623. Emergence of Shigella with Decreased Susceptibility to Azithromycin -- Minnesota, 2014
Session: Oral Abstract Session: Bacteremia and Endocarditis
Thursday, October 8, 2015: 2:45 PM
Room: 32--ABC
Background: Annually in the United States, Shigella causes ~500,000 illnesses. Azithromycin is the recommended treatment for shigellosis among children aged <16 years and an alternative to fluoroquinolones in adults. Domestically-transmitted ciprofloxacin-resistant Shigella sonnei was reported in the United States in 2015, increasing the clinical importance of azithromycin. Currently, no Clinical Laboratory Standards Institute (CLSI) azithromycin breakpoints for Shigella spp. exist, creating challenges for clinical laboratories and treating clinicians. Nationally, during 2011 and 2012, Shigella spp. with decreased susceptibility to azithromycin (DSA: no zone of inhibition by using disc diffusion with 15 µg azithromycin) were 0.9% and 2.1% of ~220 S. sonnei isolates, and 10.3% and 15.3% of ~55 Shigella flexneri isolates, respectively. In 2013, a single DSA Shigella boydii was isolated in Minnesota in a female aged 1 year. We characterize DSA Shigella emergence in Minnesota.

Methods: We analyzed routine surveillance data and additional antibiotic susceptibility testing results for shigellosis reported to the Minnesota Department of Health (MDH) during 2014.

Results: During 2014, 93 shigellosis cases were reported to MDH; median age was 37 (range, <1–87) years, 49 (53%) were male. All 80 cases with isolates available underwent DSA testing. Twenty (25%) had DSA: 16 (80%) were S. sonnei, and 4 (20%) were S. flexneri. Median age was 37 (range, 24–60 years); 18 (90%) were men. Nine (45%) were HIV-infected men, and 6 (30%) had documented azithromycin treatment for gonorrhea or Chlamydia infection during the previous year. Among the 16 S. sonnei isolates, 7 distinct pulsed-field gel electrophoresis patterns in two related groupings identified these as not belonging to a single cluster but suggestive of community transmission.

Conclusion: Increasing antibiotic resistance requires treatment based on antibiotic susceptibility testing results. DSA Shigella emergence in Minnesota underscores the need for systematic DSA testing, not routinely done by clinical laboratories because lack of CLSI azithromycin breakpoints.  This information is needed by clinicians to limit transmission of an enteric infection with few treatment options.

Pamela Talley, MPH, MD1,2, Dana Eikmeier, MPH3, Stephanie Meyer, MPH4, Fe Leano, MS5, Ginette Dobbins, BS6 and Kirk Smith, DVM, PhD3, (1)Epidemiology Workforce Branch, Centers for Disease Control and Prevention, Atlanta, GA, (2)Infectious Disease Epidemiology, Prevention and Control, Minnesota Department of Health, St Paul, MN, (3)Infectious Disease Epidemiology, Prevention and Control Division, Minnesota Department of Health, St. Paul, MN, (4)Infectious Disease Epidemiology, Prevention and Control, Minnesota Deptartment of Health, St. Paul, MN, (5)Public Health Laboratory, Minnesota Department of Health, St Paul, MN, (6)Public Health Laboratory, Minnesota Department of Health, St. Paul, MN


P. Talley, None

D. Eikmeier, None

S. Meyer, None

F. Leano, None

G. Dobbins, None

K. Smith, None

Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.