Chapter12 Zoonotic bacteria

released only when cells are lysed potent – endotoxin: LPS
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Pathogenicity
• Virulence factor
F1 antigen V­W antigen Yop endotoxin MT
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Pathogenicity
• Transmission
eschar
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Control
• Prevention
– animals: burn or deep bury vaccination
– humans: vaccination
• Treatment
– Penicillin, tetracycline, erythromycin
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B. cereus
rat ←→ rat (by direct contact or biting of rat fleas) ↓by rat fleas person ←→ person (by human fleas or respiratory route)
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Pathogenicity
• Disease ­­­ plague – Bubonic plague
• Antigenic structure
– F1 antigen (fractionⅠ): capsular antigen – V­W antigen: protein­lipoprotein – Yop (Yersinia outer membrane proteins) – murine toxin (MT): exotoxin
two major serological determinants: A and M A­­­abortus antigen M­­­melitensis antigen
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Pathogenicity
• Virulence factor
endotoxin (main) invasiveness: capsule, hyaluronidase
• Treatment
streptomycin, tetracycline rapid treatment
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Bacillus
• B.anthracis: anthrax • B.cereus: food poisoning
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B.anthracis
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Biological properties
Medical Microbiology
Li Xiaoxia Department of Microbiology
November, 2006
1
Chapter 12 Zoonotic bacteria
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What’s zoonosis?
• Zoonosis
a disease that can be transmitted from animals to humans
Yersinia pestis Rodents
Plague
Bacillus antracis Cattle, goats, sheep, horses Anthrax
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Brucella
• B.abortus: cattle • B.melitensis: goat,sheep • B.suis: swine • B.canis: dog
• Transmission
intestinal tract: infected milk respiratory tract: aerosols containing the bacteria direct contact
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Pathogenicity
• Disease: brucellosis
• Virulence factor: enterotoxin • Disease
food poisoning transmission: digestive tract clinical types: emetic type, diarrheal type
eye infection transmission: trauma clinical manifestations: keratitis, endophthalmitis, panophthalmitis
• Culture
aerobic or facultative anaerobic colony: irregular margins non­hemolytic
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Biological properties
• Resistance
strong resistance: dry heat desiccation disinfectant
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Biological properties
• Cultivation facultative anaerobes slow growth colony­­irregular and rough optimum temperature: 27～30℃
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Biological properties
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Pathogenicity
• Disease ­ anthrax
source: herbivorous animals transmission:
direct contact digestive tract respiratory tract clinical types: cutaneous anthrax (90%) intestinal anthrax (5%) pulmonary anthrax (5%)
sensitivity: oxidant autoclaving
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Pathogenicity
• Virulence factors capsule: Poly­D­glutamate polypeptide anthrax toxin: protective antigen (PA): proteolytic activation lethal factor(LF) edema factor(EF) PA+EF=edema toxin PA+LF=lethal toxin → responsible for shock and death
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Biological properties
• Shape and structure
Coccobacillus: 0.4­0.8～0.5­1.5μm Gram­negative Nonmotile, non­spore­forming microcapsurties
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Pathogenicity
• Pneumonic plague
the second most common mortality rate: 90­95%
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plague / black death
• Infected fleas bite→bubonic lague→spreads →pneumonic plague→disseminated intravascular coagulation→intravascular thrombi and purpuric lesion→gangrene and blackening all over the body (the black death)
immunization – humans: vaccination for persons at high risk
• Treatment
tetracycline, ampicillin prolonged treatment
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Yersinia
Species Y. Pestis
Y. Enterocolitica Y. Pseudotuberculosis
• Shape and structure
1­3～5­10μm Gram positive rod with square ends in long chains (bamboo) central spore capsule (D­glutamate) nonmotile
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Biological properties
animals: infections of genital systems abortion (erythritol) inapparent infections (source)
humans: undulant fever
organism (as a facultative intracellular parasite) → lymphatic system → blood （bacteremia） undulant fever
– 25 million deaths
• The most recent pandemic in Asia in 1904
– a million deaths
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Biological properties
• Shape and structure
0.5­1.0～1­2μm, coccobacillus Gram­negative, bipolar staining capsule nonmotile non­spore­forming
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Pathogenicity
• Septicemic plague
the most rare mortality rate: close to 100%
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Control
• Prevention
elimination of rats and fleas effective formalin­killed vaccine
• Zoonotic bacteria
bacteria causing zoonosis
3
4
What’re primary zoonotic bacteria?
• Content
Source of human infection Disease
Brucella
Pigs, cattle, goats, sheep Brucellosis
Transmission Flea bite Respiratory tract Digestive tract Contact
Digestive tract
Disease Plague Enterocolitis Enterocolitis
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Y. Pestis
• During 14th century over a 5­year period
– Pneumonic plague – Septicemic plague
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Pathogenicity
• Bubonic plague
the most common enlarged and inflamed lymph nodes (around armpits, neck and groin) mortality rate: 30­75%
• Culture
Obligate aerobes 5­10% CO2 (B. abortus) fastidious slow growth: 2～5d
• Facultative intracellular pathogens
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Biological properties
• Antigenic types LPS, endotoxin
liver, spleen, bone marrow, lymph nodes
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Undulant fever
39.5
37.0
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Immunity
• Cell­mediated immunity (CMI) • Humoral immunity
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Control
• Prevention
– pasteurization of milk for drinking – animals: slaughter
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Question
1. What is zoonosis ? 2. B.anthracis is responsible for three clinical forms of anthrax.
Name them and the route of acquisition. 3. What are the two major virulence factors of B.anthracis ? 4. Please choose the one best response to each question.