Source / episode info

• **Episode:**12
• **Title:**Divine Intervention Episode 12-Bacterial Cases A.
• **Published:**2018-03-29
• Source:Episode page

One-liner

This episode reviews high-yield bacteriology covering organisms like Rickettsia (RMSF), Proteus mirabilis (Staghorn calculi), and Klebsiella/E. coli (UTIs); atypical pathogens (Legionella, C. trachomatis); GI infections (Shigella, C. difficile, Bacillus cereus); and neonatal sepsis coverage (Group B Strep, Neisseria meningitidis).

High-yield summary

• Rickettsial Infections (RMSF): Caused by Rickettsia rickettsii. Treat with Doxycycline for all ages, regardless of age (<8 years old), due to low risk of tooth discoloration. Rash spreads centripetally, involving palms and soles.
• Urease-Positive Bugs: Proteus mirabilis is the classic urease-positive organism that causes struvite/staghorn calculi. These stones are often associated with high urine pH.
• Atypical Pneumonia: The "MCL" mnemonic covers three common atypical pathogens: Mycoplasma, Chlamydia, and Legionella. Treatment is typically a macrolide (e.g., Azithromycin).
• UTI Bugs & Clues: E. coli is the most common UTI cause but often requires considering Staphylococcus saprophyticus if E. coli isn't an option. Remember that S. saprophyticus is nitrite negative and urease positive.
• Neonatal Meningitis Coverage: Empiric coverage for neonatal meningitis (first 20 days of life) must include Ampicillin (Listeria) + Ceftriaxone (or Cefotaxime, preferred over Ceftriaxone in neonates due to bilirubin risk) + IVG (for HSV).
• Diphtheria: The toxin is encoded by a bacteriophage and causes ADP ribosylation of elongation factor 2 (EF-2), inhibiting protein synthesis. Treatment requires macrolides or penicillin, plus anti-toxin if active disease is present.

Learning objectives

• Identify the clinical presentation, transmission route, and diagnostic tests for major bacterial pathogens (e.g., Rickettsia, Legionella, Shigella).
• Differentiate between various UTI-causing organisms based on biochemical properties (urease activity, oxidase status, nitrite/indole production).
• Understand the principles of empiric antibiotic coverage for high-risk infections, such as neonatal meningitis and suspected sepsis.
• Recognize the mechanism of action and clinical implications of bacterial toxins (e.g., Shiga toxin, Diphtheria toxin).
• Correlate environmental exposures (water sources, animal contact) with specific infectious diseases (Legionella, Leptospira).