Micro Lec 17 - Yersinia
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Transcript of Micro Lec 17 - Yersinia
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FACULTAS MEDICINAE ET CHIRURGIAE
PRAYER BEFOREPRAYER BEFORE
CLASSCLASS
Oh Lord Our God,Oh Lord Our God,May the inpouring of the Holy SpiritMay the inpouring of the Holy Spirit
Purify our hearts andPurify our hearts and
make them fruitful by themake them fruitful by the
sprinkling with the dew of His grace.sprinkling with the dew of His grace.
We ask this throughWe ask this through
Our Lord Jesus Christ, Your Son,Our Lord Jesus Christ, Your Son,
Who lives and reigns with YouWho lives and reigns with Youand the Holy Spirit,and the Holy Spirit,
One God forever and ever.One God forever and ever.
Amen.Amen.
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YERSINIA and
PASTEURELLA
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Generalities
short, pleomorphic, gram (-) rods
exhibit bipolar staining (hairpin-like)
microaerophilic or facultative anaerobe
catalase (+), oxidase (-)
most have animals as natural host
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3 Pathogenic species ofYersinia
Y pestis
Y pseudotuberculosis
Y enterocolitica
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Yersinia pestis & Plaque
Plaque: an infection of wild rodents,
sometimes transmitted to man
responsible for pandemics of
black death
organism transmissible by aerosol
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Morphology & Identification
gram (-) rod, exhibits bipolar staining
non motile, facultative anaerobe
optimum growth: media with blood or
tissue fluids at 30C
virulent strains: gray & viscous colonies
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Antigenic Structure
all have lipopolysaccharides with endotoxicactivity
The 3 pathogenic species have antigens &toxins, that act as virulence factors
V & W antigens: produced by virulent strains plasminogenactivatingprotease, which has
coagulase & fibrinolytic activity involvedin dissemination from flea bite injection site
capsule: antiphagocytic activity phospholipase D: survival in the flea midgut Yersiniabactin: iron-scavenging siderophore
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Pathology & Pathogenesis
Flea feeds on a rodent with Y pestis
organism multiply in the gut of flea
blocks its proventriculus no food
passes through flea becomeshungry flea bites ferociously
organism is regurgitated into the bite
wound (contd next slide)
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Contd..
Organism phagocytosed by PMN &
macrophages killed by PMN but
multiply in the macrophages
organism reach lymphaticslymphadenopathy & hemorrhagic
inflammationnecrosis
dissemination to all organs
meningitispneumonia, pleuropericarditis
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NB.
Primary pneumonic plague results from
inhalation of infective droplets with
hemorrhagic consolidation, sepsis & death
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Clinical Findings
Incubation period: 2-7 days
S/S: high fever, painful lymphadenopathy,
(groin or axillae), vomiting & diarrhea
may develop with early sepsis Later: DIC hypotension, altered mental
status, renal & cardiac failure
Terminal: pneumonia & meningitis
NB. Plague should be suspected in febrile patients exposed to
rodents in known endemic areas
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Laboratory Tests
specimens: blood, aspirates from LN, sputum,CSF
smears: Gram staining; for bipolar appearance,
use the ffg: Wrights, Giemsa, Waysons culture: BAP, CAP, McConkey, BHI broth biochemical reactions: catalase (+), indole-
oxidase-urease (-), nonmotile
serology: antibody titer (1:16 or greater) presumptive evidence ofY pestis infection
NB. Definite Identification of culture best by IF or by lysis byspecific Y pestis bacteriophage
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Treatment
DOC: streptomycin
gentamycin
doxycycline
NB. untreated plaque has a mortality rate of about
50%; pneumonic plaque, nearly 100%
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Epidemiology & Control
plaque is an infection of wild rodents,
that occurs in many parts of the world
humans can be infected by flea bites, or
by contact
commonest vector: rat flea
control of plaque: destruction of plaque-
infected animals & isolation of allpatients with suspected plaque
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Y enterocolitica &Y pseudotuberculosis
gram (-) bacilli, nonlactose fermenter urease (+), oxidase (-) found in the GIT of a variety of animals,
(in which they may cause disease) transmissible to humans, producing a variety
of clinical syndrome transmission to humans: probably by
contaminated food, drink or fomites human infection: probably by ingestion of
materials contaminated with animals feces
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Pathogenesis & ClinicalFindings incubation period: 4 7 days
organism multiply in the gut mucosa
(esp. ileum) inflammation & ulceration
fecalysis: WBC
S/S: fever, abdominal pain, diarrhea(watery to bloody)
diarrhea: may be due to an enterotoxin orinvasion of mucosa (contd next slide)
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immunologic reaction:
arthralgia, arthritis & erythema nodosum
(those with histocompatibility antigen HLA-B27)
most cases: self-limited
rarely: pneumonia, meningitis, sepsis
Pathogenesis & Clinical Findings(contd)
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Laboratory Tests
specimens: stool, blood, material from
surgical exploration
culture: cold enrichment of stool :(buffered saline, pH 7.6, 4C, 2-4 wk)
then, cultured on McConkey
serology: Agglutinating antibodies,
(however, cross reactions between otherorganism may confuse results)
NB. stained smears are not contributory
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Treatment
aminoglycosides chloramphenicol tetracycline
TM-SMX piperacillin 3rd gen cephalosporins
fluoroquinolones
NB. typically resistant to ampicillin & 1st gen cephalosporins
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Prevention & Control
most human infections: contact with
animals, their feces, or contaminated
materials
meat & dairy products, contaminatedfood & drink
NB. no specific preventive measures
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Pasteurella
primarily animal pathogens
nonmotile, gram(-) coccobacilli, with
bipolar appearance
aerobic or facultative anaerobe
oxidase-catalase (+)
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P multocida
distribution: worldwide perhaps the most common organism in
human wounds inflicted by bites fromcats & dogs
P bettyae: infections of human genital tract& of newborns
P pneumotropica: normal inhabitant of RT& gut of mice
P ureae: mixed flora in human chronicrespiratory disease or other suppurativeinfections
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Clinical Findings
most common presentation: history ofanimal bite, followed within hours by anacute onset of redness, swelling & pain
regional lymphadenopathy is variable,fever often low grade sometimes: presentation is bacteremia or
chronic respiratory infection (withoutevident animal connection)
P multocida: penicillin G (DOC),tetracycline, fluoroquinolones
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Oh god, Who teachesOh god, Who teachesthe hearts of the faithfulthe hearts of the faithful
by the light of the Holy Spirit:by the light of the Holy Spirit:
Grant, by the same Spirit,Grant, by the same Spirit,
That we may relish what is right,That we may relish what is right,
And ever rejoice in His consolation.And ever rejoice in His consolation.
We ask this throughWe ask this through
Our Lord Jesus Christ, Your Son,Our Lord Jesus Christ, Your Son,Who lives and reigns with YouWho lives and reigns with You
and the Holy Spirit,and the Holy Spirit,
One God forever and ever.One God forever and ever.
AmenAmen
FACULTAS MEDICINAE ET CHIRURGIAEFACULTAS MEDICINAE ET CHIRURGIAE
PRAYER AFTERPRAYER AFTER
CLASSCLASS