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Arthur JD, Mullen JL, Uzal FA, Nagamine CM, Casey KM. Epizootic of enterocolitis and clostridial overgrowth in NSG and NSG-related mouse strains. Vet Pathol 2024; 61:653-663. [PMID: 38140953 DOI: 10.1177/03009858231217197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2023]
Abstract
While the immunodeficient status of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) and NSG-related mice provides utility for numerous research models, it also results in increased susceptibility to opportunistic pathogens. Over a 9-week period, a high rate of mortality was reported in a housing room of NSG and NSG-related mice. Diagnostics were performed to determine the underlying etiopathogenesis. Mice submitted for evaluation included those found deceased (n = 2), cage mates of deceased mice with or without diarrhea (n = 17), and moribund mice (n = 8). Grossly, mice exhibited small intestinal and cecal dilation with abundant gas and/or digesta (n = 18), serosal hemorrhage and congestion (n = 6), or were grossly normal (n = 3). Histologically, there was erosive to ulcerative enterocolitis (n = 7) of the distal small and large intestine or widespread individual epithelial cell death with luminal sloughing (n = 13) and varying degrees of submucosal edema and mucosal hyperplasia. Cecal dysbiosis, a reduction in typical filamentous bacteria coupled with overgrowth of bacterial rods, was identified in 18 of 24 (75%) mice. Clostridium spp. and Paeniclostridium sordellii were identified in 13 of 23 (57%) and 7 of 23 (30%) mice, respectively. Clostridium perfringens (7 of 23, 30%) was isolated most frequently. Toxinotyping of C. perfringens positive mice (n = 2) identified C. perfringens type A. Luminal immunoreactivity to several clostridial species was identified within lesioned small intestine by immunohistochemistry. Clinicopathologic findings were thus associated with overgrowth of various clostridial species, though direct causality could not be ascribed. A diet shift preceding the mortality event may have contributed to loss of intestinal homeostasis.
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Si C, Nickerson K, Simmons T, Denton P, Nichols MR, Dysko RC, Hoenerhoff M, Mani R, Woods C, Henderson KS, Freeman ZT. Next-Generation Sequencing-Based Identification of Enterobacter hormaechei as Causative Agent of High Mortality Disease in NOD.Cg- PrkdcscidIl2rgtm1Wjl/SzJ (NSG) Mice. Toxicol Pathol 2024; 52:67-80. [PMID: 38477038 DOI: 10.1177/01926233241231286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice, lacking many components of a mature immune system, are at increased risk of disease. General understanding of potential pathogens of these mice is limited. We describe a high mortality disease outbreak caused by an opportunistic bacterial infection in NSG mice. Affected animals exhibited perianal fecal staining, dehydration, and wasting. Histopathologic lesions included a primary necrotizing enterocolitis, with inflammatory and necrotizing lesions also occurring in the liver, kidneys, heart, and brain of some mice. All affected individuals tested negative for known opportunistic pathogens of immunodeficient mice. We initially identified a member of Enterobacter cloacae complex (ECC) in association with the outbreak by traditional diagnostics. ECC was cultured from extraintestinal organs, both with and without histopathologic lesions, suggesting bacteremia. Infrared spectroscopy and MALDI-TOF mass spectrometry demonstrated that isolates from the outbreak shared molecular features and likely a common origin. We subsequently hypothesized that advanced sequencing methods would identify a single species of ECC associated with clinical disease. Using a novel targeted amplicon-based next-generation sequencing assay, we identified Enterobacter hormaechei in association with this outbreak. Knowledge of this organism as a potential opportunistic pathogen in NSG mice is critical for preclinical studies to prevent loss of animals and confounding of research.
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Affiliation(s)
- Catherine Si
- University of Michigan, Ann Arbor, Michigan, USA
| | | | | | | | | | | | | | - Rinosh Mani
- Michigan State University, East Lansing, Michigan, USA
| | - Cheryl Woods
- Charles River Laboratories, Wilmington, Massachusetts, USA
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Fagre AC, Pugazhenthi U, Cheleuitte-Nieves C, Crim MJ, Henderson KS, Fong DL, Leszczynski JK, Schurr MJ, Daniels JB, Manuel CA. Antimicrobial Susceptibility of Corynebacterium bovis Isolates from Immunodeficient Rodents. Comp Med 2021; 71:210-214. [PMID: 33836843 PMCID: PMC8223865 DOI: 10.30802/aalas-cm-20-000107] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/03/2020] [Accepted: 02/02/2021] [Indexed: 01/05/2023]
Abstract
Corynebacterium bovis, the causative agent of hyperkeratotic dermatitis in immunodeficient mice, is a significant problem in preclinical oncology research. Infection results in lifelong skin colonization and a decrease in successful engraftment of patient-derived xenograft tumor models. The use of antimicrobial agents for C. bovis is controversial in light of reports of poor efficacy and the possibility of selection for resistant strains. The purpose of this study was to describe the antimicrobial susceptibilities of C. bovis isolates obtained exclusively from immunodeficient rodents in order to aid in antimicrobial dose determination. Between 1995 and 2018, 15 isolates were collected from 11 research institutions across the United States. Antimicrobial susceptibility testing was performed for 24 antimicrobials commonly used against gram-positive bacteria. Our results provide an updated understanding of the susceptibility profiles of rodent C. bovis isolates, indicating little variability between geographically and temporally distant isolates. These results will facilitate appropriate antimicrobial use to prevent and treat C. bovis infections in immunodeficient rodents.
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Affiliation(s)
- Anna C Fagre
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado
| | - Uma Pugazhenthi
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Christopher Cheleuitte-Nieves
- Center of Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center and Weill Cornell Medicine, New York, New York
| | - Marcus J Crim
- Molecular Diagnostics and Microbiology, IDEXX BioAnalytics, Columbia, Missouri
| | - Kenneth S Henderson
- Research Animal Diagnostic Services, Charles River Laboratories, Wilmington, Massachusetts
| | - Derek L Fong
- Office of Laboratory Animal Resources, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jori K Leszczynski
- Office of Laboratory Animal Resources, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Michael J Schurr
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Joshua B Daniels
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado
| | - Christopher A Manuel
- Office of Laboratory Animal Resources, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado; University of Colorado Cancer Center, Aurora, Colorado;,
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