Term
| Which bacteria are associated with kidney stones? |
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Definition
| Proteus and ureaplasma both have the enzyme urease, which converts urea to CO2 and ammonia. This raises the pH of the urine, facilitating the precipitation of magnesium, phosphate, and ammonium into "struvite stones". |
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Term
| Detection of what compound in the urine would suggest infection by enterobacteriaceae (ex: E. coli) ? |
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Definition
Nitrites!
Enterobacteriaceae convert nitrates into nitrites. Recall that E. coli is the most common cause of UTIs.
With bacterial UTIs, leukocyte esterase would also be detectable. |
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Term
| Pyelonephritis-Associated Pili and X/F-adhesins are found on what bacterium? |
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Definition
These are found on pyelonephritic strains of E. coli and facilitate the ascension of the bacterium up the urinary tract.
P-Pili bind to uroepithelium.
X/F-adhesins bind to P blood group antigens. |
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Term
| What bacterium is responsible for acne? |
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Definition
| Propionibacterium acne causes acne. |
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Term
| What fungus is the cause of Dandruff (seborrheic dermatitis) and Tinea Versicolor? |
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Definition
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Term
| What process can be used to detect C. perfringens alpha-toxin? |
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Definition
The Naegler Reaction detects C. perfringens alpha-toxin.
Here, an agar plate containing lecithin is made. Half of it also contains antitoxin. A streak of cultured bacteria is placed across the atitoxin containing and no-antitoxin portions of the agar. The alpha toxin will visibly metabolize the lecithin in the normal agar but be inhibited from metabolizing the lecithin on the portion containing antitoxin. This confirms the presence of alpha-toxin, and C. perfringens infection. |
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Term
Which C. perfringens toxin causes hemolysis and tissue destruction?
Which is cardiotoxic and promotes capillary leakage? |
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Definition
Hemolysis and tissue destruction = alpha-toxin
(this is a lecithinase, ex: phospholipase C, that destroys membranes) detect it with the naegler reaction
Cardiotoxic and leakage = theta-toxin |
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Term
| Risus sardonicus, jockjaw (trismus) and opisthotonus are signs of what condition? |
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Definition
Tetanus!
(opisthotonus is rigid hyperextension of the back and legs) |
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Term
| You observe a gram (+), anaerobic, spore-forming rod with a tennis-racket shaped appearance. What is this bacterium? |
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Definition
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Term
| A patient with less than 3 doses of tetanus vaccine in their history and a dirty, tetanus prone wound should be given what? |
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Definition
| Give both the tetanus vaccine (tetanus toxoid) and the tetanus antitoxin (TIG/ tetanus immunoglobulin) |
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Term
| A patient with less than three doses of tetanus vaccine in their history and clean wounds (not-tetanus prone) should be given what treatment? |
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Definition
| Just the tetanus vaccine (tetanus toxoid) |
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Term
| A patient with 3 or more doses of tetanus vaccine in their history and dirty, tetanus prone wounds should be given what treatment? |
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Definition
| Do not give the tetanus vaccine or tetanus antitoxin (unless it has been greater than 5 years since their last vaccination... then give the vaccine). |
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Term
| How does C. tetani cause spastic paralysis? |
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Definition
| Clostridium tetani spores enter wounds and germinate. They then elaborate the neurotoxin tetanospasmin (tetanus toxin). This inhibits GABA/glycine (the inhibitory neurotransmitters). |
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Term
| Nail punctures through a tennis shoe, third degree burns, and cystic fibrosis are risk factors for what bacterial infection? |
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Definition
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Term
| What are virulence factors of P. aeruginosa? |
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Definition
Endotoxin (pseudomonas is a gram neg.)
Exotoxin A (similar to diphtheria: blocks EF-2)
Pyocyanine (iron scavenger = blue pigment) |
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Term
| A patient has inflamed hair follicles from the neck down after a soak in a hot tub. What is the disease and causitive organism? |
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Definition
Folliculitis caused by pseudomonas aeruginosa
aka: pseudomonas folliculitis |
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Term
| A burn victims wounds have a blue-green, sweet-smelling pus. What has this patient become infected with? |
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Definition
| This is indicative of a Pseudomonas aeruginosa infection. The blue-green color comes from pyocyanine and pyoverdin (fluoroscein). |
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Term
| You have a patient with skin lesions that have a black, necrotic center with rolled/raised, red edges. What are possible differentials? |
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Definition
| Consider cutaneous anthrax (eschars) or pseudomonas infection (ecythema gangrenosum) |
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Term
| Malignant otitis externa is most commonly found in what patients? |
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Definition
| Malignant otitis externa is most commonly found in DIABETICS. It involves bone invasion by pseudomonas aeruginosa |
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Term
| What disease is frequently associated with the wool industry (shearers, spinners, weavers)? |
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Definition
Pulmonary/inhalation anthrax is most commonly associated with the wool industry.
recall, this is associated with mediastinal widening on X-ray and is a severe, life-threatening condition. |
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Term
| What are some signs of cutaneous anthrax? |
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Definition
| Painless, black ulcers (Eschars = scabs) and local edema are found in cutaneous anthrax. This lesion is referred to as a "malignant pustule" |
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Term
| What are the components of the anthrax toxin? |
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Definition
The anthrax toxin is a collective term for 2 exotoxins, Lethal Factor and Edema Factor. Each of these have an A and B component. The B component for each is called "protective antigen" and aids the entry of LF and EF into the host cells.
Edema toxin increases cAMP and promotes exit of fluid from the cell.
Lethal factor inhibits the MAPK pathway that would normally stimulate cell growth. |
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Term
| A sous chef working at a seafood restaurant develops a cellulitis demonstrated by hot tender skin and abrupt systemic symptoms of malaise, fever, headache and chills. What is a likely causative agent. |
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Definition
Vibrio vulnificus is a cause of cellulitis. Like v. cholera, it is also associated with raw seafood ex: oysters.
V. vulnificus can develop into a septicemia, which carries a 50% mortality rate! |
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Term
| Cat bites are likely to be infected with what bacteria? What is the treatment? |
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Definition
Pasteurella is common in cat bites. Do not put a dressing over the wound or suture it up. This only increases the probability of infection.
Standard treatment for cat or dog bites is with "augmentin", the amoxicillin-clavulanate combination.
Recall: amoxicillin is an amino-penicillin and clavulanate is a beta-lactamase inhibitor. |
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Term
| Bacillary angiomatosis is caused by what organism(s)? |
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Definition
Bartonella henselae (cat scratches) and bartonella quintana (body lice) are the causes of bacillary angiomatosis. This is characterized by proliferation of blood vessels into a tumor like mass. Red papules will be evident in the skin.
This is more of a danger in AIDS or transplant patients (immunocompromised) |
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Term
| List some virulence factors of Streptococcus pyogenes. |
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Definition
Streptococcus pyogenes has:
capsule
streptolysin
streptokinase (fibrinolytic)
Hyaluronidase (important in necrotizing fascitis, as it hydrolyzes ground substance and allows spread)
M-Protein (ARF/RHD association)
SPE-A exotoxin (similar to staph. aureus toxic shock syndrome toxin) |
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Term
| What does SPE-A exotoxin do? |
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Definition
SPE-A exotoxin stands for strep. pyogenes exotoxin A. It decreases liver clearance of LPS. Recall that strep is gram (+) so this LPS is from other bacteria, such as normal flora that die and shed endodoxin all the time.
SPE-A also activates macrophages and stimulates fever, shock, and capillary leakage.
It is cardiotoxic and acts as a superantigen. |
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Term
| What are some disease states that S. pyogenes causes? |
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Definition
Impetigo (honey-colored skin sores)
Necrotizing Fascitis
Pharyngitis
Endocarditis
Puerperal Fever |
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Term
| What are some features of S. pyogenes that allow you to identify it |
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Definition
S. pyogenes is a gram (+) coccus.
It is catalase(-) and beta-hemolytic.
It is PYR test (+) and susceptible to bacitracin. |
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Term
| What are some features of Staph. aureus that allow you to identify it? |
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Definition
| Staph. aureus is a gram (+) coccus. It is catalase (+) and coagulase (+). It is also beta-hemolytic. |
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Term
| What are some virulence factors of Staph. aureus? |
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Definition
Coagulase: cleaves fibrinogen to fibrin, which coats it in fibrin allowing it to evade phagocytosis.
alpha-toxin: promotes cell permeability leading to cell death
TSST-1: toxic shock syndrome toxin, which decreases LPS clearance, is pyrogenic, and promotes capillary leakage (similar to SPE-A toxin of S. pyogenes)
Protein A: binds Fc fragment of IgG, minimizing opsonization |
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Term
What is the likely causative agent of osteomyelitis in:
1) patients with sickle cell
2) patients with trauma
3) patients with neither trauma nor hemotological disorders |
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Definition
1) Osteomyelitis in sickle cell patients is often caused by Salmonella
2) Osteomyelitis in patients after trauma is most often caused by pseudomonas (also recall malignant otitis externa leading to skull base osteomyelitis)
3) Staphylococcus aureus is the cause of most other cases of osteomyelitis. |
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Term
| What are signs of toxic shock syndrome? |
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Definition
| Toxic shock syndrome involves a high fever (ex: 104), hypotension leading to shock, kidney or multiorgan failure, and a diffuse erythematous rash resembling a sunburn that may involve the skin of the palms and soles. |
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