Lecture 11 Flashcards
What are the main characteristics of the Bordetella species?
super small gram– coccobacillus (short rods), strictly aerobic and non-invasive but produces many toxins
What is the reservoir for Bordetella?
humans and some animals
What are the 3 species of Bordetella bacteria discussed?
B. pertussis, B. parapertussis, B. bronchiseptica
Which of the 3 species discussed is the most important?
B. pertussis
What is B. parapertussis?
a species of Bordetella similar to B. pertussis that causes a milder form of pertussis || “para” = resembling=similar
What does “pertussis” mean?
“per” = severe and “tussis” = cough»_space; severe cough
What does “bronchiseptica” stand for?
“bronchi” = bronchus=trachea and “septica” = septic=infection»_space; infection of bronchus
What is B. bronchiseptica?
species of Bordetella that causes respiratory infection in animals which can be passed onto humans causing a -pertussis-like disease || zoonotic
What are the main characteristics of B. pertussis?
same as all Bordetella but: non-motile and not easy to grow; very sensitive to sunlight and dry environments
What kind of media can B. pertussis only grow on and why?
complex media with presence of blood because it is nutritionally fastidious
What is the reservoir for B. pertussis? What microenvironment is it part of?
humans, part of the normal flora in adults
What kind of pathogen is B. pertussis considered to be and why?
mucosal pathogen because it colonizes the mucosal epithelial membranes of the respiratory tract
What is one of the most contagious and easily transmitted respiratory disease known?
pertussis
What is the mode of transmission with B. pertussis?
airborne (droplet nuclei) and direct contact
What disease does B. pertussis cause?
pertussis aka: whooping cough | respiratory disease in kids over 5yo more commonly and in some adults
Is pertussis a new or old disease and why?
old disease, first epidemic reported around 1500s
Who isolated B. pertussis and when?
1901 - Bordet and Gengou @ Pasteur Institute (France)
What is the origin of pertussis? (theoretically) What supports this?
originally infection of ducks but passed on to humans after the domestication of ducks — supported by evolutionary evidence
How many pertussis cases/year in the US?
~25,000
What continent does pertussis commonly occur at?
Africa
What are the causes of a significant increase in pertussis in older children and adults in recent years after the introduction of vaccine?
anti-vaccination and the vaccine wears off over time and booster-shots are not always taken = susceptible to infection
What is the incubation period for patients with pertussis disease?
1-2 weeks
What is the first (1st) stage symptom of pertussis? How long does it last for?
cold-like lasting for 1-2 weeks | will see a peak in bacterial numbers but declines
What is the second (2nd) stage symptom of pertussis? How long does it last for?
more specific symptoms to pertussis: dry cough, excess mucus, vomiting, cyanosis, weight loss | several weeks
What is the sequence of events of B. pertussis infection?
bacterium enters host »_space; multiplies »_space; spreads to parts of respiratory tract »_space; colonize and produce toxins
What are the 2 modes of pathogenesis of B. pertussis?
colonizes respiratory ciliated epithelial cells but doesn’t invade and causes damage to localized tissue by producing toxins along with other virulence factors
What are the 8 major virulence factors of B. pertussis?
FHA, peractin, pili, 3 toxins: pertussis, tracheal cytotoxin, adenylate cyclase, and LPS A and X
What does FHA stand for? What is it?
filamentous hemagglutination adhesin | a protective antigen that is already used in vaccine production
What is peractin?
autotransporter adhesin, also a protective antigen
What physiological effect does FHA have on the host?
adherence and alter’s host’s innate immunity
What physiological effect does peractin have on the host? Is this being used for treatment?
adherence, not used for treatment
What function does the pili serve for B. pertussis?
adherence to respiratory epithelium
What kind of toxin is and what physiological effect does the pertussis toxin have on the host? What toxin does it resemble?
AB toxin, impairs immunoresponses against bacterium | resembles cholera toxin
What physiological effect does the adenylate cyclase toxin have on the host?
mimics pertussis toxin, increases capillary permeability thus leads to edema, hemolytic activity
What endotoxin does B. pertussis have? What is it’s physiological effect on the host? What can this endotoxin be used for?
LPS-A and LPS-X | fever; used as an adjuvant
What physiological effect does the tracheal cytotoxin have?
kills ciliated respiratory epithelial cells; cytopathological damage to tracheal epithelia
What is the tracheal cytotoxin of B. pertussis? What can this toxin be used for?
murein, part of cell wall that when the bacteria is lysed/cell wall breaks down = cytotoxin is released | used as an adjuvant
What is an adjuvant?
substance that helps the host’s immune system
What system is unique to B. pertussis? What is it used for?
2-component regulatory system for signal transduction
What are the 2 components of the 2-component regulatory system?
sensor and regulator
What is the function the 2-component regulatory system?
controls the expression of the virulence factors and pertussis toxin
What is the “sensor” component of the 2-component regulatory system? Where is it located?
located on cytoplasmic membrane | protein kinase that senses the environmental for a signal
What is the “regulator” component of the 2-component regulatory system? Where is it located?
located in the cytoplasm | transcription factor that interacts with specific genes on DNA
How does the 2-component regulatory system work? (sequence of events)
Environmental signal activates “sensor” (protein kinase) »_space; “sensor” phosphorylates “regulator” »_space; “regulator” interacts with specific gene on DNA (of B. pertussis) to stimulate or reduce expression of speciic gene
In which Gram+ bacteria species is found to have the 2-component regulatory system?
Salmonella
In which Gram– bacteria species is found to have the 2-component regulatory system?
S. aureus and S. pyogenes
How do we diagnose for pertussis?
take a swab that has penicillin on it »_space; let bacteria grow on special media »_space; identification is done via antibody assay or PCR
What is the name for the media used to culture B. pertussis?
Bordet-Gengou media
What is required prior to diagnosing a patient for pertussis? Why?
patient needs to be suspected to have the infection because diagnosis process is not easy
Why must we add penicillin onto the swab prior to sampling a patient’s throat?
to kill the other bacteria present in the respiratory system
What is a mode of treatment against pertussis?
antibiotics: erythromycin and chloramphenicol (= ErythChlor)
What is used in efforts to prevent pertussis?
vaccines
What vaccines are available against pertussis?
DPT (diphteria, pertussis, and tetanus) and DT(alpha)P
What is the difference between DPT and DT(alpha)P?
DT(alpha)P contains inactive components of pertussis toxin and FHA (filamentous hemagglutination adhesin)
What are the general characteristics of Legionella pneumophila?
Gram– rods that don’t stain well, doesn’t grow on general bacterial media, facultative (optional) intracellular pathogen, motile = has flagella; LPS is less toxic compared to other bacteria
What is the reservoir for Legionella pneumophila?
aquatic and soil habitats
What toxins do Legionella pneumophila produce?
none have yet been identified
Where does Legionella pneumophila multiply?
inside free-living amoebas, macrophages and other protozoa
What type of secretion system does the Legionella pneumophila have?
Type IV (TYPE 4!)
What diseases does Legionella pneumophila cause?
Legionnaire’s disease and Pontiac fever
Is Legionnaire’s disease a new or old disease?
new
What does it mean when a disease is a “new” disease?
the bacteria did not originally cause a disease but something provided the bacterium the opportunity to cause a disease
What is Legionnaire’s disease?
a severe toxic pneumonia, infection in the lower respiratory system
What is Pontiac fever?
milder self-limiting disease infecting the upper respiratory tract; not life-threatening
How many cases/year of Legionnaire’s disease are there in the US?
25,000/year
Where was the first outbreak of Legionnaire’s disease?
1976 Philidelphia at American Legion Convention
What is the mode of transmission of Legionella pneumophila?
environmental source = gets into the water that is used in humidifiers and cooling systems »_space; distributed via airborne route (infectious aerosols) | no person-person transmission detected
How does Legionella pneumophila survive the water treatment (chlorination) and filtration system?
they form biofilms
What are the early symptoms of Legionnaire’s disease?
flu-like = difficult to diagnose patient for Legionnaire’s disease
What are the late/2nd stage symptoms of Legionnaire’s disease?
fever, cough, dyspnea, possible CP (chest pain) and/or secretory diarrhea
Where does the Type IV secretion system evolve from?
pilus
Where in the body does Legionella pneumophila survive in?
survives in macrophages
Where does the Type III secretion system evolve from?
flagella
Why does Legionella pneumophila use the Type IV secretion system? What is the benefit of this for the bacteria?
to prevent phagolysosomal fusion at the early stage of entry so bacteria is not destroyed and can multiply
Does Legionella pneumophila invade?
not cells but invades only macrophages
What is the problem in diagnosing for the presence of Legionella pneumophila?
not very sensitive and only 50% effective
What are the 2 specimens collected from the patient to perform a diagnostic test?
sputum and urine
What diagnostic test does not require specimen collection and how does it detect presence of Legionella pneumophila?
chest x-ray determines lung damage due to pathogen
How can the sputum sample be used to detect presence of Legionella pneumophila? How sensitive is this method?
use sputum by direct fluorescent antibody staining (DFA); only 50% sensitive
How can the urine sample be used to detect presence of Legionella pneumophila?
use urine to detect Legionella pneumophila sergroup 1 via ELISA
Why is culturing Legionella pneumophila not an effective diagnosis?
incubation takes 3-5 days
What is the media used to culture Legionella pneumophila?
charcoal yeast extract agar
What vaccines are available against Legionella pneumophila?
none at the moment
What antibiotics are available to treat Legionnaire’s disease?
azithromycin, fluoroquinolone, erythromycin = (Az-Fl-Er)
Which antibiotics are not recommended for use against Legionella pneumophila and why?
betalactam antibiotics because most Legionella strains produce beta-lactamases = very resistant to beta-lactam antibiotics
What are 3 prevention methods against Legionella?
check water systems regularly for Legionella | improve methods for decontaminating water systems | use sterile water
