microbio ch. 21 - respiratory system infections

What groups of organisms are common members of the normal flora of the respiratory system?

staphylococcus, corynebacterium and streptococcus species, moraxella, haemophilus species

What is the most common etiological agent of strep throat?

streptococcus pyogenes

What is the epidemiology of strep throat?

natural infections of humans only, spread through respiratory droplets, asymptomatic carriers

What are the symptoms of strep throat?

pharyngitis, pustules, fever; can be mild or asymptomatic

How can strep throat be prevented?

(b-lactam antibiotic) penicillin or erythromycin within 10 days of symptoms

Why is it important to treat within the first 10 days after the onset of symptoms for strep throat?

so that antibodies aren’t formed = at risk for streptococcal sequelea

What virulence factors are associated with Streptococcus pyogenes?

C5a peptidase, hyaluronic acid capsule, m protein, fibronectin-binding proteins, streptococcal pyrogenic exotoxins, streptolysins O and S, tissue-damaging enzymes

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: C5a peptidase

inhibits recruitment of phagocytes by destroying complement component C5a - limit attraction of wbc

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: hyaluronic acid capsule

inhibits phagocytosis - capsule of strep. pyo. is made out of hyaluronic acid

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: m protein

interferes with phagocytosis by causing inactivation of complement component C3b (normally causes opsonization and activates complement), an opsonin; involved in attachment to host cells

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: fibronectin-binding proteins (FBPs)

responsible for attachment to host cells via fibrin

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: streptococcal pyrogenic exotoxins (SPEs)

superantigens responsible for scarlet fever, toxic shock, “flesh-eating” fasciitis

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: streptolysins O and S

lyse leukocytes and erythrocytes - secretes zone of beta-homolysis

What are the functions of the virulence factors (for strep. pyo.) and how do they contribute to disease or the avoidance of the host immune response?: tissue-damaging enzymes

enhance spread of bacteria by breaking down proteins, hyaluronic acid, blood clots, and other components

 What syndromes can develop in individuals that contract strep throat?

scarlet fever, rheumatic fever, acute glomerulonephritis

What are the characteristics of scarlet fever? 

red rash, white coating on tongue 1-2 days after onset of strep throat, strawberry appearance of tongue

What virulence factor is associated with scarlet fever? 

erythrogenic toxin (type of SPE = superantigen that non-specifically activate T cells): spreads systemically

What are the characteristics of rheumatic fever? 

fever, inflammation of heart, joints, blood vessels, subcutaneous tissues (also can have chronic inflammation that damages mitral valves): symptoms appear within 1 month of untreated strep throat

What are the possible causes of rheumatic fever?

in response to infection by strep. pyo., cross-reacting antibodies (produced against antigens on a pathogen that can also recognize and bind to epitopes on our tissue) are created.

What are the characteristics of acute glomerulonephritis? 

begins abruptly 10 days after strep throat, no bacteria present, only a few strains capable of causing AGN

What are the symptoms of acute glomerulonephritis? 

fever, fluid retention, high bp, blood/protein in urine, inflammation in glomeruli (accumulation of antigen-antibody complexes that initiate inflammatory response)

What causes AGN?

strep throat - antigen/antibody complexes = symptoms

What is the etiological agent of diphtheria? 

corynebacterium diptheriae = part of normal flora (infected with lysogenic phage)

Why don’t all strains of C. diphtheriae cause the disease?

What are the symptoms of diphtheria?

sore throat, fever, formation of membrane on throat/tonsils, heart/kidney failure and paralysis possible, 10% mortality

What is the epidemiology of diphtheria?

humans primary reservoir, aerosol droplets/direct contact spread

What virulence factor is responsible for the symptoms of diphtheria?

What is the mechanism of action of the diphtheria toxin?

inactivates EF-2 (elongation factor 2): protein required for translation = protein synthesis shuts down = cell death

How is diphtheria prevented and treated?

vaccination, antiserum (solution of antibodies that bind to pathogens), penicillin or erythromycin

What are the most common agents of conjunctivitis, otitis media, and sinusitis? 

haemophilus influenze, streptococcus pneumoniae (normal flora)

How can sinusitis lead to conjunctivitis or otitis media? 

What causes the symptoms associated with conjunctivitis, otitis media, and sinusitis?

What is the most common agent of the common cold? 

rhinoviruses

What are the symptoms of the common cold? 

malaise, runny nose, sneezing, cough, sore throat, hoarseness

What measures can be taken to prevent/treat the common cold? 

no treatment except control of symptoms; handwashing, avoiding sick ppl, not touching face

What are the symptoms of adenoviral pharyngitis?

fever, sore throat, swollen lymph nodes of neck, pus on tonsils and throat = looks like strep throat

How are adenoviral pharyngitis and the common cold transmitted?

inhalation of infectious droplets

What are the three most common bacterial agents of bacterial pneumonia? 

pneumococcal, klebsiella, mycoplasmal

What are the symptoms associated with pneumococcal pneumonia? 

cough, sudden chills and fever, shortness of breath, chest pain, cyanosis, rust-colored sputum

What are the symptoms associated with klebsiella pneumonia? 

cough, repeated chills, fever, shortness of breath, chest pain, cyanosis, bloody jelly-like sputum

What are the symptoms associated with mycoplasmal pneumonia? 

gradual onset of dry cough, fever, fatigue, headache, and muscle aches

How are the agents of pneumococcal pneumonia transmitted? 

inhalation of infected droplets; colonization of alveli triggers an inflammatory response; fluid and inflammatory cells fill the alveoli

How are the agents of klebsiella pneumonia transmitted? 

inhalation of infected droplets; destruction of lung tissue and abscess formation common; infection spreads via blood to other body tissues

How are the agents of mycoplasmal pneumonia transmitted? 

inhalation of infected droplets; damage to respiratory epithelium; inflammatory response and destruction of cells via CARDS toxin

How can pneumococcal pneumonia be prevented and treated?

antibiotics; conjugate or polysaccharide vaccine

How can klebsiella pneumonia be prevented and treated?

combination of antibiotics; resistance is a problem - no vaccine

How can mycoplasmal pneumonia be prevented and treated?

antibiotics (excluding cell wall synthesis inhibitors); no vaccine available; avoid crowding in schools, etc.

What is the etiological agent of whooping cough (pertussis)?

What are the symptoms of whooping cough (pertussis)?

three stages: catarrhal (runny nose, cough, fever), paroxysmal (spasms of violent coughing that can lead to vomiting and convulsions), convalescent (less frequent coughing)

What is the epidemiology of whooping cough (pertussis)?

direct contact with respiratory secretions or inhalation of infected droplets; older children and adults have mild symptoms - more severe in kids

What is the pathogenesis of whooping cough (pertussis)? 

colonization of ciliated respiratory tract surfaces; destructive toxins produced; increased mucus along with decreased ciliary action results in the severe coughing spasms; air can enter bronchioles but not escape

What virulence factors does the bacterium of whooping cough (pertussis) possess and how do these factors contribute to disease?

what abt stuff on slide?

How can whooping cough (pertussis) be prevented/treated? 

certain antibiotics given before coughing spasm stage; acellular vaccine for immunization of infants/children; booster for adults

Why does treating a patient with antibiotics do little good after the onset of the symptoms of whooping cough (pertussis)?

What is the etiological agent of tuberculosis?

What are the symptoms of tuberculosis?

chronic fever, weight loss, cough, sputum production

What is the epidemiology of tuberculosis?

inhalation of airborne organisms; latent infections can reactivate.

What is the pathogenesis of tuberculosis? 

bacterial cells survive and multiply within alveolar macrophages; organisms may be carried to other body tissues; granulomas form.

What causes the formation of granulomas?

what abt slide stuff?

How can tuberculosis be prevented/treated? 

lengthy process requiring anti-TB medications; DOT; detection tests including tuberculin (Mantoux) skin test and interferon-gamma release assays (IGRAs) allows early treatment to limit spread; treatment of latent infections.

Why does treatment for tuberculosis extend over such a long period of time? 

How does treatment for tuberculosis being extended contribute to the emergence of drug resistant strains?

What type of microbiological stain is used to detect M. tuberculosis in clinical samples?

acid fast

How does the TB skin test work? 

What information does the TB skin test it provide?

if the person has tb or not

What are the symptoms of influenza associated infections of the lower respiratory tract? 

fever, muscle aches, lack of energy, headache, sore throat, nasal congestion, cough

What is the epidemiology of influenza? 

antigenic drift is responsible for seasonal influenza; antigenic shift is responsible for pandemic influenza.

What is the pathogenesis of influenza? 

infection of respiratory epithelium; cells destroyed and virus released to infect other cells. Secondary bacterial infection results from damaged mucociliary escalator.

What roles do the hemagglutinin and neuraminidase play during the influenza replication process?

How can influenza be prevented/treated? 

antiviral medications somewhat effective for treatment when given early in the disease; vaccines developed and given annually.

What factors contribute to the need to develop a new influenza vaccine every year? 

What is the difference between genetic shift and genetic drift?

What diseases are caused by Coronaviruses?

What specific viruses cause SARS, MERS and COVID-19?

severe coronaviruses: SARS-CoV-2, SARS-CoV, and MERS-CoV

How are SARS, MERS and COVID-19 transmitted?

alveolar damage, inflammation, fluid accumulation; cytokine storm may damage tissue.

Be familiar with the symptoms for SARS, MERS and COVID-19.

fever, muscle aches, cough; eventual respiratory distress or pneumonia

How are coronavirus infections prevented/treated?

antivirals; vaccines available to prevent COVID-19 (mRNA vaccine, paxlovid: a protease inhibitor)

What is the etiological agent of coccidioidomycosis (Valley Fever)? 

In what forms do you find the fungus (coccidioidomycosis/Valley Fever) in the environment and in human infections? 

Where is the fungus (coccidioidomycosis/Valley Fever)  found in nature? 

How is coccidioidomycosis (Valley Fever) transmitted to humans? 

inhaled arthroconidia develop into spherules that mature and rupture to release endospores, which can each develop into another spherule; inflammatory response damages tissue

What are the symptoms of coccidioidomycosis (Valley Fever)? 

fever, fatigue, cough, chest pain; less frequently, night sweats, muscle and joint pain, rash and painful nodules on extremities

How can coccidioidomycosis (Valley Fever) be treated/prevented?

antifungal medications; dust control and avoiding dust.

What is the etiological agent for histoplasmosis?

Where is the fungus (histoplasmosis) found in nature?

How is histoplasmosis transmitted to humans?

microconidia inhaled, change to yeast phase, multiply in macrophages; granulomas form; disease spreads throughout the body in people with AIDS or other immunodeficiencies.

What are the symptoms of histoplasmosis?

mild respiratory symptoms, mainly fever, cough, and chest pain; also headaches, chills, fatigue, and body aches in some patients

In what forms do you find the fungus (histoplasmosis) in nature and in human infections?