FA Day 1 Flashcards
Which bugs show up on Giemsa stains?
Chlamydia, Borrelia, Rickettsia, Trypanosomes, Plasmodium
Which bugs stain poorly on gram stain?
These Microbes May Lack Real Color
- Treponema (too thin)
- Mycobacteria (high lipid content)
- Mycoplasma (no cell wall)
- Legionella (intracellular)
- Rickettsia (intracellular)
- Chlamydia (intracellular)
What is a PAS stain? What does it identify?
Glycogen stain, used to identify Tropheryma whipplei
What is the Ziehl-Neelsen stain used for?
Acid-fast bacteria and protozoa (Cryptosporidium)
What is india ink used for?
Cryptococcus neoformans, stains red
What is a silver stain used for?
Fungi, Legionella, H pylori
Which bugs are anaerobes? What do they lack? What Abx is ineffective?
Fusobacterium, clostridium, bacteroides, actinomyces; lack catalase or superoxide dismutase; aminoglycosides require O2 to wnrer bacteria
Which bugs are obligate intracellular? Why?
Rickettsia, Chlamydia, and Coxiella, they rely on host ATP
What are facultative intracellular bugs?
Some Nasty Bugs May Live FacultativeLY
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
What are the encapsulated bacteria? How are they killed? What are vaccines made from?
Strep pneumo, H flu, Neisseria meningitidis, E Coli, Salmonella, Klebsiella, Group B strep -Opsonized by spleen, vaccine= capsule+ protein conjugate to promote T cell activation and class switching
What are the urease positive organisms?
CHuck norris hates PUNKSS
Cryptococcus, H. Pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S. Epidermis, S. Saprophyticus
What does catalase do? What are the catalase positive organisms? What disease has recurrent infections from this?
It degrades hydrogen peroxide into water and oxygen before being processed by myeloperoxidase.
Cats Need PLACESS
-Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E.Coli, Staph, Serratia
Pigments! Actinomyces israelii? Pseudomonas aeruginosa? Staph aureus? Serratia marcescens?
Actinomyces: yellow
S. Aureus: yellow
Pseudomonas: blue-green
Serratia: red
What organisms make protein A? What does it do?
Staph aureus, Bind Fc region of IgG, prevents opsonization and phagocytosis
What does IgA protease do? What bugs secrete it?
It cleaves IgA to colonize respiratory mucosa
-Strep pneumoniae, H influenzae, Neisseria
What makes M protein? What does it do?
Group A Strep, helps prevent phagocytosis
What is an endotoxin? What does it cause? What are important features?
LPS from outer membrane of GNs
It activates macrophages causing fever and hypotension IL1, NOand TNF-alpha. It activates complement causing edema, neutrophil chemotaxis, and activates tissue factor -> DIC.
-heat labile
What does Diphtheria toxin do?
It inhibits protein synthesis by inactivating elongation factor (2) causing pharyngitis with pseudomembranes and lymphadenopathy
What does Pseudomonas toxin do?
Exotoxin A: inhibits protein synthesis by inactivating EF-2 causing host cell death
What does Shiga toxin do?
(Shigella) It inhibits protein synthesis by inactivating 60S ribosome through removal of adenine from rRNA
-causes dysentery, also HUS through cytokine release
What is the EHEC toxin? What does it do?
Shiga-like toxin inhibits protein synthesis by inactivating 60S ribosome through adenine removal by rRNA
-enhances cytokine release, causing HUS (O157:H7), no cell invasion
ETEC has two toxins
Heat labile-inc cAMP, inc Cl secretion and H20
Heat stable- inc cGMP, dec NaCl and H2O
Causes watery diarrhea
What does Bacillus anthracis exotoxin do?
Edema toxin- mimics cAMP, causes endematous borders for anthrax
What does Vibrio cholera do?
Inc fluid secretion by activating Gs causing cAMP overactivity (Cl secretion and H2O efflux) causing rice-water diarrhea
What does Bordetella pertussis toxin dk?
It inhibits phagocytosis by overactivating cAMP through disabling Gi
-Whooping cough!
What does Clostridium tetani toxin do?
(Tetanospasmin) inhibits release of GABA from Renshaw cells in spinal cord by cleaving SNARE
Causes spasticity, lockjaw
What does Colstridium botulinum toxin do?
It inhibits release of ACh by cleaving SNARE
Causes flaccid paralysis, floppy baby
What does clostridium perfringens toxin do?
(Alpha toxin) phospholipase degrades tissues and cell membranes causing myonecrosis (gas gangrene) and hemolysis
What does strep pyogenes toxin do?
Streptolysin O degrades cell membeanes, lyses RBCs causing beta hemolysis. Anyibodies diagnose Rheumatic fever
What’s toxic shock syndrome?
Caused by staph aureus exotoxin, binds to MHC II causing release of IL1 and 2, IFN-gamma, and TNF-alpha
-Presents with fever, rash, shock
What does strep pyogenes toxin do?
(Exotoxin A) binds to MHC II causing release of IL1 and 2, IFN-gamma, and TNF-alpha
-Presents with fever, rash, shock
How is MRSA resistant to methicillin/nafcillin?
Altered penicillin-binding protein
When does Staph aureus food poisoning look like?
Short (2-6 hr) incubation with nonbloody diarrhea and emesis. Enterotoxin is heat stabile
What does Staph epidermis cause?
Infects prosthetic devices and iv catheters, makes biofilms, novobiocin sensitive
What does staph saprophyticus do?
2nd most common cause of UTIs in young women, Novobiocin resistant
What does strep pneumo do? Important features?
Meningitis, Otitis media, pneumonia, sinusitis
-encapsulated, lancet shaped Diplococci, IgA protease, optochin sensitive
What does viridians strep do? Features?
Normal oral flora, causes caries (mutans) and bacterial endocarditis from damaged heart valves (sanguinis)
-alpha hemolytic, optochin resistant
What does strep pyogenes do? Features?
- Pyogenic: pharyngitis, cellulitis, impetigo
- Toxigenic: scarlet fever, TS like
- Immuno: rheumatic fever, glomerulonephritis
- group A, Bacitracin sensitive, beta hemolytic, PYR+, M protein antibodies
Whats the major criteria for acute rheumatic fever?
JONES
Joints, Carditis, Nodules (subcutaneous), Erythema marginatum, Sydenham cholera
What does Strep agalactiae do? Features?
- Causes sepsis, pneumonia, meningitis in babies
- Pregnant women are screened and treated with intrapartum penicillin
