Podcast
Questions and Answers
During which stage of a Bordetella pertussis infection is the risk of transmission to other individuals highest?
During which stage of a Bordetella pertussis infection is the risk of transmission to other individuals highest?
- Paroxysmal stage, due to the forceful expulsion of respiratory droplets during coughing fits.
- Convalescent stage, due to the persistence of weakened bacteria.
- Catarrhal stage, because the symptoms are similar to a common cold, making it difficult to diagnose. (correct)
- Incubation stage, since the bacteria are multiplying rapidly without noticeable symptoms.
A researcher is investigating the pathogenesis of Bordetella pertussis. Which finding would provide the strongest evidence that a particular virulence factor contributes to the paroxysmal stage of whooping cough?
A researcher is investigating the pathogenesis of Bordetella pertussis. Which finding would provide the strongest evidence that a particular virulence factor contributes to the paroxysmal stage of whooping cough?
- The virulence factor inhibits phagocyte migration to the site of infection.
- The virulence factor is a pili-like adhesion protein that facilitates attachment to ciliated epithelial cells.
- The virulence factor causes ADP-ribosylation, increased cAMP, and edema of the respiratory mucosa. (correct)
- The virulence factor is highly expressed during the catarrhal stage.
Why is it difficult to recover Bordetella pertussis in culture, even under ideal laboratory conditions?
Why is it difficult to recover Bordetella pertussis in culture, even under ideal laboratory conditions?
- Bordetella pertussis is a fastidious species that requires freshly prepared media for optimal growth. (correct)
- Bordetella pertussis is an obligate anaerobe that cannot survive in the presence of oxygen.
- Bordetella pertussis readily forms spores, which are difficult to germinate in vitro.
- Bordetella pertussis produces a biofilm that inhibits growth on artificial media.
A patient presents with a persistent cough, and the physician suspects Bordetella pertussis infection. Why is it best to diagnose the pertussis during the catarrhal phase?
A patient presents with a persistent cough, and the physician suspects Bordetella pertussis infection. Why is it best to diagnose the pertussis during the catarrhal phase?
A researcher aims to develop a novel therapeutic strategy to combat Bordetella pertussis infection by targeting its virulence factors. Which approach would likely be most effective in preventing the initial colonization of the respiratory tract?
A researcher aims to develop a novel therapeutic strategy to combat Bordetella pertussis infection by targeting its virulence factors. Which approach would likely be most effective in preventing the initial colonization of the respiratory tract?
How does tracheal cytotoxin contribute to the pathogenesis of Bordetella pertussis infection?
How does tracheal cytotoxin contribute to the pathogenesis of Bordetella pertussis infection?
What is the primary mechanism by which pertussis toxin contributes to the development of the paroxysmal stage of whooping cough?
What is the primary mechanism by which pertussis toxin contributes to the development of the paroxysmal stage of whooping cough?
Why is azithromycin often considered to have limited effectiveness in treating whooping cough, particularly during the paroxysmal stage?
Why is azithromycin often considered to have limited effectiveness in treating whooping cough, particularly during the paroxysmal stage?
An unvaccinated infant is exposed to Bordetella pertussis. Besides antibiotic treatment, what supportive care intervention is critical during the paroxysmal stage to manage severe coughing fits?
An unvaccinated infant is exposed to Bordetella pertussis. Besides antibiotic treatment, what supportive care intervention is critical during the paroxysmal stage to manage severe coughing fits?
What is the primary difference between the acellular pertussis vaccine and the killed whole-cell pertussis vaccine?
What is the primary difference between the acellular pertussis vaccine and the killed whole-cell pertussis vaccine?
Flashcards
Whooping Cough Cause
Whooping Cough Cause
Bordetella pertussis causes this uncontrollable and violent cough, while Bordetella parapertussis causes a milder form.
Bordetella pertussis Morphology
Bordetella pertussis Morphology
Small, encapsulated, gram-negative, coccobacillus, aerobic bacteria.
Stages of Whooping Cough
Stages of Whooping Cough
- Catarrhal stage (common cold-like). 2. Paroxysmal stage (classic whooping cough). 3. Convalescent stage (recovery).
B. pertussis Virulence Factors
B. pertussis Virulence Factors
Signup and view all the flashcards
Pertussis Toxin Action
Pertussis Toxin Action
Signup and view all the flashcards
Adenylate Cyclase/Tracheal Cytotoxin
Adenylate Cyclase/Tracheal Cytotoxin
Signup and view all the flashcards
Pathogenesis of Pertussis
Pathogenesis of Pertussis
Signup and view all the flashcards
Whooping Cough Treatment
Whooping Cough Treatment
Signup and view all the flashcards
Whooping Cough Prevention
Whooping Cough Prevention
Signup and view all the flashcards
Laboratory diagnosis of pertussis
Laboratory diagnosis of pertussis
Signup and view all the flashcards
Study Notes
- Bordetella pertussis causes whooping cough, characterized as uncontrollable and violent coughing.
- Bordetella parapertussis causes a milder form of pertussis.
- Bordetella pertussis is a gram-negative, coccobacillus, aerobic bacterium.
- It has a worldwide distribution and primarily infects infants and young children.
- Vaccination has led to a decline in the number of cases in the U.S.
- Transmission occurs through air droplets from sneezing or coughing, or by touching contaminated surfaces.
Clinical Symptoms (Whooping Cough)
- Incubation period is 7-10 days.
- Cough progresses through three stages: catarrhal, paroxysmal, and convalescent.
- Catarrhal Stage:
- Resembles the common cold, with symptoms such as rhinorrhea, sneezing, malaise, and low-grade fever.
- Lasts for 1-2 weeks.
- Poses the highest risk of transmission to contacts.
- Paroxysmal Stage:
- Ciliated epithelial cells are extruded from the respiratory tract, impairing mucus clearance.
- Classic "whooping" cough paroxysms occur, often terminated with vomiting and exhaustion.
- Lasts for 2-4 weeks.
- Decreased oxygen levels can lead to seizures, encephalopathy, and even death.
- Risk of secondary pneumonia caused by other pathogens is increased.
- Convalescent Stage:
- Paroxysms diminish in number and severity.
- Secondary complications can still occur.
Virulence Factors and Pathogenesis
- Attachment to ciliated epithelial cells is mediated by pili proteins: filamentous hemagglutinin, pertactin, and agglutinogens (fimbriae).
- Tracheal cytotoxin:
- Paralyzes cilia, allowing Bordetella pertussis to stay attached to the epithelia.
- Induces nitric oxide, which kills ciliated epithelial cells.
- Pertussis toxin:
- An AB5 exotoxin that attaches to cilia and impairs their function, leading to mucus production.
- Causes ADP-ribosylation, increasing cAMP and leading to edema of the respiratory mucosa, resulting in a severe cough.
- Adenylate cyclase toxin:
- Blocks phagocytes from reaching the infection site and prevents them from killing the bacteria.
Diagnosis
- Best to diagnose during the catarrhal phase.
- Nasopharyngeal swab is used for diagnosis.
- Culture is difficult due to the fastidious nature of the species, requiring freshly prepared media. Bordet-Gengou medium can be used.
- ELISA can detect antibodies to pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae antigens.
- Direct fluorescent antibody staining of nasopharyngeal swab.
- PCR can detect bacterial DNA.
Treatment and Prevention
- Azithromycin is the drug of choice, but has little effect on the prolonged cough stage.
- Supportive care (oxygen therapy and suction of mucus) is important during the paroxysmal stage, especially in infants.
- Acellular vaccine (5 antigens purified from the organism) and killed vaccine are available.
- Acellular vaccine is currently used in the U.S.
- Pertussis vaccine is usually given combined with diphtheria and tetanus toxoids in three doses, starting at two months of age, termed DPT vaccine.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
