3. Corynebacterium
Some species are part of normal flora of
skin and mm.
Medically important species is
Corynebacterium diphtheriae
4. Morphology
Gram-positive bacilli
Club-shaped
Arranged at acute angles or
parallel to each other
(Chinese letters).
Meta-chromatic granules.
Non-spore forming
20. Diagnosis of carriers
Throat or nasal swabs are subjected to
the same procedures:
Isolation
+
Toxigenicity tests
21. 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.
22. 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)
24. Case
A 4-year-old male child
presented with fever of 38°C.
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.
25. Case (cont.)
The child’s course worsened, he
became increasingly lethargic,
developed respiratory distress and
was hospitalized.
On admission, he had a fever of
38°C and an exudate in the
posterior pharynx described as a
yellowish, thick membrane which
bled when scraped and removed.
The patient’s medical history
revealed that he had received no
immunizations.
29. 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)
30. 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
31. 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
32. 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.
35. 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
36. 3- Which of the following is a toxigenicity test
for C.diphtheriae ?
a- Elek’s test
b- Coagulase
c- Catalase test
d- Culture on blood tellurite
e- ELISA test for antibody detection
37. 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
38. 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.
39. 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
