Bacteriology classification of bacteria & select gram ⊕ & gram ⊝ infections

Gram-negative Organisms (5) Mycoplasma pneumoniae  Pleomorphic (Illust.)  Classic cause of atypical “walking” pneumonia (insidious onset, headache, nonproductive cough, patchy or diffuse interstitial infiltrate)  X-ray looks worse than patient  High titer of cold agglutinins (IgM)  Grown on Eaton agar  Treatment: macrolides, doxycycline, or fluoroquinolone  (N.B. penicillin ineffective since Mycoplasma have no cell wall) o Not seen on Gram stain  Bacterial membrane contains sterols for stability  Mycoplasmas pneumonia is more common in patients < 30 years old  Frequent outbreaks in military recruits and prisons Marc Imhotep Cray, M.D.