Emergence of multidrug-resistant Salmonella enterica serovar Typhi with reduced susceptibility to fluoroquinolones in Cambodia

From December 2006 to April 2009, we conducted an etiology study among Cambodian patients presenting with acute fever of unknown origin. Salmonella enterica serovar Typhi was detected in 0.9% (41/4985) blood cultures. Antimicrobial susceptibility testing showed decreased susceptibility to ampicillin (56% resistant; MIC90, >256 μg/mL), chloramphenicol (56% resistant; MIC90, >256 μg/mL), trimethoprim/sulfamethoxazole (56% resistant; MIC90, >256 μg/mL), nalidixic acid (81% resistant; MIC90, not defined), ciprofloxacin (0% resistant; MIC90, 0.5 μg/mL), and ceftriaxone (0% resistant; MIC90, 0.094 μg/mL). Multidrug resistance, defined as antimicrobial resistance to ampicillin, chloramphenicol, and trimethoprim/sulfamethoxazole, was found in 56% of the isolates, and 80% had reduced susceptibility to ciprofloxacin (defined as MIC ≥0.12 μg/mL).