Microbiology Quiz on Brucella and Hemophilus

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Questions and Answers

Which of the following statements regarding the growth of Brucella is accurate?

Brucella can ferment carbohydrates for energy.

Brucella requires enriched blood agar for growth. (correct)

Brucella grows in anaerobic conditions.

Brucella has a rapid growth rate of less than 24 hours.

What is the primary virulence factor of Brucella that aids in its pathogenesis?

Evading toll-like receptors and surviving intracellularly. (correct)

Resistant to antibacterial treatments.

Rapid replication in extracellular environments.

Inducing severe inflammation in host tissues.

Which of the following is NOT a symptom associated with acute brucellosis?

Myalgia

Chills

Coughing (correct)

Weight loss

How does Brucella abortus enhance its survival within host cells?

By inhibiting apoptosis and prolonging host cell life. Signup and view all the answers

Which diagnostic method is employed to confirm a Brucella infection?

Plate agglutination test. Signup and view all the answers

What is the primary factor in the cultivation of Hemophilus influenzae?

X factor – hematin Signup and view all the answers

What is the size range of Hemophilus influenzae?

1.0-1.5 µm Signup and view all the answers

Which of the following statements about the serotypes of Hemophilus influenzae is true?

Type b capsule contains polyribose-ribitol phosphate Signup and view all the answers

What was Hemophilus influenzae mistakenly thought to be responsible for until 1933?

Influenza Signup and view all the answers

Which characteristic is not true of Hemophilus influenzae?

It is motile Signup and view all the answers

Which mode of transmission is associated with Hemophilus influenzae?

Respiratory droplets Signup and view all the answers

What type of bacteria are Hemophilus influenzae classified as?

Gram-negative rods Signup and view all the answers

Which condition is associated with increased risk for invasive H influenzae disease?

Asplenia Signup and view all the answers

What is the primary culture medium used for identifying H influenzae?

Chocolate agar Signup and view all the answers

Which factor is essential for the growth of H influenzae when cultured?

X factor (hematin) Signup and view all the answers

How is Haemophilus ducreyi primarily transmitted?

Sexual contact Signup and view all the answers

What is a key characteristic of the ulcers caused by Haemophilus ducreyi?

Deeply necrotizing and painful Signup and view all the answers

What is the typical antibiotic treatment for chancroid?

Ceftriaxone Signup and view all the answers

Which organism is strictly a human pathogen and is transmitted via aerosolized droplets?

Bordetella pertussis Signup and view all the answers

What is the incubation period for Haemophilus ducreyi infection?

1 day to 2 weeks Signup and view all the answers

What is a common misconception about diagnosing chancroid?

It requires a blood test for confirmation Signup and view all the answers

What is a noted consequence of untreated large lymph node swellings caused by Haemophilus ducreyi?

Necrosis requiring surgical intervention Signup and view all the answers

Which species of Brucella is primarily associated with high pathogenicity for humans and commonly found in sheep and goats?

B.melitensis Signup and view all the answers

Which of the following statements about Brucella spp. is incorrect?

They are non-aerobic organisms. Signup and view all the answers

What is the primary method of human infection with Brucella spp.?

Ingestion of contaminated dairy products Signup and view all the answers

Which of the following Brucella species primarily infects dogs?

B.canis Signup and view all the answers

Brucella spp. are classified as which type of bacteria?

Gram-negative coccobacilli Signup and view all the answers

Which species of Brucella is recognized for moderate pathogenicity in humans?

B.abortus Signup and view all the answers

Which of the following is NOT a reservoir for any Brucella species?

Cats Signup and view all the answers

What makes Brucella spp. a significant concern in laboratory settings?

They can be transmitted via inhalation of contaminated aerosols. Signup and view all the answers

Brucella spp. causes abortions in which type of animals?

Cattle, goats, and pigs Signup and view all the answers

During which decade was Brucella weaponized for bioterrorism purposes by the US and the former Soviet Union?

1950s Signup and view all the answers

Which statement correctly describes the properties of invasive strains of Hib?

Most invasive strains are type b. Signup and view all the answers

What characterizes the capsule of Hib in relation to immune response?

It helps in evading phagocytosis. Signup and view all the answers

What type of vaccine is the Hib vaccine classified as?

A polysaccharide conjugate vaccine. Signup and view all the answers

Which invasive disease is most commonly attributed to Hib?

Pneumonia caused by serotype f. Signup and view all the answers

What is a clinical hallmark of acute epiglottitis caused by Hib?

Cherry-red swollen epiglottis. Signup and view all the answers

What is the main role of the Hib anticapsular antibody?

To provide bactericidal activity and protection. Signup and view all the answers

Following what conditions could acute purulent meningitis occur?

Sinusitis or otitis. Signup and view all the answers

What is a significant implication of the Hib conjugate vaccine?

It does not protect against nontypeable strains. Signup and view all the answers

What is the primary mechanism of invasion used by Hib when infecting respiratory cells?

Attachment via pili and outer membrane proteins. Signup and view all the answers

Study Notes

Lecture 11: Microbiology - Some Other Important Bacteria

The lecture covers various bacterial species, including their biological characteristics, infection and immunity, pathogenesis, diagnosis, treatment, and prevention. Key species covered include Haemophilus influenzae, Bordetella, Brucella, Bacillus anthracis, and Legionella pneumophila.

Haemophilus influenzae

Formerly known as Pfeiffer's bacillus or Bacillus influenzae.
Described by Richard Pfeiffer during an 1892 influenza pandemic.
Initially mistaken for the cause of influenza.
The viral cause of influenza was identified later in 1933.
Small bacteria, 1.0-1.5 µm in size.
Gram-negative rods (cocobacilli).
Facultative anaerobes.
Non-motile.
May or may not have a capsule.
Requires growth factors (X factor-hematin, V factor-nicotinamide adenine dinucleotide (NAD)) present in erythrocytes; often grown on chocolate agar.
Transmitted via respiratory droplets or contact with contaminated secretions.
Part of the normal flora of the human respiratory tract and oral cavity.
Six capsulated serotypes.
Type B is strongly associated with virulence.
No known exotoxins.
95% of invasive diseases caused by type B.
Non-encapsulated strains (non-typable) are part of the normal flora.

Clinical Importance of H. influenzae

H. influenzae type B is an important human pathogen leading to various conditions.
Other Haemophilus species are normal flora.
H. ducreyi is a sexually transmitted pathogen (chancroid).
H. parainfluenzae can cause pneumonia & endocarditis.
H. aphrophilus can cause pneumonia & endocarditis.
H. aegyptius causes pink eye (purulent conjunctivitis).

Public Health Aspects

Incidence of H. influenzae type B significantly decreased after vaccination.
Pre-immunization, type B was the most common invasive species.

Bordetella pertussis - Whooping Cough

Strict aerobe Gram negative.
Small coccobacillus (0.5-1.0 µm).
Transmission by aerosolized droplets.
Non-invasive, strictly human pathogen.
Two-stage process.
Respiratory colonization (7-10 days, no symptoms, positive cultures)
Toxin-mediated disease (clinical symptoms).

Virulence Factors (Bordetella pertussis)

Pertussis toxin (PT).
Adenylyl cyclase toxin (AC).
Tracheal cytotoxin (TCT).
Dermonecrotic toxin.

Brucella Species

Gram-negative, intracellular coccobacilli.
Aerobic and non-motile.
Lack a diffuse sugary capsule around their membrane.
Capable of causing disease in various animals and humans.
Several species are medically important, examples include B. melitensis (high), B. abortus(moderate), B. suis(high), B. canis(moderate), B. ceti, and B. pinnipedialis.

Reservoir & Epidemiology (Brucella)

Reservoirs include cattle, buffalo, camels, sheep, goats, camels, swine, and dogs.
Human infection often occurs through ingestion of contaminated milk, dairy products.
Transmitted through breathing or skin wounds.
Veterinarians at higher exposure risk.
The US has implemented a control program following identification of infection in 1934.

Bacillus anthracis

Gram-positive, large non-hemolytic.
Endospores, survival in nature.
A wide range of pathogenic mechanisms.
Disease patterns include cutaneous anthrax (95%), inhalation, and gastrointestinal anthrax.

Bacillus cereus

Can cause food poisoning from food intoxication or infection.
Characterized by emetic form, implicated food sources include rice.
Characterized by diarrheal form, implicated food sources include meat and vegetables.

Legionella pneumophila

Thin, aerobic, pleomorphic, non-spore forming.
Gram-negative capsulated bacteria.
Motile with polar, subpolar, and lateral flagella.
Staining with silver impregnation methods.
16 serogroups; L. pneumophila 1 is the most common, known as Philadelphia strain.
Disease patterns: Legionnaires' disease, and Pontiac Fever.
Diagnosis using specimens like sputum, bronchial aspirate, or lung biopsy; culture methods, fluorescent methods, serology, ELISA, or Urine Antigen Test.

Bacillus cereus, Bacillus anthracis, and Legionella pneumophila

Diseases including food poisoning, anthrax, and Legionnaires' disease are discussed in more detail.
Epidemiology, signs and symptoms, diagnosis, and treatment procedures are summarized.

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Description

Test your knowledge on the growth, symptoms, and pathogenic mechanisms of Brucella and Hemophilus influenzae. This quiz covers crucial diagnostic methods, virulence factors, and historical misconceptions about these bacteria. Perfect for microbiology students and enthusiasts.