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100 Cards in this Set
- Front
- Back
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Which bacteria form long, branching filaments resembling fungi? |
- Actinomyces
- Nocardia |
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Which bacteria causes oral/facial abscesses that drain through sinus tracts forming yellow "sulfur" granules? How do you treat?
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Actinomyces - treat with Penicillin
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Characteristics of Actinomyces?
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- G+ anaerobe
- Forms long-branching filaments that resemble fungi - Not acid fast - Normal oral flora - Causes oral/facial abscesses that drain through sinus tracts forming yellow "sulfur granules" - Treat with Penicillin |
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Which bacteria causes pulmonary infections in immunocompromised patients and cutaneous infections after trauma in immunocompromised patients? How do you treat?
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Nocardia - treat with Sulfonamides
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Characteristics of Nocardia?
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- G+ aerobe
- Forms long, branching filaments resembling fungi - Acid fast (weak) - Found in soil - Causes pulmonary infections in immunocompromised patients - Causes cutaneous infections after trauma in immunocompromised patients - Treat with Sulfonamides |
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What causes Tuberculosis? Different forms of infection?
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Infection with Mycobacterium tuberculosis
- Primary infection: non-immune host (usually a child) - Secondary infection: partially immune hyper-sensitized host (usually adult) |
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What are the signs of a Primary Tuberculosis?
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Occurs in a non-immune host (usually a child)
- Ghon Complex: Hilar nodes & Ghon focus (usually in mid zone of lung) |
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What can Primary Tuberculosis lead to?
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- Heals by fibrosis → immunity and hypersensitivity → Tuberculin (+)
- Progressive lung disease (HIV, malnutrition) → death (rare) - Severe bacteremia → miliary tuberculosis → death - Pre-allergic lymphatic or hematogenous dissemination → dormant tubercle bacilli in several organs → REACTIVATION in adult life |
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What are the signs of a Secondary Tuberculosis?
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Fibrocaseous cavitary lesion (usually in upper lobes)
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What can Secondary Tuberculosis lead to?
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Extrapulmonary Tuberculosis |
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What does a positive PPD test mean?
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Either:
- Current infection with Mycobacterium tuberculosis - Past exposure to Mycobacterium tuberculosis - BCG vaccinated |
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What does a negative PPD test mean?
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Either:
- No infection - Anergic (steroids, malnutrition, immunocompromise) and in sarcoidosis |
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Which test is more specific than PPD for Mycobacterium tuberculosis infection?
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Interferon-γ Release Assay (IGRA)
- More specific - Fewer false positives from BCG vaccination |
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Which vaccine is used to prevent Tuberculosis?
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BCG vaccine
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What is the appearance of a caseating granuloma in tuberculosis infection?
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- Central necrosis (pinkish region in upper left) |
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What are the symptoms of TB?
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- Fever
- Night sweats - Weight loss - Hemoptysis |
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What are the species of Myocbacterium? What disease do they cause?
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- M. tuberculosis (TB, often resistant to multiple drugs)
- M. kansasii (pulmonary TB-like symptoms) - M. avium-intracellulare (causes disseminated, non-TB disease in AIDS; often resistant to multiple drugs; prophylactic tx with azithromycin) - M. leprae (Leprosy / Hansen disease) |
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What are the characteristics of all Mycobacteria?
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All are acid-fast organisms
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Which bacteria causes disseminated, non-TB disease in AIDS patients? Treatment / prevention?
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Mycobacterium avium-intracellulare
- Often resistant to multiple drugs - Prophylactic treatment with Azithromycin |
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What is released by virulent strains of Mycobacteria? Implication?
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Cord fator is found in virulent strains
- Inhibits macrophage maturation - Induces release of TNF-α Sulfatides (surface glycolipids) - Inhibit phagolysosomal fusion |
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Which bacteria causes this appearance?
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Mycobacterium leprae (Leprosy / Hansen disease)
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Characteristics of Mycobacterium leprae?
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- Acid-fast bacillus
- Likes cool temperatures - Cannot be grown in vitro - Reservoir in US: armadillos |
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What does Mycobacterium leprae infect?
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- Skin
- Superficial nerves: "glove and stocking" loss of sensation - Armadillos (reservoir) |
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What are the forms of Leprosy / Hansen disease? Characteristics?
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Lepromatous:
- Diffuse presentation over skin - Leonine (lion-like) facies - Communicable - Characterized by low cell-mediated immunity w/ a humoral Th2 response Tuberculoid: - Limited to a few hypoesthetic, hairless skin plaques - Characterized by high cell-mediated immunity with a largely Th1 type immune response |
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Which form of Leprosy has a LOW cell-mediated immunity with a humoral Th2 response?
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Lepromatous form
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Which form of Leprosy has a HIGH cell-mediated immunity with a largely Th1-type immune response?
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Tuberculoid form
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How do you treat the two forms of Leprosy / Hansen disease?
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Lepromatous form:
- Dapsone, Rifampin, and Clofazimine for 2-5 years Tuberculoid form: - Dapsone and Rifampin for 6 months |
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How should you first distinguish G- (pink) bacteria?
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Shape
- Diplococci - "Coccoid" rods - Rods - Oxidase (+) comme shaped |
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Which bacteria are G- diplococci? How do you distinguish them?
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Distinguish based on ability to ferment maltose
- Neisseria meningitidis (ferments maltose - meningitiids starts with "m") - Neisseria gonorrhoeae (non-fermenter) |
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Which bacteria are G- coccoid rods? How do you distinguish them?
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* Haemophilus influenzae (requires factors V and X)
* Bordetella pertussis - Pasteurella (animal bites) - Brucella (brucellosis) |
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Which bacteria are G- rods? How do you distinguish them?
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Distinguish based on ability to ferment lactose and distinguish non-fermenters by oxidase capability:
Lactose fermenters: - Fast: Klebsiella, E. coli, Enterobacter - Slow: Citrobacter, Serratia, etc. Lactose non-fermenters: - Oxidase (+): Pseudomonas - Oxidase (-): Shigella, Salmonella, Proteus, Yersinia |
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Which bacteria are lactose fermenting G- rods? How do you distinguish them?
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Fast fermenters:
* Klebsiella * E. coli - Enterobacter Slow fermenters: - Citrobacter - Serratia Lactose is "KEE" - Test with Mac"C"on"KEE'S" agar |
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Which bacteria are non-lactose fermenting G- rods? How do you distinguish them?
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Oxidase (+):
- Pseudomonas Oxidase (-): - Shigella - Salmonella - Proteus - Yersinia |
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Which bacteria are oxidase (+), comma shaped G-? How do you distinguish them?
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Grows in 42°C:
- Campylobacter jejuni Grows in alkaline media: - Vibrio cholerae Produces urease: - Helicobacter pylori |
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How do you determine if a bacteria can ferment lactose?
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*If it can grow pink colonies on MacConkey agar
Remember macConKEE'S agar to remember which bacteria can ferment lactose - - Citrobacter (slow) - Klebsiella (fast) - E. coli (fast) - Enterobacter (fast) - Serratia (slow) *Can also test on EMB agar - lactose fermenters grow as purple/black colonies (E. coli grows purple colonies w/ a green sheen) |
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Can E. coli ferment lactose? Why or why not?
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Yes - E. coli produces β-galactosidase, which breaks down lactose into glucose and galactose
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G- bacilli are resistant to what antibiotics? What are they susceptible to?
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- Resistant to Penicillin G and Vancomycin (G- outer membrane layer inhibits entry)
- Susceptible to Penicillin derivatives such as Ampicillin and Amoxicillin |
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Neisseria species are what type of bacteria? What can they ferment?
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G- diplococci
- MeninGococci ferment both Maltose and Glucose (meningitidis) - Gonococci ferment Glucose (gonorrhoeae) |
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What do Neisseria species produce?
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IgA proteases
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Which bacteria is sexually transmitted and can also cause septic arthritis, neonatal conjunctivitis, pelvic inflammatory disease (PID), and Fitz-Hugh-Curtis Syndrome? Treatment?
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Neisseria gonorrhoeae
Treat: Ceftriaxone (+ Azithromycin or Doxycycline for possible Chlamydia co-infection) |
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Characteristics of Neisseria gonorrhoeae?
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G- diplococci
- Produces IgA proteases - Ferments glucose only - Often intracellular (within neutrophils) - No polysaccharide capsule - No vaccine (d/t rapid antigenic variation of pilus proteins) |
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What can Neisseria gonorrhoeae infection cause? Prevention?
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Prevent sexual transmission w/ condoms
- Gonorrhea - Septic arthritis - Neonatal conjunctivitis (prevent transmission w/ erythromycin ointment) - Pelvic Inflammatory Disease (PID) - Fitz-Hugh-Curtis Syndrome |
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Which bacteria is spread via respiratory and oral secretions, causing meningococcemia and meningitis as well as Waterhouse-Friderichsen syndrome? Treatment?
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Neisseria meningitidis
Treat: Ceftriaxone or Penicillin G |
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Characteristics of Neisseria meningitidis?
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G- diplococci
- Produces IgA proteases - Ferments glucose AND maltose - Polysaccharide capsule - Vaccine (none for type B) - Spread via respiratory and oral secretions |
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What can Neisseria meningitidis infection cause? Prevention?
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- Meningococcemia (picture)
- Meningitis - Waterhouse-Friderichsen syndrome Prevent: Rifampin, Ciprofloxacin, or Ceftriaxone prophylaxis in close contacts (Ceftriaxone or Penicillin G can be used for treatment) |
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Which bacteria causes an infection that leads to the "thumbprint sign" on lateral neck radiograph?
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Haemophilus influenzae epiglottitis
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Characteristics of Haemophilus influenzae?
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Small G- coccobacillary rod
- Aerosol transmission - Most invasive disease caused by capsular type B - Produces IgA protease - Culture on chocolate agar requires factors V (NAD+) and X (Hematin) for growth |
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Which type of Haemophilus influenzae causes the most invasive disease? What do the other types cause?
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- Most invasive disease caused by capsular type B
- Nontypeable strains cause mucosa infections (eg, otitis media, conjunctivitis, or bronchitis) |
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What kind of infection is caused by Haemophilus influenzae?
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HaEMOPhilus causes
- Epiglottitis ("cherry red" in children) - Meningitis - Ototis media - Pneumonia |
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How do you culture Haemophilus influenzae?
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On Chocolate agar, requires:
- Factor V (NAD+), also can be grown w/ S. aureus which provides Factor V - Factor X (hematin) "When a child has "flu", mom goes to five (V) and dime (X) store to buy some chocolate" |
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How do you treat Haemophilus influenzae infections?
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- Mucosal infections (eg, otitis media, conjunctivitis, bronchitis) with Amoxicillin +/- Clavulanate
- Meningitis with Ceftriaxone |
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How do you prevent spread / infection of Haemophilus influenzae infections?
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- Prevention in close contacts exposed to AEROSOL TRANSMISSION: Rifampin
- Prevention w/ vaccine: contains type B capsular polysacchardie (polyribosylribitol phosphate) conjugated to diphtheria toxoid or other protein (given between 2-18 months) |
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Which bacteria causes severe pneumonia, fever, GI and CNS symptoms?
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Legionella pneumophila (Legionnaire's disease)
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Characteristics of Legionella pneumophila?
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G- rod
- Gram stains poorly (use SILVER stain) - Grow on CHARCOAL yeast extract culture with IRON and CYSTEINE - Detected clinically by presence of antigen in urine - Aerosol transmission from environmental water source habitat (eg, AC systems, hot water tanks); no person-to-person transmission "Think of a French LEGIONNAIRE (soldier) with his SILVER helmet, sitting around a campfire (CHARCOAL) with his IRON dagger - his is no SISSY (CYSTEINE)" |
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How do you diagnose Legionella pneumophila? Other signs?
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* Presence of antigen in urine is used clinically
- Labs show hyponatremia - G- rod, better stained w/ Silver Stain - Cultured on Charcoal yeast extract with Iron and Cysteine |
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How does Legionella pneumophila get spread?
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- Aerosol transmission from environmental water source habitat (eg, A/C systems, hot water tanks)
- Not person-to-person |
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What disease states can Legionella pneumophila infection cause? Treatment?
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- Legionnaires' Disease: severe pneumonia, fever, GI and CNS symptoms |
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Which bacteria is associated with wound and burn infections?
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Pseudomonas aeruginosa
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Characteristics of Pseudomonas aeruginosa?
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G- Rod:
- Aerobic (AERuginosa - Non-lactose fermenting - Oxidase (+) - Produces pyocyanin (blue-green pigment) - Grape-like odor - Water source - Produces endotoxin (fever, shock) and exotoxin A (inactivates EF-2) |
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What toxins does Pseudomonas aeruginosa produce? Effects?
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- Endotoxin → fever and shock
- Exotoxin A → inactivates EF-2 |
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What color is Pseudomonas aeruginosa? How?
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Blue/green pigment called Pyocyanin
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What kind of infections does Pseudomonas aeruginosa cause?
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PSEUDOmonas associated with wound and burn infections:
- Pneumonia (especially in cystic fibrosis) - Sepsis - External otitis (swimmer's ear) - UTI - Drug use - Diabetic Osteomyelitis (and malignant otitis externa in diabetics) - And hot tub folliculitis |
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Which bacteria causes hot tub folliculitis?
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Pseudomonas aeruginosa
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How does Pseudomonas aeruginosa affect immunocompromised patients?
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Ecthyma gangrenosum
- Rapidly progressive - Large ulcer (arrows) - Necrotic cutaneous lesions (arrowheads) |
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What bacteria is associated with chronic pneumonia in cystic fibrosis patients?
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Pseudomonas aeruginosa (associated with biofilms)
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What are the virulence factors of E. coli?
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- Fimbriae
- K capsule - LPS endotoxin |
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What kind of infections are enhanced by the E. coli virulence factor "fimbriae"?
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- Cystitis |
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What kind of infections are enhanced by the E. coli virulence factor "K capsule"?
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- Pneumonia
- Neonatal meningitis |
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What kind of infections are enhanced by the E. coli virulence factor "LPS endotoxin"?
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Septic shock
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What are the strains of E. coli?
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- EIEC
- ETEC - EPEC - EHEC |
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Which bacteria causes invasive dysentery (severe diarrhea with the presence of blood and mucus in the feces)? Mechanism?
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EIEC (Invasive)
- Microbe invades intestinal mucosa and causes necrosis and inflammation - Clinical manifestation is similar to Shigella |
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Which bacteria causes Travelers' Diarrhea (watery)? Mechanism?
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ETEC (Travelers')
- Produces heat-labile and heat-stable enteroToxins - No inflammation or invasion |
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Which bacteria causes diarrhea usually in children? Mechanism?
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EPEC (Pediatrics)
- No toxin produced - Adheres to apical surface - Flattens villi - Prevents absorption |
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Which bacteria causes non-invasive dysentery (severe diarrhea with the presence of blood and mucus in the feces)? Mechanism?
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EHEC (O157:H7 is the most common serotype) |
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What are the components of Hemolytic Uremic Syndrome? Cause?
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- Anemia
- Thrombocytopenia - Acute renal failure - Caused by EHEC - Microthrombi form on endothelium damaged by toxin → mechanical hemolysis (forms schistocytes) and ↓ renal blood flow - Microthrombi consume platelets → thrombocytopenia |
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What is the difference between EIEC and EHEC?
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- EIEC: invasive, the microbe invades intestinal mucosa, causing necrosis and inflammation leading to dysentery
- EHEC: not-invasive, toxin alone causes necrosis and inflammation leading to dysentery |
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Besides the presentation and mechanism, how does EHEC differ from other forms of E. coli?
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Does not ferment sorbitol
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Which form of E. coli does not ferment sorbitol?
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EHEC
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Which bacteria is associated with the 4 A's (Aspiration pneumonia, Abscess in lungs and liver, Alcoholics, and di-A-betics)?
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Klebsiella
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Characteristics of Klebsiella?
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G- Rod
- Fast lactose fermenter - Part of intestinal flora |
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What does Klebsiella cause? Who is affected?
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*Causes lobar pneumonia (via Aspiration)
- Forms Abscesses in lungs and liver - Common in Alcoholics and di-A-betics - Forms mucoid colonies d/t abundant polysaccharide capsules - Red "currant jelly" sputum (remember 4 A's) *Also cause of nosocomial UTIs |
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Which bacteria causes patients to have a lobar pneumonia that leads to red "currant jelly" sputum?
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Klebsiella
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What are the similarities of Salmonella and Shigella?
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G- rods
- Invades intestinal mucosa and cause bloody diarrhea - Do not ferment lactose - Oxidase (-) |
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How do Salmonella and Shigella differ in movement?
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Salmonella:
- Flagella (salmon swim) Shigella: - No flagella |
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How do Salmonella and Shigella differ in dissemination?
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Salmonella
- Hematogenously (salmon swimming) Shigella - Cell-to-cell transmission - No hematogenous spread |
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How do Salmonella and Shigella differ in reservoirs?
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Salmonella
- Many animal reservoirs (salmon is an animal) Shigella - Only in humans and primates |
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How do Salmonella and Shigella differ in production of hydrogen sulfide?
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Salmonella
- Produces hydrogen sulfide Shigella - Does not produce hydrogen sulfide |
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How do Salmonella and Shigella differ in their response to antibiotics?
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Salmonella
- Antibiotics may PROLONG fecal excretion of organism Shigella - Antibiotics SHORTEN duration of fecal excretion of organism |
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How do Salmonella and Shigella differ in their immune system response?
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Salmonella
- Invades intestinal mucosa and causes a MONOCYTIC response Shigella - Invades intestinal mucosa and causes a PMN infiltration |
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Which disease is characterized by rose spots on the abdomen, fever, headache, and diarrhea and can remain in the gallbladder causing a carrier state? Cause?
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Typhoid Fever (caused by Salmonella typhi) - only found in humans
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What are the symptoms of Typhoid Fever (Salmonella typhi)?
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- Rose spots on abdomen
- Fever - Headache - Diarrhea - Can remain in gallbladder and cause a carrier state |
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Characteristics of Salmonella?
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- Flagella (salmon swim)
- Can disseminate hematogenously - Have many animal reservoirs - Produce hydrogen sulfide - Antibiotics may PROLONG fecal excretion of organism - Invades intestinal mucosa and causes a monocytic response - Can cause bloody diarrhea - Does not ferment lactose |
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Characteristics of Shigella?
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- No flagella
- Cell to cell transmission, no hematogenous spread - Only reservoirs are humans and primates - Does not produce hydrogen sulfide - Antibiotics shorten duration of fecal excretion of organism - Invades intestinal mucosa and causes a PMN infiltration - Often causes bloody diarrhea - Does not ferment lactose |
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What bacteria is a major cause of bloody diarrhea (especially in children), and is spread through foods such as poultry, meat, and unpasteurized milk?
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Campylobacter jejuni |
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Characteristics of Campylobacter jejuni?
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G- Comma or S-shaped
- Oxidase (+) - Grows at 42°C ("Campylobacter likes the hot campfire") |
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How is Campylobacter jejuni acquired?
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Fecal-oral transmission through foods such as:
- Poultry - Meat - Unpasteurized milk |
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What does Campylobacter jejuni cause?
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- Major cause of bloody diarrhea (especially in children)
- Common antecedent to Guillain-Barré syndrome and reactive arthritis |
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Which bacteria produces profuse "rice-water diarrhea"? Mechanism? Treatment?
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Vibrio cholerae
- Enterotoxin permanently activates Gs → ↑cAMP → rice-water diarrhea - Treat with prompt oral rehydration |
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Characteristics of Vibrio cholerae?
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G- comma shaped
- Oxidase (+) - Grows in alkaline media |
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Where is Vibrio cholerae more common? Treatment?
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- Endemic to developing countries
- Prompt oral rehydration is necessary |
