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Antibiotic Treatment and Resistance

Antibiotic Treatment

Pneumonia caused by Mycoplasma pneumoniae is routinely treated with antibiotics, although the disease is usually self-limiting. The disease is treated with macrolide, tetracycline, or fluoroquinolone classes of antibiotics. All mycoplasmas lack a cell wall and, therefore, all are inherently resistant to beta-lactam antibiotics (e.g., penicillin).

Macrolides (e.g., azithromycin) are generally considered the treatment of choice for both children and adults. In addition to macrolides, fluoroquinolones are recommended for the treatment of adults and tetracyclines (e.g., doxycycline) can be used for older children and adults. Neither fluoroquinolones nor tetracyclines are considered acceptable for young children under normal circumstances. Fluoroquinolones are bactericidal (macrolides and tetracyclines are primarily bacteriostatic), but they exhibit a minimum inhibitory concentration that is significantly higher than macrolides.

Physicians should practice prudent use of macrolide drugs due to the emergence of macrolide-resistant strains of M. pneumoniae.

Antibiotic Resistance

Resistance to macrolides has been emerging in M. pneumoniae since 2000. This issue is especially troubling in Asia, where resistance rates have been shown to be as high as 90%, but macrolide resistance has also been reported in the United States and Europe. Current data suggest that the prevalence of macrolide resistance in M. pneumoniae is probably rising in the United States, possibly due to increased use of azithromycin in recent years to treat a number of illnesses.

Some studies have cited that patients infected with macrolide-resistant strains of M. pneumoniae may respond less well to macrolide antibiotics, with fever and persistent cough for a longer duration than patients infected with macrolide-sensitive strains; however, these data are not definitive. In some patients with macrolide-resistant strains, improvement in symptoms occurred after changing to doxycycline or a fluoroquinolone.

Enough is not yet known about the extent of macrolide-resistance and its clinical implications in the United States to alter prescribing guidance for pneumonia caused by M. pneumoniae infections.