Question 1

Bordetella pertussis colonies growing on Regan-Lowe medium yields which of the following colonial morphologic appearances?&#10;A) Star-shaped colonies&#10;B) Mercury-drop colonies&#10;C) Yellow-pigmented colonies&#10;D) Shiny black-pigmented colonies

Accepted Answer

Bordetella pertussis typically produces small, smooth, gray, and shiny colonies with a characteristic “mercury-drop” appearance on Regan-Lowe medium.

Question 2

Which of the following toxins contributes to the virulence of Bordetella pertussis and works by hemolyzing red cells and activating cyclic adenosine monophosphate, which inactivates several types of host immune cells?

A) Endotoxin
B) Pertussis toxin
C) Tracheal cytotoxin
D) Adenylate cyclase toxin

Accepted Answer

Adenylate cyclase toxin hemolyzes red cells and activates cyclic adenosine monophosphate, thereby inactivating several types of host immune cells.Pertussis toxin induces lymphocytosis and suppresses chemotaxis and oxidative responses in neutrophils and macrophages.Tracheal cytotoxin causes ciliary dysfunction and damage, and endotoxin is a lipopolysaccharide released upon cell death.

Question 3

During the paroxysmal stage of pertussis, symptoms are:&#10;A) runny nose and mild cough.&#10;B) severe and violent coughing.&#10;C) neutrocytosis and fever.&#10;D) lymphadenitis.

Accepted Answer

Classic pertussis is usually a disease of children and can be divided into three symptomatic stages: catarrhal, paroxysmal, and convalescent.After the catarrhal stage, episodes of severe and violent coughing increase in number, marking the beginning of the paroxysmal stage.

Question 4

Because of its longer shelf life, the medium of choice to cultivate Bordetella spp.is:&#10;A) buffered charcoal yeast extract (BCYE).&#10;B) thiosulfate citrate bile salts sucrose (TCBS) agar.&#10;C) Bordet-Gengou agar.&#10;D) Regan-Lowe agar.

Accepted Answer

Regan-Lowe agar contains charcoal agar with 10% horse blood and cephalexin and has a 4- to 8-week shelf life, whereas Bordet-Gengou agar contains potato infusion agar with glycerol and sheep blood with methicillin or cephalexin and has a short shelf life.BCYE is the medium of choice for cultivating Legionella spp., and TCBS is the medium of choice for cultivating Vibrio spp.

Question 5

Pertussis (whooping cough)is an epidemic disease that is a highly contagious, acute infection of the upper respiratory tract caused by the:&#10;A) Brucella spp.&#10;B) Bordetella spp.&#10;C) Pasteurella spp.&#10;D) Francisella spp.

Accepted Answer

Before the introduction of vaccines and in populations in which immunization is not performed, pertussis (whooping cough)is an epidemic disease with cycles every 2 to 5 years.Pertussis is a highly contagious, acute infection of the upper respiratory tract caused primarily by Bordetella pertussis and less commonly by B.parapertussis.

Question 6

If real-time polymerase chain reaction (PCR)is performed on a Bordetella isolate, then it must be noted that this type of swab is unacceptable for collection because of the presence of which of the following inhibitory factors?

A) Dacron
B) Cotton
C) Rayon
D) Calcium alginate

Accepted Answer

Calcium alginate swabs with aluminum shafts are not recommended for PCR; they may inhibit the polymerase enzyme in PCR detection.In addition, cotton swabs may be inhibitory to specimen growth and are also not recommended.

Question 7

During the catarrhal stage of pertussis, symptoms are:&#10;A) runny nose and mild cough.&#10;B) severe and violent coughing.&#10;C) vomiting and &#34;whooping&#34; as air is rapidly inspired into the lungs past a swollen glottis.&#10;D) lymphocytosis and fever.

Accepted Answer

Classic pertussis is usually a disease of children and can be divided into three symptomatic stages: catarrhal, paroxysmal, and convalescent.During the catarrhal stage, symptoms are the same as a mild cold with a runny nose and mild cough; this stage may last for several weeks.

Question 8

A nasopharyngeal aspirate is cultured on Bordet-Gengou agar, and growth is observed.The colonies are also subjected to a direct fluorescent antibody (DFA)stain, which is also positive.On the basis of these findings, the antimicrobial therapy that should be administered to the patient is:

A) azithromycin.
B) gentamycin.
C) streptomycin.
D) imipenem.

Accepted Answer

Laboratories do not currently perform routine susceptibility testing of B.pertussis and B.parapertussis because the organisms remain susceptible to erythromycin or the newer macrolides (e.g., clarithromycin, azithromycin), ketolides, quinolones, and additional antibiotics such as tetracyclines, chloramphenicol, and trimethoprim-sulfamethoxazole combination.However, because of three erythromycin-resistant isolates of B.pertussis, continued surveillance of B.pertussis is advised.

Question 9

Acceptable specimens for the detection of Bordetella pertussis are:&#10;A) throat swabs.&#10;B) sputum.&#10;C) nasopharyngeal aspirates.&#10;D) anterior nose swabs.

Accepted Answer

Nasopharyngeal aspirates or nasopharyngeal swabs (e.g., calcium alginate, Dacron on a wire handle)are acceptable specimens because B.pertussis colonizes the ciliated epithelial cells of the upper respiratory tract.Specimens obtained from the throat, sputum, or anterior nose are unacceptable because these sites are not lined with ciliated epithelium.For collection, the swab is bent to conform to the nasal passage and held against the posterior aspect of the nasopharynx.If coughing does not occur, then another swab is inserted into the other nostril to initiate the cough.The swab is left in place during the entire cough, removed, and then immediately inoculated onto a selective medium at the bedside.

Question 10

The mode of transmission of Bordetella pertussis can best be described as:&#10;A) person-to-person contact.&#10;B) exposure to contaminated water.&#10;C) inhalation of contaminated air.&#10;D) close contact with animals.

Accepted Answer

Infection by B.pertussis is transmitted from person to person, presumably by airborne transmission from the cough of an infected person.Humans are the only reservoir.

Deck 36: Bordetella Pertussis, Bordetella Parapertussis, and Related Species