Microbiology of the Respiratory System

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Questions and Answers

What is the primary role of normal microbiota in the upper respiratory system?

To produce mucus for filtering air

To suppress pathogens through competitive inhibition (correct)

To break down particulate matter in the air

To aid in gas exchange in alveoli

Which of the following statements about the lower respiratory system is true?

It is the primary site of pathogen growth.

It contains a diverse range of microbiota.

It has a higher density of immune cells than the upper respiratory system.

It is predominantly sterile under normal conditions. (correct)

What role do alveolar macrophages play in respiratory health?

They exercise competitive inhibition against bacteria.

They facilitate the exchange of oxygen and carbon dioxide.

They produce mucus to trap pathogens.

They serve as a first line of defense against inhaled pathogens. (correct)

What is the primary function of hairs in the nasal passages?

To filter and trap particles from inhaled air Signup and view all the answers

How does competitive inhibition help maintain respiratory health?

It allows beneficial microbes to outcompete harmful pathogens. Signup and view all the answers

What type of bacteria causes diphtheria?

Corynebacterium diphtheriae Signup and view all the answers

Which symptom is associated with diphtheria?

Gray membrane formation in the throat Signup and view all the answers

How is diphtheria primarily treated?

Antibiotics and antitoxins Signup and view all the answers

What vaccine is used to prevent diphtheria?

DTaP vaccine Signup and view all the answers

Which of the following is a common pathogen associated with otitis media?

Haemophilus influenzae Signup and view all the answers

Which anatomical structure is NOT part of the lower respiratory system?

Tonsils Signup and view all the answers

What is the function of the epiglottis in the respiratory system?

To prevent food from entering the trachea Signup and view all the answers

Which of the following structures serves as a voice box in the lower respiratory system?

Larynx Signup and view all the answers

Which structure is responsible for conducting air from the throat to the lungs?

Trachea Signup and view all the answers

What role do bronchioles have in the respiratory system?

They distribute air to the alveoli Signup and view all the answers

Which part of the respiratory system is primarily involved in gas exchange?

Alveoli Signup and view all the answers

What anatomical structure connects the pharynx to the lungs?

Trachea Signup and view all the answers

Which component is responsible for regulating airflow in the respiratory system?

Bronchioles Signup and view all the answers

What is the primary causative agent of streptococcal pharyngitis?

Streptococcus pyogenes Signup and view all the answers

Which symptom is NOT commonly associated with streptococcal pharyngitis?

Coughing Signup and view all the answers

What is the recommended treatment for streptococcal pharyngitis?

Penicillin Signup and view all the answers

What complication can arise from untreated streptococcal pharyngitis?

Scarlet fever Signup and view all the answers

How is the diagnosis of streptococcal pharyngitis commonly confirmed?

Enzyme immunoassay (EIA) tests Signup and view all the answers

Which factor contributes to the virulence of Streptococcus pyogenes?

Cytotoxic streptolysins Signup and view all the answers

Which other condition is commonly associated with streptococcal pharyngitis?

Otitis media Signup and view all the answers

Which of the following statements about scarlet fever is correct?

It is caused by a toxin from Streptococcus pyogenes. Signup and view all the answers

Which bacterial species is associated with the appearance of a grayish membrane in the throat?

Corynebacterium diphtheriae Signup and view all the answers

Which of the following diseases is NOT routinely prevented through childhood immunization?

Streptococcus pyogenes infection Signup and view all the answers

What is the characteristic feature of Bordetella pertussis?

Gram-negative coccobacillus Signup and view all the answers

During which stage of whooping cough do prolonged coughing fits with a 'whooping' sound occur?

The paroxysmal stage Signup and view all the answers

What is the transmission route for Mycobacterium tuberculosis?

Airborne transmission Signup and view all the answers

What type of bacteria is known for having a capsule and damaging ciliated cells in the respiratory tract?

Bordetella pertussis Signup and view all the answers

Which of the following respiratory diseases is caused by an acid-fast rod?

Tuberculosis Signup and view all the answers

What is a common symptom of infections caused by Streptococcus pyogenes?

Sore throat and fever Signup and view all the answers

Which virus is NOT typically associated with the common cold?

Simplex virus Signup and view all the answers

What percentage of common cold cases is caused by rhinoviruses?

30–50% Signup and view all the answers

Which complication is NOT commonly associated with the common cold?

Pneumonia Signup and view all the answers

Which of the following is true regarding treatment for the common cold?

Cough suppressants can reduce discomfort Signup and view all the answers

How long do symptoms of the common cold typically last?

5-7 days Signup and view all the answers

Which type of coronavirus is associated with the common cold?

Alphacoronavirus Signup and view all the answers

What is the approximate percentage of common colds caused by coronaviruses?

10–15% Signup and view all the answers

Which symptom is most explicitly linked to a complication of the common cold?

Headache Signup and view all the answers

Study Notes

Normal Microbiota of the Respiratory System

Suppress pathogens through competitive inhibition in the upper respiratory system
The lower respiratory system is generally sterile, primarily due to alveolar macrophages

Test Your Understanding (Respiratory Tract)

Nasal hairs function to filter inhaled air
Lower respiratory tract is mostly sterile due to the actions of alveolar macrophages

Test Your Understanding (Respiratory Diseases)

The lower respiratory system is comprised of the lungs, bronchi, and trachea
The pharynx is part of the upper respiratory system

Streptococcal Pharyngitis (Strep Throat)

Causative agent: Streptococcus pyogenes
Resistant to phagocytosis
Symptoms: local inflammation and fever; swelling of tonsils and potential ear infections
Diagnosis via enzyme immunoassay (EIA) tests
Treatment: penicillin
Scarlet fever: related condition with pink-red rash and fever, produced by erythrogenic toxins from lysogenized S. pyogenes.

Diphtheria

Causative agent: Corynebacterium diphtheriae, gram-positive rod
Symptoms: sore throat, fever, malaise, swelling of the neck; gray membrane formation
Diagnosis via tests for presence of diphtheria toxin
Treatment: antibiotics and antitoxins
Prevention through DTaP vaccine (diphtheria toxoid)

Otitis Media

Common bacterial causes:
- S. pneumoniae
- H. influenzae
- M. catarrhalis
- S. pyogenes
- S. aureus
Incidence of S. pneumoniae reduced by vaccine

Common Cold

Primarily caused by rhinoviruses (~30-50%) and coronaviruses (~10-15%)
Symptoms last about a week, with complications possible such as laryngitis and otitis media
Cough suppressants and antihistamines can ease discomfort, but don't hasten recovery

Upper Respiratory Diseases

Pharyngitis (sore throat)
Laryngitis (inflammation of larynx)
Tonsillitis (inflammation of tonsils)
Sinusitis (inflammation of sinuses)
Epiglottitis (inflammation of epiglottis), often due to H. influenzae type b

Lower Respiratory System Diseases- Pertussis (Whooping Cough)

Causative agent: Bordetella pertussis
Symptoms characterized by stages including catarrhal, paroxysmal, and convalescent
Severity in paroxysmal stage with prolonged coughing
Transmission through airborne droplets
Prevention through DTaP vaccine (acellular Pertussis cell fragments)

Tuberculosis

Causative agent: Mycobacterium tuberculosis
Transmitted human-to-human, with a <1% rate from M. bovis
Symptoms can vary from initial infection to a mature tubercle
Diagnosis involves microscopic examination of sputum, blood tests, and skin tests.
Treatment is prolonged (6+ months) multiple antibiotic treatment

Detection of Tuberculosis

Microscopic examination of sputum
Blood tests, measuring release of IFN-y from white blood cells
Nucleic acid amplification tests (NAATs)
Skin test

Pneumonia (General)

Infectious inflammation of the alveoli (air sacs of lungs) characterized by fluid accumulation.
Bacterial, viral, or fungal causes

Haemophilus influenzae Pneumonia

Predisposing factors: alcoholism, poor nutrition, cancer, diabetes
Symptoms resemble pneumococcal pneumonia
Diagnosis by isolation, special media (X and V factors)
Treatment: cephalosporins

Pneumococcal Pneumonia

Causative agent: Streptococcus pneumoniae (encapsulated diplococci)
Symptoms: infected alveoli, fluid accumulation interfering with oxygen uptake
Diagnosis: optochin-inhibition test, bile solubility test, or serological typing tests on bacteria
Treatment: macrolides, fluoroquinolones
Prevention: pneumococcal vaccines

Mycoplasmal Pneumonia

Causative agent: Mycoplasma pneumoniae (wall-less bacteria)
Symptoms: generally mild, respiratory symptoms, cough, headache
Diagnosis: PCR, serological (IgM) testing
Treatment: tetracyclines

Legionellosis

Causative agent: Legionella pneumophila
Transmitted by inhaling aerosols; not by person-to-person
Symptoms: potentially fatal pneumonia
Diagnostic methods: culture on selective media, DNA probe
Treatment: erythromycin

Psittacosis (Ornithosis)

Causative agent: Chlamydophila psittaci
Transmitted to humans by elementary bodies from bird droppings; reorganizes into reticulate body in host cells
Symptoms: fever, headache, chills
Diagnosis via bacteria growth in eggs or cell cultures
Treatment: tetracyclines

Pontiac Fever

Causative agent: Legionella pneumophila
Mild respiratory infection characterised by fever, muscle aches, and cough
Self-limiting condition

Chlamydial Pneumonia

Causative agent: Chlamydophila pneumoniae
Transmitted from person to person
Affects mostly young people
Symptoms resembling mycoplasmal pneumonia
Diagnosis via serological tests
Treatment: tetracyclines

Q Fever

Causative agent: Coxiella burnetii
Reservoir: large mammals; can be contracted from unpasteurized milk
Symptoms: mild respiratory disease, complications include endocarditis
Diagnosis by detection in cell culture
Treatment: doxycycline

Melioidosis

Causative agent: Burkholderia pseudomallei
Reservoir: soil
Symptoms are pneumonia or tissue abscesses, and severe sepsis
Diagnosis: bacterial culture
Treatment: ceftazidime

Pneumocystis Pneumonia

Causative agent: Pneumocystis jirovecii
Symptoms: Pneumonia, few symptoms if unaffected immune system
Diagnosis: microscopy
Treatment: trimethoprim

Blastomycosis

Causative agent: Blastomyces dermatitidis
Reservoir: soil in the Mississippi valley
Symptoms: abscesses, cutaneous ulcers, extensive tissue damage
Diagnosis: Isolation of pathogen from pus or biopsy specimens.
Treatment: amphotericin B

Coccidioidomycosis

Causative agent: Coccidioides immitis (Valley fever)
Reservoir: desert soils of the southwestern U.S.
Symptoms: chest pain, fever, and cough
Diagnosis: serological tests.
Treatment: amphotericin B.

Case Studies

(These are presented in the provided text but need details for specific notetaking)

COVID-19

Causative agent: Betacoronavirus SARS-CoV-2
Transmission: droplets or aerosols
Symptoms: range from minor to severe
Diagnostic methods: home ELISA test kits, PCR
Treatment: varying, including remdesivir, Paxlovid, and convalescent plasma

Respiratory Syncytial Virus (RSV)

Common in infants; causes significant respiratory infections
Causes cell fusion (syncytium) in cell culture
Symptoms: pneumonia in infants
Diagnosis: serological test
Treatment: ribavirin, palivizumab

Influenza (Flu)

Symptoms: chills, fever, aches.
Transmission: airborne droplets
Diagnosis: PCR or serological test
Treatment: zanamivir, oseltamivir
Prophylaxis: multivalent vaccine

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Description

Explore the role of normal microbiota in the respiratory system, including how they suppress pathogens. Understand the structure of the respiratory tract and related diseases like Streptococcal Pharyngitis. This quiz will test your knowledge of critical concepts and details in respiratory microbiology.