Atlanta—Pharmacists need to be aware of changes in recommendations on the best ways to treat a common infectious disease. The CDC is now recommending against routine prescriptions for ciprofloxacin to treat Shigella.

A CDC health advisory announced new advice for diagnosing and managing strains of the infection because of possible reduced susceptibility to ciprofloxacin. The U.S. has about 500,000 cases of shigellosis every year, making it the third most common bacterial enteric disease in the nation. Symptoms include bloody diarrhea, abdominal pain, tenesmus, fever, and malaise, the CDC says.

“Infections with emerging strains of Shigella may be harder to treat with ciprofloxacin, an antibiotic often used when treatment is needed, due to emerging quinolone resistance,” explained Gail Bolan, MD, director of the CDC’s Division of STD Prevention. “Antimicrobial susceptibility tests may not accurately predict whether Shigella infections with certain resistance genes can be treated effectively with ciprofloxacin. Using an antibiotic that isn’t effective can contribute to the growing problem of multidrug-resistant Shigella and increase the chance of others getting sick from this highly contagious bacteria.”

In its advisory, the CDC recommends that prescribers:
• Test for antibiotic resistance in all shigellosis cases to determine which antibiotics might be most effective against the bacteria
• Avoid antibiotics unless necessary for Shigella infections
• Refrain from using ciprofloxacin when the minimum inhibitory concentration is ≥0.12 ug/mL, even if the laboratory report identifies the isolate as susceptible

The advisory points out that current interpretive criteria provided by the Clinical and Laboratory Standards Institute categorize these strains as susceptible to ciprofloxacin, a fluoroquinolone antibiotic commonly used in the management of Shigella infections.

Recent data from the CDC and state and local public health departments show, however, that these strains often have a quinolone resistance gene that may lead to clinically significant reduced susceptibility to fluoroquinolone antibiotics.

What makes fluoroquinolone resistance especially worrying is that many Shigella isolates with a quinolone resistance gene are also resistant to many other commonly used treatment agents, such as azithromycin, trimethoprim-sulfamethoxazole, amoxicillin-clavulanic acid, and ampicillin, according to the CDC, which notes that the susceptibility profile might have led to stepped-up prescribing of fluoroquinolones.

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