LAUSR

OBJECTIVES Most patients with Campylobacter infections do not require antibiotics; however, they are indicated in severe cases. Clinical breakpoints for many antibiotics have not yet been established by the Clinical and Laboratory Standards Institute, making antibiotic selection for resistant infections challenging. During an outbreak of pet store puppy-associated extensively drug resistant (XDR) Campylobacter jejuni infections resistant to seven classes of antibiotics, several patients required antibiotics. The aims of this study were to describe the minimal inhibitory concentrations (MICs) of the outbreak strain for various antibiotics and the successful treatment of two patients using imipenem-cilastatin, a drug not traditionally used to treat Campylobacter infections. METHODS We used whole genome multi-locus sequence typing (wgMLST) to determine the genetic relatedness of Campylobacter isolates collected from two human patients' stool samples with the outbreak strain. We performed extended antimicrobial susceptibility testing on 14 outbreak isolates and 6 control strains to determine MICs for 30 antibiotics from 14 classes. RESULTS Isolates from both patients were found to be highly related to the outbreak strain by wgMLST. MICs indicated resistance of outbreak strain to most antibiotic classes; exceptions included phenicols, glycylcyclines, and carbapenems. Due to potential side effects of phenicols and safety issues precluding use of glycylcyclines like tigecycline when alternatives agents are available, we used carbapenems to treat patients who got severely ill from the outbreak strain infections. CONCLUSIONS Stewardship and clinical vigilance are warranted when deciding whether and how to treat patients with suspected C. jejuni diarrhea with antibiotics. Clinicians should maintain a high index of suspicion for XDR Campylobacter when patients fail to improve and consider use of carbapenems in such settings.