h.influenzae modified 2012

7/31/2019 H.influenzae Modified 2012

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HaemophilusHaemophilus

--Small pleomorphic gramSmall pleomorphic gram vevecoccobacilli or rodscoccobacilli or rods..

--Non-motileNon-motile..

--Require X factor or V factor orRequire X factor or V factor orbothboth..

--The genus includes the followingThe genus includes the following

speciesspecies::H. influenzae, H. aegyptius, H.H. influenzae, H. aegyptius, H.

haemolyticushaemolyticus,,

H. suis, H. parainfluenzae, H.H. suis, H. parainfluenzae, H.


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Haemophilus influenzaeHaemophilus influenzae

HabitatHabitat::--Non capsulated types:Non capsulated types: normalnormal

commensals in URT of mancommensals in URT of man..

--Capsulated types:Capsulated types: less frequentless frequent.. MorphologyMorphology::

--Small gramSmall gram ve rods and coccobacillive rods and coccobacilli..

--Show pleomorphismShow pleomorphism..--Capsules may be present (recentlyCapsules may be present (recently

isolated, young culturesisolated, young cultures(.(.


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Morphology of H. influenzaeMorphology of H. influenzae


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Cultural charactersCultural characters::--Aerobes and facultative anaerobesAerobes and facultative anaerobes..

--Optimum temperature: 37COptimum temperature: 37C..

--Cannot grow on ordinary mediaCannot grow on ordinary media..

--RequiresRequiresboth X and Vboth X and Vfactorsfactors..

11--X factor:X factor: HaeminHaemin.. 22--V factor:V factor: NADNAD--Growth is better onGrowth is better on chocolate agarchocolate agar oror

better onbetter on chocolate with Isovitalexchocolate with Isovitalex(NAD, and other growth factors (glucose,(NAD, and other growth factors (glucose,

glutamine, adenine , guanine, cystine,glutamine, adenine , guanine, cystine,cysteine, vit Bcysteine, vit B1212, thiamine, co-carboxylase, thiamine, co-carboxylasepara-amino benzoic acid and ferric nitratepara-amino benzoic acid and ferric nitrate(.(.


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Colonies of H. influenzae onColonies of H. influenzae on

chocolate agarchocolate agar


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Satellitism:Satellitism:Colonies of H. influenzae growing nearColonies of H. influenzae growing near

those of Staph. Aureus (which producethose of Staph. Aureus (which produceV factor) are largerV factor) are larger..


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Antigenic structureAntigenic structure::--Non-capsulate strains: antigenicallyNon-capsulate strains: antigenically

heterogeneousheterogeneous..

-Capsulated strainsCapsulated strains::-66serological types (a,b,c,d,e,f)serological types (a,b,c,d,e,f)

according to capsularaccording to capsular

polysaccharidepolysaccharide..The capsular Ag isThe capsular Ag isantiphagocyticantiphagocytic..

Type b capsule is the majorType b capsule is the majorvirulence Agvirulence Ag..


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Respiratory Tract DiseasesRespiratory Tract Diseases

caused by H. influenzaecaused by H. influenzae11--Acute epiglottitis:Acute epiglottitis: (type b)(type b) , mainly in, mainly in

childrenchildren,,

sometimes in adultssometimes in adults..

22--Pneumonia in adults with old age,Pneumonia in adults with old age,

chronic lung disease, alcoholism,chronic lung disease, alcoholism,immunodeficiency, sometimes inimmunodeficiency, sometimes in

healthy adultshealthy adults..

33--Otitis media: 10% by type b , 90% byOtitis media: 10% by type b , 90% by

non-typable strainsnon-typable strains..

--The non-typable strains can causeThe non-typable strains can cause::

a) Acute sinusitis in adultsa) Acute sinusitis in adults..

b) Exacerbations of chronic bronchitis,b) Exacerbations of chronic bronchitis,


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Laboratory diagnosisLaboratory diagnosis

Specimens:Specimens: Nasopharyngeal swabs,Nasopharyngeal swabs,

pus, blood, CSFpus, blood, CSF..

Smears:Smears:

Gram stain can detectGram stain can detect

organism if present in large numbersorganism if present in large numbers

Culture:Culture: On chocolate agar +On chocolate agar +

isovitalexisovitalex..

Suspected colonies are tested for X, V,Suspected colonies are tested for X, V,X +V factors on a ar lates.


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Testing for X and V requirement:Testing for X and V requirement:

Colonies of H. influenzae occur onlyColonies of H. influenzae occur only

where both X and V factors havewhere both X and V factors have

diffuseddiffused..


11/12

TreatmentTreatment::

---Many type b strains areMany type b strains are

susceptible to ampicillin, 25%susceptible to ampicillin, 25%may be resistant ( produce betamay be resistant ( produce beta

lactamase plasmid mediatedlactamase plasmid mediated(.(.

---All strains are susceptible toAll strains are susceptible to

new cephalosporinsnew cephalosporins

))cefotaxime I.Vcefotaxime I.V.(.(


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PreventionPrevention::VaccineVaccine::A conjugate vaccine for H. influenzae type bA conjugate vaccine for H. influenzae type b::

It is made of H.influenzae type bIt is made of H.influenzae type bpolysaccharidepolysaccharide

Conjugated with protein carrierConjugated with protein carrier

mutant Corynebacterium diphtheria toxinmutant Corynebacterium diphtheria toxin

protein orprotein orwith diphtheria toxoidwith diphtheria toxoid..

ChemoprophylaxisChemoprophylaxis::Non-immune children less than 4y whoNon-immune children less than 4y who

were close contacts should receive rifampinwere close contacts should receive rifampin..

h.influenzae modified 2012

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