BRUCELLA

1. BRUCELLA

2. Main species • Brucella melintensis • Brucella abortus • Brucella suis

3. Normal habitat • Obligate intracellular pathogens of animals • B. melitensismainly found in goat and sheep • B. abotusinfects cattle • B. suisfound in pigs and occasionally in goat • Other animal including horse, camel, eland and wild rodents

4. Routes of infection • Mosquitoes helps in transfer Brucellafrom animal to human • Also by ingesting unpastuerized milk or milk products, enter damaged skin or eyes, inhaled in airborne particles or aerosols.

5. Laboratory diagnostics

6. Microscopic observation • Non-motile • Gram negative • Coccobacili • Show bipolar staining • Rarely found in direct smear from uncultured specimen • On Gram stain they appear as dense clumps of Gram-negativecoccobacilli and are exceedingly difficult to see.

7. Culture characteristics • Mostly cultured from blood of high fever patient(Brucellosis) • Isolation is extremely rare in chronic brucellosis • In all blood culture, they need carbon dioxide • Blood culture should be kept in 4 – 6 weeks before result as no organisms isolated • To reduce the risk of contamination, use the diphasic medium such as Castaneda or tryptic soy broth or agar • Brucellae are aerobic with enriched of carbon dioxide

8. Biochemical tests Serology tests • Urease and hydrogen sulphide production • All brucella strains are catalase positive • Possess two antigens called A and M Famous test serum: • Rapid slide agglutination test • Tube agglutination titration test

9. Serology test • It is crucial to be able to differentiate Brucella from Salmonella which could also be isolated from blood cultures and are Gram-negative. Testing for urease would successfully accomplish the task; as it is positive for the Brucellaand negative for the Salmonella.

10. HAEMOPHILUS

11. Medical important species • Haemophilus influenzae • Haemophilus aegyptius • Haemophilus ducreyi

12. Normal habitat • H.influenzae (mostly non-capsulated strains), H. parainfluenzaeand H.aegyptiusis normal flora of the upper respiratory tract • Infections causing: • Pyogenic meningitis • Acute epiglottitis • Cellulitis, middle ear infection,etc

13. conjuctivitis

14. Laboratory diagnosis

15. microscopy • Small, non-motile, Gram negative rods or coccobacili • Long thread-like form in old csf culture

16. Microscopic observation

17. Culture of H.influnzae • H.influenzae grows better in aerobically compare to anaerobically • The optimum temperature for growth 35 – 37oC • The are X and V factor • Both represent in blood agar and permit the culture to grow • H.influenzae and H.aegyptius need X and V factor, H. parainfluenzaeneed V factor and H.ducreyi need X factor

19. Biochemical tests • Not usually used to identify hemophilus • 6 biovars of H.influenzae are recognized based on the indole, urease and ornithinedecarboxylase (ODC) reactions of the diff strains

20. serology • Consist of 1 – f serotypes • Mostly causing meningitis belong to serogroup b • Most strains that cause chronic bronchial disease are non-capsulated Antimicrobial sensitivity • Resistant towards chloramphenicol, ampicilin, tetracycline, erythromycin and cotrimoxazole • H. ducreyiis sensitive to sulphonamides • Ampicillin resistant are common

21. STAPHYLOCOCCUS & STREPTOCOCCUS

22. Staphylococcus Staphylococcus aureus Staphylococcus epidermidis Staphylococcus saprophyticus

23. introduction • Are microbial flora of the skin, upper respiratory tract and intestinal tract • S.aureus usually cause abscesses, boils, conjuctivitis, pneumonia, septicemia, food poisoning and scalded skin syndrome • S. epidermidis causingbacteraemia • S. saprophyticus causing cystitis and acute urethritis

24. Laboratory diagnosis Microscopy • Non-motile • Non capsulate • Gram positive cocci • Arrangement single or in pair • Size 1 µm diameter

26. Culture • Grow well in aerobically and also in present of carbon dioxide • Temperature between 10 – 420C, optimum temperature are between 35 - 370C

27. S.aureus • Produce yellow to cream in blood and chocolate agar (heated agar) • Occationally produce white 1-2 mm in diameter colonies • Some strain produce beta-hemolytic when grown aerobically • Colonies are slightly raised and easily emulsified on a slide • Non- lactose fermenterin MacConkey agar • Mannitol salt agar is a useful differential and selective agar to identify S.aureus

28. On blood agar

29. S.epidermidis • Colony is white • Non hemolytic in blood agar S. saprophyticus • Maybe white or yellow • There are non-hemolytic in BA • Not grow anaerobically • No growth in MacConkey agar

30. Biochemical reactions S.aureus • DNAse test will be positive for S.aureus but negative in other species • Catalase test will be positive in all staphylococcus but negative in all streptococcus S. epidermidisand S. saprophyticus • Coagulase negative • DNAse negative • Catalase positive

31. Antimicrobial sensitivity • Erythromycin • Clindamysin • Fucidin • Vancomycin • Many strains of S.aureus are penicillin-resistant • S.epidermidis are more resistant than S.aureus to antibiotics • S. saprophyticus less resistant to antibiotics than S.aureus and S.epidermidis

32. streptococcus Streptococcus pyogenes Streptococcus agalactiae Enterococci

33. To be continue..

34. Explain what happens in the following biochemical tests: i) Indole test ii) Methyl red test 8 marks) b) Write the scientific name of a bacterium that gave positive results for both tests. (2 marks)

36. Question State all group of gram positive and gram negative bacteria.