68 Questions
What is the type species of the genus Legionella?
Legionella pneumophila
What percentage of Legionella-associated cases are caused by Legionella pneumophila?
85%
What is the primary mode of transmission of Legionella?
Inhalation of contaminated aerosols
What is the typical incubation period of Legionnaires' disease?
2-10 days
What is the most common demographic affected by Legionnaires' disease?
People over 50 years old
What is the typical outcome of untreated Legionnaires' disease?
Progressive pneumonia with respiratory failure
What is the primary mode of transmission of Legionella pneumophila?
Inhalation of contaminated aerosols
Which of the following bacteria is not a Gram-negative obligate anaerobe?
Haemophilus influenzae
What was the site of the first outbreak of Legionella pneumophila in 1976?
Bellevue-Stratford Hotel, Philadelphia
Who is credited with the discovery of Legionella pneumophila in thermal waters?
Dr. Carl Fliermans
What is the name of the disease caused by Bordetella pertussis?
Whooping Cough
What is the age range of children most susceptible to meningitis and septicaemia caused by Haemophilus influenzae?
Children < 6 months
What is the characteristic of Legionella pneumophila lipids that is similar to those of thermophilic bacteria?
They resemble those found in Yellowstone National Park
What was the initial suspect in the 1976 outbreak of Legionella pneumophila?
A terrorist plot
What is the primary location where Legionella bacteria multiply?
In alveolar macrophages
What is the primary effect of Legionella infection on the lungs?
Obliteration of the air spaces
What is the role of amoeba and other protozoa in the environment of Legionella?
They provide a protective environment for Legionella growth
What is the primary mechanism of Legionella dissemination?
Aerosol generation from artificial water systems
What is the primary factor contributing to the creation of ideal conditions for Legionella growth?
Human modification of the environment
What is the primary factor that determines the susceptibility of a host to Legionella infection?
Age and sex of the individual
What is the most common way Legionella enters the lungs?
Through aspiration
What is the order that Burkholderia is classified under?
Burkholderiales
What is the shape of Bordetella pertussis?
Coccobacillus
What is the primary way Bordetella pertussis is transmitted?
Through droplets and inhalation
What is the duration of the incubation period of pertussis?
5-10 days
What is the typical duration of the paroxysmal stage of pertussis?
1-6 weeks
What is a common complication of pertussis?
All of the above
Why has there been an increase in pertussis cases in recent years?
Waning immunity and better detection methods
What is the primary location where gram-negative obligate anaerobes colonize in huge numbers?
Large bowel
What is the approximate ratio of gram-negative obligate anaerobes to aerobic bacteria in the human body?
100:1
What is the most common gram-negative obligate anaerobe associated with intra-abdominal infections?
Bacteroides fragilis
What is the primary cause of acute necrotizing gingivitis?
A mixed bacterial infection including anaerobes
What is a common characteristic of gram-negative obligate anaerobes in terms of pathogenicity?
Few species are pathogens
What is a common feature of infections caused by gram-negative obligate anaerobes?
Often polymicrobial infections
Legionella species are obligate aerobic bacteria.
True
All species of Legionella are motile via multiple polar flagella.
False
Legionnaires' disease can be acquired through the ingestion of contaminated food.
False
Legionella species can grow in artificial media without additional nutrients.
False
The incubation period of Legionnaires' disease can be up to 20 days.
False
Legionella species can only multiply in the environment when certain nutrients are present.
True
Legionnaires' disease primarily affects individuals under the age of 50.
False
The primary reservoir of Legionella is soil.
False
Legionella is a type of Gram-positive bacteria.
False
The primary mechanism of Legionella transmission is through direct contact with an infected person.
False
Legionella can only grow in environments with temperatures above 40°C.
False
The role of amoeba and other protozoa is to provide a natural habitat for Legionella to multiply and protect itself from environmental stressors.
True
Legionella pneumophila causes a disease that is typically associated with young children.
False
Bordetella pertussis is a Gram-negative obligate anaerobe.
False
The initial suspect in the 1976 outbreak of Legionella pneumophila was a terrorist plot.
True
Legionella pneumophila lipids are similar to those of thermophilic bacteria found in Antarctica.
False
Dr. Joseph McDade discovered Legionella pneumophila in 1976.
False
The 1976 outbreak of Legionella pneumophila occurred at a hotel in New York City.
False
Legionella pneumophila tends to live as a single cell in water.
False
Bacteroides is a type of Gram-positive bacteria.
False
The genus Bordetella is classified under the order Burkholderiales.
True
Bordetella pertussis is a Gram-positive bacterium.
False
The catarrhal stage of pertussis typically lasts for 1-6 weeks.
False
The paroxysmal stage of pertussis can last for up to 6 months.
True
Bordetella pertussis is a strictly aerobic bacterium.
True
Pneumonia is a common complication of pertussis.
True
The increase in pertussis cases in recent years is due to a lack of awareness and detection methods.
False
Legionella enters the lungs primarily through inhalation of contaminated droplets.
False
Gram-negative obligate anaerobes outnumber aerobic bacteria by 1-10 fold.
False
Bacteriodes fragilis is associated with 20% of intra-abdominal infections.
False
Treponema is a type of fungus that causes acute necrotizing gingivitis.
False
Gram-negative obligate anaerobes are the predominant bacteria in the skin and soft tissue.
False
Prevotella is a type of gram-positive obligate anaerobe.
False
Fusobacterium is a type of gram-positive aerobe.
False
Study Notes
Gram-Negative Bacteria
- Miscellaneous but important bacteria:
- Legionella pneumophila: causes Legionnaire's disease
- Bordetella pertussis: causes whooping cough
- Gram-negative obligate anaerobes: diverse group, includes Bacteroides, Fusobacterium, Prevotella, and Porphyromonas
Legionella pneumophila
- Causes Legionnaire's disease
- First outbreak: 1976, Philadelphia, 34 deaths, 221 cases
- Epidemiological evidence suggested exposure in lobby of Bellevue-Stratford Hotel
- Dr. Joseph McDade isolated the bacterium in 1977
- Lipids similar to those of thermophilic bacteria in Yellowstone National Park
Characteristics of Legionella
- Type species: Legionella pneumophila
- 42 species characterized, 18 associated with human illness, L. pneumophila accounts for 85% of cases
- Non-spore forming, Gram-negative rods, varying from short thin forms to longer filamentous forms
- Most species are motile via a single polar flagellum
- Aerobic, grows in tap water and water, but nutritionally fastidious in artificial media
Transmission and Disease
- Most common form of transmission: inhalation of contaminated aerosols
- Infection can also occur by aspiration of contaminated water or ice
- Incubation period: 2-10 days, up to 16 days in some outbreaks
- Death occurs through progressive pneumonia with respiratory failure and/or shock and multi-organ failure
- Untreated Legionnaires' disease usually worsens during the first week
- 75-80% of reported cases are in people over 50 years, 60-70% are male
- Community, travel, or hospital-acquired
Legionella in the Environment
- Found naturally in freshwater streams, lakes, warm springs, rivers, and riverbanks
- Intracellular parasite of amoeba and other protozoa, protected from chlorine, drying, and heat
- Artificial water systems create ideal conditions for Legionella growth
Chain of Causation for Legionella Infection
- Environmental reservoir
- Multiplication (stagnation, temperature, nutrients)
- Dissemination by aerosol generation
- Inhalation into lungs by susceptible host
Bordetella pertussis
- Causes whooping cough (pertussis)
- Aerobic, Gram-negative, small coccobacillus
- Specific only to humans, colonizes the respiratory tract
- Transmission via droplets/inhalation
- Incubation period: 5-10 days
- Catarrhal stage: 1-2 weeks, mild cough, rhinorrhoea
- Paroxysmal stage: 1-6 weeks, forceful, hacking coughs, whoop when air rushes back into lungs
- Complications: pneumonia, otitis media, asthma
Bordealla pertussis: Epidemiology
- Increased awareness and better detection methods
- Waning immunity in older children and adults
- Acellular vaccines provide a shorter duration of protection
- Vaccine research ongoing, correlate of protection unknown
- COVID-19 pandemic impact unknown
Gram-Negative Obligate Anaerobes
- Colonize the human body's anaerobic environments in huge numbers
- Predominant bacteria in upper respiratory tract, GI and GU tract
- Outnumber aerobic bacteria by 10-100 fold
- Many species, but few pathogens
- Clinical diseases: periodontal infections, abscesses, intra-abdominal infections, gynecological infections
- Bacteroides fragilis: associated with 80% of intra-abdominal infections
- Often polymicrobial infections
Gram-Negative Bacteria
- Miscellaneous but important bacteria:
- Legionella pneumophila: causes Legionnaire's disease
- Bordetella pertussis: causes whooping cough
- Gram-negative obligate anaerobes: diverse group, includes Bacteroides, Fusobacterium, Prevotella, and Porphyromonas
Legionella pneumophila
- Causes Legionnaire's disease
- First outbreak: 1976, Philadelphia, 34 deaths, 221 cases
- Epidemiological evidence suggested exposure in lobby of Bellevue-Stratford Hotel
- Dr. Joseph McDade isolated the bacterium in 1977
- Lipids similar to those of thermophilic bacteria in Yellowstone National Park
Characteristics of Legionella
- Type species: Legionella pneumophila
- 42 species characterized, 18 associated with human illness, L. pneumophila accounts for 85% of cases
- Non-spore forming, Gram-negative rods, varying from short thin forms to longer filamentous forms
- Most species are motile via a single polar flagellum
- Aerobic, grows in tap water and water, but nutritionally fastidious in artificial media
Transmission and Disease
- Most common form of transmission: inhalation of contaminated aerosols
- Infection can also occur by aspiration of contaminated water or ice
- Incubation period: 2-10 days, up to 16 days in some outbreaks
- Death occurs through progressive pneumonia with respiratory failure and/or shock and multi-organ failure
- Untreated Legionnaires' disease usually worsens during the first week
- 75-80% of reported cases are in people over 50 years, 60-70% are male
- Community, travel, or hospital-acquired
Legionella in the Environment
- Found naturally in freshwater streams, lakes, warm springs, rivers, and riverbanks
- Intracellular parasite of amoeba and other protozoa, protected from chlorine, drying, and heat
- Artificial water systems create ideal conditions for Legionella growth
Chain of Causation for Legionella Infection
- Environmental reservoir
- Multiplication (stagnation, temperature, nutrients)
- Dissemination by aerosol generation
- Inhalation into lungs by susceptible host
Bordetella pertussis
- Causes whooping cough (pertussis)
- Aerobic, Gram-negative, small coccobacillus
- Specific only to humans, colonizes the respiratory tract
- Transmission via droplets/inhalation
- Incubation period: 5-10 days
- Catarrhal stage: 1-2 weeks, mild cough, rhinorrhoea
- Paroxysmal stage: 1-6 weeks, forceful, hacking coughs, whoop when air rushes back into lungs
- Complications: pneumonia, otitis media, asthma
Bordealla pertussis: Epidemiology
- Increased awareness and better detection methods
- Waning immunity in older children and adults
- Acellular vaccines provide a shorter duration of protection
- Vaccine research ongoing, correlate of protection unknown
- COVID-19 pandemic impact unknown
Gram-Negative Obligate Anaerobes
- Colonize the human body's anaerobic environments in huge numbers
- Predominant bacteria in upper respiratory tract, GI and GU tract
- Outnumber aerobic bacteria by 10-100 fold
- Many species, but few pathogens
- Clinical diseases: periodontal infections, abscesses, intra-abdominal infections, gynecological infections
- Bacteroides fragilis: associated with 80% of intra-abdominal infections
- Often polymicrobial infections
Learn about the transmission, epidemiology, and diseases caused by Legionella sp, Bordetella pertussis, and Gram-negative obligate anaerobes.
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