First Aid Microbiology 5

Question 1

Typhoid fever

Answer 1

Caused by Salmonella typhi.

Presents w/ fever, headache, abdominal pain (diffuse or RLQ), and truncal rash shown below.

S. typhi invade intestinal mucosa and regional lymph nodes, eventually seeding multiple organ systems. Organisms can survive intracellularly in macrophages following phagocytosis. It may hide in the gall bladder as a reservoire and be transmitted by the fecal-oral route.

Diagnose w/ blood, urine, and stool culture. Widal test is classically used for diagnosis. Treat w/ ciprofloxacin or ceftriaxone

Question 2

Types of chancre

Answer 2

• Painless usually indicates syphilis – treat w/ penicillin
• Painful usually indicates Haemophilus ducreyi - treat w/ azithromycin

Question 3

If you administer trimethoprim-sulfamethoxazole and your patient presents with new jaundice, fatigue, and anemia, then they probably have underlying. . .

Answer 3

. . . G6PD deficiency!

TMP-SMX is a common trigger for G6PD hemolytic anemia

Question 4

Utility of MacConkey agar

Answer 4

MacConkey agar culture tells you if an organism can ferment lactose or not. It is primarily useful for differentiating among gram negative rods.

E. coli, Enterobacter, Klebsiella all ferment lactose rapidly.

Serratia and Citrobacter ferment lactose slowly.

Proteus, Pseudomonas, Salmonella, and Shigella cannot ferment lactose, and will not appear pink.

Question 5

Aztreonam

Answer 5

The magic bullet for gram negative bacteria

A monobactam. Only works on gram negatives, but works on basically ALL gram negatives.

Often used with clindamycin or vancomycin for gram positive coverage.

Question 6

Antibiotics that cover the anaerobes (including B. fragilis!)

Answer 6

• Penicillins w/ beta-lactamase inhibitors
• 2nd generation cephalosporines
• Carbapenems
• Clindamycin
• Metronidazole
• Tigecycline
• Moxi Floxacin

Question 7

Antibiotics that cover difficult-to-kill gram positives

Answer 7

• Vancomycin
• Linezolid
• Daptomycin
• Quinupristin/dalfopristin
• Tigecycline

Question 8

The antipseudomonal penicillins

Answer 8

• Used when you want to cover gram negatives and anaerobes and P. aeruginosa is a possibility
• They are:
  
  • Piperacillin
  • Ticarcillin
  • Carbenicillin

Question 9

Ureaplasma urealyticum

Answer 9

Closely related to Mycoplasma, and similarly has no cell wall.

A common cause of non-gonococcal urethritis, which (unlike chlamydia) will be urease positive.

Treat with erythromycin or a tetracycline.

Question 10

Pleurodynia

Answer 10

• Sudden occurrence of lancinating chest pain or abdominal pain attacks, commonly associated with fever, malaise, and headaches.
• Caused by Coxsackievirus B
• Treatment is supportive

Question 11

Scotch tape test

Answer 11