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# Mycoplasma (pathogen, not a drug)
## Overview
*Mycoplasma* species are bacteria that lack a cell wall, making them intrinsically resistant to cell wall-inhibiting antibiotics such as penicillins and cephalosporins. Different species cause various infections, including respiratory tract infections (e.g., *Mycoplasma pneumoniae*), genitourinary infections (e.g., *Mycoplasma genitalium*, *Ureaplasma urealyticum*), and others. Treatment selection depends on the specific species and site of infection.
## Primary Indications
Treatment is indicated for symptomatic infections caused by susceptible *Mycoplasma* species.
## Adult Dosing
* **For *Mycoplasma pneumoniae* (respiratory infections):**
* Azithromycin: 500 mg on day 1, then 250 mg once daily for 4 more days.
* Clarithromycin: 500 mg twice daily for 7-14 days.
* Doxycycline: 100 mg twice daily for 7-14 days.
* Levofloxacin: 500 mg once daily for 7 days or 750 mg once daily for 5 days.
* Moxifloxacin: 400 mg once daily for 7 days.
* **For *Mycoplasma genitalium* (genitourinary infections):**
* Azithromycin: 1 g orally once, followed by 500 mg orally once daily for 3 days (total 2g). Higher doses may be needed for macrolide-resistant *M. genitalium*.
* Moxifloxacin: 400 mg once daily for 7-14 days.
* Doxycycline: 100 mg twice daily for 14 days (often used in combination with azithromycin for potential synergy and to treat co-infections).
* **For *Ureaplasma urealyticum/parvum*:** Dosing varies; often similar to *M. pneumoniae* or *M. genitalium*, but susceptibility testing is crucial.
## Pediatric Dosing
* **For *Mycoplasma pneumoniae* (respiratory infections) in children > 6 months:**
* Azithromycin: 10 mg/kg on day 1 (max 500 mg), then 5 mg/kg once daily for 4 more days (max 250 mg daily).
* Erythromycin: 30-50 mg/kg/day divided into 4 doses (max 1 g/day) for 10-14 days (less preferred due to dosing frequency and GI side effects).
* (Macrolide resistance is increasing in *M. pneumoniae*, consult local guidelines).
* Dosing for *M. genitalium* and *Ureaplasma* in children is not well established and depends heavily on clinical context and susceptibility.
## Dose Adjustments
* **Renal Impairment:** Generally, no dose adjustment is needed for azithromycin or doxycycline. Clarithromycin and levofloxacin may require adjustment in severe renal impairment.
* **Hepatic Impairment:** No specific dose adjustments are typically recommended for azithromycin, doxycycline, or clarithromycin, but caution is advised.
## Contraindications
* Hypersensitivity to the specific antibiotic prescribed.
* Concurrent use of certain medications (e.g., specific statins with azithromycin, QTc-prolonging drugs with fluoroquinolones).
## Adverse Effects
Common adverse effects depend on the chosen antibiotic:
* **Azithromycin/Clarithromycin:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), rash, QT prolongation.
* **Doxycycline:** Photo-sensitivity, gastrointestinal upset, tooth discoloration in children < 8 years (generally avoided unless definitive indication), esophageal irritation.
* **Levofloxacin/Moxifloxacin:** Gastrointestinal upset, headache, dizziness, tendon rupture (black box warning), QT prolongation, C. difficile-associated diarrhea, peripheral neuropathy.
## Key Drug Interactions
* **Azithromycin:** May increase digoxin levels, may increase levels of certain other drugs metabolized by CYP3A4 (e.g., some statins, antiepileptics, anticoagulants).
* **Doxycycline:** Decreased absorption with divalent/trivalent cations (antacids, iron, calcium, dairy products). Reduced efficacy of oral contraceptives.
* **Clarithromycin:** Significant CYP3A4 inhibitor, numerous interactions (e.g., warfarin, statins, colchicine, benzodiazepines).
* **Fluoroquinolones (Levofloxacin, Moxifloxacin):** Reduced absorption with cations. Increased risk of QT prolongation with other QTc-prolonging agents.
## Monitoring
* Monitor for signs and symptoms of infection resolution.
* Monitor for adverse drug reactions specific to the chosen antibiotic.
* Consider repeat testing for *M. genitalium* if symptoms persist, especially to assess for treatment failure or resistance.
## Clinical Pearls
* *Mycoplasma* species are common causes of atypical pneumonia, often presenting with a gradual onset, dry cough, and headache.
* Diagnosis can be challenging and is often based on clinical presentation and response to empiric therapy, as nucleic acid amplification tests (NAATs) are not widely available for all species.
* Macrolide resistance is a growing concern for *M. pneumoniae* and particularly *M. genitalium*. Susceptibility testing is recommended for *M. genitalium* infections, especially if treatment failure occurs.
* Tetracyclines (like doxycycline) are generally effective against *Mycoplasma* but are typically avoided in children under 8 years of age due to the risk of tooth discoloration; however, short courses for specific indications may be considered under specialist guidance.
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*Disclaimer: This information is intended for healthcare professionals and does not substitute for professional medical advice. Always consult the most current prescribing information, clinical practice guidelines, and institutional protocols before making therapeutic decisions. Dosing and recommendations may vary based on patient-specific factors and evolving scientific knowledge.*
