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OTITIS MEDIAPROBLEM BASED LEARNING (PBL)

PREPARED BY: MUHAMMAD ARIFF B. MAHDZUBBACHELOR MEDICINE AND SURGERY (MBBS)UNIVERSITY COLLEGE SHAHPUTRA, KUANTAN

LAB TEST-OTITIS MEDIA-

Otitis media is inflammation of the middle ear

Haemophilus influenzae

• Small• Gram negative• Coccobacilli• Fastidious organism• Required hemin (iron containing porphyrin)

for growth

Gram staining

• As we know that H. influenzae is gram negative bacteria

• Thus by performing gram staining method, we can determine whether the fluid from the middle ear is gram + or gram – bacteria

• If the result show pink,thus it is gram negative bacteria

Gram staining result

• Showing gram (-) H. influenzae (pink)

CHOCOLATE AGAR PLATE

• The standard medium used for growth of Haemphilus influenzae is a chocolate agar plate (CAP), which can be prepared with heat-lysed horse blood

• good source of both hemin and NAD because NAD is released from the blood during the heating process of chocolate agar preparation

• Examination of growth on CAP shows large,round,colorless and opaque colonies

CHOCOLATE AGAR PLATE

Haemphilus influenzae colonies on a chocolate agar plate

KOVAC’S OXIDASE TEST

• Determines the presence of cytochrome oxidase• By using filter paper method, the filter paper will turn purple

if the organisms containing cytochrome c as part of their respiratory chain

• Positive reactions will develop within 10 seconds • Negative reactions will not produce a colour change on the

treated filter paper.

H. Influenzae vs H. haemolyticus• H. influenzae is a fastidious organism and can be identified on

the basis of growth requirements for hemin and NAD

• But there is also another haemophilus species that required both hemin and NAD for growth

• It is H. haemolyticus, but this species differ from H. influenzae by producing beta-haemolyticus

• To differentiate between the two species, hemolysis must be checked on the blood agar

OTHER HAEMOPHILUS SPECIES

H. haemolyticus usually causes hemolysis on these media (blood agar media) while H. influenzae does not.

Organisms Required hemin Required NAD Beta-haemolysis

H. influenzae + + -

H. haemolyticus +

+ +

H. aphrophilus + - -

H. parainfluenzae - + -

H. parahaemolyticus - + +

H. paraphrophilus - + -