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What are the two most common species of Staphylococcus that infect mice?

S. aureus - can be highly pathogenic
S. epidermidis - generally nonpathogenic


What is a common cause of botryomycosis?

S. aureus


Staphylococcus is a gram_________, coagulase____________ organism.

positive, positive


Most streptococcal infections is laboratory mice are caused by ___________ hemolytic organisms in Lancefield’s group ____________.

β, C


A common Strep. syndrome in mice is _________ lymphadenitis with fistulous drainage to the ___________.

cervical; neck


T/F Escherichia coli is highly pathogenic organism that causes disease in immunocompetent mice.

False: Escherichia coli is a gram neg. rod that is a normal inhabitant of the mouse intestine, but may cause hyperplastic typhlocolitis in SCID mice.


Name two species of Klebsiella found in laboratory mice.

K. pneumoniae, K. oxytoca


T/F K. pneumoniae and K. oxytoca are significant causes of disease in mice.



Clostridia are large rod/cocci shaped, gram positive/negative, anaerobic/aerobic bacteria.

rod; positive; anaerobic


Naturally occurring clostridial infection in mice is rare, but what species of Clostridium has been associated with high mortality in suckling mice?

C. perfringens type D


T/F Mycobacteria are gram-negative, acid-fast, obligate intracellular bacteria.

False: Mycobacteria are gram-positive, acid-fast, intracellular bacteria.


Name two species of Mycobacterium that are known to be pathogenic in laboratory mice.

M. avium-intracellulare (extremely rare) and M. lepraemurium


What is the etiologic agent of murine leprosy?

M. lepraemurium. It has been used as a model for human leprosy.


What are clinical signs and gross lesions associated with murine leprosy?

Clinical signs include alopecia, thickening of skin, subcutaneous swelling, and cutaneous ulceration. Disease can lead to death or clinical recovery. Gross lesions include nodules in SQ tissues and organs (lung, spleen, lymph nodes, bone marrow, and thymus).


What is the histologic hallmark of murine leprosy?

The histologic hallmark is perivascular granulomatosis with accumulation of large, foamy epithelioid macrophages (lepra cells) filled with acid-fast bacilli.


T/F Clinical disease resulting from Proteus mirabilis infection is typically only seen in association with stress or immunosuppression (induced or innate).



T/F Leptospirosis usually causes clinically apparent disease in mice.

False: Leptospirosis in mice is generally asymptomatic


Leptospirosis in mice is primarily associated with what organism?

Leptospira interrogans serovar ballum


How is Leptospirosis diagnosed in mice?

PCR & isolation of the organism from kidney.


What two rickettsia are known to infect mice?

Mycoplasma coccoides, Mycoplasma muris
(Formerly Epyerythizoon coccoides, and Hemobartonella muris)


How are M. coccoides & M. muris transmitted?

M. coccoides is transmitted by the mouse louse Polyplax serrata, and M. muris is transmitted by the rat louse Polyplax spinulosa.


What are two possible clinical outcomes in mice infected with M. coccoides?

Mice may remain clinically normal, or develop febrile, hemolytic anemia and splenomegaly, which may be fatal.


Latent infection with M. coccoides can be reactivated by _______________.

Splenectomy. Splenectomy or inoculation of test material into splenectomized mice is the most sensitive means to detect infection.


T/F Chlamydia trachomatis has been known to cause disease in mice.

True, but typically natural infections are asymptomatic but persistent; A strain, called the Nigg agent, has been associated with natural infection in mice.
Causes ocular and urogenital infections in people!


Pneumocystis carinii was originally classified as a ___________, but is now characterized as a _______________.

protozoan; fungus


What clinical signs of pneumocystosis are seen in immunocompetent mice vs. immunodeficient mice?

immunocompetent: generally asymptomatic. immunodeficient: dyspnea, hunched posture, wasting, and scaly skin. Severe cases may be fatal.


What type of stains are used to visualize Pneumocystis cysts?

silver-based stains


What virus has been shown to accelerate the development of Pneumocystosis in SCID mice?

Pneumonia virus of mice.


________________ is the most common fungal agent of mice.

Trichophyton mentagrophytes


T/F T. mentagrophytes frequently causes clinical disease in infected mice, and organisms can be detected using a Wood’s lamp.

False; Infection rarely causes disease, and T. mentagrophytes rarely fluoresces under uv light.


Name two common flagellates that inhabit the duodenum of mice, rats, and hamsters.

Giardia muris and Spironucleus muris


T/F Giardia muris infection is usually asymptomatic, but if organisms proliferate extensively, it can cause weight loss, rough hair coat, and abdominal distension.

True; additionally, clinical signs usually don’t include diarrhea, and heavy infestations may be fatal in immunodeficient mice.


T/F Spironucleus muris can be distinguished from Giardia muris and Tritrichomonas muris by their small size, horizontal movements, and the absence of a sucking disk or undulating membrane.



____________ is a nonpathogenic protozoan that occurs in the cecum, colon, and small intestine of rats, mice, and hamsters. No cysts are formed, and transmission is via ingestion of trophozoytes.

Tritrichomonas muris


______________ is a pathogenic coccidian that occurs in the epithelial cells of the large intestine of mice, but is rare in the United States.

Eimeria falciformis


_______________ is a renal coccidian of mice.

Klossiella muris


T/F K. muris frequently causes renal failure in infected mice.

False; Infections are generally asymptomatic, although destruction of tubular epithelium may impair renal physiology.


___________ is a slightly pathogenic sporozoan that adheres to the gastric mucosa of mice, while _____________ inhabits the small intestine and is usually nonpathogenic.

Cryptosporidium muris; Cryptosproidium parvum


____________ is a nonpathogenic protozoan found in the cecum and colon of mice, rats, and hamsters. Organisms live in the lumen, where they feed on particles of food and bacteria.

Entamoeba muris


________________ is a gram-positive microsporidian that infects rabbits, mice, rats, guinea pigs, dogs, nonhuman primates, and humans. This organism has a direct life cycle, and is an intracellular parasite.

Encephalitozoon cuniculi


E. cuniculi infection is generally ____________, and transmission is via spores shed in the ____________.

asymptomatic; urine


_________________ is a ubiquitous gram negative coccidian parasite for which the mouse serves as a principal intermediate host. What is the definitive host?

Toxoplasma gondii; cats are the definitive host.


How are E. cuniculi and T. gondii differentiated based on staining properties?

E. cuniculi is gram positive, stains poorly with H&E, and has a capsule that readily accepts Giemsa and Goodpasture stains. T. gondii is gram negative.


_______________ is a cestode that has no rostellar hooks or polar filaments, while ______________ is a cestode with rostellar hooks and polar filaments.

Rodentolepis diminuta; Rodentolepis nana
(Formerly Hymenolepis)


What unique feature of R. nana makes it a particular concern in lab animal facilities?

It is zoonotic, and the life cycle may be direct (only known cestode that does not require an intermediate host)


The ova of which common mouse oxyurid can be detected by pressing cellophane tape to the perineal area?

Syphacia obveleta


How are the ova of Aspicularis tetraptera detected?

Eggs are detected in the feces. They are laid in a mucuous layer on the fecal pellets (not deposited in perineal area).


T/F Because the lifecycle of Aspicularis tetraptrera is shorter than that of Syphacia obveleta, the number of mice that are apt to be infected with A. tetraptera is correspondingly greater.

False; The lifecycle of Syphacia is much shorter, so the number of mice infected with Syphacia is apt to be correspondingly greater than Aspicularis.


Which two common mouse mites are morphologically similar? How can they be differentiated?

Myobia musculi (one claw on 2nd pair of legs) and Radfordia affinis (two claws of unequal size on 2nd pair of legs)


__________ , the most common ectoparasite of lab mice, is a surface dweller that feeds on superficial epidermis.

Myocoptes musculinus


T/F Mouse mites commonly occur as mixed infections.



Which mouse mite inhabits hair follicles, and creates cyst-like nodules that are visible on the undersurface of reflected skin?

Psorergates simplex


What is the difference between primary and secondary amyloidosis?

Primary amyloidosis is a naturally occurring disease, associated with the deposition of amyloid proteins consisting primarily of immunoglobulin light chains. Secondary amyloidosis is associated with antecedent inflammation (often chronic).


T/F Primary amyloidosis is common among aging mice.

True; also seen in young mice of certain strains (A and SJL; later in C57BL)


Which strains of mice are highly resistant to amyloidosis?

BALB/c and C3H


Soft tissue mineralization occurs naturally in the myocardium, epicardium, and other tissues. In what strains does this occur commonly?

BALB/c, C3H, and especially DBA


A Reye’s-like syndrome characterized by swollen, pale live and kidneys, has been reported in what strain of mice?



While the cause of ulcerative dermatitis in C57BL mice remains unknown, what factors are suggested to play a role?

The incidence appears to show seasonal fluctuations, suggesting environmental factors may play a role. There is also some evidence that diet may play a role, although specific dietary factors have not been identified.


Atrial thrombosis has a high prevalence in what strain? Which atrium/auricle is more commonly affected?

RFM; left


__________ is an incidental finding that is characterized histologically by alveoli filled with macrophages containing eosinophilic crystalline material.

Pulmonary histiocytosis


Name three age-associated live lesions.

Cellular and nuclear pleomorphism, biliary hyperplasia, hepatocellular vacuolization, amyloidosis, lipofuscinosis, hemosiderosis, and fibrosis.


T/F Age associated osteoporosis or senile osteodystrophy is associated with severe renal disease or parathyroid hyperplasia.



What strains develop immune complex glomerulonephritis as an autoimmune disease resembling human lupus erythematosus?

NZB and NZB x NZW F1.


T/F Interstitial nephritis in mice can be caused by bacterial or viral infections, but may also be idiopathic.



Symmetrical mineral deposits commonly occur in the thalamus, midbrain, cerebellum , and cerebrum of aged mice and are particularly common in the __________ strain of mice.



Name two strains of mice that are genetically predisposed to retinal degeneration.

C3H and CBA
C3H/He mice express the rd gene, which leads to retinal degeneration within the first few weeks of life and is a model of retinitis pigmentosa.


Name two causes of vestibular syndrome in mice.

Infectious otitis, necrotizing vasculitis (unknown etiology)


What type of virus is associated with lymphopoetic and hematopoetic neoplasia in mice?

retrovirus (type C oncornavirus)


What is the most common hematopoietic malignancy in the mouse?

Lymphocytic leukemia that originates in the thymus.


Reticulum cell sarcomas are common in older mice, especially in inbred strains such as _______________ and ______________.

C57BL/6 and SJL.


____________ sarcomas are composed primarily of reticulum cells, and cause splenomegaly and nodular lesions in other organs, while ______________ sarcomas are generally follicular center cell lymphomas.

Dunn type A; Dunn type B


T/F Myelogenous leukemia is uncommon in mice and is associated with retrovirus infection.



T/F Erythroleukemia is common in mice.



The primary tumor virus associated with mammary tumors in mice is ______________, which is highly oncogenic and transmitted through ___________.

MMTV-S (Bittner virus); milk of nursing females.


T/F As seen in rats, spontaneous mammary tumors in mice are typically well encapsulated, benign masses.

False; Spontaneous mammary tumors in mice metastasize with high frequency.
C3H, A, and DBA/2 (BALB/c, C57BL, and AKR have a low prevalence).


Which mouse strains have a high natural prevalence of mammary tumors?

C3H, A, and DBA/2 have high natural prevalence, while BALB/c, C57BL, and AKR have a low prevalence


T/F Almost all strains of mice have a significant prevalence of hepatic tumors.



T/F Spontaneous live tumors in mice typically arise from hepatocyes, whereas cholangiocellular tumors are rare.



Primary respiratory tumors of mice occur in relatively high frequency. What is the most common type of respiratory tumor seen in mice?

Pulmonary adenomas that arise from either type 2 pneumocytes or from Clara cells lining terminal bronchioles.


The prevalence of respiratory tumors is strain dependent, with a high prevalence in aging __________ strain mice but low in aging ____________.

A, C57BL