Microbiology Quiz: Haemophilus & Legionella
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Questions and Answers

At what temperature do most Haemophilus species grow best?

  • 30-32 degrees centigrade
  • 40-42 degrees centigrade
  • 25-28 degrees centigrade
  • 35-37 degrees centigrade (correct)

Which Haemophilus species requires an increased supply of CO2 for growth?

  • H.aegypticus
  • H.ducreyi
  • H.influenzae (correct)
  • H.parainfluenzae

What type of agar is used for isolating H.influenzae?

  • Horse’s blood-bacitracin agar (correct)
  • MacConkey agar
  • Nairobi biplate medium
  • Chocolate agar

Which of the following is true regarding Brucella species?

<p>They can induce spontaneous abortion among animals. (B)</p> Signup and view all the answers

What is the preferred specimen for isolation of Haemophilus species?

<p>Blood and bone marrow (C)</p> Signup and view all the answers

How does H.aegypticus appear under microscopy?

<p>Small coccobacilli with a 'sandy appearance' (B)</p> Signup and view all the answers

Which of the following cultures would show colonies that are non-haemolytic and yellowish?

<p>H.aegypticus (C)</p> Signup and view all the answers

What type of bacteria does the HACEK group consist of?

<p>Fastidious Gram-negative bacteria (C)</p> Signup and view all the answers

Which of the following characteristics apply to Legionella species?

<p>Can infect amoebae and ciliated protozoa (B)</p> Signup and view all the answers

What is a significant virulence factor of Pasteurella species?

<p>Endotoxin and capsule (B)</p> Signup and view all the answers

Which of the following serogroups is not associated with Legionnaire's disease?

<p>8 (B)</p> Signup and view all the answers

Which culture medium is preferred for isolating Legionella pneumophila?

<p>Buffered charcoal yeast extract (BCYE) with L-cysteine (B)</p> Signup and view all the answers

What is a characteristic growth appearance of Mycobacterium tuberculosis in culture?

<p>Buff in color, raised and dry colonies (B)</p> Signup and view all the answers

Legionella pneumophila is primarily isolated from which of the following environments?

<p>Freshwater lakes and rivers (D)</p> Signup and view all the answers

Which biochemical test result is positive for Mycobacterium tuberculosis?

<p>Catalase positive (A)</p> Signup and view all the answers

What microscopic appearance is characteristic of Legionella species?

<p>Small, straight bacilli with a 'safety-pin' appearance (C)</p> Signup and view all the answers

Which of the following factors is a virulence factor associated with Mycobacterium species?

<p>Cording factor (B)</p> Signup and view all the answers

Which of the following statements about Pasteurella multocida is true?

<p>It is the most commonly isolated species in humans. (C)</p> Signup and view all the answers

What is the primary function of the Bacillus Calmette–Guérin (BCG) vaccine?

<p>Act as a live attenuated strain against tuberculosis (B)</p> Signup and view all the answers

Which biochemical test result is characteristic of Legionella species?

<p>Catalase positive (C)</p> Signup and view all the answers

Which rapid method is effective for the diagnosis of Mycobacterium tuberculosis?

<p>DNA test (PCR) (A)</p> Signup and view all the answers

How do Mycobacterium species generally respond to heat, cold, and drying?

<p>They are resistant to these environmental conditions (D)</p> Signup and view all the answers

Which of the following describes the morphology of Mycobacterium species?

<p>Slender, beaded rods (B)</p> Signup and view all the answers

What is the specific gravity range of Mycobacterium species?

<p>0.79 - 1.07 (C)</p> Signup and view all the answers

What is a common environmental source of avium complex infections?

<p>Natural waters (C)</p> Signup and view all the answers

Which test is used to differentiate avium complex based on biochemical properties?

<p>Tween 80 hydrolysis (D)</p> Signup and view all the answers

What type of colonies does avium complex typically produce in culture?

<p>Smooth, yellow-orange colonies (C)</p> Signup and view all the answers

In patients without AIDS, what type of infections are most commonly associated with avium complex?

<p>Cervical lymphadenitis (C)</p> Signup and view all the answers

What is the primary infection caused by avium complex in HIV-negative immunocompromised patients?

<p>Pulmonary infections (B)</p> Signup and view all the answers

How is M. xenopi commonly transmitted?

<p>Aerosols from hot water taps (C)</p> Signup and view all the answers

What type of disease is less common in patients with AIDS when infected with avium complex?

<p>Extrapulmonary infections (C)</p> Signup and view all the answers

What growth temperature is optimal for the avium complex?

<p>42°C (C)</p> Signup and view all the answers

What type of infections are associated with Mycobacterium ulcerans?

<p>Cutaneous and subcutaneous infections (A)</p> Signup and view all the answers

In what type of climate do infections from Mycobacterium ulcerans commonly occur?

<p>Tropical or temperate climates (C)</p> Signup and view all the answers

Where has Mycobacterium xenopi been recovered from?

<p>Hot and cold-water taps, and birds (A)</p> Signup and view all the answers

What is a potential outcome of Mycobacterium xenopi infection in immunocompromised adults?

<p>Pulmonary infection (A)</p> Signup and view all the answers

What infectious condition is associated with Mycobacterium terrae?

<p>Cervical lymphadenitis in children (A)</p> Signup and view all the answers

How is Mycobacterium ulcerans primarily transmitted?

<p>Through insect salivary glands (C)</p> Signup and view all the answers

Which age group most commonly experiences mild skin infections from Mycobacterium?

<p>Preadolescents or early adolescents (C)</p> Signup and view all the answers

What is the initial host from which Mycobacterium ulcerans was first isolated?

<p>African toad (A)</p> Signup and view all the answers

What is the positive result of the iron uptake test for mycobacteria?

<p>Rusty brown colonies in egg-based medium (B)</p> Signup and view all the answers

Which organism can be differentiated from others using the urease test?

<p>M.scrofulaceum (D)</p> Signup and view all the answers

At what optimal temperature does M.kansasii grow?

<p>30°C (A)</p> Signup and view all the answers

What color change signifies a positive urease test within three days?

<p>Pink (C)</p> Signup and view all the answers

Which organism is known to be incapable of growth in artificial culture media?

<p>M.leprae (D)</p> Signup and view all the answers

What is a significant source of infection for leprosy?

<p>All persons with active leprosy (B)</p> Signup and view all the answers

What is the significance of the p-nitroacethylamino-B-hydroxypropiophenone in the NAP inhibition test?

<p>It is a precursor for chloramphenicol synthesis (C)</p> Signup and view all the answers

What distinct arrangement is characteristic of rod-shaped mycobacteria like M.kansasii?

<p>Cigar pocket arrangement (A)</p> Signup and view all the answers

Flashcards

Haemophilus Growth Temperature

Haemophilus species, excluding H. ducreyi, grow optimally at 35-37 degrees Celsius.

H. ducreyi Growth Temperature

H. ducreyi, unlike other Haemophilus, thrives at 35 degrees Celsius.

Haemophilus CO2 Requirement

Haemophilus species require carbon dioxide (CO2) for growth.

Selective Media for Haemophilus

H. influenzae, H. aegyptius, and H. ducreyi need specific media for growth.

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H. influenzae Satellite Growth

H. influenzae grows as "satellites" around other bacteria on blood agar plates (BAP).

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Brucella Significance

Brucella species are important pathogens in both humans and animals.

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Brucella Habitat

Brucella species prefer environments rich in erythritol, particularly the placenta.

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Brucella Characteristics

Brucella species are non-motile, do not ferment sugars, and lack capsules.

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Pasteurella

This facultatively anaerobic bacterium can be isolated from animal bites, primarily from cats.

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Pasteurella multocida

Pasteurella species commonly isolated in dog and cat bite infections.

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Legionella: Intracellular Survival

A distinguishing feature of Legionella is its ability to multiply inside free-living amoebae, protozoa, and biofilms.

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Legionella: Environmental Habitat

Legionella is often found in water sources, including lakes, rivers, hot springs, and even mud.

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Legionella pneumophila: Common Pathogen

Despite its resistance to chlorine, the most common Legionella species isolated in humans is Legionella pneumophila.

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Legionella: Intracellular Pathogenicity

Legionella, particularly Legionella pneumophila, can invade and multiply within macrophages, making it a facultative intracellular pathogen.

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Legionella: Environmental Transmission

Legionella, particularly Legionella pneumophila, is associated with air-conditioned units, cooling towers, and nebulizers.

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Legionella pneumophila: Serogroups

Legionella pneumophila exhibits different serogroups, with serogroups 1, 4, and 6 being associated with Legionnaire's disease.

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Mycobacteria

A genus of non-motile, non-spore-forming, non-encapsulated, acid-fast bacilli with high lipid content, often associated with slow-growing diseases.

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Mycobacterium tuberculosis Complex (MTC)

A group of mycobacteria that includes the causative agent of tuberculosis, Mycobacterium tuberculosis.

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Nontuberculous Mycobacteria (NTM)

Mycobacteria that are not part of the Mycobacterium tuberculosis Complex, often causing lung infections in immunocompromised individuals.

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BCYE Medium

A selective growth medium used for culturing Mycobacterium tuberculosis, containing L-cysteine, ferric salt, and a-ketoglutarate.

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Acid-Fast Staining

A microscopic technique for identifying Mycobacterium tuberculosis, where the bacteria retain their red color after acid-alcohol treatment because of their waxy cell walls.

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Mycobacterium tuberculosis (Koch Bacillus)

The causative agent of tuberculosis, identified under microscopy as slender, beaded rods with X, V, Y and L formations.

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Bacillus Calmette–Guérin (BCG)

A live attenuated strain of Mycobacterium bovis used as the only vaccine against tuberculosis, often given to newborns.

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Cord Factor

A virulence factor of Mycobacterium tuberculosis responsible for its ability to form clumps, making it harder for the immune system to attack.

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What are scotochromogens?

A group of mycobacteria that are slow-growing and pigmented when exposed to light.

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What is Mycobacterium xenopi?

A mycobacterium species that is commonly found in water, especially hot water taps in hospitals.

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What type of infection is most common caused by Mycobacterium xenopi?

The most common infection caused by Mycobacterium xenopi is pulmonary infection.

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How is Mycobacterium xenopi commonly transmitted?

Mycobacterium xenopi is believed to be transmitted through aerosols.

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How does Mycobacterium xenopi typically present in patients with and without AIDS?

In patients with AIDS, Mycobacterium xenopi can cause disseminated disease. However in immunocompromised individuals without AIDS, the infection typically manifests as pulmonary infections.

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What is Mycobacterium avium complex (MAC)?

Mycobacterium avium complex (MAC) is a group of mycobacteria that can cause infections in both immunocompromised and immunocompetent individuals.

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In which group of patients is MAC infection more common?

An infection caused by MAC is more common in patients with AIDS.

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What is a common source of MAC infections?

Infections caused by MAC are usually caused by environmental sources such as soil and natural water.

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Mycobacterium ulcerans

Mycobacterium ulcerans is a slow-growing, acid-fast bacterium that causes cutaneous infections, particularly in tropical regions. These infections are known as Buruli ulcer or Bairnsdale ulcer.

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Where does Mycobacterium ulcerans live?

This species typically thrives in stagnant tropical water, often at temperatures ranging from 22 to 37 degrees Celsius (72-99 degrees Fahrenheit).

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What makes Mycobacterium ulcerans infections indolent?

Mycobacterium ulcerans infections, also known as Buruli ulcer or Bairnsdale ulcer, are characterized by a lack of pain or inflammation, making them 'indolent'.

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What type of infections does Mycobacterium ulcerans cause?

Mycobacterium ulcerans infections primarily affect the skin and subcutaneous tissues, leading to 'cutaneous and subcutaneous' infections.

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Mycobacterium xenopi

Mycobacterium xenopi is a species that is commonly found in hot and cold water taps, especially in the water storage tanks of hospitals. It's a potential pathogen, mainly causing pulmonary infections in adults.

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Mycobacterium haemophilium

Mycobacterium haemophilium thrives in the lungs, particularly in immunocompromised individuals. This organism might also cause disseminated disease, spreading beyond the initial infection site.

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Mycobacterium terrae

Mycobacterium terrae is associated with trauma and respiratory routes, causing various infections. In children, cervical lymphadenitis is common. In adults, tenosynovitis and pulmonary infections are more prevalent.

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How does Mycobacterium terrae spread?

Mycobacterium terrae can be spread through different ways, but trauma, respiratory infections are common routes. In children and adolescents, infections might lead to cervical lymphadenitis. Adults are susceptible to tenosynovitis and pulmonary infections.

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Iron Uptake Test

A laboratory procedure that involves using ferrous ammonium sulfate as a reagent to identify mycobacteria that produce red pigment. This test helps differentiate M. kansasii, M. marinum, and M. xenopi from other mycobacteria.

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Urease Test

A test that checks if mycobacteria can utilize urea. A positive reaction indicates the presence of urease enzyme and is helpful in differentiating M. scrofulaceum from M. gordonae.

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NAP Inhibition Test

A test using NAP (p-nitroacethylamino-B-hydroxypropiophenone) to inhibit the growth of mycobacteria. This test helps in identifying Mycobacterium species by observing their susceptibility to NAP.

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Slow-growing Mycobacteria

A type of mycobacteria that is slow-growing, usually takes weeks or months to culture. These species cause a wide range of infections like skin infections, pulmonary disease and lymphadenitis.

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Leprosy

A disease caused by Mycobacterium leprae, a slow-growing, acid-fast bacillus.

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Mycobacterium tuberculosis (Mtb)

The most common species of mycobacteria responsible for human infection, causing tuberculosis. It is an acid-fast bacillus that spreads through the air.

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Acid-Fast Staining (AFB)

The process by which mycobacteria are stained using specific techniques to highlight their unique characteristics. This helps in identifying the presence of Mycobacterium in clinical specimens.

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Rapid growing Mycobacteria (RGM)

A type of mycobacteria that grows rapidly in culture, usually within a few weeks. These species are commonly associated with skin and soft tissue infections.

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Study Notes

Small, Pleomorphic, Gram-Negative Bacilli

  • Haemophilus species are "blood-loving"
  • Obligate parasites on human mucous membranes
  • Primarily inhabit the upper respiratory tract (URT)
  • Haemophilus influenzae type b (Hib) is a leading cause of meningitis in unvaccinated children
  • Haemophilus ducreyi causes chancroid, a highly communicable sexually transmitted genital ulcer disease
  • Fastidious bacteria requiring specific growth factors (X and V factors)

Haemophilus Species

  • Haemophilus are small, pleomorphic, gram negative bacilli
  • Rapidly die in clinical specimens and are susceptible to drying and extreme temperatures.
  • Grow best at 35-37°C with 5-10% CO2
  • Various growth factors depending on the species

Differential Characteristics of Haemophilus Species

  • Various species have differentiating characteristics
  • Different infections can be caused by different species
  • Diagnostic tests and cultures need to be applied as appropriate to each species

Brucella spp.

  • Species of this genus are important human and animal pathogens
  • Obligate intracellular parasites with various subtypes, which have different infections associated.
  • Difficult to culture under standard conditions.
  • Can infect specific tissues amongst humans, which is useful in differentiation
  • Pathogens are spread through various exposure paths.

Francisella tularensis

  • Category A select bioterrorism agent, non-motile, gram-negative
  • Causes tularemia (rabbit fever)
  • Transmitted primarily through vectors like insect bites
  • Requires biosafety level 3 conditions for lab work.

Legionella

  • Fastidious, aerobic motile, and non-carbohydrate fermenter
  • Legionnaire's disease and Pontiac fever are caused by L. pneumophilia
  • Infection typically acquired through inhalation of water droplets from contaminated sources.
  • Can replicate within certain types of protozoa.

Pasteurella

  • Facultatively anaerobic, nonmotile
  • Associated typically with animal bites, particularly those from cats or dogs.

Bordetella

  • Causes whooping cough (pertussis)
  • Highly contagious, affecting the upper respiratory tract
  • Characterized by three distinct stages: catarrhal, paroxysmal, and convalescent.

Mycobacteria

  • Mycobacteria are non-motile, non-spore forming, acid-fast bacilli, which are resistant to various disinfectants
  • Slow-growing mycobacteria take multiple weeks or months to grow.
  • The two common groups are the Mycobacterium tuberculosis complex (M. tuberculosis itself, as well as others) and nontuberculous mycobacteria (NTM).

Spirochetes

  • Spirochetes are an unusual group of bacteria (genus Treponema)
  • Exhibit unique motility patterns and spiral shape
  • Syphilis, relapsing fever, and Lyme disease are all caused by spirochete species
  • Different species have various reservoirs
  • Can be detected using dark-field microscopy.

Anaerobic Bacteria

  • Anaerobes are bacteria that grow in the absence of oxygen.
  • They are found in soil, in freshwater and seawater sediments, etc.
  • Anaerobes are grouped as either endogenous, which exist inside animals, or exogenous, which exist outside of animals.
  • Endogenous anaerobes are found in the gut, oral cavity or other human tissues.
  • Exogenous forms from environment are more likely from animal bites, wounds or exposure to contaminated soil or water, typically Clostridium spp.
  • Indicators include presence of sulfur granules, foul odor when opened, double zone of hemolysis, brick red fluorescence or absence of superoxide, etc

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Description

Test your knowledge on Haemophilus and Legionella species, including their growth requirements, isolation techniques, and characteristics. This quiz covers essential microbiological concepts and culturing methods used in clinical laboratories.

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