Med Bac - Yersinia

What were the 3 major pandemics of Yersinia?

Plague of Justinian, Black Death, and Modern Plague

Who originally discovered Yersinia pestis?

Alexandre Yersin

What was Y. pestis originally called?

Pasteurella pestis

It was originally through that Y. pestis was spread by what?

Rats

Y. pestis maintains a wide reservoir in what animals?

Rodentia → squirrels, prairie dogs, marmots, rats, chipmunks

How many Yersinia species are there?

26

What are the 3 major Yersinia human pathogens?

Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis

Describe Yersinia

Gram negative coccobacilli, variable motility (Y. pestis is NOT motile), can form short chains

Y. pestis exhibits a bipolar safety pin staining pattern under what stain?

Wayson’s stain

What causes the bipolar stain in Wayson’s stain?

Membrane infoldings

(T/F) Y. pestis is an obligate zoonotic pathogen, and transmission is primarily indirect with transmission done by flea bites (vectors)

True

What is the entry mechanism for Y. pestis?

Parenteral

(T/F) A flea is the vector that transmits Y. pestis to humans → the initial infections is bubonic disease which is NOT transmittable → Bubonic disease can progress to pneumonic disease which IS transmittable directly via aerosolization.

True

Bubonic disease is an infection of primarily what?

Lymphatic system

Y. enterocolitica is the leading cause of what?

Yersiniosis (localized gastroenteritis)

(T/F) Y. pestis is a pathogen to humans, animals, and arthropods.

True

In fleas, Y. pestis is a GIT pathogen that multiplies where?

Proventricular valve

(T/F) Infection of the proventricular valve of fleas via feeding on Y. pestis infected rat causes proventricular occlusion that causes fleas to not be able to eat bloodmeal. This causes fleas to become starved which causes them to bite humans. Y. pestis then replicates at the bite site and disseminates in the lymphatics.

True

(T/F) Bubonic disease is the most common form → infection presents as papule at entry site and flu like symptoms → spreads to regional lymph nodes and growth leads to suppurative localized lymphadenitis.

True

What is the hallmark of bubonic disease?

Bubo

(T/F) Sepsis, secondary to adenitis, may leads to LPS-mediated endotoxic shock.

True

What type of invasion mechanism does Y. pestis use?

Zipper

What outer membrane protein (OMP) is used by Y. pestis to invade immune tissues?

Ail (attachment invasion locus)

(T/F) Ail binds to multiple ECM proteins such as FN, LN, UFH, and VTN.

True

(T/F) Invasion involves actin condensation and entry via phagosome.

True

(T/F) Similar to Salmonella, Y. pestis survives inside phagosomes to form Yersinia containing vesicles (YCVs) → this is also mediated by sequestration of Rab proteins (Rab1, Rab4, Rab11) → also similar to Salmonella, Y. pestis eventually breaks out of the YCV to further replicate in the cytoplasm.

True

What does Y. pestis use to destroy immune tissues and disseminate?

Yops (Yersinia outer proteins)

How are Yops secreted into immune tissues?

YSC (Yersinia secretion complex) → YSC is a T3SS (first one discovered)

YSC is normally “plugged” by what protein?

LcrG

What protein (called V-antigen) is used to “unplug” YSC by binding to LcrG?

LcrV

What protein induces programmed cell death (PCD) in immune tissues?

YopJ (transacetylase)

What does YopJ do?

Transacetylates MAP37K and IKKB → leads to caspase-1 medicated cell death

Expression of what capsule allows for hematologic dissemination and complication of LPS-mediated septic shock?

F1 (fraction 1) capsule

What symptoms are used for presumptive ID of bubonic disease?

Symptoms of lymphadenitis and bubo, fever, and hypotension
Hemoptysis for pneumonic disease → chest radiograph

What POCT is used for bubonic disease?

F1 rapid diagnostic (F1RDT)

Definitive ID for bubonic disease primarily uses identification of what?

F1 capsule

What 2 methods can be used to identify F1 capsule (caf1)?

PCR and Direct Fluorescent Antibody (DFA)

What is the primary vaccine used against Y. pestis that is a heat-killed cellular vaccine?

Haffkine

What are the other 2 vaccines for Y. pestis?

EV76 (USSR) and F1-V antigen (USAMRIID)

What drugs are primarily used to treat bubonic disease?

Aminoglycosides (gentamicin, streptomycin), trimethoprim

(T/F) Very low levels of antibiotic resistance reported for Y. pestis.

True