Chapter 13 Zoonotic bacteria

What’s zoonosis? Zoonosis Zoonotic bacteria a disease that can be transmitted from animals to humans Zoonotic bacteria bacteria causing zoonosis

What’re primary zoonotic bacteria? Content Source of human infection Disease Brucella Pigs, cattle, goats, sheep Brucellosis Yersinia pestis Rodents Plague Bacillus antracis Cattle, goats, sheep, horses Anthrax

Brucella

Brucella B.abortus: cattle B.melitensis: goat,sheep B.suis: swine B.canis: dog

Biological properties Shape and structure Coccobacillus: 0.4-0.8～0.5-1.5μm Gram-negative Nonmotile, non-spore-forming microcapsule (some)

Biological properties Culture Obligate aerobes 5-10% CO2 (B. abortus) fastidious slow growth: 2～5d Facultative intracellular pathogens

Biological properties Antigenic types LPS, endotoxin two major serological determinants: A and M A---abortus antigen M---melitensis antigen

Pathogenicity Virulence factor endotoxin (main) invasiveness: capsule, hyaluronidase

Pathogenicity Transmission intestinal tract: infected milk respiratory tract: aerosols containing the bacteria contact

Pathogenicity animals: infections of genital systems Disease: brucellosis animals: infections of genital systems abortion (erythritol) inapparent infections (source) humans: undulant fever organism (as a facultative intracellular parasite) → lymphatic system → blood （bacteremia） liver, spleen, bone marrow, lymph nodes undulant fever

Immunity Cell-mediated immunity (CMI) Humoral immunity

Control Prevention Treatment tetracycline, ampicillin pasteurization of milk for drinking animals: slaughter immunization humans: vaccination for persons at high risk Treatment tetracycline, ampicillin prolonged treatment

Yersinia

Yersinia Species Transmission Disease Y. Pestis Flea bite Respiratory tract Plague Y. Enterocolitica Digestive tract Contact Enterocolitis Y. Pseudotuberculosis Digestive tract

Y. Pestis During 14th century over a 5-year period 25 million deaths The most recent pandemic in Asia in 1904 a million deaths

Biological properties Shape and structure 0.5-1.0～1-2μm, coccobacillus Gram-negative, bipolar staining capsule nonmotile non-spore-forming

Biological properties Cultivation facultative aerobes slow growth colony--irregular and rough optimum temperature: 27～30℃

Biological properties Antigenic structure F1 antigen (fractionⅠ): capsular antigen V-W antigen: protein-lipoprotein Yop (Yersinia outer membrane proteins) murine toxin (MT): exotoxin released only when cells are lysed potent endotoxin: LPS

Pathogenicity Virulence factor F1 antigen V-W antigen Yop endotoxin MT

Pathogenicity Transmission rat ←→ rat (by direct contact or biting of rat fleas) ↓by rat fleas person ←→ person (by human fleas or respiratory route)

Pathogenicity Disease--- plague Bubonic plague Pneumonic plague Septicemic plague

Pathogenicity Bubonic plague the most common enlarged and inflamed lymph nodes (around armpits, neck and groin) mortality rate: 30-75%

Pathogenicity Pneumonic plague mortality rate: 90-95% the second most common mortality rate: 90-95%

plague / black death Infected fleas bite bubonic plague spreads pneumonic plague disseminated intravascular coagulation intravascular thrombi and purpuric lesion gangrene and blackening all over the body (the black death)

Pathogenicity Septicemic plague the most rare mortality rate: close to 100%

Control Prevention elimination of rats and fleas Treatment effective formalin-killed vaccine Treatment streptomycin, tetracycline rapid treatment

Bacillus

Bacillus B.anthracis: anthrax B.cereus: food poisoning

B. cereus Virulence factor: enterotoxin Disease food poisoning transmission: digestive tract clinical types: emetic type, diarrheal type eye infection transmission: trauma clinical manifestations: keratitis, endophthalmitis, panophthalmitis others

B.anthracis

Bacillus B.anthracis: anthrax B.cereus: food poisoning

B.anthracis

Biological properties Shape and structure 1-3～5-10μm Gram positive rod with square ends in long chains (bamboo) central spore capsule (D-glutamate) nonmotile

Biological properties Culture aerobic or facultative anaerobic colony: irregular margins non-hemolytic

Biological properties Resistance strong resistance: dry heat desiccation disinfectant sensitivity: oxidant autoclaving

Pathogenicity Virulence factors capsule: Poly-D-glutamate 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

Pathogenicity Disease - anthrax source: herbivorous animals transmission: direct contact digestive tract respiratory tract clinical types: cutaneous anthrax (90%) intestinal anthrax (5%) pulmonary anthrax (5%) Papule丘疹- Vesicle水泡- Ulcer - Eschar焦痂 eschar

Control Prevention Treatment animals: burn or deep bury vaccination humans: vaccination Treatment Penicillin, tetracycline, erythromycin Sporulation of B anthracis requires oxygen therefore does not occur inside a closed carcass regulations in most countries forbid postmortem examination of animals when anthrax is suspected The vegetative cells in the carcass are killed in a few days by the process of putrefaction

B. cereus Virulence factor: enterotoxin Disease food poisoning transmission: digestive tract clinical types: emetic type, diarrheal type eye infection transmission: trauma clinical manifestations: keratitis, endophthalmitis, panophthalmitis

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. 1)Transmission of Y.pestis (bubonic form) is by a. fleas b. ticks c. lice 2) Plague is caused by a. Y. pestis b. Y. enterocolitica c.Y. pseudotuberculosis 3) which bacteria can be cause food poisoning? a. B.cereus b. Y. pestis c. B.anthracis

4)Yersinia pestis, the causative agent of plague, is enzoonic in the United States west of the one-hundredth meridian. Human plague can be bubonic or pneumonic. The primary epidemiologic difference between the two clinical forms of plague is a. season of the year b. route of infection c. age of the patient d. health of the animal vector 5. Please match the organisms with the animal reservoir B.abortus goat B.melitensis cattle B.suis dog B.canis swine

Disease Anthrax--- herbivorous animals ---Sudden onset ---Bleeding from body openings (epistaxis) --- Edema (bloating) --- High fever --- "Peracute" death (within 1 - 2 hours after onset)

Evolution of an anthrax eschar in a 4-year-old boy. (A&B) the lesion when first seen (day 0).Note the arm swollen from the characteristic edema. (C) Day 6. (D) Day 10. (E) Day 15.