Chapter 20 other bacteria

1. Chapter 20 other bacteria Bacillus , Brucella, Yersinia Disease: anthrax, brucellosis, plague

2. 教学大纲 • 掌握：炭疽杆菌的形态特征、培养特性、致病物质；布鲁菌属的种类、致病物质与所致疾病；鼠疫杆菌的形态特性、致病物质、特异性菌苗预防；小肠结肠炎耶氏杆菌的致病性。 • 熟悉：炭疽临床类型、鼠疫临床类型。

3. section 4 Bacillus B. anthracis anthrax

4. Biological characterization • B. anthracisgram positive, non-motile , rectangular, rod • Have square end, attached by a joint to other cells. • In artificial media, can form long chains as a streptobacillus (bamboo-like ), can produce spores • Virulent strain has capsule

7. culture Colony: 2-5 mm , R Wavy margin and small projections, called medusa head appearance. (curled-hair) Hemolysis is uncommon (common with saprophytic bacilli) blood agar

8. pathogenesis Virulence factors • Capsule :coded by plasmids gene, antiphagocytic • Exotoxin (anthrax toxin) : coded by plasmids gene, consisting of : protective antigen (PA) edema factor (EF) lethal factor (LF)

9. Anthrax toxin • Be considered “classical” AB toxin A (PF) : bind with ATR on host cell B (EF or LF): EF :causing elevated intracellular cAMP, fluid excretion and edema LF: necrosis ,fever, hypoxia ,shock

10. ANTHRAX TOXINS PA LF 20 kDa PA EF Host Protease PA HOST CELL LF

11. Habitat: animals (Herbivores) • Transmission: by contact with infected animal and animal products , inhalation, digestion

12. Clinical finding Anthrax infections are classified by route of entry • Cutaneous • Gastrointestinal • Respiratory

13. Cutaneous Anthrax • > 95% • Spores enter breaks in skin after contact with contaminated animal products • Papule- Vesicle- Ulcer - Eschar • Up to 20% case fatality rate if untreated • Mortality with treatment < 1%

14. In hand , forearm or head

15. Vesicles & Black Eschar

17. Cutaneous anthrax local edema and necrosis

18. Pulmonary anthrax • Bacillusspores are inhaled and ingested by alveolar macrophages • These cells carry the bacteria to theregional lymph nodes, causing necrotic hemorrhagingwhich leads to death Fever, malaise, myalgia, nonproductive cough.

19. Intestinal anthrax • Ingestion of contaminated meat produces systemic symptoms which can lead to death • Mortality may be 50%

20. Protective immunity • Absagainst protective antigen

21. Handling of carcasses动物尸体 • forbid postmortem examination of animals when anthrax is suspected • animals that die suddenly should be handled cautiously (cremation or deep burial )

22. control • Livestock should be vaccinated annually. • Patients: antibiotics

23. Brucella • brucellosis • Brucella melitensis 羊 Brucella suis 猪 Brucella abortus 牛 Brucella canis 犬 • Are all intracellular organisms

24. Brucella are small (0.4～0.8 ×0.5～1.5μm), non-motile, non-spore, G- coccobacilli. • aerobic • Medium: enrich with animal serum and glucose • 5-10% carbon dioxide • Growth is slow

26. Antigenic Structure and classification • Two main antigen: A and M • The three main Brucella differ from one another in the amount B.abortus 牛 : A:M=20:1 B.melitensis 羊: A:M=1:20 B.suis 猪: A:M=2:1

27. Pathogenesis • Bacteria is animal pathogens, excreted in genital secretions (including semen), milk, colostrum of animals. • Widespread:Cattle, Bison, Elk, Deer, Moose, Horse, Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats, mice, Camels and Human.

28. Spread of Brucella in the body

29. Portals of entry • Ingestion of contaminated animal products (often raw milk) via alimentary tract • Inhalation of bacteria via respiratory tract • Via skinabrasions

30. Brucellosis • undulant fever波浪热 *Abortion occurs only in cows and goat.

31. Clinical Manifestations • Influenza-like with fever reaching 38 to 40oC • Limb and back pains, night sweating , fatigue . • Anorexia (loss of appetite), weakness, loss of weight, depression • Headache

32. Occupational hazard • Farmers, abattoir workers, butchers and veterinarians are particularly at risk

33. Prevention • Eradication of brucellosis in cattle • Active immunization of humans against brucella infection • pasteurization of milk and milk products Treatment • tetracyclines or ampicillin.

34. Yersinia • Y. pestis • Y. enterocolitica • Y. pseudotuberculosis

35. Epidemiology • Plague • Probably originated in Asia or central Africa. • One of the earliest record pandemics occurred in 542 B.C. • Three pandemics in the history. • 1989－1998：5440 cases, 681 dead. • 2003: 2118 cases

36. Y. pestis Biological Features Small, G- rods or cocco bacilli. • Bipolar Staining:Retaining stain at the ends of cells. • Nonmotile ,non-sporing, but has capsule

38. Cultural Features • Facultative anaerobes. • 30˚C. • in media containing blood or tissue fluids.

39. Pathogenicity Transmission: Flea Bite Respiratory Tract

40. 鼠 人蚤 鼠蚤 人 人 呼吸道 鼠 Epidemiology • 临床表现为发热、显著的毒血症症状和出血倾向。

41. Virulent factors • Envelope(F1 Antigen) : antiphagocytic • V,W Antigen: rapid proliferation and septicemia • Endotoxin (LPS) • Outer membrane proteins (Yop) • Murine toxin

42. Pathogenesis Lymph Nodes In Groin and Axilla Invade Y. pestis Phagocyte Enter Respiratory System Pneumonic Plague Bubonic Plague Invade Blood Stream Septicemic Plague meningitis

43. Pathogenicity • Clinical Forms : • Bubonic Plague:High fever, Swelling, Bleeding, Necrosis of lymph nodes • Pneumonic Plague: chills, cough, respiratory failure, circulatory collapse ——Black Death • Septicemic Plague: Fever (39-40 ˚C) , Shock , DIC

45. Bubonic plague

47. Diagnosis • Specimens: • Aspirates of lymph nodes • Cerebrospinal fluid • Blood • Sputum • Smears and staining; culture • Serological test:

48. Treatment • Streptomycin • Tetracycline: alternative drug combination with streptomycin essential for control early in disease • Sulfonamides

49. Latest progress • B.anthracis: study of rapidly detecting and identifying methods; search for new vaccine • Y.pestis: manufacture better vaccine

50. summary • B.anthracis: morphology and stain, structure; culture , pathogenesis (transmission and diseases) • Brucella: stain, pathogenesis (transmission and diseases) • Y.pestis: morphology and stain, special structure, pathogenesis (transmission and diseases)