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AbstractObjectives:The primary aim of this study was to assess the epidemiology of carbapenem-resistant Acinetobacter baumannii(CRAB) for 9 months following a regional outbreak with this organism. We also aimed to determine the differential positivity rate from different body sites and characterize the longitudinal changes of surveillance test results among CRAB patients.Design:Observational study.Setting:A 607-bed tertiary-care teaching hospital in Milwaukee, Wisconsin.Patients:Any patient admitted from postacute care facilities and any patient housed in the same inpatient unit as a positive CRAB patient.Methods:Participants underwent CRAB surveillance cultures from tracheostomy secretions, skin, and stool from December 5, 2018, to September 6, 2019. Cultures were performed using a validated, qualitative culture method, and final bacterial identification was performed using mass spectrometry.Results:In total, 682 patients were tested for CRAB, of whom 16 (2.3%) were positive. Of the 16 CRAB-positive patients, 14 (87.5%) were residents from postacute care facilities and 11 (68.8%) were African American. Among positive patients, the positivity rates by body site were 38% (6 of 16) for tracheal aspirations, 56% (9 of 16) for skin, and 82% (13 of 16) for stool.Conclusions:Residents from postacute care facilities were more frequently colonized by CRAB than patients admitted from home. Stool had the highest yield for identification of CRAB.

AbstractBackground:The association between Clostridioides difficilecolonization and C. difficileinfection (CDI) is unknown in solid-organ transplant (SOT) patients. We examined C. difficilecolonization and healthcare-associated exposures as risk factors for development of CDI in SOT patients.Methods: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. difficileclinical 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.Results: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. difficilecolonization (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.Conclusions:Although CDI was more frequent in C. difficilecolonized SOT patients, the overall incidence of CDI was low in this cohort.

AbstractObjective:Describe the epidemiological and molecular characteristics of an outbreak of Klebsiella pneumoniaecarbapenemase (KPC)–producing organisms and the novel use of a cohorting unit for its control.Design:Observational study.Setting:A 566-room academic teaching facility in Milwaukee, Wisconsin.Patients:Solid-organ transplant recipients.Methods: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.Results: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 cloacaecomplex, and Escherichia coli. blaKPCwas identified on at least 2 plasmid backbones.Conclusions:A complex KPC outbreak involving both clonal and plasmid-mediated dissemination was controlled using weekly surveillances and a cohorting unit.

AbstractIn 2018, the Clostridium difficileLabID event methodology changed so that hospitals doing 2-step tests, nucleic acid amplification test (NAAT) plus enzyme immunofluorescence assay (EIA), had their adjustment modified to EIA-based tests, and only positive final tests (eg, EIA) were counted in the numerator. We report the immediate impact of this methodological change at 3 Milwaukee hospitals.