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Brucella

Brucella. The genus Brucella consists of six species, four of which cause human brucellosis 布鲁菌病： Brucella melitensis 羊布鲁菌 , Brucella suis 猪布鲁菌 , Brucella abortus 牛布鲁菌 , and Brucella canis 犬布鲁菌 Are all intracellular organisms B. neotomae; B. ovis.

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Brucella

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  1. Brucella • The genus Brucella consists of six species, four of which cause human brucellosis 布鲁菌病： Brucella melitensis羊布鲁菌, Brucella suis 猪布鲁菌, Brucella abortus牛布鲁菌, and Brucella canis犬布鲁菌 • Are all intracellular organisms • B. neotomae; B. ovis

  2. Brucella are small (0.4～0.8 ×0.5～1.5μm), non-motile, non-capasulate, gram-negative coccobacilli. • The organism is aerobic, and their nutritional requirements are complex. • All strains grow best in a medium enrich with animal serum and glucose • 5-10% carbon dioxide

  3. Antigenic Structure and classification • Two main antigen: A and M • The three main Brucella differ from one another in the amount or the two main antigen they have in common : B.abortus : A:M=20:1 B.melitensis: A:M=1:20 B.suis: A:M=2:1

  4. B. abortus • Bacteria is excreted in genital secretions (including semen), milk, colostrum. • Survival time: Cheese at 4oC: 180 days !!! Water at 25oC: 50 days Meat and salted meat: 65 days Manure at 12oC: 250 days !!!! • Widespread:Cattle, Bison, Elk, Deer, Moose, Horse, Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats, mice, Camels and Human.

  5. B. abortus • Sources of Human Infection: Raw milk and products /Direct contact • Portal of entry: oral mucosa, nasopharynx and conjunctivae, genital then X in regional lymph node and spread to RES (nodes of udder, uterus, erythritol...). Placentitis with endometritis. Fetus die with edema /congestion of lung, dissimenated hemorrhages of epicardium and splenic capsule. Bacteria in lung and digestive tract of the fetus.

  6. B. melitensis • Goat (1886), Sheep, Cow (1905 in Malta), Swine, Hares, Camels, Buffalo, Impala.

  7. B. suis • Wild pigs, Rats, Swine. • Abortion,metritis, bursitis, spondylitis (Lumbar and sacral), arthritis, orchitis, paralysis.

  8. Brucella canis • Brucella canis was first described as a cause of abortion in beagles in the USA • It was subsequently shown to infect dogs in many other countries, irrespective of breed • An occasional cause of brucellosis in humans

  9. Spread of Brucella in the body

  10. Incubation period • Acute or subacute disease follows an incubation period which can vary from 1 week to 6 or more months. • In most patients for whom the time of exposure can be identified, the incubation period is between 2 and 6 weeks • The length of the incubation period may be influenced by many factors • virulence of the infecting strain • size of the inoculum • route of infection • resistance of the host

  11. Portals of entry • Oral entry - most common route • Ingestion of contaminated animal products (often raw milk or its derivatives) • contact with contaminated fingers • Aerosols • Inhalationof bacteria • Contamination of the conjunctivae • Percutaneous infection through skin abrasions or by accidental inoculation

  12. Clinical Manifestations • The presentation of brucellosis is characteristically variable • The onset may be insidious or abrupt • Influenza-like with fever reaching 38 to 40oC • Limb and back pains are unusually severe, night sweating and fatigue are marked. • Anorexia, weakness, severe fatigue and loss of weight, depression • Headache • The leukocyte count tends to be normal or reduced, with a relative lymphocytosis • Relative leukopenia • On physical examination, splenomegaly may be the only finding.

  13. COURSE OF BRUCELLOSIS • If the disease is not treated, the symptoms may continue for 2 to 4 weeks • Many patients will then recover spontaneously • Others may suffer a series of exacerbations • May produce an undulant fever in which the intensity of fever and symptoms recur and recede at about 10 day intervals.

  14. Brucellosis • Cyprus fever/Gibraltar fever/Malta fever/Rock fever/Undulant fever • Most affected persons recover entirely within 3 to 12 months • Some will develop complications • involvement of various organs, • a few may enter an ill-defined chronic syndrome.

  15. COMPLICATIONS • Arthritis, often sacroiliitis, and spondylitis (in about 10 percent of cases) • central nervous system involvement including meningitis (in about 5%) • Uveitis, epididymo-orchitis • Endocarditis very rare • In contrast to animals, abortion is not a feature of brucellosis in pregnant women.

  16. LARGE JOINTS

  17. SPONDYLITIS脊椎炎

  18. SACROILIITIS 骶髂关节炎

  19. Chronic Brucellosis- Depression

  20. Population risk • The main source of infection for the general population is dairy produce prepared from infected milk. • B. melitensis presents the greatest hazard. • The milk of infected sheep and goats may contain large numbers of viable organisms, which become concentrated in products such as soft cheeses. • Indeed, soft cheese has been recognized as a major vehicle of infection in the Mediterranean region, the Middle East and Latin America

  21. Occupational hazard • Infection arises from occupational or domestic contact with infected animals or with an environment contaminated by their discharges • Farmers and their families, abattoir workers, butchers and veterinarians are particularly at risk • Infected animals that have recently aborted or given birth present the greatest hazard

  22. Extending spectrum of zoonosis • The recent isolation of distinctive Brucella strains, tentatively named Brucella maris, from marine animals in the United Kingdom and the United States extends the ecologic range of the genus and, potentially, its scope as a zoonosis • seals, sea otters, dolphins and porpoises • An incident of laboratory-acquired infection suggests that this type is pathogenic for humans • Infection could result from occupational contact with infected seals or cetaceans.

  23. CLINICAL DIAGNOSIS

  24. Sanitary • Pasteurization of dairy products and use of protective clothing prevent human infection. More importantly, systematic identification and elimination of infected animals and vaccination of animals reduces the reservoir.

  25. Prevention • Eradication of brucellosis in cattle can be attempted by test and slaughter,active immunization of heifers with avirulent live strain 19,combined testing,segregation, and immunization.Cattle are examined by means of agglutination tests • Active immunization of humans against brucella infection is experimental.Control rests on limitation of spread and possible eradication of animal infection,pasteurization of milk and milk products, and reduction of occupational hazards wherever possible.

  26. Treatment • Brucella may be susceptible to tetracyclines or ampicillin. • Symptomatic relief may occur within a few days after treatment with these drugs is begun. • However ,because of their intracellular location,the organisms are not readily eradicated completely from the host. • For best results,treatment must be prolonged.Combined treatment with streptomycin and a tetracycline may be considered

  27. YERSINIA

  28. Genus Yersinia Enterobacteriaceae • Y. pestis • Y. enterocolitica • Y. pseudotuberculosis Genus Escherichia

  29. Biological Features • Small, 0.5-0.8 μm in width 1.0-2.0 μm in length. • Gram-negative rods. • Sometimes appearing as cocco bacilli. • Bipolar Staining:Retaining stain at the ends of cells.

  30. Biological Features • Cultural Features • Facultative anaerobes. • Optimal growth temperature range form 28˚C to 30˚C. • Optimal growth pH: 6.9～7.2. • Growth is more rapid in media containing blood or tissue fluids. • Nonmotile when grow at temperatures above 30 ˚C.

  31. Pathogenicity Transmission: Flea Bite Respiratory Tract

  32. Antigenic Structure • F1 Antigen: • V,W Antigen: • Yersinia Outer membrane Protein (Yop) • Murine Toxin (MT) 0.3%-0.4% formaldehyde Toxoid • Endotoxin (LPS)

  33. Ca2+ Dependent Gene F1 Antigen V-W Gene F1 Gene W Antigen V Antigen LPS Y. Pestis Virulence factors schematic diagram Plasmid Plasmid

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

  35. 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

  36. Gram negative, No capsule, No spore, Facultative anaerobes V－W antigen More than 50 serotypes of Y.Enterocolitica 6 serotypes of Y.Pseudotuberculosis Diseases: Gastroenteritis terminal ileitis, appendicitis, mesenteric lymphadenitis, dermatitis contusiformia, arthritis Septicemia Sanitary precautions, Antibiotic Y.Enterocolitica & Y.Pseudotuberculosis Back

  37. 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.

  38. Immunity Cellular Immunity Humoral Immunity Antibody To: 1) F1 Ag 2) V,W Ag Phagocytose Promote phagocytose , agglutinate and kill bacteria

  39. Diagnosis • A. Specimens: • Aspirates of lymph nodes • Cerebrospinal fluid • Blood • Sputum • B. Smears: • Giemsa’s stain • immunofluorescent stain

  40. Diagnosis • C. Culture: • All materials Cultured on blood agar and MacConkey’s agar and in infusion broth • Positive in 24 hours • Tentatively identified by biochemical reations Definite identified by immunofluorescence CAUTION: All cultures are highly infectious and must be handled with extreme caution

  41. Diagnosis • D. Serology: In patients who have not been previously vaccinated, a convalescent serum antibody titer of 1:16 or greater is presumptive evidence of Y.pestis infection.A titer rise in two sequential specimens confirms the serologic diagnosis.

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

  43. Summary of Yersinia infections

  44. 12. Spore-Forming Gram-Positive Bacilli: Bacillus

  45. Bacillus Species • At least 48 species are known but only • B. anthracisandB. cereus cause defined diseases in humans. • B. anthracis is responsible for the disease anthrax. • This is a disease primarily of animals(zoonosis) but humans can acquire via handling, inhaling or ingesting contaminated animal products. • B. cereus is predominantly responsible for food poisoning in humans. • Bacitracin and polymyxin are two well-known antibiotics obtained from Bacillus species. • Spores of many Bacillus species are resistant to heat, radiation, disinfectants and desiccation

  46. It was from studies on anthrax that Koch established his famous postulates in 1876 • Pasteur (1881) developed a vaccine against anthrax

  47. B. anthracis Gram staindemonstrating spores

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