15. The isolated organism is Corynebacterium diphtheriae Is it Toxigenic or Not?
16. E- Toxigenicity Tests: a) Eleks test: most common assay. b) PCR: detection of toxin gene. c) ELISA: detection of toxin from culture.
17. Eleks test: An antigen-antibody reaction in which the Ag is soluble Precipitation.
18. Eleks Test
19. Diagnosis of carriers Throat or nasal swabs are subjected to the same procedures: Isolation + Toxigenicity tests
20. What treatment is prescribed? Treatment should be IMMEDIATELY started if diphtheria is clinically suspected. Diphtheria antitoxin and antibiotics. Treatment of symptoms & complications e.g. respiratory support.
21. How can we prevent this disease? By Vaccination Diphtheria toxoid + pertussis vaccine + tetanus toxoid in a trivalent vaccine: DPT For close contacts of a case: (booster of diphtheria toxoid + antibiotic chemoprophylaxis)
22. Diphtheroids Corynebacteria that resemble C.diphtheriae in morphology. They are mainly commensals.
23. Case A 4-year-old male child presented with fever of 38C. Physical examination revealed clear chest, exudative pharyngitis and bilaterally enlarged cervical lymph nodes. A throat culture was taken and a course of penicillin was started.
24. Case (cont.) The childs course worsened, he became increasingly lethargic, developed respiratory distress and was hospitalized. On admission, he had a fever of 38C and an exudate in the posterior pharynx described as a yellowish, thick membrane which bled when scraped and removed. The patients medical history revealed that he had received no immunizations.
27. Listeria resembles Corynebacteria in morphology but is MOTILE.
28. Diseases Abortion, premature delivery or sepsis during the peripartum period. Neonatal meningitis Septicaemia and meningitis (in immunocompromised adults). Food poisoning (dairy products or undercooked meat)
29. Neonatal meningitis Meningitis caused by Listeria is almost always seen in neonates. Causes of Neonatal Meningitis: 1. Group B Streptococci 2. E. coli K1 3. Listeria monocytogenes
30. Case A one month old girl was admitted to hospital with acute meningitis. The Gram stain of CSF revealed Gram-positive short rods. What is the cause of neonatal meningitis? a. N. meningitidis, group A b. N. meningitidis, group C c. Listeria monocytogenes d. S. pneumoniae
31. How did the mother contract it? Listeriosis is a food-borne infection. Listeria resists drying, heating and freezing without forming spores. Commonly contaminated food items: 1. Dairy products (esp. unpasteurized milk and soft cheeses). 2. Undercooked meat (chicken, hot-dogs). 3. Refrigerated food.
34. 2- Blood tellurite agar is a(n): a- Enriched medium b- Enrichment medium c- Simple medium d- Selective and differential medium e- Indicator medium only
35. 3- Which of the following is a toxigenicity test for C.diphtheriae ? a- Eleks test b- Coagulase c- Catalase test d- Culture on blood tellurite e- ELISA test for antibody detection
36. 4- C. diphtheriae has the following morphology: a- Gram negative cocci arranged in pairs b- Gram positive cocci arranged in chains c- Gram positive club-shaped bacilli d- Gram positive cocci in clusters e- Gram positive capsulated diplococci
37. 5- The toxin of C. diphtheriae is only produced by those strains that are: a- Encapsulated. b- Glucose fermenters. c- Sucrose fermenters. d- Lysogenic e- Endotoxin producers.
38. 6- A 1-week old newborn develops meningitis. Short gram-positive rods are isolated. The mother had eaten unpasteurized cheese during pregnancy. What is the most likely etiological diagnosis? a- C. diphtheriae. b- S. pyogenes. c- L. monocytogenes. d- S. pneumoniae. e- S. agalactiae