Haemophilus Influenza Flashcards
Is Haemophilus influenza gram positive or negative?
Haemophilus inlfuenza = GRAM NEGATIVE
> think peptidoglycan layer
do not take purple stain
safranin pink dye
Where does haemophilus influenza normally colonise?
Respiratory tract
What are the 2 major categories for Haemophilus influenza?
> ENCAPSULATED = 6 sera types
- A B C D E F
- Haemophilus influenza B - most common to cause human infection
> UNCAPSULATED = nontypable as it does not contain the polysaccharide capsule
-most common to cause human infection
Why strain of haemophilus influenza is most common to cause human infection?
Haemophilus influenza ENCAPSULATED sera type B
and
Haemophilic influenza uncapsulated NONTYPABLE
What is the shape of haemophilus influenza?
COCCOBACILLUS
> COCOUS (round)
BACILLUS (linear)
Is haemophilus influenza motile or non motile?
Non-motile
Is haemophilus influenza catalase positive OR negative?
haemophilus influenza is CATALSE POSITIVE
> destroys H2O2 produced by phagosome and able to survive inside neutrophils
Is haemophilus influenza oxidase positive or negative?
haemophilus influenza is OXIDASE POSITIVE
What type of anaerobes?
FACULTATIVE ANAERBOES
> grow best in media enriched with CO2
> can survive in aerobic and anaerobic
What culture mediums are used for haemophilus influenza?
1)chocolate agar: containing (help with growth)
> factor X (hemin)
> factor V (nicotiamide adenine nucleotide)
2)blood agar: along with staphylococcus aureus species
>provides factor 5 via RBC hemolysis
Explain how chocolate agar helps to grow haemophilus influenza
Chocolate agar:
>factor X (hemin)
>factor V (nicotinamide adenine nucleotide)
Explain how blood agar help to grow haemophilus influenza
Blood agar: cultured with staphylococcus aureus
> provides factor 5 via RBC hemolysis
Describe the colonise formed in chocolate and blood agar for haemophilus influenza
> convex
smooth
grey or transparent colonies
How does the capsule of homophilus influenza act as a virulence factor?
Capsule - polysaccharide layer
> contain pili to attach to host cell surface
>also contain ADHESION PROTEINS - HMW1 + HMW2 (also help with attachment to host surface)
What is the function of the lipooligosacharide (LPS) found in the outer-membrane of homophilus influenza?
> inhibits mucocillary clearance
mucus not able to clear out the foreign bacterias
h.influenza can now colonise the respiratory tract as it won’t get cleared
Which Ig protease is secreted by the hemophilus influenza and what is the function?
hemophilus influenza secretes:
>IgA proteases which destroys IgA produced by host immune system (mainly found in nasopharyngeal mucosa and opsonises any invading bacteria)
IgA PROTEASES NEUTRALISES FIRST LINE OF MUCOSAL DEFENCE IN NASOPHARYNX
Outline the virulence factors of encapsulated h.influneza
1) VARIATION PHASE:
>ability to change to ooligosacharide so the immune cell are no longer able to recognise and produce a fast response
2) BIOFILMS
>sticky layer made of EXPOLLYSACHARIDES - bacteria hides from host IS + antibiotics
What other invasive diseases does ENCAPSULATED H.influenza cause?
From Nasopharynx:
> can reach EPIGLOTTIS = EPIGLOTITIS
> can reach face soft tissues = CELLULITIS
> from nasopharynx epithelium - can enter blood = BACTEREMIA
»_space; MENINGTIS
»_space; OSTEOMYLITIS
»_space; SEPTIC ARTHRITIS
Once H.influenze is in the blood (bacterimia) - what other diseases can it cause?
> SEPTIC ARTHRITIS (joints)
> MENINGITIS (meninges in brain)
> OSTEOMYLETISI (bone)
Which H.infuluenze is more invasive causing more disease?
ENCAPSULATED OR UNCAPSULATED?
ENCAPSULATED:
- epiglotitis
- celulitis
- bacterimia (meningitis, osteomyelitis, septic arthritis)
What less invasive diseases does UNCAPSULATED H.influenza cause?
FROM NASOPHARYNX:
> can enter eustachian tube - OTITIDIS
> can enter respiratory tract - BRONCHITIS
> can enter nasal sinuses - SINUSITIS
How is H.influenza transmitted?
> respiratory droplets
> respiratory secretions
Which type of encapsulated H.infulenza is the most dangerous?
H.influenza encapsulated TYPE B
Who is most at risk for H.influenza encapsulated TYPE B?
> children
> P with SPLEEN ISSUES: sick cell diseases + splenectomy
> malignancies
> congenital deficiencies of complement components
> acute viral infections
Who is at most risk for untypable uncapsulated H.influenza?
> children
> immunecomprising conditions
- HIV
- DIABTES
- MALIGNANCY
- VIRAL INFECTIONS
> COPD
What biological samples can be taken for diagnosis of H.influenza?
> BLOOD
> CSF
> SYNOVIAL FLUID
> PLEURAL FLUID
> SINUS FLUID
What serological methods can be carried out to detect Ab against h.influenza?
> Latex agglutination
> Enzyme immunoassay
> Coagglutination
How is H.influenza type B - causing meningitis treated?
> Ceftriaxone
> Chloramphenicol
How are the nontypable infection caused by H.influenza treated?
MUCOSAL INFECTION:
> AMOXICILLIN with or without clavulanante
> 3rd generation of cephalosporins
macrolides
fluroquinolones
What vaccine is available for H.influenza type B
HIB VACCINE:
»Vaccine containing type B capsular polysaccharide conjugated with diphtheria toxoid
> give for 2-18months olds
MAINLY TO PREVENT MENINGITIS ; as it is more common in unimmunised children
What treatment is given to those in contact with H.influenza type B children ?
RIFAMPICIN
> CHEMOPROPHYLAXYS by using RIFAMPICIN
What other species are under Hemophilus?
H. influenza (most common one)
H. ducreyi
H. parainfluenziae
H. aegyptius
What are the virulence factors of Hemophilus influenza?
> polysaccharide capsule
> endotoxins
What is the quellung test? Why is this test done?
Specific Ab interaction with capsule pollysacharide
>causing capsular swelling and visible under microscopy
Definitive diagnosis for h.influenza
What is the treatment for Otitidis and Sinusitis by H.influenza?
COAMOXICLAY
