Mycotic/parasitic Flashcards
Altered Schaedler’s flora
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
Pneumocytosis
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
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
Lung from a mouse with Pneumocystis pneumonia that has failed to collapse after removal
Pneumocystis pneumonia, illustrating Pneumocystis cysts in alveoli (Gomori methenamine silver stain)
Dermatomycosis
Trichophyton mentagrophytes
Rarely causes clinical disease
Stained with silver stain or Schiff’s reagent
Giardia muris
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
Spironucleosis
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
Spironucleus ID
Small size, horizontal or zig-zag movements, absence of sucking disk or undulating membrane
Klosiella muris
Renal coccidioisis in wild mice
Infect endothelial cells linging renal arterioles and glomerular capillaries
Sporocytes excreted in urine
Eggs of H. nana
Cryptosporidium muris
Sporozoan, adheres to gastic mucosa
Cryptosporidium parvum
Inhabits small intestine
S. obvelata egg
Aspiculuris tetraptera
Hymenolepis nana
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
Hymenolepis microstoma
Found in bile ducts of rodents
Larger eggs compared to R. nana
M. musculinus male
Syphacia obvelata
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
M. musculi female
R. affinis female
Aspiculuris tetraptera
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
Acariasis in mice
Myobia musculi, Radfordia affinis, Myocoptes musculinus
Less commonly Psorergates simplex
Trichoecius romboutsi
Mouse mite
Mite differentiation
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
Myocoptes musculinus
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
Myobia musculi
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
Radfordia affinis
True precense is conjectural
Mesotigmoid mites
Blood-sucking Ornithonyssys bacoti and Laelaps echidnina can infect lab rodent colonies
May transmit zoonotic infections
Polyplax serrata
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
