Spontaneous bacterial and fungal infections in genetically engineered mice: Is Escherichia coli an emerging pathogen in laboratory mouse?

Abstract

The impact of particular microbes on genetically engineered mice depends on the genotype and the environment. Infections resulting in clinical disease have an obvious impact on animal welfare and experimentation. In this study, we investigated the bacterial and fungal aetiology of spontaneous clinical disease of infectious origin among the genetically engineered mice from our institution in relation to their genotype. A total of 63 mice belonging to 33 different mice strains, from severe immunodeficient to wild-type, were found to display infections as the primary cause leading to their euthanasia. The necropsies revealed abscesses localized subcutaneously as well as in the kidney, preputial glands, seminal vesicles, in the uterus, umbilicus or in the lung. In addition, pneumonia, endometritis and septicaemia cases were recorded. Escherichia coli was involved in 21 of 44 (47.72%) of the lesions of bacterial origin, whereas [Pasteurella] pneumotropica was isolated from 19 of 44 (43.18%) cases. The infections with the two agents mentioned above included three cases of mixed infection with both pathogens. Staphylococcus aureus was considered responsible for five of 44 (11.36%) cases whereas Enterobacter cloacae was found to cause lesions in two of 44 (4.54%) mice. Overall, 16 of the 44 (36.36%) cases of bacterial aetiology affected genetically engineered mice without any explicit immunodeficiency or wild-type strains. The remaining 19 cases of interstitial pneumonia were caused by Pneumocystis murina. In conclusion, the susceptibility of genetically modified mice to opportunistic infections has to be regarded with precaution, regardless of the type of genetic modification performed. Beside the classical opportunists, such as [Pasteurella] pneumotropica and Staphylococcus aureus, Escherichia coli should as well be closely monitored to evaluate whether it represents an emerging pathogen in the laboratory mouse.

• Authors: Laurentiu Benga, W Peter M Benten, Eva Engelhardt, Christina Gougoula, Martin Sager
• Journal: Berliner und Munchener tierarztliche Wochenschrift (Berl Munch Tierarztl Wochenschr) 2015 Jul-Aug Vol. 128 Issue 7-8 Pg. 278-84 ISSN: 0005-9366 [Print] Germany
• PMID: 26281439 (Publication Type: Journal Article)

Topics

• Animals
• Communicable Diseases, Emerging (genetics, microbiology, veterinary)
• Escherichia coli Infections (genetics, pathology, veterinary)
• Immunocompromised Host
• Mice
• Mice, Inbred Strains
• Mice, Transgenic (microbiology)
• Mycoses (genetics, pathology, veterinary)
• Opportunistic Infections (genetics, pathology, veterinary)
• Rodent Diseases (genetics, microbiology)