The study, published in the Journal of the American Medical Association, finds more and more typhoid cases are being identified as drug-resistant strains, including nalidixic acid-resistant S Typhi as well as ciprofloxacin-resistant. The researchers raise concerns that strains resistant to fluroquinolones may become more prevalent.
"Over the last 20 years, emergence of S Typhi strains resistant to anti-microbial agents has complicated treatment of infected patients," the study authors say in a statement. "Reducing the burden of typhoid fever in the United States will require increased attention to prevention measures by travelers, including improved vaccination coverage among travelers to typhoid-endemic areas."
The Centers for Disease Control and Prevention study, led by Dr. Michael Lynch, was based on data from 1999-2006 for 1,902 people with typhoid fever submitted to the CDC, and 2,016 S Typhi isolates from public health laboratories sent to the CDC for anti-microbial susceptibility testing.