Azithromycin treatment failure in community-acquired pneumonia caused by Streptococcus pneumoniae resistant to macrolides by a 23S rRNA mutation.

In this report, we describe an azithromycin treatment failure in community-acquired pneumonia. During the first three days of azithromycin, the patient's symptoms worsened, and she was subsequently admitted to the hospital. Blood cultures were positive for a penicillin-susceptible, macrolide-resistant S. pneumoniae. DNA sequencing revealed an A2059G mutation in domain V of the 23S rRNA. To our knowledge, this is the first clinical report of an azithromycin failure in the treatment of S. pneumoniae resistant to macrolides by this mechanism.