Chapter 24 - Microbial Diseases of the Respiratory System Flashcards
What are the diseases of the upper respiratory tract?
-strep throat
-scarlet fever
-otitis media
-diphtheria
What is the scientific name for “strep throat”?
streptococcal pharyngitis
Which pathogen causes strep throat?
GAS (group A streptococci pyogenes)
Why is GAS so pathogenic?
have M proteins that resist phagocytosis
What are the two enzymes produced by GAS?
streptokinases and streptolysins
Streptokinases
lyse fibrin clots
Streptolysins
are cytotoxic to tissue cells, RBCs and leukocytes
What are the symptoms of strep throat?
-redness
-inflammation
-tonsilitis
-enlarged lymph nodes
How is strep throat diagnosed?
throat swab cultured on blood agar
Exudate
fluid that leaks out of blood vessels into nearby tissues made of cells and proteins
What antibiotic is used to treat strep throat?
penicillin
What is the sequel to strep throat?
scarlet fever
What is the toxin produced by S. pyogenes that results in scarlet fever?
erythrogenic toxin
Is erythrogenic toxin an endotoxin or exotoxin?
exotoxin
The strain that produced scarlet fever has bee lysogenized meaning…
the genetic information of a bacteriophage has been incorporated into the chromosomes of the bacteria, altering them
What are the symptoms of scarlet fever?
-red skin rash
-high fever
-swollen, strawberry red tongue
-red cheeks
What can scarlet fever develop into left untreated?
Rheumatic fever
S_______ P_______ E________
strep pyrogenic exotoxin
What organism is responsible for diphtheria?
Corynebacterium diphtheriae
Corynebacterium diphtheriae
-gram-positive
-rod
-pleomorphic
Diphtheria is a p__________ disease.
progressive
What kind of exotoxin does diphtheria produce?
A-B exotoxin
What does the diphtheria exotoxin do?
circulate in blood and damage heart and kidneys
Diphtheria Phase I Symptoms
-mild fever
-sore throat
-fatigue
-swelling of the neck
What is used to treat phase I diphtheria?
erythromycin
Diphtheria Phase II Symptoms
-fluid oozes out that thickens and coats the respiratory tract
-resulting in a PSEUDOMEMBRANE
How is a pseudomembrane removed?
surgical removal
Diphtheria Phase III Symptoms
-pseudomembrane covers respiratory tract and occludes airways
-leads to possible suffocation or death
How is diphtheria phase III treated?
-tracheostomy tube
What does the D in ‘‘DTaP’’ stand for?
-diphtheria toxoid, an inactivated toxin
-produced antibodies against diphtheria toxin
What is cutaneous diphtheria?
-ulcer or skin lesion
-covered with a grey membrane
What circulatory symptom sets in with cutaneous diphtheria?
septicemia
What do antibiotics need to be mixed with when treating diphtheria? Why?
-antitoxin
-antibiotics don’t neutralize diphtheria toxin
What is a common complication of respiratory tract infections?
otitis media
What is otitis media?
middle infection ear
Otitis media affects ___% of children before age 3.
85%
What forms that puts pressure on the ear drum and causes pain?
pus
What is used to treat otitis media?
semi-synthetic penicillin aka amoxicillin
What are some of the bacteria that cause otitis media?
-S. pneumoniae
-H. influenzae
-Moraxella sp.
-S. pyogenes
-viruses (RSV)
What is the most common cause of otitis media?
S. pneumoniae
What is another name for pertussis?
whooping cough
Pertussis is an infection of the _________ respiratory tract.
lower
What pathogen causes pertussis?
Bordetella pertussis
Bordetella pertussis
-obligate aerobe
-gram-negative
-coccobacilli
-has a capsule
How and where does pertussis attach?
-by a capsule
-to ciliated cells in the trachea
What does the aP in “DTaP” stand for?
acellular pertussis
What are the toxins produced by pertussis?
-tracheal cytotoxin
-pertussis toxin
What do the pertussis toxins produce?
-damage to ciliated cells
-mucus
Does pertussis produce an endotoxin?
yes
Stage I Pertussis: Catarrhal Stage
-resembles common cold: fever (endotoxin) and runny nose
Stage II Pertussis: Paroxysmal Stage
-violent coughing bouts that can cause broken ribs, bloodshot eyes, and even a small brain hemorrhage
Stage III Pertussis: Convalescence Stage
-lasts weeks/moths of coughing
What antibiotic commonly treats pertussis?
erythromycin
What bacteria causes tuberculosis?
Mycobacterium tuberculosis
Mycobacterium tuberculosis
-rod
-obligate aerobe
-acid-fast
How does TB affect healthy individuals?
-hardly at all
-innate immunity by macrophages arrest the disease
TB Partial Immunity Failure
-symptoms may appear
-tubercule forms with calcified lesions
What are GHON complexes?
-healed calcified lesions that are seen on X-ray films
TB Total Immunity Failure
-tubercule breaks and bacilli spread into the circulatory and lymphatic systems
Miliary Tuberculosis
-TB consumes the patient
-defenses are overwhelmed
What are the symptoms of miliary TB?
-loss of weigh and rigour
-productive, bloody cough
What is the tuberculin skin test?
-protein mycobacterium derivative injected into forearm
-if a reaction occurs, progression of TB is measured
How long does TB treatment take?
~9 months
Why is multiple-drug therapy needed for TB?
minimize emergence of resistant strains
First-line TB Drugs
- Isoniazid
- Ethambutol
- Rifampin
- Pyrazinamide
What does the first-line do?
suppress cell wall synthesis
Second-line TB Drugs
- Aminoglycosides
- Fluoroquinolones
- Streptomycin
- Para-aminosalicylic acid
Multi-Drug-Resistant (MDR) TB Strains
-resist first line drugs rifampin and isoniazid
Extensively Drug-Resistant (XDR) TB Strains
-resist second line
-virtually untreatable
Is there a TB vaccine?
-yes, Bacilli Calmette Guérin (BCG) Vaccine
What is pneumonia?
-pulmonary (lung) infection
-inflammation
-alveoli fill with fluid
Pneumonia is a common _________ infection.
nosocomial (HAI)
What is the most common pathogenic cause of pneumonia?
Streptococcus pneumoniae
What causes typical pneumonia?
Streptococcus pneumoniae
Streptococcus pneumoniae
-has a capsule
-gram-positive
What is another name for typical pneumonia?
Pneumococcal pneumonia
How many strains of S. pneumoniae exist? How many have a vaccine?
90 exist, 20 have a vaccine
What are the symptoms of pneumococcal pneumonia?
-high fever
-difficulty breathing
-chest pain
-rust coloured sputum (blood containing) is coughed up
Does pneumococcal pneumonia have a toxin?
no
What are some susceptible populations to pneumococcal pneumonia?
-COPD patients
-diabetics
-kidney disease patients
-people who smoke/drink
-HIV patients
Where does pneumococcal pneumonia first invade? (Hint: circulatory)
bloodstream
Where does pneumococcal pneumonia invade second? (Hint: lungs)
pleural cavity surrounding the lungs
What can pneumococcal pneumonia invade and cause disease in some cases?
meninges, causing meningitis
What are some other causes of Streptococcus pneumoniae?
-pneumonia
-meningitis
-otitis media
-sepsis
What was typical pneumonia treated with before resistance was developed?
cephalosporin
How is pneumococcal pneumonia diagnosed?
presence of capsular antigen in urine
Does pneumococcal pneumonia have a vaccine?
yes, conjugated pneumococcal vaccine
What is typical pneumonia now usually treated with?
macrolides
What are the possible causes of Atypical pneumonia?
-fungi
-protozoa
-viruses
-other bacteria
What is the symptom difference for atypical pneumonia rather than typical?
-Atypical has slower onset, less fever and chest pain
What are some bacteria that cause atypical pneumonia?
-Haemophilus influenzae
-Mycoplasma pneumoniae
-Legionella pneumophila
-Coxiella burnetti
What is the primary atypical pneumonia cause?
mycoplasma pneumoniae
Haemophilus influenzae
-gram-negative
-coccobacillus
How is H. influenzae pneumonia diagnosed?
-chocolate agar media culture
-recall X and V factors
What is used to treat H. influenzae pneumonia?
cephalosporins
What is the drug of choice for H. influenzae pneumonia?
3rd gen cephalosporins
What is the HiB vaccine used for?
H. influenzae
Mycoplasmas do not have ____ _____
cell walls
What is walking pneumonia?
mycoplasmal pneumonia
What is the drug of choice for mycoplasmal pneumonia?
tetracycline
Legionella pneumophila
-gram-negative
-aerobic
-rod
-replicates in macrophages
Is person-to-person transmission possible with L. pneumophila?
no
What is L. pneumophila also responsible for?
pontiac fever
What does coxiella burnetti cause?
Q fever
Coxiella burnetti is the only gram-______ that has ________
gram-negative; endospores
Acute Q Fever Symptoms
-high fever
-muscle aches
-headache
-coughing
Chronic Q Fever Symptoms
endocarditis (may occur years later)
How is Q fever transmitted?
inhalation of aerosols from animals and unpasteurized milk
What is used to treat Q fever?
-doxycycline
-tetracycline
What is a virus that commonly causes viral pneumonia?
Respiratory Syncytial Virus (RSV)
What ages groups does RSV usually affect?
infants and elderly
Syncytium
-formed by RSV
-fusion of cells to create giant cells in the lungs
Why was RSV called ‘Houdini Virus’?
it escaped the immune system
RSV Symptoms
-persistent coughing and wheezing
-fever only with bacterial complications
-bronchiolitis
RSV Treatment
-prophylaxis
-palivizumab
What are influenza symptoms?
-chills
-fever
-headache
-muscular-aches
-coldlike symptoms post fever
Is “stomach-flu” really the flu?
-no, influenza has no GI symptoms
-it is probably gastroenteritis
What kind of spikes does influenza have?
hemagglutination (HA) and neuraminidase (NA) spikes
What do HA spikes do?
allow virus to recognize and attach to body cells
What do NA spikes do?
-use enzymes to help virus separate from infected cell after reproduction
Spikes account for the ___________ changes that makes influenza have many ___________
antigenic; variations
Antigenic Drift
-minor change in genome spikes
Antigenic Shift
-major change in genome
-evades most immunity
Influenza vaccines are usually m_____valent
multivalent
Multivalent
-directed at 3 or 4 most important strains currently circulating
What are some disadvantages to the multivalent vaccine for influenza?
-hard to produce
-no long-term immunity
What is influenza treated with?
-zanamivir
-oseltamivir
What is the goal of antivirals on influenza?
inhibit neuraminidase
