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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 (penicillins, cephalosporins, carbapenems). Treatment focuses on protein synthesis inhibition.
## Primary Indications
Treatment of community-acquired pneumonia (CAP) or tracheobronchitis caused by *M. pneumoniae*.
## Adult Dosing
* **Macrolide (1st line):** Azithromycin 500 mg PO on day 1, then 250 mg PO daily for days 2–5.
* **Tetracycline (Alternative):** Doxycycline 100 mg PO/IV twice daily 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
* **Macrolide (1st line):** Azithromycin 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) daily for days 2–5.
* **Tetracycline (Age ≥8 years):** Doxycycline 2.2 mg/kg per dose twice daily (max 100 mg/dose) for 7–14 days.
* **Fluoroquinolone:** Generally avoided in pediatrics due to potential for arthropathy; reserved for cases where benefit outweighs risk when other options fail or are contraindicated.
## Dose Adjustments
* **Renal:** Tetracyclines and macrolides generally do not require adjustment; however, fluoroquinolones require significant dose reduction for CrCl <50 mL/min.
* **Hepatic:** Use caution with macrolides in severe hepatic impairment.
## Contraindications
* **Macrolides:** Known hypersensitivity; history of cholestatic jaundice.
* **Tetracyclines:** Pregnancy (second/third trimester), children <8 years (unless critical/short term due to tooth discoloration risk).
* **Fluoroquinolones:** Hypersensitivity, known history of myasthenia gravis, or risk of QTc prolongation.
## Adverse Effects
* **Macrolides:** GI upset (diarrhea/nausea), QTc prolongation, hepatotoxicity (rare).
* **Tetracyclines:** Photosensitivity, esophageal irritation, dental enamel hypoplasia.
* **Fluoroquinolones:** Tendonitis/tendon rupture, CNS effects, glucose disturbances, QTc prolongation.
## Key Drug Interactions
* **Macrolides:** Strong CYP3A4 inhibitors. Risk of increased levels of warfarin, cyclosporine, and statins.
* **Tetracyclines/Fluoroquinolones:** Chelation with divalent/trivalent cations (antacids, iron, calcium, magnesium). Separate administration by at least 2 hours before or 4–6 hours after supplements.
## Monitoring
* Monitor clinical response (fever reduction, respiratory status).
* If using fluoroquinolones, monitor for signs of tendon pain or cardiac rhythm disturbances (ECG if high risk).
## Clinical Pearls
* **Resistance:** Macrolide resistance in *M. pneumoniae* is increasing globally. If a patient fails to improve after 48–72 hours of macrolide therapy, consider switching to a tetracycline or fluoroquinolone.
* **Diagnostics:** Nucleic Acid Amplification Tests (NAAT/PCR) are preferred over serology for acute diagnosis.
* **Protocol:** Local antibiotic stewardship protocols and susceptibility patterns should always guide empiric therapy choices.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice varies by institution. Always verify current prescribing information, institutional guidelines, and drug compatibility before administration.
