Mycotic/parasitic

Question 1

Altered Schaedler’s flora

Answer 1

Four members of the original SF (two lactobacilli, Bacteroides distasonis, and EOS fusiform bacteria), a spiral-shaped bacterium, and three new fusiform ROS bacteria Mucispirillum schaedleri, Clostridium, L. murinus, Flexstipes, Clostridium, E. plexicaudatum, and Bacteroides

Question 2

Pneumocytosis

Answer 2

Pneumocystis murina (Pm)

Common opportunisitc organism of lab mice and other mammals

Originally mistaken as T. cruzi

P. carnii - rats

P. jiroveci - humans

Can be clinically severe in immunodeficient mice - functional T lymphocytes

Proceeds slowly and leads to clinical signs of pneumonia within a few months

Pm known to infect ferrets, rats, mice, and humans

Question 3

Answer 3

Pneumocystis pneumonia, hypercellular alveolar septa and alveoli containing proteinaceous exudate and macrophages

Can be activated by immunosuppression

Lungs fill with trophic and cystic forms

Lungs - rubbery and fail to deflate

Need silver based stains

Question 4

Answer 4

Lung from a mouse with Pneumocystis pneumonia that has failed to collapse after removal

Question 5

Answer 5

Pneumocystis pneumonia, illustrating Pneumocystis cysts in alveoli (Gomori methenamine silver stain)

Question 9

Dermatomycosis

Answer 9

Trichophyton mentagrophytes

Rarely causes clinical disease

Stained with silver stain or Schiff’s reagent

Question 10

Giardia muris

Answer 10

Duodenum of young and adult mice, rats, and hamster

Often subclinical

C3H/He mice are susceptible, BALB/c and C57BL/10 are resistant

Ellipsoid cysts with 4 nuclei

Tx: 0.1% dimetridazole to drinking water for 14 days

Question 11

Spironucleosis

Answer 11

Spironucleus muris, inhabits crypts of Lieberkuhn

Pathogenic for young, stressed, or immunocompromised mice

Poor hair coat, sluggish, weight loss (3-6 weeks of age)

Fecal-oral, can between hamsters and mice

Watery, red-brown, gaseous intestinal contents

Distension of crypts and intervillous spaces by pear-shaped trophozoites and inflammatory edema of lamina propria, PAS staining

Tx: 0.1% dimetridazole to drinking water for 14 days

Question 12

Spironucleus ID

Answer 12

Small size, horizontal or zig-zag movements, absence of sucking disk or undulating membrane

Question 13

Klosiella muris

Answer 13

Renal coccidioisis in wild mice

Infect endothelial cells linging renal arterioles and glomerular capillaries

Sporocytes excreted in urine

Question 14

Answer 14

Eggs of H. nana

Question 15

Cryptosporidium muris

Answer 15

Sporozoan, adheres to gastic mucosa

Question 16

Cryptosporidium parvum

Answer 16

Inhabits small intestine

Question 17

Answer 17

S. obvelata egg

Question 18

Answer 18

Aspiculuris tetraptera

Question 19

Hymenolepis nana

Answer 19

Dwarf tapeworm

Mice, rats, humans

Prominent polar filaments and rostellar hooks

THE ONLY CESTODE THAT DOES NOT REQUIRE AN INTERMEDIATE HOST

Cysticerci are found in lamina propria of SI, adtuls in lumen

R. nana eggs have polar filaments

Tx: praziquantel, albendazole, mebendazole, thiabendazole

Question 21

Hymenolepis microstoma

Answer 21

Found in bile ducts of rodents

Larger eggs compared to R. nana

Question 22

Answer 22

M. musculinus male

Question 23

Syphacia obvelata

Answer 23

Mouse pinworm, rat, gerbil, hamster

Eggs are flattened on one side and have pointed ends

Direct life-cycle, 11-15 days

Prevalence higher in 4-5 weeks old ice

Fecal exam not reliable (deposited outside GI tract)

Tape test (do not find A. tetraptera)

Eggs become infective 6h

Question 24

Answer 24

M. musculi female

Question 25

Answer 25

R. affinis female

Question 28

Aspiculuris tetraptera

Answer 28

Eggs are ellipsoidal

Life cycle 10-12 day longer than S. obvelata (occurs in older mice)

Require 6-7 days to become infective

Eggs not deposited in perianal area

Question 29

Acariasis in mice

Answer 29

Myobia musculi, Radfordia affinis, Myocoptes musculinus

Less commonly Psorergates simplex

Question 30

Trichoecius romboutsi

Answer 30

Mouse mite

Question 32

Mite differentiation

Answer 32

Myocoptes - oval profile with heavily chitinized body, pigmented third and fourth legs, tarsal suckers

Myobia and Radfordia have similar elongated profile, with bulges between legs

Myobia has single tarsal claw on the second pair of legs

Radfordia has two claws of unequal size on the terminal tarsal structure on the seoncd pair of legs

Question 35

Myocoptes musculinus

Answer 35

Most common ectoparasite of the lab mouse, frequently occurs in conjection with Myobia musculi

Eggs usually attached to middle third of the hair shaft

Requires diret contact (not bedding)

Inhabit larger areas of body, inguinal region, abdominal skin, and back (plus head and neck)

Feeds on superficial epidermis

Question 36

Myobia musculi

Answer 36

Life cycle can be completed in 23 days

Eggs attach to base of hair shaft and hatch in 7-8 days

Thought to feed on skin secretions and interstitial fluid

Transmitted primarily through contact

B6 are very susceptible to hypersensitivity dermatitis

Question 37

Radfordia affinis

Answer 37

True precense is conjectural

Question 38

Mesotigmoid mites

Answer 38

Blood-sucking Ornithonyssys bacoti and Laelaps echidnina can infect lab rodent colonies

May transmit zoonotic infections

Question 39

Polyplax serrata

Answer 39

Mouse louse

Eggs deposited at the base of the hair shafts and nymph/adults can be found on the dorsum

Historically the vector for Mycoplasma coccoides