Three cases of ciprofloxacin treatment failure in imported typhoid fever

Recently, the role of ciprofloxacin in the empirical treatment of typhoid fever has been limited with the increased incidence of nalidixic acid-resistant Salmonella enterica serovar Typhi in South-central and Southeast Asia, as well as multidrug-resistant strains. We experienced three cases of imported typhoid fever that did not respond to ciprofloxacin. All of the blood isolates were susceptible to ciprofloxacin in vitro, but the patients failed to achieve clinical improvement with ciprofloxacin and were treated with ceftriaxone or azithromycin. Although nalidixic acid-resistant strains may be reported as susceptible to ciprofloxacin on disk diffusion tests, they frequently show a poor clinical response to ciprofloxacin because of the increased minimum inhibitory concentration of ciprofloxacin. Therefore, if clinical improvement is delayed or fails with ciprofloxacin, imported typhoid fever from South-central or Southeast Asia should be considered as being due to nalidixic acid-resistant strains and should be treated with high-dose ciprofloxacin, ceftriaxone, or azithromycin. (Korean J Med 77:377-381, 2009)