. saprophyticus (can cause UTI's)
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What is the organism that is gram + cocci, catalase -, shows green colonies on hemolysis, and bile soluble?
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S. pneumoniae (also has a capsule, and is optochin sensitive)
*green colonies is partial hemolysis, alpha hemolysis |
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What are the characteristics of Group A strep (S. pyogenes?)
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Gram + cocci, catalase -, beta hemolysis of blood agar (complete hemolysis: clear), and bacitracin sensitive
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What is the organism that is gram + cocci, catalase -, alpha hemolytic, and has no capsule?
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Viridans streptocci (is also optochin resistant, and not bile soluble)
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What is the organism that is gram + cocci, catalase -, beta hemolytic, and bacitracin resistant?
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Group B strep (S. agalactiae)
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What are the 4 bacteria that are beta hemolytic?
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1. Group A strep (S. pyogenes)
2. Group B strep (S. agalactiae) 3. S. aureus 4. Listeria monocytogenes (narrow zone of beta hemolysis) |
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Tumbling motility, causes meningitis in the newborn, in unpasteurized milk
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Listeria monocytogenes (narrow zone of beta hemolysis)
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What does catalase do? What bugs are catalase positive?
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It degrades H2O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase. It is made by Staphlococcus (S. aureus, S. epidermatidis, S. saprophyticus)
*People with CGD (NADPH oxidase deficiency) have problems killing catalase + organisms - b/c the organisms degrade H2O2 and the cell can't use that for killing |
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Protein A is the virulence factor for what bug?
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S. aureus - it binds Fc-IgG inhibiting complement fixation and phagocytosis
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What does S. aureus cause?
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1. Inflammatory disease - skin infections, organ abcesses, pneumonia
2. Toxin-mediated disease - toxic shock syndrome (TSST-1 toxin), scalded skin syndrome (exfoliative toxin), rapid-onset food poisoning (enterotoxins) 3. MRSA - major cause of nosocomial and community acquired infections |
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What are the 3 toxins formed by S. aureus?
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1. TSST-1 toxin - causes toxic shock syndrome
2. exfoliative toxin - causes scalded skin syndrome 3. enterotoxins - causes rapid-onset food poisoning |
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MRSA is resistant to what antibiotics besides methicillin?
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B-lactams because of altered penicillin-binding protein
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What does TSST superantigen bind to?
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MCH II (activates CD 4 T cells) and T cell receptor, resulting in polyclonal T-cell activation
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acute bacterial endocarditis and osteomyelitis is caused by what bug?
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S. aureus
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What bug commonly infects prosthetic devices, and intravenous catheters and how does it do it?
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Staphlococcus epidermidis - produces adherent biofilm
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What bug commonly contaminates blood cultures?
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Staphylococcus epidermidis - it is a common component of normal skin flora
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What drugs do you use to treat Staphylococcus?
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Vancomycin + rifampin or gentamycin for resistant strains (lots of strains are resistant)
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Streptococcus pneumoniae is the most common cause of what diseases?
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MOPS
Meningitis Otitis media Pneumonia Sinusitis *patients with sickle cell are at risk of these infections (creating sepsis) |
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What bug is encapsulated and has an IgA protease?
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Strephtococcus pneumoniae
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What bug is associated with "rusty" sputum?
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streptococcus pneumoniae
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What bug can cause sepsis in people with sickle cell and a splenectomy?
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Streptococcus pneumoniae
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What bug causes dental caries and are part of normal flora of oropharynx?
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S. mutans (part of viridans group streptococci)
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What bug can cause subacute bacterial endocarditis and is alpha hemolytic, optochin resistant?
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S. sanguis (part of viridans group streptococci)
*Sanguis = blood (there is lots of blood in the heart) |
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What does group A strep cause?
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1. pyogenic - pharyngitis, cellulitis, impetigo
2. toxigenic - toxic shock syndrome, scarlet fever 3. immunologic - rheumatic fever, actue glomerulonephritis *PHaryngitis can result in scarlet "PHever" and glomerulonePHritis* |
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What are M proteins - what is so special about them?
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S. pyogenes has M proteins - Antibodies to M protein enhance host defenses against S. pyogenes - but can give rise to rheumatic fever
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ASO antibodies detects what type of infection?
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S. pyogenes - antistreptolysin O antibody
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what are symptoms of rheumatic fever?
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"No "rheum" for SPECCulation"
1. Subcutaneous plaques 2. polyarthritis 3. Erythema marginatum 4. Chorea 5. Carditis |
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What bug causes pneumonia, meningitis, and sepsis mainly in babies
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"B for babies"
Streptococcus agalactiae (group B |
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What bacteria are part of normal colonic flora and are penicillin G resistant and cause UTI's and subacute endocarditis?
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Enterococci (group D streptococci) - Enterococcus faecalis and E. faecium
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Group D streptococci include what 2 groups?
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1. enterococci - Enterococcus faecalis and E. faecium
2. non-enterococcal - streptococcus bovis *has variable hemolysis *lancefield grouping |
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Lancefield grouping is based on what?
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differences in C carbohydrate in bacterial cell walls (for group D strep)
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VRE causes what?
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(vancomycin resistant entercoccus) causes nosocomial infections
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What can grow on 6.5% NaCl?
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Enterococci (it is hardier than nonenterococcal group D strep)
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Where does Streptococcus bovis live?
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colonizes the gut - can cause bacteriema and subacute endocarditis in colon cancer patients
*It is nonenterococcus group D strep |
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bactermia and subactue endocarditis in colon cancer patients is caused by what bug?
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Streptococcus bovis (nonenterococcus group D strep)
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An exotoxin encoded by B-prophage causes what disease and what does exotoxin do?
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diphtheria (caused by corynebacterium) - exotoxin inhibits protein synthesis via ADP riboxylation of EF-2
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Pseudomemebranous pharyngitis with grayish-white membrane with lymphadenopathy is caused by what? What else do you see?
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Diphtheria (Corynebacterium diphtheriae) also see ABCDEFG
ADP ribosylation (what the exotoxin does) Beta-prophage (what the exotoxin is encoded by) Corynebacterium (bug) Diphtheriae (bug) Elongation Factor 2 (what gets riboxylated - to inhibit protein synthesis) Granules (metachromatic red/blue granules) seen in lab |
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gram positive rod with metachromatic (blue and red) granules... what bug?
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corynebacterium diphtheriae
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What prevents diphtheriae?
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toxoid vaccine!
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Corynebacterium shape and what does it grow on?
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club shape - grows on tellurite agar, loffler's media
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what organisms can form spores? When are they formed?
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some gram + rods - they are formed when nutrients are limited - formed at the end of stationary phase
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What are spores?
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highly resistant to destruction by heat and chemicals - has dipicolinic acid in their core
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Do spores have metabolic activity?
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NO
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How do you get rid of spores?
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Must autoclave to kill the spores (as is done to surgical equipment)
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What bugs form spores that are found in the soil?
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Clostridium tetnus, bacillus anthracis, Clostridium perfringens
Other spore formers: B. cereus, C. botulinum |
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gram positive, spore-forming, obligate anaerobic bacilli
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Clostridia
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tetanospasmin exotoxin is caused by what bug?
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Clostridium tetani - causes tetnus
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What does tetnus do?
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blocks glycine release (inhibitor neurotransmitter) from renshaw cells in spinal cord
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spastic paralysis, trismus (lockjaw), and risus sardonicus is caused by what?
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clostridium tetani
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what causes flaccid paralysis?
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Clostridium botulimum - from canned foods and honey
from preformed toxin in adults from ingestion of spores in babies (floppy baby syndrome) |
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What does the toxin do in botulism?
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heat-labile toxin that inhibits Ach release at the neuromuscular junction,
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What bug produces an alpha toxin that can myonecrosis (literally muscle necrosis) (gas gangrene) and hemolysis?
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Clostridium perfringens
toxin is "lecithinase", a phospholipase *perfringens perforates a gangrenous leg |
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Cause of pseudomembranous colitis? How does it cause disease?
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Clostridia difficile - produces a cytotoxin, an exotoxin that kills enterocytes
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What antibotic commonly causes C. difficile? What do you treat it with?
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Clindamycin sometimes ampicillin - treat with Metronidazole
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What is the only bacterium with a polypeptide capsule (that contains D-glutamate)?
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Bacillus anthracis (gram +, spore forming rod that produces anthrax toxin)
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What are the 2 types of anthracis?
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1. cutaneous anthrax - from contact
2. pulmonary anthrax - from inhalation of spores |
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black eschar (painless ulcer) on skin, can progress to bacteremia and death what bug?
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bacillus anthracis (cutaneous anthracis)
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on microscopy serpentine or medusa-head on appearance
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Anthrax - bacillus anthracis
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Black skin lesions surrounded by edematous ring
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cutaneous anthrax - caused by lethal factor and edema factor
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Woolsorter's disease
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pulmonary Anthrax! - spores in contaminated wool!
*most common in goat hair |
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flu-like symptoms that rapidly progress to fever, pulmonary hemorrhage, medastitnis (with enlarged mediastinum) and shock
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pulmonary anthrax - from inhalation of spores
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acquired by ingestion of unpasteruized milk/goat cheese and deli meats
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Listeria monocytogenes - can be transferred to the fetus during birth
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actin rockets that move the bug from cell to cell is seen in what condition?
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listeria monocytogenes
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What is the only gram + bacteria with endotoxin?
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Listeria - has tumbling motility at 22 degrees celsius
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How is listeria killed?
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macrophages ingest listeria - cytotoxic T cells kill intracellular listeria
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Listeria can cause what?
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amnionitis, septicemia, spontaneous abortion, granulomatosis infantiseptica, neonatal meningitis, meningitis in ICH and mild gasteroenteritis in healthy individuals
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gram positive rods forming long branching filaments resembling fungi
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actinomyces and nocardia
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gram + anaerobe, causes oral/facial abscesses that may drain through sinus tract in skin
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actinomyces israelii (has yellow sulfar granules in sinus tracts)
* part of normal oral flora |
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gram + anaerobe, weakly acid fast aerobe in soil, causes pulmonary infection in ICH
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nocardia
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what do you use to treat nocardia and actinomyces?
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SNAP
Sulfa for nocardia Penicillin for actinomyces |
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What is primary TB?
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nonimmune host - usually a child - usually ghon complex forms (TB granuloma + lobar and perihilar lymph node involvement
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What are the 4 outcomes of primary TB?
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1. heals by fibrosis - immune and hypersensitivity, tuberculin positive
2. progressive lung disease (HIV, malnutrition) - death (rare) 3. severe bacteremia - miliary TB - death 4. preallergic lymphatic or hematogenous dissemination - dormant tubercule bacilli in serveral orangs - can REACTIVATE in adult life |
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What are the ways you can get extrapulmonary TB?
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1. from a secondary TB infection - getting reactivation
2. from dormant tubercule in organs reactivating |
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what is extrapulmonary TB?
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1. CNS (parenchymal tuberculoma or meningitis)
2. Vertebral body (pott's disease) 3. lymphadenitis 4. renal 5. GI |
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What is Pott's disease?
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reactivation of TB in the vertebral column
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with secondary TB what type of lesion do you see in the lungs?
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fibrocaseous cavitary lesion (usually upper lobes)
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where are ghon complexes usually found?
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in the lower lobes
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If you are PPD + what can that mean?
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1. that you currently have TB
2. that you have been exposed to TB 3. that you have had the BCG vaccine |
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If you are PPD - what can that mean
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1. that you don't have TB and never had
2. anergic (if on steroids, ICH, sarcoidosis) |
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red snappers
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mycobacterium tuberculosis
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fever, night sweats, weight loss, hemoptysis
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TB (often resistant to MANY drugs)
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what bug causes TB like symptoms?
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Mycobacterium kansasii
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M. avium-intracellulare
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often resistant to multiple drugs - causes disseminated disease in AIDS
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gram positive, acid fast organisms
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mycobacterium
1. tuberculosis 2. kansasii 3. avium-intracellulare |
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Hansen's disease
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leprosy
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loss of eyebrows
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lepromatous leprosy (hansen's disease)
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nasal collapse
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lepromatous leprosy (hansen's disease or wegners
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lumpy earlobe
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lepromatous leprosy (hansen's disease)
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leonine facies
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of lepromatous leprosy
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What are they leonine facies of lepromatous leprosy?
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1. loss of eyebrows
2. nasal collapse 3. lumpy earlobe |
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acid fast bacillus that likes cool temperatures
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mycobacterium leprae - cause of leprosy
*since it likes cool temperatures it tends to affect noses, fingers, toes etc. |
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where does Mycobacterium leprae infect?
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skin and superficial nerves
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reservoir in US is armadillos
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Mycobacterium leprae - it cannot be grown in vitro
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what is the treatment for leprosy?
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dapsone; toxicity is hemolysis and methemoglobinemia
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what drug's toxicity is hemolysis and methemoglobinemia?
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dapsone - treatment for leprosy
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what is an alternate treatment for leprosy?
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rifampin and combination of clofazimine and dapsone
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what are the two forms of hansen's disease?
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hansen's disease is leprosy
1. lepromatous - presents diffusely over the skin and is communicable (failed cell-mediated immunity) 2. tuberculoid - limited to a few hypoesthetic nodules LEPROSY can be LETHAL!!! |
