The association between Clostridioides difficile colonization and C. difficile infection (CDI) is unknown in solid-organ transplant (SOT) patients. We examined C. difficile colonization and healthcare-associated exposures as risk factors for development of CDI in SOT patients.

The retrospective study cohort included all consecutive SOT patients with at least 1 screening test between May 2017 and April 2018. CDI was defined as the presence of diarrhea (without laxatives), a positive C. difficile clinical test, and the use of C. difficile-directed antimicrobial therapy as ordered by managing clinicians. In addition to demographic variables, exposures to antimicrobials, immunosuppressants, and gastric acid suppressants were evaluated from the time of first screening test to the time of CDI, death, or final discharge.

Of the 348 SOT patients included in our study, 33 (9.5%) were colonized with toxigenic C. difficile. In total, 11 patients (3.2%) developed CDI. Only C. difficile colonization (odds ratio [OR], 13.52; 95% CI, 3.46–52.83; P = .0002), age (OR, 1.09; CI, 1.02–1.17; P = .0135), and hospital days (OR, 1.05; 95% CI, 1.02–1.08; P = .0017) were independently associated with CDI.

Although CDI was more frequent in C. difficile colonized SOT patients, the overall incidence of CDI was low in this cohort.

Describe the epidemiological and molecular characteristics of an outbreak of Klebsiella pneumoniae carbapenemase (KPC)–producing organisms and the novel use of a cohorting unit for its control.

Observational study.

A 566-room academic teaching facility in Milwaukee, Wisconsin.

Solid-organ transplant recipients.

Infection control bundles were used throughout the time of observation. All KPC cases were intermittently housed in a cohorting unit with dedicated nurses and nursing aids. The rooms used in the cohorting unit had anterooms where clean supplies and linens were placed. Spread of KPC-producing organisms was determined using rectal surveillance cultures on admission and weekly thereafter among all consecutive patients admitted to the involved units. KPC-positive strains underwent pulsed-field gel electrophoresis and whole-genome sequencing.

A total of 8 KPC cases (5 identified by surveillance) were identified from April 2016 to April 2017. After the index patient, 3 patients acquired KPC-producing organisms despite implementation of an infection control bundle. This prompted the use of a cohorting unit, which immediately halted transmission, and the single remaining KPC case was transferred out of the cohorting unit. However, additional KPC cases were identified within 2 months. Once the cohorting unit was reopened, no additional KPC cases occurred. The KPC-positive species identified during this outbreak included Klebsiella pneumoniae, Enterobacter cloacae complex, and Escherichia coli. blaKPC was identified on at least 2 plasmid backbones.

A complex KPC outbreak involving both clonal and plasmid-mediated dissemination was controlled using weekly surveillances and a cohorting unit.