Tag: Haemophilus influenzae

Haemophilus influenzae

Haemophilus influenzae

Q. 1

Which of the following is not permeable through the Blood Brain Barrier?

 A

Water

 B

Lipophilic drugs

 C

Gas

 D

Proteins

Q. 1

Which of the following is not permeable through the Blood Brain Barrier?

 A

Water

 B

Lipophilic drugs

 C

Gas

 D

Proteins

Ans. D

Explanation:

Proteins [Ref. Guyton 11/e p766; Ganong 23/e p572.1

Blood brain barrier:

  • is highly permeable to

– water

– carbon dioxide

– oxygen

– most lipid-soluble substances such as alcohol and anaesthetics

  • is slightly permeable to

– electrolytes such as sodium, chloride and potassium

  • is totally impermeable to

– plasma proteins

– non-lipid soluble large organic molecules

Cause of blood brain barrier: The reason for the low permeability of the blood-brain barriers is the presence of tight junctions in between the endothelial cells of the brain capillaries. That is, the membranes of the adjacent endothelial cells are tightly fused rather than having large slit-pores between them, as is the case for most other capillaries of the body.

Also Know:

  • Circumventricular organs
  • They are named so as they are positioned around the margins of the ventricular system of the brain.
  • Circumventricular organs are a group of areas of the brain which lie outside the blood brain barrier.
  • Importance of being outside the blood brain barrier is that they have sensory receptors that respond to specific changes in the body fluids, such as changes in osmolality and in glucose concentration, as well as receptors for peptide hormones that regulate thirst, such as angiotensin II.
  • Circumventricular organs include the following:
  • Subfornicial organ
  • Organurn vasculosum of the lamina terminalis
  • Median eminence
  • Posterior pituitary(neurohypophysis)
  • Subcommissural organ
  • Pineal gland
  • Area postrema

Q. 2

A child presented with otitis media. The suspected organism is Hemophilus influenzae. All are TRUE about H. influenzae, EXCEPT:

 A

Requires Factors X and V for growth

 B

In CNS, mostly causes meningitis

 C

Outer membrane protein plays important role in pathogenesis in type ‘b’ H. influenzae

 D

Not a common cause for meningitis in less than 2 months of life

Q. 2

A child presented with otitis media. The suspected organism is Hemophilus influenzae. All are TRUE about H. influenzae, EXCEPT:

 A

Requires Factors X and V for growth

 B

In CNS, mostly causes meningitis

 C

Outer membrane protein plays important role in pathogenesis in type ‘b’ H. influenzae

 D

Not a common cause for meningitis in less than 2 months of life

Ans. C

Explanation:

  • The polyribose phosphate capsule of type b H influenzae is the major virulence factor.
  • H influenzae was the most common cause of bacterial meningitis in children age 5 months to 5 years.
  • H influenzae is differentiated from related gram-negative bacilli by its requirements for X and V factors and by its lack of hemolysis on blood agar.

Also know:

  • H influenzae does not grow on sheep blood agar except around colonies of staphylococci (“satellite phenomenon”).
  • H influenzae does not produce exotoxin.

Ref: Brooks G.F., Carroll K.C., Butel J.S., Morse S.A., Mietzneron T.A. (2010). Chapter 18. Haemophilus, Bordetella, Brucella, & Francisella. In G.F. Brooks, K.C. Carroll, J.S. Butel, S.A. Morse, T.A. Mietzneron (Eds), Jawetz, Melnick, & Adelberg’s Medical Microbiology, 25e.


Q. 3

Which among the following is NOT TRUE about H. influenzae?

 A

Requires factor X and V for growth

 B

Rarely presents as meningitis in children less than 2 months of age

 C

Capsular polypeptide protein is responsible for virulence

 D

M.C invasive disease of H influenza is meningitis

Q. 3

Which among the following is NOT TRUE about H. influenzae?

 A

Requires factor X and V for growth

 B

Rarely presents as meningitis in children less than 2 months of age

 C

Capsular polypeptide protein is responsible for virulence

 D

M.C invasive disease of H influenza is meningitis

Ans. C

Explanation:

H.influenzae is a small gram negative, non motile, non sporing bacilli. The accessory growth factors named X & Y present in blood are essential for growth.

Factor X(hemin) —> It is required for synthesis of cytochrome. Factor V (NAD) – It is essential for oxidation de adenine dinucleotide reduction.

There are 3 main antigens:capsular polysaccharide, outer membrane protein, lipooligosaccharide.

Influenzae does not secrete any exotoxins, the polysaccharide capsule is considered to be the major factor in virulence.

There are “6” types of capsule designated a, b, c, d, e and f of these type “b” is commonly associated with invasive Haemophilus influenzae disease in children. The capsular PRP antigen of Hib induces IgA,  IgM, IgA antibodies which are bactericidal, opsonic & protective.

Diseases caused by H.influenzae are: meningitis, laryngo epiglottitis, pneumonia, suppurative lesions, bronchitis.
 
Do You Know:
 
HACEK group bacteria – Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens & Kingella kingae.
 
Ref: Ananthanarayanan & Paniker’s textbook of microbiology Ed 8Th pg – 331.

Quiz In Between


Q. 4

The major antigenic determinant of H.influenzae is‑

 A

‘IVY protein

 B

Capsular polysaccharide

 C

Catalase

 D

Coagulase

Q. 4

The major antigenic determinant of H.influenzae is‑

 A

‘IVY protein

 B

Capsular polysaccharide

 C

Catalase

 D

Coagulase

Ans. B

Explanation:

Ans. is `b’ i.e., Capsular polysaccharide 


Q. 5

All of the following are true regarding Haemophilus influenzae except –

 A

It can be a part of the normal flora in some persons

 B

The serotyping is based on the bacterial outer membrane porteins

 C

It requires Haemin and NAD for growth in culture medium

 D

Type b is responsible for invasive disease

Q. 5

All of the following are true regarding Haemophilus influenzae except –

 A

It can be a part of the normal flora in some persons

 B

The serotyping is based on the bacterial outer membrane porteins

 C

It requires Haemin and NAD for growth in culture medium

 D

Type b is responsible for invasive disease

Ans. B

Explanation:

Ans. is ‘b’ i.e., The serotyping is based on the bacterial outer membrane protein

.  The major antigenic determinant of capsulated strains is the capsular polysaccharide based on which H. influenzae strains have been classified into six capsular types – types a to f.

.  H. influenzae strains lacking a capsule can not be typed and are called non typable strains.

About other options

Option ‘a’

“Non typable strains colonize the upper respiratory tract of up to three-fourth of healthy adults”

Option `b’

The accessory growth factors, named X and V present in blood are essential for growth.

.  The X-factor is hem in or other porphyrins required for the synthesis of cytochrome and other heme enzyme such as catalase and peroxidase involved in aerobic respiration.

The V factor is a coenzyme, nicotinamide adenine dinucleotide (NAD) or (NADP) which acts as a hydrogen acceptor in the metabolism of the cell.

Option

. Diseases due to H. influenzae may be considered under two groups invasive and noninvasive diseases.

.  Group ‘b’ (Hib) accounts for 95% cases of invasive disease.



Q. 6

Rhinitis most common bacterial cause ‑

 A

Haemophilus influenza

 B

Streptococcus haemolyticus

 C

Pasturellamultocida

 D

Cornybacterium diphtheria

Q. 6

Rhinitis most common bacterial cause ‑

 A

Haemophilus influenza

 B

Streptococcus haemolyticus

 C

Pasturellamultocida

 D

Cornybacterium diphtheria

Ans. A

Explanation:

Ans. is ‘a’ i.e., Haemophilus influenza

Acute bacterial rhinitis is most commonly seen among children, but adult may develop the condition after nasal trauma, viral upper respiratory tract infection, or surgery.

  • The clinical presentation of acute bacterial rhinitis may be identical to that of common cold.
  • Most common causative organisms include S. pneumoniae, H. influenzae and Moraxella Catarrhalis.

Note: Overall, most common cause of infective rhinitis is viral infection (viral rhinitis).

Quiz In Between


Q. 7

Which among the following is NOT TRUE about the organism marked by a black arrow in the photomicrograph below? 

 A

Requires factor X and V for growth.

 B

Rarely presents as meningitis in children less than 2 months of age.

 C

Capsular polypeptide protein is responsible for virulence.

 D

M.C invasive disease of H influenza is meningitis.

Q. 7

Which among the following is NOT TRUE about the organism marked by a black arrow in the photomicrograph below? 

 A

Requires factor X and V for growth.

 B

Rarely presents as meningitis in children less than 2 months of age.

 C

Capsular polypeptide protein is responsible for virulence.

 D

M.C invasive disease of H influenza is meningitis.

Ans. C

Explanation:

The organism shown in the photomicrograph above represents H. influenzae.

H.influenzae is a small gram negative, non motile, non sporing bacilli. The accessory growth factors named X & Y present in blood are essential for growth.

Factor X(hemin) —> It is required for synthesis of cytochrome. Factor V (NAD) – It is essential for oxidation de adenine dinucleotide reduction.

There are 3 main antigens:capsular polysaccharide, outer membrane protein, lipooligosaccharide.

Influenzae does not secrete any exotoxins, the polysaccharide capsule is considered to be the major factor in virulence.

There are “6” types of capsule designated a, b, c, d, e and f of these type “b” is commonly associated with invasive Haemophilus influenzae disease in children. The capsular PRP antigen of Hib induces IgA,  IgM, IgA antibodies which are bactericidal, opsonic & protective.

Diseases caused by H.influenzae are: meningitis, laryngo epiglottitis, pneumonia, suppurative lesions, bronchitis.
 



Q. 8

A 5 year old boy presented with sudden onset of  fever, dysphagia, drooling, muffled voice, inspiratory retractions, cyanosis and soft stridor.On X ray of neck,the following is seen.Which is the most common causative organism of this condition?

 A

Staphylococcus aureus.

 B

H influenza.

 C

Streptococcus.

 D

Pseudomonas.

Q. 8

A 5 year old boy presented with sudden onset of  fever, dysphagia, drooling, muffled voice, inspiratory retractions, cyanosis and soft stridor.On X ray of neck,the following is seen.Which is the most common causative organism of this condition?

 A

Staphylococcus aureus.

 B

H influenza.

 C

Streptococcus.

 D

Pseudomonas.

Ans. B

Explanation:

Ans;B.)H.influenza.

The condition shown in the X-ray above represents Acute Epiglottitis.

Enlarged epiglottis in epiglottitis is stubby like thumb instead of its usual thin finger projection.(Thumb Sign)

ACUTE EPIGLOTTITS

  • It is an acute inflammation of epiglottis with inflammatory edema of hypopharynx.
  • H.influenzae Influenza Type B  is the most common causative organism.
  • Other organisms are – Pneumococci, Streptococcus pyogenes, N.meningitidis, Staphylococcus.

CLINICAL FEATURES OF EPIGLOTTITIS

  • Onset is sudden.
  • Most common in 2 to 7 years of age.
  • Symptoms are fever, dysphagia, drooling, muffled voice, inspiratory retractions, cyanosis and soft stridor.
  • Patients often sit in sniffing dog position.
  • Complications:
    • The main complication is death from respiratory arrest due to acute airway obstruction.
    • Other complications are rare but include epiglottic abscess, pulmonary edema secondary to relieving airway obstruction and thrombosis of internal jugular vein (Lemierre’s syndrome)

DIAGNOSIS AND TREATMENT OF EPIGLOTTITIS

  • Laryngoscopy-“Cherry red” swollen epiglottis is seen.
    • Acute Laryngeal Spasm may occur during Indirect Laryngoscopy.
  • Radiograph – Culture of blood and secretions covering Epiglottis
    •  A plain lateral soft tissue radiograph of neck shows the following specific features
      • Thickening of the epiglottis—the thumb sign
      • Absence of a deep well-defined vallecula—the vallecula sign
  • Treatment
    • Immediate endotracheal intubation.
    • IV antibiotics to cover H.influenzae.
      • The antibiotic of choice in acute epiglottitis pending culture sensitivity report is Ampicillin or 3rd generation Cephalosporin like Ceftriaxone.

Q. 9

Infection by which organism is seen after surgical removal of the organ shown in the image by ‘A’?

 A

 Staphylococcus aureus

 B

 E. coli 

 C

Hemophilus influenzae 

 D

Klebsiella pneumoniae

Q. 9

Infection by which organism is seen after surgical removal of the organ shown in the image by ‘A’?

 A

 Staphylococcus aureus

 B

 E. coli 

 C

Hemophilus influenzae 

 D

Klebsiella pneumoniae

Ans. C

Explanation:

Ans:C.) Hemophilus influenzae

Spleen is shown in the image marked by ‘A’

  • An overwhelming post-splenectomy infection (OPSI) is a rare but rapidly fatal infection occurring in individuals following removal of the spleen.
  • The infections are typically characterized by either meningitis or sepsis, and are caused by encapsulated organisms: Streptococcus pneumoniae, Salmonella typhi, Neisseria meningitidis, E. coli, Hemophilus influenzae, Streptococcus agalactiae, Klebsiella pneumoniae).
  • Vaccination for pneumococcus, H. influenza and meningococcus should be given pre-operatively if possible to minimize the chance of overwhelming post-splenectomy infection 

Quiz In Between



Haemophilus influenzae

Haemophilus influenzae


Habitat

  • Mucous membrane of the upper respiratory tract of humans.
  • Found in the nasopharynx of approx. 75% of healthy peoples.

Morphology

  • Slender, short, gram-negative rods or coccobacillus
  • Non-Motile, No flagella or pilli
  • Capsules are present and important in pathogenicity.
  • Encapsulated form are coccobacilli.
  • Non-Capsulated are pleomorphic, long, thread, filamentous
  • Fastidious Microorganism
  • It is the first free-living organisms to have its entire genome sequenced; 1,830,140 bp of DNA and 1740 Genes.

Cultural characteristics

Culture

Characteristics

On Blood Agar

  • Translucent, low, convex or flat pinpoint colonies
  • Satellitism

On Chocolate Agar

  • Grayish, Transparent, smooth, low, convex or flat with a slightly splayed out, entire edge, mucoid, pale

Levinthal’s Broth or Filde’s Broth

  • Uniform Turbidi
  •  Facultative anaerobes and aerobic, grow also in 5% CO2.
  • Optimum Temperature: 35-37oC, Min: 20-25oC, Optimum pH: 7.6
  • Killed at 55oC for 30 minutes of heating
  • Fastidious,requires 2 accessory growth factors:
    • X-Factor
    • V-Factor

X-Factor(Hemin)

  • A head stable growth promoting substances present in Red Blood Cells 
  • Hemin, plays a role as an enzyme in respiration.

V-Factor(NAD)

  • A heat labile vitamin like substances.
  • V-Factor is involved in oxidation-reduction process in the growing bacterial cell.
  • Heating blood agar to about 75oC, until it acquires a chocolate agar, releases V-Factor from Red cells and also inactivates NADase activity.
  • Satellitism
    • On blood agar colonies of S Aureus release V-Factor during growth
    • Which defuses into the surrounding medium
    • Enhancing the growth of H. influenzae.
  • Influenzae requires pantothenic acid, thiamine and uracil.

Biochemical reaction

Test

Reaction

Catalase

+

Oxidase

+

Haemolysis

Fermentation:

Glucose 

 

+

Fructose

Galactose

+

Lactose

Mannose

Sucrose

Trehalose

Xylose

+

Antigenic Properties 

  • Capsular polysaccharide
    • Major antigenic determinant
    • based on which, it is typed into six capsular types a to f 
    • While noncapsulated strains are nontypable
    • Isolates from acute invasive infections belong to ‘b” mainly.
    • Type b capsule has unique structure containing pentose sugar (ribose and ribitol) in the form of Polyribosyl ribitol phosphate (PRP)
    •  Hib PRP is used in vaccine
  • Outer membrane protein (OMP)
  • Lipo-oligosaccharide
  • Serotyping of H. influenzae ie done by agglutination or quelling reaction 

Mechanism

Encapsulated organisms → penetrate the epithelium of the nasopharynx → invade the blood capillaries → infection. 

  • Capsule resists phagocytosis and complement-mediated lysis.
  • Maybe opportunistic
  • Transmitted by direct contact, inhalation of the respiratory tract droplets.

Pathogenicity

Haemophilus influenza b (Hib)

  • Major cause of childhood infectious disease.
  • Meningitis: 
    • M.C invasive disease of H influenza
    • children age 5 months to 5 years.
    • MC Complication of its meningitis – Subdural effusion
  • Primary bacteremia
  • Post-splenectomy infection(rare)
  • Pneumonia
  • Acute epiglottitis
  • Arthritis.
  • Acute bacterial rhinitis:
    • MC cause of bacterial rhinitis

Non-Capsulated influenzae (Nc-hi) 

  • Causes otitis media, conjunctivitis and sinusitis
  • Causes chronic bronchitis in adults

Diagnosis

  • Meningitis
    • CSF gram’s stain and culture on iso Vitale X-enriched chocolate agar
    • If culture negative – Detection of PRP
  • Respiratory tract infection
    • Suggested by the predominance of gram-negative coccobacilli among abundant polymorphonuclear leukocytes in sputum.

Treatment

  • DOC for H. influenzae meningitis is –> Third generation cephalosporin.
  • Ceftriaxone or cefotaxime
  • Also in other invasive infection

Vaccination

  • Hib conjugate vaccine
  • First dose: 2 months
  • Rest of primary series: 2-6 months
  • Booster Dose: 12-15 months

Exam Important

Habitat

  • Mucous membrane of the upper respiratory tract of humans.

Morphology

  • Slender, short, gram-negative rods or coccobacillus
  • Capsules are present and important in pathogenicity.

Cultural characteristics

  • Requires 2 accessory growth factors:
    • A head stable growth promoting substances present in Red Blood Cells (X-Factor) 
    • A heat labile vitamin like substances (V-Factor).

Antigenic Properties  

  • Major surface antigen
  1. Capsular polysaccharideOuter membrane protein (OMP)
    • Major antigenic determinant
    • Based on which, it is typed into six capsular types a to f 
    • While noncapsulated strains are nontypable
    • Isolates from acute invasive infections belong to ‘b” mainly.
  2. Lipo-oligosaccharide
  • Serotyping of H. influenzae ie done by agglutination or quelling reaction 

Pathogenicity

Haemophilus influenza b (Hib)

  • Major cause of childhood infectious disease.
  • Meningitis: Primary bacteremia
    • M.C invasive disease of H influenza
    • children age 5 months to 5 years.
    • MC Complication of its meningitis – Subdural effusion
  • Post-splenectomy infection(rare)
  • Pneumonia
  • Acute epiglottitis
  • Arthritis.
  • Acute bacterial rhinitis:
    • MC cause of bacterial rhinitis

Non-Capsulated influenzae (Nc-hi) 

  • Causes otitis media, conjunctivitis and sinusitis
  • Causes chronic bronchitis in adults

Treatment

  • DOC for H. influenzae meningitis Cs –> Third generation cephalosporin.
  • Ceftriaxone or cefotaxime

 

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