Background: Shigellosis outbreaks in daycare centers result in substantial disease and economic burdens in the United States. The emergence of multidrug resistant Shigella strains raises questions regarding control of transmission within daycare centers and treatment for children. From May to October 2005, 639 Shigella sonnei cases were reported in northwest Missouri, mostly among persons exposed to daycare centers.
Methods: We conducted a case-control investigation among licensed daycare centers (LDCs) in northwest Missouri to determine transmission risk factors, tested isolates for antimicrobial resistance, and described treatment practices. Case LDCs had secondary attack rates of shigellosis>or=2% (range, 2%-25%) and control LDCs<or=2% (range, 0%-1.3%). We interviewed LDC staff and performed on-site inspections. Thirty-one outbreak isolates were tested for antimicrobial resistance. We interviewed physicians and reviewed health department outbreak-related treatment data.
Results: We enrolled 18 case and 21 control LDCs. LDCs with >or=1 sink in every room (odds ratio [OR]: 0.1; 95% confidence interval [CI]: 0.02-0.5) or a diapering station in every room (OR: 0.1; 95% CI: 0.01-0.6) were less likely to be case-LDCs. Resistance to ampicillin and trimethoprim-sulfamethoxazole was found in 90% of the outbreak strains. Among 210 children treated with antimicrobial agents, azithromycin was used in 92 (44%) while a fluoroquinolone was used in 11 (5%) children.
Conclusions: During a large daycare center-associated shigellosis outbreak, strains were highly resistant to ampicillin and trimethoprim-sulfamethoxazole. Children were frequently treated with azithromycin and occasionally fluoroquinolones. Appropriate handwashing and diapering infrastructure are necessary to minimize spread of shigellosis within daycare centers, and could reduce use of antimicrobial agents.