BACKGROUND: On August 23, 2016, the Colorado Department of Public Health and Environment (CDPHE) was notified of Campylobacter jejuni isolation in 2 persons who reported consuming unpasteurized milk from the same herdshare dairy. Sale of unpasteurized milk is illegal in Colorado, but it can be legally distributed through a herdshare without regulatory oversight. Increased from past years, in 2014, ~27% of U.S. Campylobacter isolates were resistant to ciprofloxacin, a fluoroquinolone. We sought to describe outbreak magnitude and prevent additional cases.
METHODS: Probable cases were defined as having diarrhea lasting ≥1 day with onset during August 1–October 7 and known consumption of herdshare unpasteurized milk or an epidemiologic link to a confirmed case; confirmed cases had Campylobacter isolation. Cases were identified through passive surveillance and by contacting herdshareholder households. The CDPHE laboratory cultured stool specimens from ill persons and 4 milk samples, and performed pulsed-field gel electrophoresis (PFGE) on 10 patient and 2 milk isolates. CDC performed antimicrobial susceptibility testing on 3 patient isolates.
RESULTS: Ninety-one (53%) of 171 shareholder households responded to telephone interviews. We identified 5 probable and 12 confirmed cases; 1 patient was hospitalized. Confirmed cases were among patients aged 12–68 years (median: 58 years); 9 (75%) were male. C. jejuni with the outbreak PFGE pattern was confirmed in 10 patient isolates and 2 milk samples. All 3 isolates tested for antibiotic resistance were resistant to ciprofloxacin.
CONCLUSIONS: This fluoroquinolone-resistant Campylobacter outbreak was caused by unpasteurized milk from a dairy herdshare. CDPHE notified herdshareholders and cautioned against consuming unpasteurized milk on 3 occasions. Because unpasteurized milk remains available, public health’s role is ongoing education about risks associated with unpasteurized milk consumption.