The Centers for Disease Control and Prevention have issued follow-up recommendations for managing and reporting Shigella infections because of concerns about increasing antibiotic resistance and the possibility of treatment failures.
Isolates with no resistance to quinolone antibiotics have ciprofloxacin minimum inhibitory concentration (MIC) values of less than 0.015 mcg/mL. However, the CDC has continued to identify isolates of Shigella that, while still within the susceptible range for the fluoroquinolone antibiotic ciprofloxacin (that is, having MIC values less than 1 mcg/mL), have MIC values for ciprofloxacin of 0.12-1.0 mcg/mL, thus appearing to harbor one or more resistance mechanisms. Furthermore, the CDC has identified an increasing number of isolates that have MIC values for azithromycin exceeding the epidemiologic cutoff value, which suggests some form of acquired resistance.
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Shigella sonnei
The recommendations advise that, if clinicians need to use antibiotics to treat patients who have Shigella infections, they should monitor these patients carefully. In the case of an apparent treatment failure for Shigella with either fluoroquinolone or azithromycin, an infectious disease specialist should be contacted to ascertain alternative treatments, and treatment failure information should be reported to the CDC in coordination with local health department. In addition, a stool specimen should be collected for culture; further susceptibility testing should be undertaken, and the isolate should be expedited to the state public health laboratory, which also should notify the CDC to coordinate additional testing.
“CDC is particularly concerned about people who are at high risk for multidrug-resistant Shigella infections and are more likely to require antibiotic treatment, such as men who have sex with men, patients who are homeless, and immunocompromised patients. These patients often have more severe disease, prolonged shedding, and recurrent infections,” the recommendations stated.
More information can be found in the CDC’s Health Alert Network release.
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