1. Problem 1 A 75-year old man with muscle weakness,cramps, difficulty in swallowing, abd. rigidity, increased muscle tone, clenching of fists, extension of lower limbs, lockjaw, & respiratory arrest. Final diagnosis was tetanus. Q. What organism is involved ?

2. A. C.tetani Q. What is the other neurological condition caused by Clostridia spp.?

3. A. Botulism caused by C.botulinum. Q. How is tetanus prevented?

4. A.Triple vaccine (TDB) at 1-2-3 months. Booster at 4-5 & 15 years Wound cleaning Penicillin Passive immunization by immuoglobulins

5. Problem 2 (1) A 26-years old woman with lower abdominal pain, fever, vomiting, & vaginal discharge. Final diagnosis was pelvic inflammatory disease (PID) i.e. salpingitis+cervicitis. Q. Which organisms are involved?

6. A. N.gonorrhoeae – E.coli Enterococci – B.fragilis – Peptostreptococci – C.trchomatis Q. What specimens you may collect ?

7. A. Cervical swabs – fluid aspiration from the cul-de-sac behind the cervix

8. (2) Aspirated fluid was bloody foul smelling,& purulent.Gram stain showed gram neg. diplococci & gram neg. rods. Culture showed oxidase positive colonies on TM agar, that were gram neg. diplococci. Anaerobic culture showed colonies consisting of gram neg. rods Q.What bacteria isolated aerobically

9. A.N.gonorrhoeae Q.What is the organism isolated anaerobically ?

10. A. B.fragilis Q. Do you test the sensitivity for the isolated organisms ?

11. A.Yes, because resistance is expected Q. How would you test for syphilis?

12. A.VDRL or RPR if positive confirm by TPHA or FTA-ABS test

13. Problem 3 (1)A 52-year old man c/o cough, fever, anorexia, headache. Cough is productive,& nonbloody Lab.test showed:WBC 18000 – Polymorphs 77%-Lymphocytes 12% Q. What 2 specimens to collect ?

14. A. Sputum – blood Q. What quick test you do to help diagnosis ?

15. A.Gram stain of sputum (2) Sputum was collected for Gram stain & culture. Gram stain showed many pus cells, no organism, few gram-negative & gram-positive cocci. Blood culture was taken. Final diagnosis was atypical pneumonia Q. What organisms causing atypical pneumonia ?

16. A.Mycopl. pneumoniae Leg.pneumophila, Chlam. pneumoniae C.psittici Influenza virus Q.What organisms causing pneumonia in an immuno- compromized patient ?

17. A.Klebsiella Pseudomonas Legionella S.aureus Pneumocystis CMV, H.simplex, Varicella zoster Candida, Aspergillus Strongyloides

18. (3) Fluorescence examination of sputum showed L.pneumophila. Q. What is the natural habitat of this organism ?

19. A. Air conditioning units – water taps – lakes Q. Can the organism be cultured ?

20. A.Yes, not commonly done Medium used contains iron & cysteine Q. What other tests for diagnosing Legionella ?

21. A. Serology by indirect immunofluorescence test. Q. Why was not seen in Gram stain ?

22. A. Because it stains poorly with gram stain. Best detected by the fluorescence microscopy

23. Problem 4 (1) A 20-year old man c/o cough, loss of appetite, fever, bloody sputum, & loss of weight. Lab. tests showed 3% neutrophils, & X-ray showed cavitation & infiltration in lungs. Q. What quick 2 sputum tests that you may perform to identify the organism ?

24. A. Gram + ZN stains (2) Gram stain revealed mixed flora.ZN stain revealed long, slender, pink rods. Sputum was sent for culture. Q. What is your diagnosis ?

25. A. Tuberculosis Q.How is this bacteria transmitted ?

26. A. *Inhalation *Ingestion Q. What is the natural habitat of this organism ?

27. A. Human lungs Q. Why is the organism acid-fast?

28. A. Because it contains high content of lipids Q. How is the organism cultured in lab. ?

29. A.On LJ medium within 6-8 weeks, and by the automated new Bactec machine (1 week). Q. What is the role of serology in the diagnosis of TB ?

30. A.Only when negative Q. What should be done for TB contacts?

31. A. * Asymptomatic contacts : screened by Mantoux test, if positive, give INAH drug *Symptomatic contacts : do sputum microscopy & culture, if positive, give treatment. Q. What is the immunological basis for Mantoux test ?

32. A. Cell-mediated immunity to Myco.TB Q. Can atypical mycobacteria cause such an infection ?

33. A.Yes Differentiated by culture.

34. Problem 5 (1)A 10-years old immunocompromized girl has fever for 2 days. Blood test showed 10% neutrophils. Q. What common bacteria, viruses, fungi that may cause this condition ?

35. A. a) S.aureus – S. epidermidis – E.coli – K. pneumoniae – P. aeruginosa b) H.simplex type 1 – CMV- V. zoster c) C.albicans – As. fumigatus – Mucor – Rhizopus Q. Which specimens do you obtain for culture ?

36. A.Blood – urine – stool (2) All cultures showed no growth. She c/o sore throat & whitish plaques in nasopharynx. Q. What are the likely pathogen?

37. A.C.albicans – C.tropicalis Q.How would you distinguish species of Candida ?

38. A. By germ tube & sugar reactions. Q. What is the natural habitat of Candida ?

39. A.Skin, mouth, vagina, GIT Q. Could this infection be prevented?

40. A. Never

41. Problem 6 (1) A 1-year old girl c/o fever, convulsions, & neck rigidity. Lab. tests showed WBC 21000, 80% polymorphs, Q. What are the 2 specimens to collect to reach a diagnosis?

42. A. Blood & CSF Q. What quick lab. test that may identify the causative organism?

43. A. CSF gram stain Q. What are the likely causative pathogens ?

44. A.H.influenzae S.pneumoniae, N.meningitidis Q. How would you distinguish between these by Gram stain ?

45. A.H.influenzae : gram- negative coccobacilli S.pneumoniae : gram- positive diplococci N.meningitidis : gram- negative diplococci

46. (2) This is a case of bacterial meningitis. Lumber puncture is done. CSF was cloudy, 88% of cells were polymorphs, Gram stain revealed short gram-negative rods. CSF was sent for culture & estimation of glucose & protein. Blood culture was ordered Q. Which CSF serology test you do to identify the organism ?

47. A. Latex agglutination test for capsular polysaccharides of H. Influenzae S. Pneumoniae N.meningitidis

48. (3) Latex agglutination test was positive for H.influenzae. Blood culture detected small gram-negative rods. CSF culture revealed many gram- negative rods. Q. What are the growth requirements of H.influenzae?

49. A. Both X (heam) and V(nucleoside adenine dinucleotide “NAD”) factors Q. What is the virulence factor of H.influenzae ?

50. A. Capsule polysaccharide that resists phagocytosis Q. What is the habitat of this pathogen & how is it acquired ?

51. A. Human nasopharynx & acquired by inhalation of respiratory secretions. Q. Does the organism contain endotoxin ? Do exotoxins play a role in pathogenesis?

52. A. Yes, H.influenzae has endotoxin. Exotoxins have no role in pathogenesis. Q. How do we prevent meningitis ?

53. A. a) Haemophilus vaccine for 2-18 months children b) Rifampicin & ciprofloxacin for patients & their contacts c) Polysaccharide vaccine to group A & C of N.meningitidis Q. What other agents causing meningitis ?

54. A.T. pallidum Leptospira E.coli B-hemolytic S.pyogenes Group B (S.agalactiae ) M. tuberculosis L. monocytogenes, Enteroviruses (Polio, Coxackie, ECHO) Mumps H.simplex Q. How would you identify N.meningitidis?

55. A.Culture on TM agar, chocolate, blood agar Gram stain Oxidase test Sugar reactions Serotyping.

56. Problem 7 (1) A 1-year old boy c/o fever, bulging ear drum, & later ear discharge. Q. What lab. tests you may carry out ?

57. A.Gram stain Culture of discharge. Blood culture if patient is febrile. Q. What are the causes of otitis media ?

58. A.*S.pneumoniae *H.influenzae *B-hemolytic Strep. *group A,C, G *S.aureus *Moraxella catarrhalis *E.coli *Mycoplasma pneumoniae *Viruses.

59. Problem 8 A 1-year old infant c/o respiratory distress, fever, & paroxysmal cough. Final diagnosis was whooping cough Q. What are the organisms causing whooping cough?

60. A.Viruses: parainfluenza, RSV, adenovirus B.pertussis, B. Parapertussis Mycop.pneumoniae. Q. What lab. tests you choose for diagnosis ?

61. A.Specimens are collected by cough plates & pernasal swabs. * Culture on Bordet-Gengou agar Or charcoal –cephalexin agar. * Hemolytic colonies are identified by polyvalent anti-sera.

62. Problem 9 A 35-year old man with nausea, diarrhea, abd. pain, & abd. cramps. Q. What is the diagnosis ?

63. A. Food poisoning Q. What organisms that cause food poisoning & how ?

64. A. Preformed toxin: B.cereus, S.aureus, C.botulinum (intoxication) Toxin production in vivo : C.perfringes, B.cereus, Enterotoxigenic E.coli Vibrio (not causing cholera ) Tissue invasion : C. jejuni, S. typhimurium, S. dublin, S. enteridits Enteroinvasive E.coli

65. Q. What other pathogens that may cause food poisoning ?

66. A. Norwalk virus. Q. Are there any food associated with certain pathogens?

67. A. C.perfringes : meat S.aureus : eggs, poultry B.cereus : rice Salmonella: raw eggs, poultry C.jejuni : poultry, milk Norwalk virus : shellfish Q. Give the lab. Diagnosis of food poisoning.

68. A.@ Stool to culture Salm.spp C.jejuni, E.coli, S.aureus C.perfringes, Vibrio @ Food remnants culture for S.aureus, C.perfringes Q. What are the water-borne organisms ?

69. A.Bacteria : Shigella,E.coli C.jejuni, Salm., Vibrio Viruses : Hepatits A, Norwalk, Rota