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The genus Haemophilus contains organisms that are small, gram-negative cocco-bacilli.
The genus Haemophilus contains organisms that are small, gram-negative cocco-bacilli.
True
What is the most common type of Haemophilus organism?
What is the most common type of Haemophilus organism?
Haemophilus influenzae
All Haemophilus influenzae strains possess a capsule.
All Haemophilus influenzae strains possess a capsule.
False
What is the characteristic shape of Haemophilus influenzae?
What is the characteristic shape of Haemophilus influenzae?
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Haemophilus influenzae is an obligate anaerobe.
Haemophilus influenzae is an obligate anaerobe.
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What temperature range does Haemophilus influenzae prefer for growth?
What temperature range does Haemophilus influenzae prefer for growth?
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The capsule of Haemophilus influenzae is composed of protein.
The capsule of Haemophilus influenzae is composed of protein.
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Which of these serotypes for Haemophilus influenzae is considered the most virulent?
Which of these serotypes for Haemophilus influenzae is considered the most virulent?
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Haemophilus influenzae can enter the body through the gastrointestinal tract.
Haemophilus influenzae can enter the body through the gastrointestinal tract.
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Which of the following is NOT a behavior associated with Haemophilus influenzae?
Which of the following is NOT a behavior associated with Haemophilus influenzae?
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What does Haemophilus influenzae produce that neutralizes respiratory mucosal IgA?
What does Haemophilus influenzae produce that neutralizes respiratory mucosal IgA?
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Pili help Haemophilus influenzae attach to the respiratory mucosa.
Pili help Haemophilus influenzae attach to the respiratory mucosa.
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What can occur after Haemophilus influenzae attaches to the respiratory mucosa and enters the bloodstream?
What can occur after Haemophilus influenzae attaches to the respiratory mucosa and enters the bloodstream?
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The encapsulated forms of Haemophilus influenzae are responsible for the majority of severe infections.
The encapsulated forms of Haemophilus influenzae are responsible for the majority of severe infections.
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Non-encapsulated forms of Haemophilus influenzae are commonly associated with which infections?
Non-encapsulated forms of Haemophilus influenzae are commonly associated with which infections?
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The peak incidence of Haemophilus influenzae infections is in children between the ages of 6 months and 6 years.
The peak incidence of Haemophilus influenzae infections is in children between the ages of 6 months and 6 years.
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What are two key virulence factors associated with Haemophilus influenzae?
What are two key virulence factors associated with Haemophilus influenzae?
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Symptoms of Haemophilus influenzae meningitis are similar to those caused by meningococcal and pneumococcal meningitis, but with a slower onset.
Symptoms of Haemophilus influenzae meningitis are similar to those caused by meningococcal and pneumococcal meningitis, but with a slower onset.
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Otitis media and sinusitis caused by Haemophilus influenzae are characterized by a lack redness and swelling in the affected areas.
Otitis media and sinusitis caused by Haemophilus influenzae are characterized by a lack redness and swelling in the affected areas.
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Epiglottitis, a serious infection of the epiglottis, commonly occurs in older adults.
Epiglottitis, a serious infection of the epiglottis, commonly occurs in older adults.
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Pneumonia caused by Haemophilus influenzae is most prevalent in healthy young adults.
Pneumonia caused by Haemophilus influenzae is most prevalent in healthy young adults.
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What type of agar is used to cultivate Haemophilus influenzae?
What type of agar is used to cultivate Haemophilus influenzae?
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What two factors are found in chocolate agar that Haemophilus influenzae requires for growth?
What two factors are found in chocolate agar that Haemophilus influenzae requires for growth?
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All Haemophilus species require both Factor X and Factor V for growth.
All Haemophilus species require both Factor X and Factor V for growth.
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What is the appearance of Haemophilus influenzae colonies on chocolate agar?
What is the appearance of Haemophilus influenzae colonies on chocolate agar?
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What test is used for definitive diagnosis of encapsulated Haemophilus influenzae?
What test is used for definitive diagnosis of encapsulated Haemophilus influenzae?
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What drug is considered the first-line treatment for Haemophilus influenzae meningitis and other severe infections?
What drug is considered the first-line treatment for Haemophilus influenzae meningitis and other severe infections?
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What is the typical treatment for Haemophilus influenzae otitis media and sinusitis?
What is the typical treatment for Haemophilus influenzae otitis media and sinusitis?
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The Hib vaccine is a conjugated vaccine.
The Hib vaccine is a conjugated vaccine.
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What is the recommended age range for the Hib vaccine?
What is the recommended age range for the Hib vaccine?
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Conjugated vaccines are less effective than unconjugated vaccines.
Conjugated vaccines are less effective than unconjugated vaccines.
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What drug is given to close contacts of individuals with Haemophilus influenzae infections?
What drug is given to close contacts of individuals with Haemophilus influenzae infections?
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What is the most important causative agent for whooping cough?
What is the most important causative agent for whooping cough?
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Bordetella pertussis is a large bacterium.
Bordetella pertussis is a large bacterium.
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Bordetella pertussis is a gram-positive coccobacillus.
Bordetella pertussis is a gram-positive coccobacillus.
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Bordetella pertussis is a strict anaerobe.
Bordetella pertussis is a strict anaerobe.
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Bordetella pertussis easily survives for long periods outside the human respiratory tract.
Bordetella pertussis easily survives for long periods outside the human respiratory tract.
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Bordetella pertussis is oxidase and catalase negative.
Bordetella pertussis is oxidase and catalase negative.
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What protein is found in the pili of Bordetella pertussis?
What protein is found in the pili of Bordetella pertussis?
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Bordetella pertussis is spread through direct contact.
Bordetella pertussis is spread through direct contact.
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Whooping cough is a highly contagious disease.
Whooping cough is a highly contagious disease.
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Whooping cough is primarily a disease of adults.
Whooping cough is primarily a disease of adults.
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Bordetella pertussis does not directly invade cells.
Bordetella pertussis does not directly invade cells.
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What are the major virulence factors associated with Bordetella pertussis?
What are the major virulence factors associated with Bordetella pertussis?
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Pertussis toxin is a single antigen associated with tissue damage.
Pertussis toxin is a single antigen associated with tissue damage.
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The B subunit of pertussis toxin binds to receptors and allows entry of the whole toxin.
The B subunit of pertussis toxin binds to receptors and allows entry of the whole toxin.
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The A subunit of pertussis toxin inhibits adenylate cyclase.
The A subunit of pertussis toxin inhibits adenylate cyclase.
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Adenylate cyclase can inhibit the bactericidal activity of phagocytes.
Adenylate cyclase can inhibit the bactericidal activity of phagocytes.
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Tracheal cytotoxin is a component of the bacterial flagella.
Tracheal cytotoxin is a component of the bacterial flagella.
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Tracheal cytotoxin leads to an increase in nitric oxide production.
Tracheal cytotoxin leads to an increase in nitric oxide production.
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What is the type of inflammation affecting the upper respiratory tract that describes the early stage of whooping cough?
What is the type of inflammation affecting the upper respiratory tract that describes the early stage of whooping cough?
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The paroxysmal stage of whooping cough is characterized by a mild cough.
The paroxysmal stage of whooping cough is characterized by a mild cough.
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The convalescent stage of whooping cough typically resolves within a week.
The convalescent stage of whooping cough typically resolves within a week.
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Bordetella pertussis can be isolated from nasopharyngeal swabs.
Bordetella pertussis can be isolated from nasopharyngeal swabs.
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Direct fluorescent-antibody staining is not a reliable method for diagnosing Bordetella pertussis.
Direct fluorescent-antibody staining is not a reliable method for diagnosing Bordetella pertussis.
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Erythromycin is a common treatment for Bordetella pertussis.
Erythromycin is a common treatment for Bordetella pertussis.
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Prevention of whooping cough is primarily achieved through use of anti-viral medications.
Prevention of whooping cough is primarily achieved through use of anti-viral medications.
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Study Notes
Haemophilus Influenzae
- Haemophilus organisms are small gram-negative coccobacilli
- Haemophilus influenzae is the most common type
- Some strains have a capsule
- It is a gram-negative rod (coccobacillus)
- Facultative anaerobe, grows best in CO2-enriched media
- Temperature requirements 32-37 degrees Celsius
- Has a polysaccharide capsule
- Non-capsulated forms also exist
- Six serotypes (a, b, c, d, e, f)
- Serotype b is the most virulent type
- Enters the body via the respiratory tract
- Two types of behaviours: asymptomatic colonization and infections (e.g., sinusitis, otitis media, pneumonia)
- Produces IgA protease which neutralizes respiratory mucosal IgA
- Pili help in attachment to respiratory mucosa
- Can enter the bloodstream and cause bacteremia and meningitis
- 95% of encapsulated forms (type b) responsible for these diseases
- Non-capsulated forms cause otitis media, sinusitis, and pneumonia
- Children 6 months to 6 years are most prone to infection
- Peak incidence is 6 months to 1 year
- Virulence factors are the polysaccharide capsule and endotoxin
- Meningitis similar to meningococcal and pneumococcal, but onset of symptoms including drowsiness is rapid
- Otitis media and sinusitis cause pain, redness, and bulging of the tympanic membrane
- Other complications include septic arthritis, cellulitis, sepsis, and rarely epiglottitis in young children. Pneumonia in elderly, especially those with chronic respiratory disease
- Diagnosed by Gram staining and grown on chocolate agar (enriched with factors X and V)
- Colonies are greyish-white, small, and mucoid
- Definitive diagnosis with Quellung test
Bordetella Pertussis
- The genus Bordetella contains seven species
- Bordetella pertussis is the causative agent of whooping cough
- Other important species include Bordetella parapertussis and Bordetella bronchiseptica
- A tiny (0.5 to 1.0 µm), gram-negative cocco-bacillary rod
- Encapsulated
- Obligate aerobe
- Very susceptible to environmental changes, survives a short time outside the human respiratory tract
- Oxidase and catalase positive
- Pili of cell wall contain filamentous haemagglutinin (fha)
- Spreads via droplets produced by patients in the early stages of illness
- Highly contagious, infecting 80-100% of exposed susceptible persons
- Strict human pathogen, primarily a disease of infants and children
- Attaches to respiratory mucosa with filamentous haemagglutinin (fha)
- Bacteria immobilize cilia and progressively destroy ciliated cells
- Doesn't directly invade or spread to deeper tissues, but produces toxins:
- Pertussis toxin (exotoxin): single antigen, causes local tissue damage associated with inflammation
- B subunit binds to cell receptors, "unlocks" cell entry of A subunit
- A subunit activates adenylate cyclase, inhibiting phagocytosis
- Extra-cytoplasmic adenylate cyclase; the enzyme inhibits phagocytic cells
- Tracheal cytotoxin is a bacterial peptidoglycan fragment that damages ciliated cells
- Pertussis toxin (exotoxin): single antigen, causes local tissue damage associated with inflammation
- Tracheal cytotoxin and endotoxin cause nitric oxide to kill ciliated epithelial cells
- Whooping cough is an acute tracheobronchitis, starts with mild upper respiratory symptoms, followed by severe paroxysmal cough, lasting 1-4 weeks
- Occurs in three distinct stages:
- Catarrhal stage: mild upper respiratory infection
- Paroxysmal stage: extends to lower respiratory tract, severe cough
- Convalescent stage: less severe cough, may persist months
- Diagnosed by Gram staining, isolating from nasopharyngeal swabs during paroxysmal stage, using Bordet-Gengou or Regan-Lowe medium for culture, and direct fluorescent-antibody staining or polymerase chain reaction
- Treated with erythromycin to reduce organisms in the throat and decrease risk of complications
- Prevented by vaccination
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Description
This quiz covers key information about Haemophilus influenzae, including its characteristics, pathogenic behavior, and types of infections it causes. Dive into details about its serotypes, growth conditions, and the populations most affected by this organism.
