lecture 7-corynebacterium and listeria

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم

GENUS: GENUS: CORYNEBACTERIUMCORYNEBACTERIUMProf. Khalifa Sifaw Ghenghesh

• Diptheroides = Coryneforms

• Gram +ve,

• Nonmotile Rods.

• Arranged in V forms or Palisades

• Catalase +ve

1. 1. Corynebacterium diphtheriaeCorynebacterium diphtheriae

• Diphtheria.

• Pleomorphic Bacilli• Cells Contain Metachromatic Granules.

Morphology

Corynebacterium diphtheriaeCorynebacterium diphtheriaeClub-shaped, Gram-positive rodsClub-shaped, Gram-positive rods

Cultural CharacteristicsCultural Characteristics

• i. Loeffler's Serum Slope.

• ii. Tellurite BA.

- Temp. 37oC,

- Aerobic and Facultative AnO2.

Corynebacterium diphtheriaeCorynebacterium diphtheriae forms black forms black colonies on tellurit agar (left), on blood agar colonies on tellurit agar (left), on blood agar

colonies appear white (right)colonies appear white (right)

PATHOGENICITYPATHOGENICITY

• Diphtheria is a Toxaemia.– Exotoxin: M. wt 62000– 2 Fragaments >> A & B– Inhibits Protein Synthesis.– Has Special Affinity for Certain Tissues

"Mycocardium, Adrenals, Nerve Endings".

• Toxin >> Toxoid.

• Site of Infection >> Faucial.– Toxin >> Pseudomemebrane.

LABORATORY DIAGNOSISLABORATORY DIAGNOSIS

• Important >> Specific Treatment Should Be Started Immediately on Suspicion of Diphtheria.

• Specimen: Two Swabs from the Lesion.

• Culture:i. Loeffler's Serum Slope >> Albert Stain.

ii. Tellurite BA.

iii. BA >> Streptococcal or Staphylococcal Pharyngitis.

PATHOGENICITY TESTSPATHOGENICITY TESTS

• In-vivo Tests:i. Subcutaneous Test:ii. Intracutaneuos Test:

• In-vitro Test:– Elek Test ( Gel Precipitaion Test).

• Tissue Culture:

TREATMENTTREATMENT

• i. Antitoxin: > Moderate Cases:> Severe Cases:

• ii. Antibiotic:

• i. Active Immunization >> PDT.• ii. Passive Immunization:• iii. Combined:

PREVENTIONPREVENTION

SCHICK TESTSCHICK TEST

• > Injection of 0.2 ml of Diphtheria Toxin Intradermally.

• > Positive Reaction >> Erythema + Swelling

______________________________________________________________________Result Test Arm Control Arm Interpretation Diphthri

(Toxin) Inactivated Toxin Immunization

36h 120h 36h 120h______________________________________________________________________Negative -- -- -- -- Immune, Not

Not Hypersensitive Required

----------------------------------------------------------------------------------------

Positive + + -- -- Not Immune, Not RequiredHypersensitive

---------------------------------------------------------------------------------------------------------------------Negative + -- + -- Immune Not

Hypersensitive Required---------------------------------------------------------------------------------------------------------------------Positive & + + + -- Not Immune Contra-Pseudo Hypersensitive indicated______________________________________________________________________

SCHICK TESTSCHICK TEST

الرحيم الرحمن الله الرحيم بسم الرحمن الله بسم

Listeria monocytogenesListeria monocytogenes

• Listerosis.Listerosis.

• G+ve Coccobacilli > in Short Chains.

• Motile at 25oC But Not at 37oC.

• Aerobic to Microaerophilic.• On BA > Narrow Zone of -Haemolysis.

• Listerolysin O >

DISEASEDISEASE

• Incidence and Transmission >

• i. In Adults:

• ii. Neonatal Infections:a. Early Type:

b. Late Type:

LABORATORY DIAGNOSISLABORATORY DIAGNOSIS

• i. Specimen: Depend on Syndrome: Blood, CSF, Genital Tract

Secretions.

• ii. Media: Selective Media.

• Penicillin, Ampicillin.

TREATMENTTREATMENT