Minocycline treatment failure in pneumonia caused by minocycline-sensitive Streptococcus pneumoniae

A previously healthy 23-year-old white woman had fulminant pneumococcal pneumonia complicated by empyema and bilateral pneumothoraces. Despite early treatment with the recommended doses of minocycline, the disease progressed. The S pneumoniae isolate was resistant to a 30microgram tetracycline disk and showed an MIC of 3.13microgram/ml for minocycline and 12.5 microgram/ml for tetracycline; these levels are considered by the manufacturer to indicate sensitivity to minocycline and intermediate sensitivity to tetracycline. The tetracyclines, including minocycline, should not be used to treat bacterial pneumonia since resistant strains of pneumococci are not uncommon and inffective treatment can lead to rapid progression of the infection. This case suggests that the levels of minocycline considered to indicate sensitivity in vitro be reassessed.