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Brucella and mycoplasma


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Brucella and mycoplasma

  1. 1. BrucellaBrucellosis Dr Kamran AfzalAsst Prof Microbiology
  2. 2. Background Brucella melitensis discovered by Bruce in 1887 Members of this genus are pathogenic to animals from which they are transmitted to man causing „brucellosis‟ (Undulant or Malta fever)
  3. 3. The genus includes Br. melitensis, causing infection in goats and sheep Br. abortus, causing abortion of cattle Br. suis, causing infection in pigs Br. ovis, causing infection in birds Br. canis, causing infection in dogsPathogenic types in humans: Br. melitensis, abortus, canis and suis Zoonotic disease
  4. 4. Epidemiology
  5. 5. Morphology Gram negative short cocco-bacilli, non- motile, non- sporing and non capsulated Aerobes, require enriched media for growth 10-20% CO2 is required for primary growth of Br. abortus but not for the others Br. abortus and Br. suis produce H2SAntigenic structure: Two Lp antigens, A and M are present in different proportions in the four species They can be differentiated by specific monoclonal antibodies
  6. 6. Who is at Risk? Occupational Disease  Cattle ranchers/ dairy farmers  Veterinarians  Abattoir workers  Meat inspectors  Lab workers Hunters Travelers Consumers of unpasteurized dairy products
  7. 7. TransmissionThree methods of transmission: Ingestion – unpasteurized milk or dairy products Ingestion is most common method of transmission Inhalation – breathing in the aerosolized organism Lab workers are at high risk
  8. 8.  Inoculation/Wound contamination – high risk occupations include hunters, slaughterhouse workers, meat packing plant workers and veterinarians
  9. 9. Transmission
  10. 10. Pathogenesis Incubation period 1-6weeks Can multiply and survive within the neutrophils and macrophages Reticuloendothelial system  Liver spleen and bone marrow (Septicemia)
  11. 11.  Cell mediated response of the host results in granuloma and abscess formation in the bone or any organ
  12. 12. Brucellosis: Undulant fever An acute bacteraemic phase A chronic stage that may extend over many years and may involve many tissues Intermittent fever, bouts of fever for 3-4 weeks, alternating with afebrile period of a similar duration A prolonged course accompanied with weakness, malaise, profuse sweating, headache, joint and muscle pain Enlarged lymph nodes, liver, and spleen It may be complicated by osteomyelitis
  13. 13. Lab Diagnosis Specimens  Blood, pleural/peritoneal fluids, CSF, Bone marrow (92% sensitive), biopsy: liver, spleen and lymph node
  14. 14. Lab DiagnosisI-Blood Culture: Isolation of the organism from the blood by repeated blood cultures incubated in 10-20% CO2 for 4-6 weeks Subcultures are done on serum dextrose agar (SDA), chocolate agar, Thayer-Martin medium Isolated organisms are serologically identified by specific antisera
  15. 15. II-Serologic diagnosis: Detection of antibodies A tube agglutination test is done using dilutions of the serum A titer of at least 1/60 in convalescent serum is diagnosticCoomb’s antiglobulin method : to detect the non-agglutinating IgA antibodies that appear during the subacute stage of infection, and tend to persist for years They are called blocking or incomplete antibodiesDetection of IgG and IgM by ELISA
  16. 16. III-Direct detection in clinical material by PCRIV- Brucellin test: It is similar to tuberculin test and is based ondelayed type hypersensitivity, it is unreliable and is rarely used
  17. 17. Treatment Prolonged treatment  Chronicity of the disease  Intracellular survival of the organism 6 weeks course of a combination of antibiotics Doxycycline and rifampin or doxycyclin and streptomycin or rifampin and trimethoprim-sulfamethoxazol are used
  18. 18. Prevention/Infection control Pasteurizing milk and dairy products Eradicating infection from herds and flocks Live attenuated vaccine is used for cattle No vaccine is available for humans Observing safety precautions for occupational exposures including  rubber boots  wearing impermeable clothing  gloves and face masks  practicing good personal hygiene
  19. 19. Biological warfare In 1954, B. suis became the first agent weaponized by the US Brucella species survive well in aerosols and resist drying Brucella and all other remaining biological weapons in the U.S. arsenal were destroyed in 1971–72 when the U.S. offensive biological weapons (BW) program was discontinued The United States BW program focused on three agents of the Brucella group:  Porcine Brucellosis (Agent US)  Bovine Brucellosis (Agent AB)  Caprine Brucellosis (Agent AM)
  20. 20. MycoplasmaMycoplasmosisAtypical pneumonia
  21. 21. Mycoplasmas Smallest free-living capable of autonomous growth Key genera: Mycoplasma, Spiroplasma Lack cell walls  Key components of peptidoglycan are missing  Muramic acid and diaminopimelic acid Mycoplasma cells are pleomorphic  Cells may be cocci or filaments of various lengths
  22. 22. Taxonomy
  23. 23. Differentiation of species M. pneumoniae - glucose M. hominis - arginine U. urealyticum - urea M. genitalium - difficult to culture
  24. 24. Diseases O rg a n is m D is e a s eM . p n e u m o n ia e U p p e r re s p ira to ry tra c t d is e a s e , tra c h e o b ro n c h itis , a ty p ic a l p n e u m o n ia , (c h ro n ic a s th m a ? ? )M . h o m in is P y le o n e p h ritis , p e lv ic in fla m m a to ry d is e a s e , p o s tp a rtu m fe v e rM . g e n ita liu m N o n g o n o c o c c a l u re th ritisU . u re a ly tic u m N o n g o n o c o c c a l u re th ritis , (p n e u m o n ia a n d c h ro n ic lu n g d is e a s e in p re m a tu re in fa n ts ? ? )
  25. 25. Morphology Smallest free-living bacteria (0.2 - 0.8 µm) Small genome size Strict aerobe Lack a cell wall Grow slowly by binary fission “Fried egg” colonies
  26. 26. “Fried Egg” Colonies of Mycoplasma M. pneumoniae colonies have a granular appearance
  27. 27. Can be part of normal flora They reside extracellularly in the respiratory and urogenital tracts and rarely penetrate the sub-mucosa, except in the case of immunosuppression or instrumentation, when they may invade the bloodstream and disseminate to numerous organs and tissues
  28. 28. Mycoplasma are cell wall deficient  Cross-section of Mycoplasma bacteria
  29. 29. Pathogenesis Adherence  P1 pili  Movement of cilia ceases  Clearance mechanism stops Toxic metabolic products  Peroxide and superoxide Immuno-pathogenesis  Activate macrophages  Stimulate cytokine production
  30. 30. Clinical manifestations Tracheo-bronchitis  70-80% of infections Pneumonia  Approximately 10% of all atypical pneumonias  “Primary atypical pneumonia”  Mild disease but long duration
  31. 31.  Incubation 2-3 weeks  Radiological signs Persistent non-productive cough precede symptoms  Slow resolution  Rarely fatal
  32. 32. Laboratory Diagnosis Microscopy  Difficult to stain Immunochromatography (ICT) Immunofluorescence (IF) Culture (definitive diagnosis)  Sputum (usually scant) or throat washings  May take 2-3 weeks Molecular diagnosis  PCR-based tests, rapid, sensitive and specific
  33. 33.  Serology  Cold agglutinins (40C)  ELISA  1/3 - 2/3 of patients  Complement fixation  Appear earlier  May take 4-6 weeks  Non-specific  Fourfold rise in titer  Presumptive diagnosis
  34. 34. Culturing Mycoplasma Mycoplasma can be cultured on liquid or solid media  Broth enriched with 20% horse or human serum Grows optimally at 35 - 370 C up to 3 weeks The colonies appear as fried egg
  35. 35. Treatment and Prevention Treatment  Tetracycline or erythromycin  Newer fluoroquinolones  They are relatively resistant to pencillins and cephalosporins Prevention  Avoid close contact  No vaccine