random bacteria facts

Question 1

Poststreptococcal glomerulonephritis and rheumatic fever - which follows what kind of streptotcoccal infections?

Answer 1

PSGN can follow either skin infection or pharyngitis. Acute rheumatic fever only follows pharyngitis.

Question 2

What is the role of optochin?

Answer 2

Differentiates the “green” (alpha-hemolytic) Streptococci: S. pneumoniae is optochin-sensitive, while viridans group Streptococci are optochin-resistant. NB copper (optochin) is green!

Question 3

What is the role of novobiocin?

Answer 3

Differentiates coagulase-negative Staphylococci: S. epidermidis is novobiocin-sensitive, while S. saprophyticus is novobiocin-resistant.

Question 4

What is the role of bacitracin?

Answer 4

Differentiates the beta-hemolytic Streptococci. S. pyogenes is bacitracin-sensitive, while S. agalacticae is bacitracin-resistant.

Question 5

What is the role of NaCl/bile?

Answer 5

Differentiates the gamma-hemolytic strep. Enterococci (faecalis and faecium) are NaCl and bile resistant, while S. bovis is only bile and not NaCl resistant.

Question 6

Genital lesions: painful, painless.

Answer 6

Painful:

• H. ducreyi: chancroid. Regional lymphadenopathy.
• HSV-2: genital herpes.

Painless:

• Klebsiella inguinale: granuloma inguinale aka “Donovanosis”. Deeply staining intracytoplasmic Donovan bodies. Lymphadenopathy uncommon.
• T. pallidum: syphilis.
• C. trachomatis serovars L1-L3: lymphogranuloma venereum. Intracytoplasmic inclusion bodies. Regional lymphadenopathy.

Question 7

C. trachomatis serovars

Answer 7

• A-C: trachoma. Ocular infection in children. “A through see”.
• D-K: urogenital infx. STD.
• L1-L3: lymphogranuloma venereum.

Question 8

Why can you become continually reinfected with N. gonorrheae, even after appropriate antibiotic treatment?

Answer 8

N. goNOrrheae uses antigenic variation on surface proteins to evade immune response. This is also why NO vaccine exists. (NO capsule, NO maltose, NO vaccine).

Question 9

Structure of lipopolysaccharide. What portion is responsible for toxic effects?

Answer 9

Core polysaccharide, O outer polysaccharide antigen, Lipid A. Lipid A produces shock by activation of macrophages and granulocytes.

Question 10

H flu causes which diseases? Which subtype?

Answer 10

AEMOP

• Arthritis (septic)
• Epiglottitis (capsule type B)
• Meningitis (capsule type B)
• Otitis media (nontypable)
• Pneumonia (capsule type B)

Question 11

Most common causes of Otitis media?

Answer 11

1. S. pneumoniae
2. **nontypable **H. influenzae
3. Moraxella catarrhalis

Question 12

What is Enterococcus resistant to, and what are the mechanisms?

Answer 12

• Vancomycin: D-ala-D-ala to D-ala-D-lac in peptidoglycan
• Penicillins: beta-lactamase and PBP mutation (like staph)
• Aminoglycosides: acetylating enzymes
• Tetracyclines: protective proteins and drug efflux pumps
• Fluoroquinolones: DNA gyrase and topoisomerase mutations

Question 13

Describe Leptospirosis. Severe form is?

Answer 13

• Spirochete found in water contaminated with animal urine
• Presents with flu-like sx, jaundice, photophobia with conjunctivitis
• Weil’s syndrome presents additionally with azotemia and hemorrhage.

Question 14

Describe the RPR test

Answer 14

Mix serum with cardiolipin, lecithin, cholesterol. Checks for anti-cardiolipin abx.

Question 15

Infectious agents associated with GBS?

Answer 15

Most common: C. jejuni. Also CMV.