Clinical Characteristics of Extended-spectrum β-lactamase Producing Shigella sonnei Infection Outbreaked in Chungju Area

Abstract

An outbreak of extended-spectrum beta-lactamase (ESBL)-producing Shigella sonnei enteritis, especially in pediatric populations, was unprecedented not only in Korea, but also throughout the world in the past. This study was intended to devise a management guideline for shigellosis caused by an ESBL-producing strain based on analysis of the clinical manifestations and response to therapy. We examined 24 strains of S. sonnei isolated from stool cultures of patients with acute enteritis, between November 2004 and February 2005, for antimicrobial susceptibility and ESBL production, and we also performed DNA sequencing with PCR for the typing of ESBL genes. In addition, we retrospectively analyzed the clinical characteristics, laboratory results, and therapeutic responses to antibiotics of the 103 patients who grew S. sonnei on stool cultures. All 24 isolates showed a very similar antibiotic sensitivity pattern and were ESBL gene type of CTX-M-14. The most frequent clinical symptom in the 103 patients was a fever, followed by diarrhea, abdominal pain, headache, vomiting, and nausea. Leukocytosis and CRP were positive in 53.4% and 78.6% of the patients, respectively. On stool direct smears, 11.7% showed more than 50 WBCs per HPF and 71% were positive on stool occult blood. Microbiological eradication rates were as follows: azithromycin and ciprofloxacin, 100%; imipenem-cilastatin, 68.8%; ampicillin-sulbactam, 42.9%; amoxicillin-clavulanic acid, 20%; ceftizoxime, 12.5%; cefdinir, 6.9%; and ceftriaxone and trimethoprim-sulfamethoxazole, 0%. We presumed that, given its cost-effectiveness and safety, azithromycin can be an attractive option for the treatment of ESBL-producing S. sonnei enteritis in pediatric populations. Although ciprofloxacin is another cost-effective agent, its use in pediatric populations is not recommended.