A case of recurrent typhoid fever in the United States: importance of the grandmother connection and the use of large restriction fragment pattern analysis of genomic DNA for strain comparison.
An 8-year old girl was infected for a second time with Salmonella typhi by contact with her grandmother, a known typhoid carrier. The S. typhi from both patient and grandmother had closely related genomic pulsed field gel electrophoresis patterns that differed from epidemiologically unrelated strains. The girl responded well to a 14-day course of oral trimethoprimsulfamethoxazole. The grandmother was treated successfully with a 28-day regimen of oral ciprofloxacin. Typhoid fever remains an endemic disease in the United States, largely because of recognized chronic stool carriers. Most of these carriers had typhoid in the preantibiotic era and remain potential sources of disease when they provide meals for others, not uncommonly grandchildren. The importance of this "grandmother" connection to endemic typhoid fever is reviewed, as is the potential use of pulsed field gel electrophoresis pattern analysis for comparison of strains of S. typhi.