Bacteria of Mice Flashcards
______ is a gram-negative spirochete that causes persistent infection in rats and mice?
Leptospira ballum
Why is leptospirosis challenging to diagnose in lab rodents
- it’s rare
- kidney culture can lead to false negatives, esp. in undiluted samples
- infected neonates don’t seroconvert but are persistently infected
What virus causes persistent infection in mouse pups without seroconversion
LCMV
What kind of tissue does Pasteurella pneumotropica like to colonize
mucus cells (respiratory, enteric, and genital tracts of clinical normal mice)
T/F Salmonella is zoonotic
true
Why is treating Salmonella typhimurium with antibiotics not the best idea?
Gut bacteria are a natural barrier and the bacteria likes to hang out in macrophages. Treating with abx will wipe the good gut bacteria and give salmonella the room it needs to get in there.
What should you do with subclinical carriers of Salmonella typhimurium
cull and start over
Gross Findings of salmonella typhimurium
- multifocal necrotizing splenitis and hepatitis
histopath findings of Salmonella typhimurium
necrotic foci in affected tissues, often accompanied by colonies of bacteria, edema, and erythema in Mesenteric LNs
Which age of mice are most susceptible to Salmonellosis
weanlings
what is the ideal tissue for diagnosis of Salmonellosis?
Ideal diagnostic?
- oral swabs or fecal culture
- culture on blood agar plates
What predisposes mice to Pseudomonas infection?
- irradiation, immunosuppression, concurrent disease (esp. MCMV)
Which mice strains are susceptible to pseudomonas aeruginosa
- C3H
- Swiss-Webster
- MyD88-/-
Where would streptococci typically colonize mice normally?
- Intestines, skin, genital tract, upper respiratory tract
What predisposes mice to streptococci infection?
- irradiation, skin wounds, experimental infection, contaminated biologicals, immunosuppression, immunodeficiency
Hematogenous spread can occur with streptococcal infections and lead to abcesses and infect which major organs?
- heart (endocarditis)
- spleen (splenomegaly)
- LNs (lymphadenopathy, cervical lymphadenitis)
- Skin (UD)
- heart and kidney infections
What are differentials in a nude mouse with furunculosis?
- staphylcoccus
- Streptococcus
- Corynebacterium bovis
- Pasteurella pneumontropica
What is the process that leads to the hallmark chronic suppurative inflammation of staphyloccal infections?
What is the name of the material?
botryomycosis
- Splendore-Hoeppli (brightly eosinophliic, amorphous-fibrillar)
How do we treat staphyloccal infections?
- Monitor
- open and drain abscesses +/- abx
- euthanize if colony is at risk
T/F Trichophyton mentagrophytes does not fluoresce under UV light
True
How do you diagnose Trichophyton mentagrophytes?
DTM culture or Sabouraud agar
What stain should you use to ID Trichophyton mentagrophytes?
Silver stain or Schiff’s
What is the name of the disease associated with Citrobacter rodentium infection in Mice?
Transmissible Murine Colonic Hyperplasia
Gross lesion of Citrobacter rodentium infection
Severe thickening of the descending colon (may extend to the transverse colon)
Histopath lesions of Citrobacter rodentium infection
Marked hyperplasia of the crypt epithelium with retention of cells on the surface and leukocytic infiltration in the lamina propria
What specific anatomic sites are affected by Citrobacter rodentium?
- the mucosal surface of the descending colon
- brush border of the enterocytes -> dissolution of brush border, actin filament rearrangement, pedestal formation from the plasma membrane
Clinical signs expected with Citrobacter rodentium infection?
- ruffled fur, slowed growth
- Soft feces, diarrhea, rectal prolapse
- moderate mortality in older suckling or recently weaned mice
Research implications of Citrobacter rodentium infection
- hyperplastic lesions predispose to cancer
- immune dysfunction
- mortality, particular in immunocompromised mice
Which strains are the most susceptible strains to Citrobacter?
- most resistant to mortality?
- infant and immunodeficient mice most susceptible to disease
- susceptible strains: C3H; AKR; FVB
- Strains resistant to mortality: DBA, NIH Swiss, and C57BL/6 mice
Diagnosis of Citrobacter
Transmission of Citrobacter
Prevention/control of citrobacter
- Dx: Isolation of bacteria in GI or feces in conjunction w/ lesions
- Tx: Fecal-oral route
- Prev/control:
– Addition of antimicrobials to water
– Disinfection/disposal of contaminated food, water, and bedding
– Sentinel monitoring
– Microbarrier caging to prevent transmission
Which bacteria are associated with Clostridial Enteropathy in mice?
- Clostridioides difficile (Toxin A (TcdA) and Toxin B(TcdB))
- Clostridium perfringens (Nontype A, type A, Type B, and Type D)
Which C. perfringens type most often produces enterotoxin
Type A
Gross pathological findings of Clostridial enteropathy
- small and large intestines gas and fluid-distended
- Mucosa is reddened, may have petechiae, ulcers, or fibrinous pseudomembranes
CS of Clostridial enteropathy
- Hunched posture, ruffled hair coat
- Enlarged or painful abdomen
- Diarrhea
- Sudden Death (C. perfringens nontype A, type B, and Type D)
Histopath findings of Clostridial enteropathy
- mucosal ulcers, hemorrhage, and inflammation w/ pseudomembranes and large #s of bacteria (mucosal necrosis is more common in C. perfringens)
- Generalized lymphoid apoptosis
- Recover phase: diffuse mucosal hyperplasia
Transmission of clostridium/clostrioides
- normal inhabitants of mouse intestine
- spread via fecal oral route (spores shed in feces)
Infections and disease of clostridium/clostridioides is often _______
secondary to intestinal dysbiosis
Diagnosis of clostridium/clostridioides
Detection of toxins in GI and feces via PCR or cytotoxicity assays
Prevention and control of clostridium/clostridioides
- Decontamination
- Prevent sudden diet changes and unnecessary antibiotic use
T/F E. coli is a normal inhabitant of the mouse intestine
true
Which mice are susceptible to disease (colibacillosis)
- nonpathogenic to immunocompetent mice
- immunodeficient mice may be susceptible
Clinical signs of colibacillosis
- lethargy, diarrhea, and fecal staining in SCID mice from non-lactose-fermenting e. coli
Gross lesions of colibacilosis
- segmental thickening of colon or cecum with reddened mucosa
- blood-tinged feces
histopath lesions of colibacillosis
- mucosal hyperplasia with inflammation and / or erosions
Diagonsis of E. coli
Prevention / control of E. coli
Research implications of E. coli
Dx: combination of lesions and non-lactose-fermenting E. coli isolation on growth plate (culture)
Prev/control:
- remove affected animals
- disinfect cage and equipment
Research implications: clinical illness in immunodeficient mice
Histological features of Chlamyida spp.
- obligate intracellular organism
- elementary and reticulate bodies within cytoplasm of infected cells
Which chlamydial species is used as a model of human chlamydial disease?
- Chlamydia muridarum (“Nigg agent”) is the model for chlamydia trachomatis infections in humans
Which other Chlamydia spp. can cause disease in mice
- Chlamydia trachomatis
- Chlamydophila psittaci
Diagnosis of Chlaymid
- PCR
- Cell culture or inoculation of embryonated chicken eggs
- Giemsa or Macchiavello stains
Clinical signs associated with chlamydial/chlamydophila infection in mice
- natural infection typically subclinical
- route of infection affects clinical signs
— conjunctivitis
— infection of the urogenital tract results in hydrosalpinx, cervical and vaginal inflammation, and/or urethritis
What does Chlamydia muridarum (Mouse Pneumonitis (MoPn) agent) infect?
What are the clinical signs in mice?
- Infects bronchiolar epithelium and type 1 pneumocytes
- infects macrophages and can spread to other organs
- CS:
– hunched posture, ruffled fur, labored breathing
– may die in 24h or persist as chronic infections with cyanosis and progressive emaciation
Clinical signs in Proteus mirabilis infection
- progressive weight loss
- diarrhea
- death over course of several weeks
Gross findings of Proteus mirabilis infection
- splenomegaly, multifocal hepatic necrosis, abscesses in organs
- pulmonary edema
- pyelonephritis with renal abscesses (presumed ascending infection)
T/F Proteus is ubiquitous unless specifically excluded by the vendor, and is typically non-pathogenic, but may be opportunistically pathogenic in immunodeficient mice
True
T/F Klebsiella spp. are not opportunistically pathogenic
False, they are opportunistically pathogenic
What do you need to diagnose a Klebsiella infection
- combination of lesions with culture of predominantly/purely Klebsiella
Gross lesions of Klebsiella oxytoca
- abscesses in many organs and other features of gram-negative septicemia
- suppurative endometritis and inflammation of the female repro tract with abscesses (has been described in C57BL/6 mice
Klebsiella pneumoniae is only pathogenic if _____
experimentally inoculated into respiratory or urinary tracts
What gram-negative curved or spiral shaped bacteria wide-spread in both conventional and barrier colonies
Helicobacter
Where is Helicobacter usually isolated form?
What other tissue can it infect?
- GI tract, feces
- Liver
Diagnosis of Helicobacter
- PCR of feces/tissues
- molecular speciation
- culture
- clinical signs
- Histo w/ sliver stains
What Helicobacter spp. may be normal flora in rodents
H. rodentium
Which Helicobacter spp. is most present in mice?
H. hepaticus
Which Helicobacter spp. is also found in rats?
H. bilis
Which Helicobacter spp. is a human pathogen also found in mice
H. pallorum
Common clinical signs associated with helicobacter
- asymptomatic
- diarrhea
- rectal prolapse
Helicobacter causes increased susceptibility of what pathology in A/JCr mice
- hepatomas and hepatocellular carcinomas
What other pathology may you see w/ Helicobacter spp. in any mice?
- Proliferative typhlitis, colitis
- Lower bowel carcinoma
- Bacterial translocation to liver: angiocentric, non-suppurative hepatitis, hepatic necrosis
Impact of Helicobacter spp. on research
- Proinflammatory
- research involving GI tracts/IBD impaired
- Immunodeficient colonies
- General confounding factor??
Control/prevention of Helicobacter spp.
- Triple therapy: amoxicillin, metronidazole, pepto-bismol
- Eradication may not be practical in large numbers
Which bacteria should be rare in research animals, but is a historic model for leprosy?
- Mycobacterium lepraemurium
What other Mycobacterium causes clinical disease in mice?
Mycobacterium avium-intracellulare
What pathogen is related to mouse mycobacterium and the causative agent for Johne’s disease in cows?
- Mycobacterium avium subspecies paratuberculosis
How do Mycobacterium spp. stain?
- gram Positive
- Acid-fast
- Intracellular
- Rods
What pathology do Mycobacterium cause?
In what tissues?
- granulomatous disease
- lungs, liver, spleen, lymph nodes
What is the causative agent of rat bite fever?
- Streptobacillus moniliformis
T/F Streptobacillus moniliformis is not zoonotic
False - it is zoonotic
Transmission of Streptobacillus moniliformis
- persistently infected rats
- Aerosol, fomites, bite wounds
Clinical signs of Streptobacillus moniliformis
- Acute: high mortality, dull/damp hair coat, KCS
- Variable: anemia, diarrhea, hemoglobinuria, cyanosis, emaciation
- Chronic: arthritis, cutaneous ulceration, gangrenous amputation, hindlimb paralysis
- Breeding: stillbirths, abortions
What is the causative agent of proliferative enteropathy
Lawsonia intracellularis
Which mice are naturally infected with Lawsonia intracellularis
wild mice (not been described in lab mice)
Transmission of Lawsonia intracellularis
fecal-oral route
Clinical signs of Lawsonia intracellularis
none
Gross lesions of Lawsonia intracellularis
Histopath lesions of Lawsonia intracellularis
gross:
- hyperplastic ileitis, typhlitis and/or colitis
- may note hemorrhagic intestines
Histopath:
- intestinal epithelial hyperplasia
Diagnoss of Lawsonia Intracelluaris
DDx of Lawsonia intracellularis
- PCR, IHC, Warthin-Starry silver staining
- C. rodentium
- Enterohepatic helicobacter spp.
Prev/control of Lawsonia intracellularis infection
Research impact of Lawsonia intracellularis
- don’t house mice with more susceptible spp. (hamsters, rabbits)
- none reported
Transmission of Filobacterium rodentium
- vertical transmission (dam to pup)
- Direct contact and fomite transfer less efficient
Other name for filobacterium rodentium
CAR bacillus
Clinical signs of Filobacterium rodentium
oculonasal discharge, increased respiratory effort, hunched posture, anorexia w/ weight loss
is filobacterium rodentium a primary or opportunistic disease-causing pathogen
opportunistic
Gross lesions of Filobacterium rodentium
- lungs lesions typically mild, with no apparent or discernable lesions with experimental infections
- If severe enough, severe pneumonia and bronchiolitis are possible
Histopath of Filobacterium rodentium
- marked peribronchiolar cuffing with plasma cells and lymphocytes
Diagnosis of Filobacterium rodentium
DDx of Filobacterium rodentium
Diagnosis:
- Serology (ELISA)
- PCR and histology for definitive diagnosis
- Silver stains (Warthin-Starry) can be used for active infections
DDx:
- Respiratory mycoplasmosis
- Bordetella
- Sendai Virus
- PVM
Why is environmental disinfection for Filobacterium effective
its non-spore forming, and therefore more susceptible
Tx of Filobacterium rodentium
Reseach impact of Filobacterium rodentium
- Sulfamerazine in drinking water
- Culling or embryo rederivation is recommended
may confound studies, esp. in immunocompromised mice
What are the two Corynebacterium pathogens of interest in mice
- Corynebacterium kutscheri
- Corynebacterium bovis
C. kutscheri is the causative agent of ______, while C. bovis is more associated with ____
- pseudotuberculosis
- hyperkeratosis
What stimulates an active C. kutscheri infections
immunosuppression or environmental stress
What is the morbidity/mortality of C. kutscheri
- high mortality with acute disease
- low mortality with chronic disease
Clinical signs of C. kutscheri
- inappetence, emaciation, rough hair coat, hunching, hyperpnea, oculonasal discharge, cutaneous ulceration, arthritis
Clinical signs of C. bovis
- hyperkeratotic dermatitis (scaly skin and alopecia)
- KCS reported in aged C57BL/6 mice
Gross lesions of C. kutscheri
- hematogenous spread
- gray-white nodules on liver, kidney, lung, etc.
- Cervical lymphadenopathy
- Mucopurulent arthritis
Histopath lesions of C. kuscheri
- Coagulative/caseous necrosis
- Colonies of Gram(+) bacteria w/ acute angle alignment
Gross lesions of C. bovis
Histopath lesions of C. bovis
- gross: hyperkeratotic dermatitis (scaly skin and alopecia)
- Histopath: prominent acanthosis and moderate hyperkeratosis accompanied by mild, nonsuppurative inflammation
Transmission of C. Bovis and C. kutscheri
- Fecal-oral
- Direct contact
- Aerosol
Diagnosis of C. kutscheri
DDx of C. kutscheri
Diagnosis:
- Culture
- Gram stain
DDx:
- mycobacterium avium
Diagnosis of C. bovis
DDx of C. bovis
Diagnosis
- PCR
- Skin culture
– hold for 7 days - slow-growing
DDX:
- Staphylococcus xylosus
- Low humidity in glabrous mice
Why should you cull colonies infected with C. bovis or C. kutscheri
treatment is not curativeRes
What is the causative agent of Tyzzer’s disease
Clostridium pilforme
CS of Clostridium piliforme
Resistant strains
Transmission
Gross lesions
stain to ID
CS:
- diarrhea and acute death
resistant strains
- C57BL/6 > DBA/2
Natural infection transmitted by ingestion of orgs.
Gross lesions:
- necrosis of liver, mesenteric LNS, and heart (less so) (white foci)
- ileum, cecum, colon may be red and dilated with watery, fetid contents
Stains: Silver stains, Giemsa, periodic acid-Schiff stains usually required
Pneumocystis murina
- CS
-Gross lesions
CS
- subclinical in immunocompetent mice
- severe in immunodeficient mice: pneumonia, dyspnea, hunched posture, wasting, scaly skin
gross lesions
- rubbery lungs that fail to inflate
