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Selection of a gyrA Mutation and Treatment Failure with Gatifloxacin in a Patient with Streptococcus pneumoniae with a Preexisting parC Mutation
Author(s) -
Kays Michael B.,
Zhanel George G.,
Reimann Megan A.,
Jacobi Judi,
Denys Gerald A.,
Smith David W.,
Wack Matthew F.
Publication year - 2007
Publication title -
pharmacotherapy: the journal of human pharmacology and drug therapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.227
H-Index - 109
eISSN - 1875-9114
pISSN - 0277-0008
DOI - 10.1592/phco.27.2.221
Subject(s) - gatifloxacin , levofloxacin , streptococcus pneumoniae , etest , mutation , microbiology and biotechnology , minimum inhibitory concentration , medicine , biology , antimicrobial , antibiotics , gene , biochemistry
An 81‐year‐old woman had pneumonia caused by Streptococcus pneumoniae (levofloxacin Etest minimum inhibitory concentration [MIC] 1.5 μg/ml) and was treated with intravenous gatifloxacin 200 mg/day. After 3 days of therapy, repeat sputum cultures were positive for S. pneumoniae , which was resistant to levofloxacin (Etest MIC > 32 μg/ml). The isolate obtained before therapy showed a preexisting parC mutation of aspartic acid‐83 to asparagine (Asp83→Asn), and the isolate obtained during therapy showed an acquired gyrA mutation from serine‐81 to phenylalanine (Ser81→Phe) and a second parC mutation from lysine‐137 to Asn (Lys137→Asn). Both isolates were the same strain, as determined with pulsed‐field gel electrophoresis. This case demonstrates the potential for resistance to emerge during 8‐methoxy fluoroquinolone therapy for fluoroquinolone‐susceptible S. pneumoniae with a preexisting parC mutation. Additional clinical failures with a fluoroquinolone may occur unless these first‐step parC mutants can be identified to assist clinicians in selecting appropriate antimicrobial therapy.