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# Mycoplasma (pathogen)
## Overview
*Mycoplasma pneumoniae* is an atypical bacterium characterized by the lack of a peptidoglycan cell wall, rendering beta-lactams (penicillins, cephalosporins) completely ineffective. Treatment targets protein synthesis (macrolides, tetracyclines) or DNA replication (fluoroquinolones).
## Primary Indications
Treatment of community-acquired pneumonia (CAP), tracheobronchitis, and extrapulmonary manifestations of *M. pneumoniae*.
## Adult Dosing
* **Macrolides (First-line):** Azithromycin 500 mg PO/IV on day 1, then 250 mg PO/IV once daily for days 2–5.
* **Tetracyclines:** Doxycycline 100 mg PO/IV twice daily for 7–14 days.
* **Fluoroquinolones (Alternative):** Levofloxacin 750 mg PO/IV once daily for 5 days OR Moxifloxacin 400 mg PO/IV once daily for 7–10 days.
## Pediatric Dosing
* **Macrolides:** Azithromycin 10 mg/kg (max 500 mg) on day 1, then 5 mg/kg (max 250 mg) once daily for days 2–5.
* **Tetracyclines:** Doxycycline is generally avoided in children <8 years due to tooth discoloration; however, short courses (up to 21 days) are now considered safe for all ages per AAP/CDC guidelines. Dose: 2.2 mg/kg/dose (max 100 mg) twice daily.
* **Fluoroquinolones:** Generally reserved for cases where macrolide resistance is suspected and no safer alternatives exist, due to theoretical concerns of arthropathy. Levofloxacin: 10 mg/kg/dose (max 750 mg) q12h (children <5 yrs) or q24h (children ≥5 yrs).
## Dose Adjustments
* **Renal/Hepatic:** Fluoroquinolones require dose adjustment for renal impairment. Azithromycin and Doxycycline generally do not require dose adjustment in renal impairment, but caution is warranted in severe hepatic impairment.
## Contraindications
* **Macrolides:** History of cholestatic jaundice/hepatic dysfunction, QT prolongation, or known hypersensitivity.
* **Doxycycline:** Severe hepatic impairment.
* **Fluoroquinolones:** History of myasthenia gravis, tendon rupture, or aortic aneurysm/dissection history.
## Adverse Effects
* **Azithromycin:** Diarrhea, nausea, QT interval prolongation (risk of Torsades de Pointes).
* **Doxycycline:** Photosensitivity, esophageal ulceration (take with full glass of water), teeth discoloration (in early childhood).
* **Fluoroquinolones:** Tendinopathy/tendon rupture, CNS effects (dizziness, insomnia), peripheral neuropathy, dysglycemia, *C. difficile* infection risk.
## Key Drug Interactions
* **Macrolides/Fluoroquinolones:** Potential for additive QT prolongation when combined with other QT-prolonging drugs (e.g., ondansetron, amiodarone).
* **Doxycycline:** Significant absorption decrease with divalent/trivalent cations (antacids, iron, calcium, magnesium). Administer 2 hours before or 4 hours after.
## Monitoring
* Monitor clinical improvement (fever resolution, respiratory status) within 48–72 hours.
* If using fluoroquinolones, assess cardiac history (baseline ECG if high-risk) and monitor blood glucose in diabetic patients.
## Clinical Pearls
* **Resistance:** Macrolide resistance in *M. pneumoniae* is increasing globally; failure to respond after 48-72 hours of azithromycin therapy necessitates switching to doxycycline or a fluoroquinolone.
* **Extrapulmonary:** *Mycoplasma* is a known trigger for Stevens-Johnson Syndrome (SJS) and *Mycoplasma*-induced rash and mucositis (MIRM).
* **Local Policy:** Always consult institutional antibiogram and local infectious disease guidelines for empirical therapy choices, as regional resistance patterns vary significantly.
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**Educational Disclaimer:** This information is intended for educational purposes for healthcare professionals. Clinical practice must be guided by institutional protocols, current patient-specific data, and official prescribing information (package inserts). Verify all doses prior to administration.
