Yersinia Flashcards
Yersinia species:
Results on MacConkey?
Type of Bacteria?
How are they stained?
How can we identify between strains?
Main Pathogens?
Non lactose fermenting Gram Negative rods.
Demonstrate Bipolar staining in Giema stained smears from animal tissues.
Serotyping/ Biotyping used to discriminate between strains.
Pathogens for animals and humans (zoonotic)
Y. pestis (plague) non motile
Y. enterocolitica (enteric disease)
**Y. pseudotuberculosis (septicemia) **
Yersinia species
Where are Y. pseudotuberculosis and Y. enterocolitica found in the body and in what species?
Comment on avian species and yersinia..
What species are important reservoirs in endemic areas?
Y. pseudotuberculosis and Y. enterocolotica are in intestinal tract of wild mammals, birds, and domestic animals. All may be reservoirs of infection.
Commensals.
Many avian species may act as amplifier hosts and may transfer the organisms mechanically (defecating everywhere –> spread infection)
Rodents are reservoirs of Y. pestis in endemic areas. (plague)
Pathogenesis of Y. enterocolitica & Y. pseudotuberculosis
What kind of bacteria are they and how do they survive in the host body?
Pathogenic enteric Yersinia invade some cells ( M cells) of Peyers patches and prevent uptake by other cells (phagocytes)
The pathogenic yersiniae are facultative intracellular organisms which possesp lasmid and chromosomal encoded virulence factors, required for survival and multiplication in macrophages.
Virulence: 70kb plasmid. Plasmid and chromosomal encoded virulence factors required for survival and inhibit phagocytosis by PMN’s and macrophages.
Survival of Y. enetercolitica and Y. pseudotuberculosis is enhanced by anti phagocytic proteins (Yops) secreted by the organisms via a **type III secretion system which interfere with the normal functioning of neutrophils and macrophages in the host. **
This is a system allowing extracellular bacteria adhering on the surface of eukaryotic cells to secrete and inject bacterial effector proteins called Yops into the cytosol of the target cell in order to disable or alter their function.
Once in the mucosa, the bacteria are engulfed by macrophages, prevent phagocytosis, replicate in mesenteric lymph nodes with the development of necrotic lesions and neutrophil infiltration*. *
Clinical infections from Y. pseudotuberculosis.
What disease caused and what species affected?
Y. pseudotuberculosis causes enteric infections that are subclinical.
Y. pseudotuberculosis causes enteric disease in farmed deer in Australia and New Zealand and sheep, goats, and cattle less than a year old.
Y. pseudotuberculosis causes Septicemia in lab rodents, and aviary birds.
Diarrhea and weight loss leads to emaciation and death. Some die suddenly for septicemia.
What are reservoirs for Y. enterocolitica?
Y. enterocolitica is a major pathogen for which species?
Wild and domestic animals may act as reservoirs.
Pig are natural reservoirs.
**Y. entercolitica is primarily a human enteric pathogen. **
How can we diagnose Y. enterocolitica and Y. pseudotuberculosis?
- Histological examination of intestinal lesions.
- Culture of Y. enterocolitica and Y. pseudotuberculosis from feces, pus, or tissue.
- Grow on MacConkey at 37 C (NLF)
- API
Plague:
Caused by gram negative Y. pestis.
Zoonotic infection in rodents transferred by fleas.
Organism in blood of rodents. Rodent bit by flea. Flea bites man (dog or cat) . Man becomes infected.
Humans are infected by flea bites.
Endemic in Africa/ Asia.
Pneumonic Plage (spread person to person via resp. droplets)
Clinical Infection of Y. pesits:
What species can be infected?
What kind of plagues does it cause?
How can humans become infected?
Y. pestis can infect both dogs and cats in endemic areas.
Cats in particular are susceptible because they predate on rodents who may be infected. Therefore cat owners and vets could get infection from flea bite.
Bubonic, septicemic, pneumonic plagues.
**Cats with pneumonic plagues are a source of human infection through aerosol generation and should be euthanized. **
Humans can become infected through cat scratches, bites and fleas from infected cats. Also aerosol inhalation if pneumonic plague.
What are the plague syndromes in man and what do they cause?
- Bubonic plague- cause lymphadenopathy- Lymph node abscesses.
- Septicemic plague- fever, hyptension, septic shock, with or without bubonic plague
- Pneumonic plague- cough, hemoptysis (expectoration of blood in sputum) with or without bubonic plague.
- Meningitis- fever, nuchal rigidity usually with bubonic plague.
What are virulence factors specific to Y. pestis?
- Fraction 1 (F1) antigen- capsule around the bacteria that is plasma encode preventing opsonization. Not a polysaccharide like most capsules. Instead made of polypeptide.
- HPI for iron acquisiton (Ye, Yp) (High pathogenicity island)
- Ymt protein on plasmid is a phosphilipase D required for survival in flea midgut.
- Hms locus required for efficient transmission of Y. pestis to subcutaneous sites. Allows flea to store bacteria in proventriculus allowing accumulation of bacterial storage before the flea bites. Bacilli lacking hms replicate in flea midgut but do not lodge en mass in preventriculas. (No Hms locus = inefficient delivery of bacteria)
- Pla is pasmid encoded and is essential for Y. pestis to desseminate from a subcutaneous site of inoculation to lymph nodes or the bloodstream.
How can we diagnose Y. pestis?
Specimens (pus, blood, lymph node aspirates) are sent to specialized lab.s
**Giemsa stained smear of pus reveal large numbers of biplolar rods. **
Culture
DFA (direct fluorescent antibody)
Passive hemagglutination on paried samples for infected cats. Rising titire suggests active infection.
How can we treat and control Y. pestis?
Bubonic plague?
Keep suspected cats in isolation.
IV tetracycline or choramphenicol for bubonic plague.
In an endemic areas routinely treat dogs and cats for fleas.
Rodent control
Pseudomonas aeruginosa & Burkholderia species
What kind of bacteria are they? Gram…
Aerobes/ Anaerobes?
Motile/ non motile?
Gram Negative rods.
Obligate aerobes
Oxidize carbohydrates (not fermentative)
Oxidase, catalase positive
Motile by one or more polar flagella
Grow well on MacConkey agar
P. aeruginosa- produces diffusible pigments (pyocyanin, pyoverdin)
P. aeruginosa is an opportunistic pathogen. (immunocompromised animals affected)
B. mallei causes glanders.
B. pseudomallei causes melioidosis.
P. aeruginosa infections:
cattle?
Sheep?
Reptiles?
cause a wide range of opportunistic infections.
Hosts will usually have predisposing factors (immunocompromised)
- Bovine mastitis linked to contaminated water for udder washing/ insertion of intramammary abx.
- Fleece rot of sheep causing suppurative dermatitis. Pyocyanin pigment produced by P. aeruginosa discolors the wool.
- Found in oral cavity of snakes causing necrotic stomatitis in reptiles kept under poor husbandry conditions.
How can we diagnose P. aeruginosa?
Non lactose fermenter on MacConkey.
Green pigment on culture due to production of pyocyanin pigment.
