Joint Pathology Center Veterinary Pathology Services WEDNESDAY SLIDE CONFERENCE 2015-2016 C o n f e r e n c e 22 27 April 2016 Cory Brayton, DVM, Ph.D., DACVP Associate Professor, Molecular & Comparative Pathobiology Johns Hopkins University School of Medicine Broadway Research Building, Suite 851 733 North Broadway Baltimore, MD 21205 CASE I: NIEHS-087 (JPC 4017222). Signalment: 11-month-old B6.129S- Cybbtm1Din/J mouse (Mus musculus) History: A breeding colony of B6.129S- Cybbtm1Din/J mice were housed in an AAALAC International accredited facility. The mice were housed in static micro isolator cases with ad libitum autoclaved food (NIH-31) and beta chip bedding. Mice were provided acidified water due to imm- unocompromised state. The mice were Body as a while, mouse. The liver was slightly enlarged, housed in the same room as B6 imm- and there are multiple tan foci in the liver and lung. (Photo courtesy of: National Institute of Environmental unocompetent mice. Sudden deaths were Health Sciences, Cellular and Molecular Pathology noted in the colony over a weekend. A total Branch and Comparative Medicine Branch, P.O. Box of 87 mice, aged from one to eleven months 12233, Research Triangle Park, NC 27709, http://www.niehs.nih.gov/research/atniehs/labs/lep/index. were affected. Of these, 45 mice were found cfm) dead and 19 sick mice were euthanized and were multifocal tan foci in the liver, spleen necropsied. Twenty males and 38 females and lung. were affected. Laboratory Results: From multiple tissues, Gross Pathology: The livers were pale and a pure culture of Burkholderia spp. was slightly enlarged. In most of the mice, there isolated. The isolate was further 1 characterized as Burkholderia cepacia with PCR. In the blood smears, monocytes Contributor’s Comment: B6.129S- contained bacterial rods. Cybbtm1Din/J mouse is a targeted mutant lacking superoxide production in Histopathologic Description: Liver: 9 Multifocally and randomly, there are areas phagocytes. 129S6 mice is the embryonic of hepatocyte necrosis containing cellular stem cell donor in which cytochrome b-245, and karyorrhectic debris and moderate nu- beta polypeptide(Cybb) targeted mu- mbers of degenerate neutrophils. Mu- tation(tm) was created by Dr. Mary C ltifocally, many blood vessels contain Dinauer(Din) thrombi. There are large areas of coagulative (http://jaxmice.jax.org/strain/002365.html; necrosis surrounding these thrombosed accessed on August 5, 2011). Superoxide blood vessels. Multifocally, the hepatocyte production is critical in host defense. cytoplasm is vacuolated (glycogen) and, Therefore, mice lacking superoxide pro- contain clear round vacuoles (lipid). duction are immunocompromised. This mouse is an animal model for X-linked Multifocal portal areas are infiltrated by 9 small numbers of lymphocytes. No bacteria chronic granulomatous disease in humans. These mice are susceptible to various were present in the Gram’s stained liver 9 section. bacterial and fungal infections. Based on the gross lesions in the affected mice Contributor’s Morphologic Diagnosis: differential diagnoses included septicemia, Liver: Hepatitis, necrosuppurative, mouse hepatitis viral infection, pox viral multifocal, random, moderate with vascular infection and Tyzzer’s disease. His- thrombosis. tologically, the absence of syncytial cells and intracytoplasmic in- clusions helped to eliminate the possibility of mouse he- patitis virus and poxvirus in- fection, respectively. Absence of bacilli in and around the necrotic hepatocytes, el- iminated the possibility of Tyzzer’s disease. The hi- stologic changes in the current case were consistent with a septicemic process. This was supported by the isolation of bacteria and evidence of bac- teremia. Burkholderia cepacia complex includes nine members. The bacteria are ubiquitous in nature and can cause pneumonia and se- pticemia in cystic fibrosis and chronic granulomatous disease Liver, mouse. Randomly throughout the section, there are pale foci of necrosis. 3,7 (HE, 5X). patients. In the current outbreak the source of 2 Liver, mouse. There are multiple areas of coagulative necrosis (black arrows), as well as partially occlusive fibrin thrombi within adjacent vessels. (HE, 181X) infection could not be determined. Because ubiquitous in the environment and can be B6.129S-Cybbtm1Din/J mouse is a model for isolated from soil, vegetables and water.1 X-linked CGD,9 only male mice should have They act as endophytic bacteria on certain been affected. However, both males and types of vegetation and have been used as a females were affected in the current case. potential catalysts, involved in the formation One possible explanation could be that of enzymes, used in the creation of certain numbers of cells in females can have alternative energy sources from perennial the mutant X-chromosome resulting in a full grasses.6 Due in part to the presence of expression of an X-linked condition.5 Also, antibiotic resistance mechanisms, they are spontaneous infections with various also important bacterial pathogens in the pathogens in both males and females have hospital setting,1 and are important op- been previously reported in this mouse portunistic pathogens in cases of septicemia model.2 and lung infection in cystic fibrosis patients.4 The organism has also been JPC Diagnosis: Liver: Hepatitis, ne- isolated from the deep pyoderma in dogs on crotizing, multifocal, random, marked with immunosuppressive therapy (cyclosporine). fibrin thrombi. In those cases the clinical course was acute and infection was widespread. Because B. Conference Comment: Burkholderia cepacia is not a commensal on canine skin, cepacia complex includes a group of motile, it is presumably acquired either from the aerobic, gram-negative bacilli that are 3 environment or within hospitals, although lipopolysaccharide (LPS), exotoxins, reports of environmental B. cepacia in lipases, siderophores and proteases as well veterinary practices are rare. B. cepacia has as the inherent antibiotic resistance of its also been reported to cause subclinical cell envelope.7 mastitis in dairy sheep.1 Contributing Institution: As discussed above, the transgenic mice in National Institute of Environmental Health this case are deficient in superoxide pro- Sciences duction in phagocytes. Once phagocytosis Cellular and Molecular Pathology Branch of an opsonized particle takes place within a and Comparative Medicine Branch neutrophil, usually via binding of com- P.O. Box 12233 plement or Fc receptors, internal signaling Research Triangle Park, NC 27709 cascades are initiated involving various http://www.niehs.nih.gov/research/atniehs/l GTPases and protein and lipid kinases, abs/lep/index.cfm eventually resulting in release of calcium from the endoplasmic reticulum and References: production of the oxidative burst within ph- agolysosomes. The oxidative burst is in- 1. Banovic F, Koch S, Robson D, Jacob M, itiated by formation of the nicotinamide Olivry T. Deep pyoderma caused by adenine dinucleotide phosphate (NADPH) Burkholderia cepacia complex associated oxidase, which stimulates generation of with ciclosporin administration in dogs: a superoxide free radicals, critical in microbial case series. Vet Dermatol. 2015; 26:287-e64. killing.8 In this case, a mutation in NAPDH 2. Bingel SA. Pathology of a mouse model oxidase is involved in superoxide deficiency of x-linked chronic granulomatous disease. and absence of a functional respiratory Contemp Top Lab Anim Sci. 2002;41: 33-38. burst.9 Reactions involving superoxide anion result in the formation of hydrogen 3. Coenye T, Vandamme P, Govan JR, peroxide, hydroxyl radical and hypochlorous LiPuma JJ. Taxonomy and identification of acid as well as peroxynitrate, all of which the Burkholderia cepacia complex. J Clin 8 are important microbicidal agents. Microbiol. 2001;39: 3427-3436. The conference histologic description was 4. Folescu TW, da Costa CH, Folescu very similar to the contributor’s description Cohen RW, da Conceicao Neto OC, et al. above. Not all sections have prominent Burkholderia cepacia complex: Clinical fibrin thrombi but in sections with thrombi course in cystic fibrosis patients. BMC Pulm areas of necrosis appear spatially associated Med. 2015;15:158. with thrombosed vessels. The differential diagnosis for this lesion includes 5. Kumar V, Abbas A, Fausto N, Aster J. Helicobacter hepaticus, Salmonella spp., Pathologic Basis of Disease. 8th ed., Proteus mirabilus and Clostridium piliforme Saunders; 2010:135-182. as well as some viral conditions such as 6. Leo VV, Passari AK, Joshi JB, Mishra mouse hepatitis virus, as mentioned above. VK, et al. A novel triculture system (CC3) Both Gram stains and silver stains failed to for simultaneous enzyme production and identify infectious organisms. Conference hydrolysis of common grasses through participants discussed B. cepacia and its submerged fermentation. Front Microbiol. various virulence factors including 2016;7:447. 4 7. Mahenthiralingam E, Urban TA, scant pale eosinophilic cytoplasm frequently Goldberg JB. The multifarious, forming thin rims around the nuclei. Mitotic multireplicon Burkholderia cepacia figures are rare. Replacing the testicular complex. Nat Rev Microbiol. 2005;3:144- parenchyma is another neoplasm, 3 x 4 mm, 156. well demarcated, unencapsulated and multilobular, composed of sheets and 8. Myers RK, McGavin D, Zachary JF. packets of round to polygonal cells Cellular adaptions, injury, and death: supported by fine fibrovascular stroma. The Morphologic, biochemical and genetic