Chinese herb-resistant clinical isolates of Escherichia coli.

Background: Many Chinese herbal formulations are used in the treatment of urinary tract infection. Clinical isolates of Escherichia coli (E. coli) resistant to Chinese herbs have been identified rarely. Report here is a case in which Chinese herbs-resistant E. coli isolate was identified.

Case: The strain of E. coli C16 was isolated from urine of a 72-year-old woman with a diagnosis of pyelonephritis. Standard disc diffusion methodology was used to test the Chinese herbal decoction against E. coli C16. The minimum inhibitory concentration value was 0.1 g/mL. The minimum bactericidal concentration value was 0.2 g/mL. The decoction was orally administered for 4 weeks.

Results: The therapeutic regimen was well tolerated initially. At the end of 4 weeks, the disease relapsed. E. coli C16 was isolated again, which was resistant to herbal solution.

Conclusions: This case illustrates that excessive exposure to Chinese herbs used in unchanging standard formulations can also lead to bacterial resistance. Appropriate clinical use of Chinese herbs is imperative.