Yersinia genus, Yersinia pestis and yersiniosis

Question 1

General features and habitat of Yersinia pestis

Answer 1

Gram – (“safety-pin” staining)

Rod shape

Habitat- zoonosis (mostly rodents)

Question 2

Biochemical Properties of Yersinia pestis

Answer 2

Capsule- anti-phagocytic

Plasminogen activator (Pla)

protease gene- prevent opsonization by degrading C3b

Question 3

Pathogenesis of Yersinia pestis

Answer 3

Main reservoir are rodents or prairie dogs

Transmitted by flea bites or Respiratory droplets, human-to-human (if pneumonic)

Question 4

Clinical Features of Yersinia pestis

Answer 4

Bubonic form:
Buboes on skin- swollen, tender lymph nodes

Septicemic form:
Enter blood, affected tissue turns black and die.
Can also cause hemorrhagic inflammation, abscesses and DIC in cutaneous organs

Pneumonic form: (if untreated- 100% lethal) Pneumonia- symptoms include: shortness of breathing, coughing of “black” blood and chest pain can also occur.
Highly contagious (direct transmission through aerosols, from human-to-human), eventually leading to death

Question 5

Diagnosis of Yersinia pestis

Answer 5

Culturing is not safe
Specimens- sputum, blood or CSF
Serology- from blood

Question 6

Treatment of Yersinia pestis

Answer 6

Aminoglycosides (Streptomycin or Gentamicin) with Doxycycline (Tetracycline)

Question 7

Prevention of Yersinia pestis

Answer 7

Active immunization with killed Y. pestis

not very efficient

Question 8

General Features of Yersinia Enterocolicita and pseudotuberculosis

Answer 8

Gram – (“safety-pin” staining)
Rod shape
Habitat- zoonosis

Question 9

Biochemical Properties of Yersinia Enterocolicita and pseudotuberculosis

Answer 9

Capsule- anti-phagocytic

Grows and motile at cold temperatures

Question 10

Pathogenesis of Yersinia Enterocolicita and pseudotuberculosis

Answer 10

Primarily transmitted by puppy feces

Transmitted also by milk products

Might be transmitted also via water

Question 11

Clinical Features of Yersinia Enterocolicita and pseudotuberculosis

Answer 11

Yersinoisis- Gastroenteritis and Enterocolitis (Y. enterocolicita)
Gastroenteritis and Mesenteric Lymphadenitis (Y. pseudotuberculosis)

Inflammation and ulceration (due to bacteremia) causing bloody diarrhea in kids

Systemic effects-
Fever, leukocytosis and abscesses

Complications:
Mesenteric lymphadenitis can mimic acute appendicitis in older kids

Immune-complex formation causes arthritis, spondylosis ankylopoetica (known as Bechterew disease) in adults

Intra-abdominal abscess, hepatitis, osteomyelitis and sepsis

Question 12

Diagnosis of Yersinia Enterocolicita and pseudotuberculosis

Answer 12

Blood agar- aerobic (“cold-enrichment”)
MacConkey agar 4c
EMB medium at 4C
Serology

Question 13

Treatment of Yersinia Enterocolicita and pseudotuberculosis

Answer 13

3rd generation Cephalosporin combined with Aminoglycosides