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# Mycoplasma (Pathogen, not a drug) – Treatment Overview
## Overview
*Mycoplasma pneumoniae* is an atypical bacterium lacking a cell wall. Beta-lactam antibiotics (penicillins, cephalosporins) are ineffective. Treatment requires macrolides, tetracyclines, or fluoroquinolones. Macrolide resistance is increasing worldwide.
## Primary Indications
- Community-acquired pneumonia (CAP) due to *M. pneumoniae*
- Acute tracheobronchitis, pharyngitis (when etiology confirmed or strongly suspected)
- Extrapulmonary manifestations (rare: hemolytic anemia, neurologic, cardiac)
## Adult Dosing
- **First-line (if low macrolide resistance):** Azithromycin 500 mg PO on day 1, then 250 mg PO days 2–5.
- **Alternative (preferred if concern for resistance):** Doxycycline 100 mg PO twice daily for 7 days.
- **Second-line:** Levofloxacin 750 mg PO once daily for 5 days.
## Pediatric Dosing
(Pediatric dosing established for age-appropriate agents)
- **Azithromycin (≥6 months):** 10 mg/kg (max 500 mg) PO on day 1, then 5 mg/kg (max 250 mg) PO days 2–5.
- **Doxycycline (≥8 years, or <8 years if no alternative for serious infection):** 2.2 mg/kg (max 100 mg) PO twice daily for 7 days.
- **Levofloxacin:** Generally reserved for severe cases with resistance; consult infectious disease. Dosing per local protocol (e.g., 10 mg/kg/dose every 12 hours, max 750 mg/day for 7–10 days).
## Dose Adjustments
- **Azithromycin:** No renal adjustment; caution in severe hepatic impairment.
- **Doxycycline:** No adjustment for renal or mild-moderate hepatic impairment.
- **Levofloxacin:** Reduce dose for CrCl <50 mL/min (e.g., 750 mg once, then 500 mg daily [adult] for 5-day course). Pediatric: adjust per local protocol.
## Contraindications
- **Azithromycin:** Hypersensitivity; prior cholestatic jaundice/hepatic dysfunction with macrolides.
- **Doxycycline:** Pregnancy (2nd/3rd trimester), children <8 years (unless serious infection with no alternative).
- **Levofloxacin:** History of tendon injury; myasthenia gravis; pregnancy; lactation; children <18 years (except specific serious infections).
## Adverse Effects
- **Azithromycin:** GI upset, QT prolongation (risk with other QT-prolonging drugs), hearing loss (prolonged use).
- **Doxycycline:** Photosensitivity, esophageal ulceration (take with water, avoid lying down), tooth discoloration in young children.
- **Levofloxacin:** Tendonitis/rupture, peripheral neuropathy, CNS effects (dizziness, seizure), dysglycemia, QT prolongation.
## Key Drug Interactions
- **Azithromycin:** Warfarin (INR increase), QT-prolonging agents (e.g., amiodarone, certain antipsychotics).
- **Doxycycline:** Antacids, iron, calcium, magnesium, bismuth (chelate – separate by 2–3 hours); oral contraceptives (reduced efficacy).
- **Levofloxacin:** NSAIDs (increase CNS toxicity risk); oral antidiabetics/insulin (dysglycemia); warfarin (INR elevation).
## Monitoring
- Clinical response: fever, cough, oxygenation (pneumonia severity).
- ECG if using azithromycin in patients with pre-existing QT prolongation or concurrent QT-prolonging drugs.
- Signs of tendonitis (fluoroquinolones) – discontinue immediately if pain/swelling.
- Macrolide resistance testing if available and severe/refractory cases.
## Clinical Pearls
- Macrolide resistance is common in Asia and parts of Europe; **doxycycline is often preferred** in adults with suspected *M. pneumoniae* pneumonia.
- In children, azithromycin remains first-line unless resistance is documented or suspected.
- Beta-lactams are **not effective** – do not use alone if *Mycoplasma* is possible.
- Co-infections with *Streptococcus pneumoniae* or viruses are possible; consider empiric coverage per local CAP guidelines.
- *Mycoplasma* often presents as "walking pneumonia" with dry cough and gradual onset; severe cases may require IV therapy.
**Educational Disclaimer:** This information is for educational purposes. Always verify local resistance patterns, formulary options, and individual patient factors. Consult current IDSA/CDC guidelines and full prescribing information for definitive treatment decisions.
