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# Mycoplasma (Pathogen)
## Overview
*Mycoplasma pneumoniae* is an atypical bacterium characterized by the lack of a peptidoglycan cell wall, rendering it intrinsically resistant to all beta-lactam antibiotics (penicillins, cephalosporins, carbapenems). Treatment targets protein synthesis inhibition.
## Primary Indications
Treatment of community-acquired pneumonia (CAP), tracheobronchitis, and extrapulmonary manifestations (e.g., hemolytic anemia, dermatologic syndromes) caused by *M. pneumoniae*.
## Adult Dosing
* **Macrolide (First-line, though resistance is increasing):** Azithromycin 500 mg PO on day 1, then 250 mg PO daily for days 2–5.
* **Tetracycline (Alternative):** Doxycycline 100 mg PO/IV every 12 hours for 7–14 days.
* **Fluoroquinolone (Alternative):** Levofloxacin 500 mg PO/IV daily for 7–14 days or Moxifloxacin 400 mg PO/IV daily for 7–14 days.
## Pediatric Dosing
* **Macrolides:** Azithromycin 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) daily for days 2–5.
* **Tetracyclines:** Doxycycline 2.2 mg/kg/dose every 12 hours (max 100 mg/dose). Although historically avoided in young children due to concerns of tooth discoloration, short-term courses (≤21 days) are now considered safe by the AAP.
* **Fluoroquinolones:** Generally reserved for severe/refractory cases due to concerns regarding cartilage toxicity (benefit vs. risk assessment required).
## Dose Adjustments
* **Renal/Hepatic:** Usually no adjustment required for azithromycin or doxycycline (monitor in severe hepatic impairment). Levofloxacin requires significant dose reduction for CrCl < 50 mL/min.
## Contraindications
* **Macrolides:** History of cholestatic jaundice or hepatic dysfunction with prior use; QT prolongation.
* **Tetracyclines:** Known hypersensitivity. Excessive use in children is generally avoided beyond short courses due to enamel hypoplasia.
* **Fluoroquinolones:** History of myasthenia gravis, tendon disorders, or documented allergy.
## Adverse Effects
* **Macrolides:** Gastrointestinal distress (diarrhea, nausea, vomiting), QT prolongation (torsades de pointes risk), transient ototoxicity.
* **Tetracyclines:** Photosensitivity, esophageal ulceration (take with full glass of water), GI upset, tooth discoloration (if prolonged).
* **Fluoroquinolones:** Tendonitis/tendon rupture, CNS effects (dizziness, confusion), dysglycemia, peripheral neuropathy.
## Key Drug Interactions
* **Macrolides:** Inhibit CYP3A4; risk of increased concentrations of warfarin, digoxin, and certain statins.
* **Tetracyclines/Fluoroquinolones:** Significant binding interactions with di- and trivalent cations (antacids, iron, calcium, magnesium). Separate administration by at least 2 hours before or 4–6 hours after.
## Monitoring
* **Clinical:** Resolution of cough, fever, and tachypnea.
* **Laboratory:** Liver function tests (if on macrolides for prolonged duration); monitoring for *C. difficile* diarrhea if symptoms persist or worsen.
## Clinical Pearls
* **Resistance:** Increasing macrolide resistance is common in many geographic regions. If a patient fails to respond to macrolides within 48–72 hours, switch to a tetracycline or fluoroquinolone.
* **Extrapulmonary:** In severe autoimmune-associated complications (e.g., Stevens-Johnson Syndrome or severe hemolysis), immunomodulatory therapy (corticosteroids or IVIG) may be required alongside antibiotics.
* **Diagnostics:** Nucleic Acid Amplification Tests (NAAT/PCR) are preferred over culture as *Mycoplasma* is fastidious and slow-growing.
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*Disclaimer: This information is for educational purposes only. Always consult the most recent institutional antibiogram, local prescribing guidelines, and official FDA-approved product labeling before prescribing or administering medication.*
