Margaret A.WinkerMD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Senior EditorIndividualAuthor
To the Editor.—We read with interest
the recent presentation and review of a case of Salmonella
typhiinfection in a pregnant woman returning from India. Dr Zenilman1discussed multidrug resistance (MDR) in S typhiand reinforced the general view that fluoroquinolones are effective
first-line therapy in the treatment of such infections.
We recently cared for a 52-year-old man who had arrived 1 week previously
from the Punjab region of northern India. He had had fever and headache for
6 days. Blood cultures grew S typhi,and he was treated
with oral ciprofloxacin (500 mg twice a day at presentation, increasing to
750 mg twice a day on day 3). Despite some clinical improvement he remained
febrile after 17 days of treatment. Ceftriaxone, 1 g once daily, was added
to his regimen, and his fever resolved within 3 days.
The S typhiisolate was sensitive in vitro
to trimethoprim, ampicillin, and ciprofloxacin. The minimum inhibitory concentration
(MIC) for ciprofloxacin, as determined by an E-test (AB Biodisk, Solna, Sweden),
was 0.25 mg/L. This MIC means that the isolate is "susceptible" using the
National Committee for Clinical Laboratory Standards breakpoint for ciprofloxacin
of 1.0 mg/L. The usual range of MICs for S typhi
to ciprofloxacin, however, is from 0.0075 to 0.03 mg/L.2
Others have also recently reported clinical failure with ciprofloxacin in S typhiinfections when the MIC has been between 0.25 and
1 mg/L.3,4Quinolone resistance
in isolates from patients returning from the Indian subcontinent have been
reported since 1991.4Interestingly, although
a reduced duration of fever has been a feature of fluoroquinolone therapy
in typhoid fever, an increase in the time to defervescence while receiving
ciprofloxacin has been noted in India.5
This may be indicative of gradually rising MICs for treatment of S typhi.
Ciprofloxacin remains a first-line antibiotic for the treatment of MDR S typhi. However, we recommend that a ciprofloxacin MIC
should be determined on all isolates of S typhifrom
patients returning from the Indian subcontinent. Clinicians should be aware
that clinical failure with fluoroquinolones may occur despite reported sensitivity.
Atkins BL, Gottlieb T. Emerging Drug Resistance and Vaccination for Typhoid Fever. JAMA. 1998;279(8):579-580. doi:10.1001/jama.279.8.579