Transcript Haemophilus


H. influenzae is found on the mucous membrane of
the upper respiratory tract in humans. It is an
important cause of meningitis, acute epiglottitis
and septic arthritis in infant and young children
and occasionally causes respiratory tract infections
in children and adults.
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Morphology: Small Gram negative cocco-bacilli
.pleomorphic.
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Organisms in young cultures have a definite
capsule used for typing H. influenzae.
Culture Characters:
› Facultative anaerobes grow on blood agar, and
better chocolate agar, each provided with the two
growth factors that require for H. influenzae
respiration namely factor X and factor V.
› Factor X (haemin); is required for the synthesis of
the respiratory enzyme cytochrome C.
› Factor V (nicotinamide adenine dinucleotide ,NAD);
is essential for oxidation-reduction processes in cell
metabolism.
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Pathogenesis & virulence factors H. influenzae
infects only man there is no animal reservoir.
 It is important as a pathogen of infants and
young children meningitis, acute epiglottitis and
septic arthritis), although it can causes diseases
to individuals of all age groups.
 It enters the body through the upper respiratory
tract (by inhalation) resulting in either
asymptomatic colonization or infections such as
otitis media sinusitis,
bronchitis or pneumonia.
acute
epiglottitis,
 The organism produces IgA protease that degrades
secretory IgA, thus facilitates attachment to the
respiratory mucosa.
 After establishment in the upper respiratory
tract the organism may enter the blood stream
and spread to meninges or joints.
 Meningitis is mainly caused by the encapsulated
H. influenzae type b 'Hib' strain.
 The antiphagocytic capsule and the endotoxin
participate in pathogenesis of disease production.
Most infections occur in children between the age
of 6 months and 6 years.
 Other infections causes by H. influenzae are;
cellulites - bacteremia & osteomyelitis.
Laboratory diagnosis:
Specimens; pus, sputum, blood or CSF.
 Direct
examination; Gram stain immunofluorescence or the specimen 1s mixed directly
with specific antisera (type b) for capsule swelling
reaction.
 Immunologic detection of type b polysaccharide
antigen in body fluids or pus using latex
agglutination test.
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Culture:
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On chocolate agar enriched with factor V and
factor X. H. influenza grow around X and V factor
only.
Treatment:
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The mortality rate of untreated H influenzae
meningitis may be up to 90%. The drug of choise for
meningitis or other serious systematic infections
caused by H. influenzae is ceftriaxone & related
cephalosporins followed by chloramphenicol,
ampicillin and trimethoprim sulfamethoxazole.
Prevention:
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Haemophilus b conjugate vaccine the vaccine
contains the capsular polysaccharide of H
influenzae type b, conjugated to diphtheria toxoid.
It is given some time between the age of 2 and 15
months.
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This vaccine is much more effective in young
children than the unconjugated vaccine.
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Meningitis, in close contacts to the patient can he
prevented by rifampin.
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It resembles H. influenzae closely, require X & V
factor for growth.
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H. aegyptius associated with a highly communicable
form of acute purulent conjunctivitis (pink eye), also
it is the etiological agent of Brazilian purpuric fever ;
a disease of children characterized by fever,
purpura, shock and death.
Treatment :
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Tetracycline topically.
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It resembles H. influenzae closely but require X factor
only for growth.
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It is the etiological agent of a sexually transmitted
disease called chancroid, (soft chancre). Chancroid is
ulcer on the genital with marked tenderness and
swelling - The regional (bubo).
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lymph nodes are enlarged and painful.
Treatment:
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The drug of choice is erythromycin followed by
ciprofloxacin, then ceftriaxone.
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It resembles H influenzae closely but requires
X factor in primary isolation only and excess CO2.
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The organism is a normal flora of the oral and
respiratory tract. It is sometimes encountered in
infective endocarditis or pneumonia.
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It is resembles H. influenzae closely, but requires V.
factor. It is a normal flora of respiratory tract.
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It may cause subacute endocarclitis, conjunctivitis
and urithritis.
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It is resembles H. influenzae closely, requires X & V
factors But it is hemolytic organism, it form beta
haemolysis on blood agar.
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It is one of the normal flora in the nasopharynx.
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It may cause urinary tract infections in childhood or
rarely upper respiratory tract infections.
It s resembles H. influenzae closely, but not required
X & V factors.
 It is normal inhabitants of female genitor-urinary
tract.
 It may cause non specific vaginitis characterized by a
foul smelling discharge.
 Vaginal discharge shows epithelial cells (clue cells)
with tiny gram negative coccobacilli (suggest non
specific vaginitis).
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Treatment
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metronidazole.