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# Mycoplasma (pathogen)
## Overview
*Mycoplasma pneumoniae* is an atypical bacterium lacking a cell wall, rendering it intrinsically resistant to all beta-lactam antibiotics (e.g., penicillins, cephalosporins). Treatment targets protein synthesis inhibition.
## Primary Indications
Community-acquired pneumonia (CAP), tracheobronchitis, and systemic infections caused by *M. pneumoniae*.
## Adult Dosing
* **Macrolide (Preferred, if susceptibility known):** Azithromycin 500 mg PO on day 1, then 250 mg PO daily for 4 days.
* **Tetracycline (Preferred for empiric therapy due to macrolide resistance):** Doxycycline 100 mg PO/IV twice daily for 5–10 days.
* **Fluoroquinolone (Alternative):** Levofloxacin 500 mg PO/IV daily for 7–10 days or Moxifloxacin 400 mg PO/IV daily for 7–10 days.
## Pediatric Dosing
* **Macrolide:** Azithromycin 10 mg/kg (max 500 mg) on day 1, followed by 5 mg/kg (max 250 mg) daily for 4 days.
* **Tetracycline (Use with caution due to tooth discoloration):** Doxycycline 2.2 mg/kg/dose (max 100 mg) twice daily for 7–10 days. (Note: Short courses <21 days are generally considered safe in children of all ages).
* **Fluoroquinolones:** Generally reserved for cases where no other options exist due to concerns regarding cartilage toxicity.
## Dose Adjustments
* **Hepatic impairment:** May require dose reduction for macrolides if symptomatic.
* **Renal impairment:** No dosage adjustment necessary for the above agents, though caution is advised with fluoroquinolones.
* *Note: Always consult local institutional antibiograms as macrolide resistance rates for M. pneumoniae can exceed 80% in some regions.*
## Contraindications
* **Macrolides:** History of cholestatic jaundice/hepatic dysfunction associated with prior use.
* **Tetracyclines:** Hypersensitivity. While historically contraindicated in young children, current guidelines allow short-term use.
* **Fluoroquinolones:** Known hypersensitivity; caution in patients with history of aortic aneurysm, myasthenia gravis, or risk factors for QT prolongation.
## Adverse Effects
* **Macrolides:** GI upset (diarrhea, nausea), QTc prolongation, ototoxicity (rare).
* **Tetracyclines:** Photosensitivity, esophageal ulceration (take with full glass of water), tooth discoloration (with prolonged use).
* **Fluoroquinolones:** Tendonitis/tendon rupture, CNS effects (dizziness, confusion), dysglycemia, QTc prolongation.
## Key Drug Interactions
* **Macrolides:** Potent inhibitors of CYP3A4; risk of toxicity with statins, warfarin, and cyclosporine.
* **Tetracyclines/Fluoroquinolones:** Chelation with divalent/trivalent cations (antacids, iron, calcium, magnesium); separate administration by at least 2–4 hours.
## Monitoring
* **Clinical:** Resolution of fever and cough.
* **Laboratory:** Monitor QTc interval if on polypharmacy with other QT-prolonging agents.
* **Toxicity:** Monitor for tendon pain (fluoroquinolones) or severe diarrhea (C. diff risk).
## Clinical Pearls
If macrolide resistance is suspected or confirmed via local epidemiology, doxycycline is considered the gold-standard first-line therapy. *M. pneumoniae* is resistant to all cephalosporins, penicillins, and vancomycin. Treatment response may be slow; clinical improvement often lags behind initiation of therapy.
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*Disclaimer: This information is for educational purposes only. Always verify current prescribing information, institutional protocols, and patient-specific factors with clinical resources or a staff pharmacist before prescribing or administering medication.*
