Effective mitigation of an outbreak of New Delhi metallo-β-lactamase-producing Escherichia coli infections in a small animal veterinary teaching hospital.

Objective: To describe infection prevention and control (IPC) interventions implemented in response to an outbreak of New Delhi metallo-β-lactamase (NDM)-producing carbapenem-resistant Enterobacterales (CRE) infections in a veterinary teaching hospital.

Methods: A multimodal intervention was introduced that included environmental surveillance, point-prevalence surveillance of hospitalized dogs and cats, mandatory education/training about CRE, alterations in personal protective equipment protocols, increased environmental cleaning/disinfection, workflow modifications, and expert consultation.

Results: The highest environmental point prevalence for all-type carbapenemase-producing CRE (CP-CRE) or NDM Escherichia coli samples was 59.4% (19 of 32) or 37.5% (12 of 32), respectively. The highest prevalence of patient colonization with all-type CP-CRE (4 of 13 [30.8%]) or NDM E coli (3 of 13 [23.1%]) occurred at the same time point. Following the interventions, NDM E coli and all-type CP-CRE in the environment rapidly declined, and no further clinical infections were documented in the subsequent 7 months. However, CP-CRE and NDM E coli patient colonization rates took several months to decline.

Conclusions: Both clinical infections and patient colonization with CRE declined by use of a multimodal IPC strategy. However, inpatient colonization rates declined more slowly, suggesting ongoing intrafacility transmission and/or unidentified environmental reservoirs that took longer to resolve.

Clinical relevance: This study described feasible IPC interventions that can be applied to inpatient small animal settings to help mitigate acquisition of CRE infections and asymptomatic colonization. Monitoring for clinical infections alone is an insensitive indicator of intrafacility CRE transmission in hospitalized patients. Substantial expenses were associated with the outbreak. Improved IPC and early intervention are recommended to prevent CRE transmission within veterinary hospitals.