Patient suffering with typhoid fever generally presents with severe, debilitating fever and headache. Frequently, diarrhea is not a symptom of Salmonella typhi infection. Humans are the only reservoir and can be asymptomatic carriers, often in the biliary tract.
Salmonella are gram-negative, flagellate, non-sporulating, facultative anaerobic bacilli that ferment glucose and reduce nitrate to nitrite. They are belongs to the members of Enterobacteriaceae family.
Serotype typhi most often has a characteristic reactivity on triple sugar iron (TSI) media. The H2S reactivity occurs as a ring just at the slant and no gas production as shown in Figure 3. If an organism displays this characteristic pattern on TSI agar, and is urease negative, then a presumptive diagnosis of Salmonella enterica serotype typhi can be made. Confirmation can be made with H antigen and further biochemical testing.
Based on the Kirby-Bauer susceptibility results he has been treated with IV ciprofloxacin. Patient showed clinical improvement with resolution of laboratory abnormalities after 4-5 days. He was discharged on oral ciprofloxacin to complete a two-week course. He resumed his full level of activity with only mild fatigue after excessive exertion. One month after his initial presentation, blood cultures were drawn to confirm clearance of the bacteria despite his lack of symptoms. The cultures were positive for Salmonella enterica serotype typhi in two out of two bottles and the isolate exhibiting resistance to nalidixic acid by E test.
In this case, the patient appeared to be sensitive to ciprofloxacin via Kirby Bauer testing but tested as resistant to nalidixic acid suggesting an in vivo resistance to fluoroquinolones. These results were supported clinically as he did not clear his bacteremia after a two-week course of ciprofloxacin. He was subsequently given a two-week course of ceftriaxone, which did clear his bacteremia. He remains asymptomatic, and follow-up stool cultures show no evidence of a carrier state.
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