Yersinioses. Plague and Tularemia. Flashcards
what are the CHARACTERISTICS OF YERSINIA ?
enterobacteriae
gram negative and rod shaped
motile except Y pests
aerobic
what are the different subtypes of yersinoses?
Y pestis
Y pseudotuberculosis
Y enterocolitica
what is the epidemiology of yersinosis?
there is a worldwide distribution of yersinosis
the reservoir - wild and domestic animals - ESP pigs
3rd commonest zoonosis in europe
what is the transmission of yersina ?
consumption of raw meat , unpasteurized milk products
contaminated water
direct / indirect contact with infected animal
what is the etiology of yersinosis
yersinia enterocolitica
yersina pseudotuberculosis
what is the incubation period for yesrinosis ?
4-6 days
what is the pathogenesis of yersinosis ?
oral route of infection
initial replication in the small intestine - invasion into the Peters patch of the distal ileum via the M cells
spread to the mesenteric lymph nodes
involvement of the liver and spleen is common
attachment to the hosts cells surface by targeting immune effector cells - alteration of host innate immunity
toxins are injected into the macrophages , neutrophils and dendritic cells - reduction of phagocytosis and inhibiting production of ROS and triggering apoptosis of macrophages
what are the clinical features of yersinosis ?
lasts 1-46 days
Y enterocolitica
inflammatory diarrhea - may be bloody in severe cases
low grade fever
vomiting
pseudo appendicitis - mesenteric lymphadenitis , particularly in the ileum with typical signs of appendicitis
children < 4y = self limiting diarrhea
- sometimes bloody
> 4yr - abdominal pain in the right iliac fossa (mimicking appendicitis)
mesenteric adeninitis and terminal ileitis
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Y pseudotuberculosis
mostly associated with mesenteric adeninitis
present with fever and abdominal pain in all age groups
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both subtypes can present septicaemia - fever
what is the complication of yersinosis ?
post infectious
in patients with HLA-B27
reactive arthritis - 2-4wks
erythema nodosum
granulomatosis appendicitis
mycotic aneurysms
focal abscesses
how do you diagnose yersinosis ?
blood / csf / stool sample cultures
direct pathogen detection in culture
agglutinating or ELISA to specific o antigens
what is the treatment to yersinosis ?
spontaneous resolution
sever cases - fluoroquinilones for 2 weeks
or 3rd gen cephalosporins
what is the EPIDEMIOLOGY OF YERSINIA PESTIS / BUBONIC PLAGUE
systemic zoonosis - affecting small rodents
its in western US
reservoir - prairie dogs , squirrels , rodents
what’s the vector yersinia pestis?
vector - fleas
what’s the route of transmission of the black plague?
flea bites
what is the pathogenesis of yersinia pestis?
3 virulent plasmids are necessary :
1) classical plasmid - genres form yersinia outer protein - yops - manipulate host cell
2) larger plasmid - coding for capsule protein - counteracts phagocytosis
3) smaller plasmid - coding for
pesticin & coagulase
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multiplication within flea & transmission to humans depend on coagulase =
temperature- dependent enzyme:
<30°C: coagulation promoting
>30°C: fibrinolysis promoting
-
flea: environmental temperature blood coagulation within the stomach coagulation mixture extends into oesophagus blockage of the oesophagus flea cannot take up any more blood stimulation of hunger next blood meal mixing of fresh blood with old coagulated blood blood mixture triggers gag reflex injection of bacteria into new host
-
host: body temperature of 37°C causes fibrinolysis
improves systemic dissemination
of agent
what is the incubation period for bubonic plague ?
2-6 days
what are the clinical manifestation of bubonic plague
sudden onset of fever, malaise, myalgia, dizziness & increasing pain due to progressive lymphadenitis
lymphadenitis affects LN (buboes) near the fleabite-
tense, tender swelling
mostly affecting the
inguinal , crural, axillary, cervical & submaxillary LN
abdominal pain from mesenteric LN involvement
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without treatment dissemination occurs causing severe illness
pneumonia
(secondary pneumonic plague) & meningitis
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primary septicemic plague
: septicaemia without preceding lymphadenopathy
increased risk for persons
older than 40y & persons with chronic conditions
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primary pneumonic plague
: caused by inhalation of infectious bacteria of droplets
from other persons/animals
with secondary/primary pneumonic plague
incubation: 2 -3d
sudden onset of fever, headache, myalgia
, weakness, vomiting,
respiratory symptoms arising after 24h: cough, dyspnea, chest pain, sputum
with haemoptysis
initially segmental pneumonitis
lobar pneumonia
bilateral lung
involvement
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plague pharyngitis
: consumption of contaminated meat or contact with an infected
person with pneumonic plague
resembles tonsillitis with peritonsillar abscess & cervical lymphadenopath
what is the prognosis of bubonic plague ////
with appropriate treatment before dissemination of the plague : fever resolution within 2 -5d,
buboes remain enlarged for >1w
what are the COMPLICATION OF PRIMARY BUBONIC PLAGUE ?
secondary pneumonic plague \: consequence of bacteraemia in 10- 15% of patients with bubonic plague
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- meningeal plague
: >1w after onset of bubonic/septicemic plague due to suboptimal antimicrobial therapy
fever & headache
what is diagnosis of bubonic plague ?
bacterial culture from buboes aspirate, blood or sputum
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Microscopy with Wayson stain taken from buboes, blood, or sputum show bipolar staining of bacteria (appearance of “closed safety pin”
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PCR
anti- F1 antibody
what is the treatment of bubonic plague
Do not delay treatment for diagnosis
First-line: IV gentamicin OR fluoroquinolones for 10–14 days
Second-line: doxycycline OR tetracycline
what is the prevention of yersina pestis ?
post - exposure
antimicrobial prophylaxis : 7d with Levofloxacin & Ciprofloxaci
what is the etiology of tularemia?
zoonosis Francisella tularensis
what is the reservoir of tularemia ?
rabbits, hares, and rodents (e.g., voles, muskrats)
what is the vector of tularemia ?
intermediate vector
Ticks (Amblyomma americanum, Dermacentor spp.)
Deer flies (Chrysops species)
Transmission without a vector is also possible via:
Inhalation of contaminated dust or aerosols (may result in pulmonary disease)
Ingestion of contaminated food or water
epidemiology of Francisella tularensis ?
The bacterium is extremely infectious,
even very small amounts
can initiate disease!
what is the transmission of Francisella tularensis ?
usually occurs with direct contact with infected rodents - voles, muskrats)
through intermediate vector bites Ticks (Amblyomma americanum, Dermacentor spp.) Deer flies (Chrysops species)
Person-to-person transmission does NOT occur!
what is the incubation period of tularemia ?
typically 3–5 days (range 1–21 days
turalemia is also called ?
rabbit fever
characteristics of turalemia ?
mall, aerobic, nonmotile, non-spore-forming, gram-
negative coccobacilli
2 subspecies of F. tularensis, subsp. tularensis and
subsp. holarctica
cause human tularemia
epidemiology of F. Tularensis
widely distributed but is primarily a disease of the
Northern Hemisphere -> Arkansas, Kansas, Missouri, and Oklahoma
-
also present in Europe, has been reported in Bulgaria
-
peaks in late spring and summer in US
can cause illness in domestic
animals (cats and dogs)
what are the risk groups in tularemia ?
hunters, wildlife
specialists, hikers, campers,
veterinarians
more common in males than
females, and higher incidence in children < 10 years of age
what is the pathogenesis of tularemia ?
obligate intracellular pathogen that enters and replicates
within the cytoplasm
of various host cells (macrophages, dendritic
cells, and polymorphonuclear neutrophils)
-
within the host -> replicates locally -> then spreading to local lymphnodes
-
-> systemic spread to the liver, spleen, and lungs
-
uncontrolled replication -> cell death, substantial tissue damage,and impairment of vital organs
-
no toxin production, but it causes the failing to stimulate the host’s
innate immunity!!
-
When there is no innate immunity, bacteria can easily grow and
replicate -> triggers a systemic inflammatory reaction that
overwhelms the host defense system -> followed by cell death
-
=> extensive tissue injury
-
Histologic hallmark: Inflammatory cell infiltration and necrosis within
lymph nodes
clinical manifestation of tularemia ?
Flu-like symptoms
High fever
Tender regional lymphadenopathy
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Localized signs depending on manifestation:
usually tick bite Ulceroglandular tularemia (45–85%): first a small papule appears at the site of organism entry -> then onset of fever papule undergoes necrosis, leaving a tender ulcer with a raised border at the entry site of F. tularensis
painful regional lymphadenopathy
- in one or more adjacent lymph nodes
In children more commonly affected are cervical and occipital; and
inguinal adenopathy in adults
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Glandular tularemia (10–25%): tender regional lymphadenopathy with no skin ulcer more common in children
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Oculoglandular tularemia (<5%): entry of organism into the eye
fever
unilateral conjunctivitis with mucopurulent discharge photophobia,
eyelid swelling, and ulcers or pustules on the palpebral conjunctivae
tender preauricular and/or cervical lymphadenopathy
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Oropharyngeal tularemia (<5%):
fever
sore throat, mouth ulcers, tonsillitis, tender cervical lymphadenopathy
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Pneumonic tularemia (< 5%): MOST severe form nonproductive paroxysmal cough, pleuritic/ retrosternal pain, dyspnea lobar and multilobar infiltrates, lung abscesses, and hilar adenopathy
exudative Pleural effusions may occur
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Typhoidal tularemia (< 5%): hepatosplenomegaly
what is the diagnosis of turalemia ?
specific hints in the anamnesis: hunters or persons in
contact with rabbits/bunnies are especially at risk!
Serology:
IFA test: four-fold increase in F. tularensis-specific antibody titers between acute and convalescent serum samples
Microbiological culture - on charcoal yeast extract agar -
from infected ulcer-scrapings, pharyngeal swab, sputum specimen
- Risky procedure since organism is very infectious! E.g. can also infect via
inhalation!
PCR
what is the treatmnet of turalemia ?
10-14 days with
Streptomycin or Gentamicin
Alternatives:
Doxycycline, Fluorochinoloes or Macrolide
what are the complication of turalemia ?
Usually from delay of treatment - Most common: suppuration of infected lymph nodes requiring surgical drainage(s) - hepatic abscesses, hepatitis - renal failure
prevention of tularaemia ?
insect repellents and wearing of long pants, long sleeves, and
long socks can reduce the risk of tick and deerfly bites
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If tick bites are found -> must be removed by tweezers
