Deck 37: Streptobacillus Moniliformis and Spirillum Minus

Question 1

A lesion from an individual that works in a research laboratory is cultured and reveals a "fried egg" appearance with a dark center when grown on blood agar after 48 hours of incubation.The organism is nonmotile,indole,catalase,oxidase,and nitrate negative.Which of the following organism was isolated?

A)Streptobacillus sp.
B)Actinobacillus sp.
C)Aggregatibacter aphrophilus
D)Cardiobacterium sp.

Answer 1

A
Streptobacillus sp.growth occurs on blood agar,incubated in a very moist environment with 5% to 10% carbon dioxide (CO₂),usually after 48 hours of incubation at 37°C.Colonies are embedded in the agar and may also have a "fried egg" appearance,with a dark center and a flattened,lacy edge.S.moniliformis does not produce indole and is nonmotile,catalase,oxidase,and nitrate negative.Actinobacillus sp.and A.aphrophilus are nitrate positive,Cardiobacterium sp.are indole positive.

Question 2

A laboratory assistant that works with mice recently noticed that their lymph nodes were swollen and that they had a lesion on their hand that was not there a few weeks ago.The lymph node tissue is sent to the laboratory for culture.The laboratory technologist noticed on the stained sample that there was an organism present that resembled a spiral,gram negative with flagella.The cultures grew no organisms.What is the most likely cause for the discrepancy?

A)The laboratory technologist misidentified the stain artifact as an organism.
B)The laboratory technologist did not culture the sample to media.
C)The organism is not able to grow on media and requires another method for identification.
D)The organism was not allowed to incubate long enough.

Answer 2

C
S.minus causes rat-bite fever in humans and is referred to as sodoku.Specimens commonly submitted for diagnosis of sodoku include blood,exudate,or lymph node tissues.S.minus cannot be grown on synthetic media and appears as a thick,spiral,gram-negative organism with two or three coils and polytrichous polar flagella.Direct visualization of characteristic spirochetes in clinical specimens can be seen using Giemsa or Wright's stains.Diagnosis is definitively made by injection of lesion material or blood into experimental white mice or guinea pigs and subsequent recovery 1 to 3 weeks after inoculation.

Question 3

Which of the following cause rat-bite fever,or Haverhill fever,which is characterized by acute onset of chills,fever,headache,vomiting,and severe joint pains,as well as a rash on the palms,soles of the feet,and other extremities?

A)Streptobacillus moniliformis
B)Brucella abortus
C)Bordetella spp.
D)Pasteurella spp.

Answer 3

A
S.moniliformis is a gram-negative bacillus that causes rat-bite fever,or Haverhill fever,in humans.

Question 4

The name given to rat-bite fever when the illness is acquired by the ingestion of the bacterium is:

A)sodoku.
B)Haverhill fever.
C)monillic fever.
D)monillic gastritis.

Question 5

The name given to rat-bite fever when the illness is caused by acquired Spirillum minus is:

A)sodoku.
B)Haverhill fever.
C)monillic fever.
D)monillic gastritis.

Question 6

A patient has an infection caused by S.moniliformis.Which of the following is the preferred antibiotic choice?

A)Penicillin
B)Tetracycline
C)Streptomycin
D)All of the above

Question 7

Rat-bite fever caused by S.minus can be differentiated from that caused by S.moniliformis by:

A)chills,fever,headache,vomiting,and often severe joint pains.
B)a granulomatous lesion.
C)septic arthritis.
D)endocarditis.

Question 8

Which of the following causes sodoku,which is characterized by swollen lymph nodes,chills,fever,headache,vomiting,and often severe joint pains,a rash on the palms,soles of the feet,and other extremities,and a granulomatous lesion?

A)S.moniliformis
B)S.minus
C)Bordetella spp.
D)Pasteurella spp.