Respiratory Microbiology (FREITAS)

Question 1

Understand the main defenses of the respiratory system, location and main function:

Answer 1

Mucociliary system: upper respiratory tract

• Function: mucus secretion and mucociliary clearance mechanism
• Includes, nasal vibrissae, action of cilia and mucous glands and globlet cells

Cough reflex: Upper respiratory tract

• Function: enhances clearance of secretions and particulates from the airways and protects from aspiration of foreign materials

Mucosal antibody: Upper respiratory tract

• Function: neutralize almost any pathogen or toxin trying to contact epithelial cells
• Mainly secretory IgA

Bronchoconstriction: Lower respiratory tract

• Function: restricts the amount of air passing into the lungs

Other Defenses: Upper and Lower respiratory tracts

• Function: kill foreign pathogens
• Includes: lactoferrin, lysozymes and a-antitrypsin

Question 2

All of the following are Upper respiratory tract defenses EXCEPT:

A. Mucociliary system

B. Cough reflex

C. Mucosal antibody

D. Bronchoconstriction

E. All of the above are upper respiratory tract defenses

Answer 2

D. Bronchoconstriction

Upper respiratory tract:

• Mucociliary system
• Cough reflex
• Mucosal antibody

Lower respiratory tract:

• Bronchoconstriction

Question 3

______ enhances clearance of secretions and particulates from the airways and protects from aspiration of foreign materials.

A. Mucociliary system

B. Cough reflex

C. Mucosal antibody

D. Bronchoconstriction

E. None of the above

Answer 3

B. Cough reflex

Question 4

_________ neutralizes almost any pathogen or toxin trying to contact epithelial cells.

A. Mucociliary system

B. Cough reflex

C. Mucosal antibody

D. Bronchoconstriction

E. None of the above

Answer 4

C. Mucosal antibody

Question 5

_______ retricts the amount of air passing into the lungs.

A. Mucociliary system

B. Cough reflex

C. Mucosal antibody

D. Bronchoconstriction

E. None of the above

Answer 5

D. Bronchoconstriction

Question 6

Which of the following functions in mucus secretion?

A. Mucociliary system

B. Cough reflex

C. Mucosal antibody

D. Bronchoconstriction

E. None of the above

Answer 6

A. Mucociliary system

Question 7

All of the following are other defenses that are located in the upper and lower respiratory tracts EXCEPT:

A. Secretory IgA

B. Lactoferrin

C. Lysozymes

D. a-antitrypsin

Answer 7

A. Secretory IgA

Mucosal antibody = IgA = upper respiratory tract

Other defenses = lactoferrin, lysozymes, a-antitrypsin = upper and lower respiratory tracts

Question 8

Virulent respiratory pathogens successfully evade the epithelial defenses by specifically __________.

Answer 8

Virulent respiratory pathogens successfully evade the epithelial defenses by specifically adhering to respiratory epithelium.

Question 9

Discuss the Sore Throat Syndrome:

• What microorganism is associated with sore throat syndrome?
  
  • What are the 6 virulence factors of this microorganism?

Answer 9

Sore Throat Syndrome

• Streptococcus Pyogenes
• Virulence factors:
  
  • Protein M
  • streptokinase
  • hyaluronidase
  • DNAse
  • capsule
  • streptolysin O

Question 10

What are the 4 complications associated with Sore Throat Syndrome?

Answer 10

1. Peritonsillar abscess: tonsillar sepsis, inflammation fo the throat (quinsy throat)

2. Sinusitis: condition where the paranasal sinuses fill w/ exudate

3. Otitis media: infection of the iddle ear; common in children

4. Scarlet fever: diffuse erythematous rash beginning on the chest and spreading to the extremities; complication of streptococcal pharyngitis (S. pyogenes) - strawberry tongue

Question 11

Discuss Rheumatic fever:

• What microorganism triggers rheumatic fever?
• What is the pathogenesis of this microorganism?
• What are the 4 affected sites?
• Laboratory diagnosis:

Answer 11

Rheumatic Fever

• Streptococcus pyogenes
• Pathogenesis:
  
  • Autoimmunity- cross-reactivity (S. pyogenes share the same antigens as heart valves)
  • Hypersensitivity type III (antibody-antigen complexes)
• Affected sites:
  
  • heart
  • kidney
  • joints and blood vessels
• Laboratory diagnosis:
  
  • Throat swabs consisting of beta-hemolytic colonies
  • Evidence for antibody to streptolysin O - produced by S. pyogenes

Question 12

S. pyogenes is _______.

A. alpha-hemolytic

B. beta-hemolytic

C. gamma-hemolytic

D. None of the above

Answer 12

B. beta-hemolytic

beta-hemolytic: complete destruction of RBCs?

Question 13

What are the two main virulence factors of S. pyogenes?

Answer 13

S. Pyogenes = Protein M and Streptolysin O

Question 14

How can Rheumatic Fever be detected in the lab?

Answer 14

Clinical: throat swabs exhibiting beta-hemolytic colonies

Serological evidence: antibody to streptolysin O (produced by S. pyogenes)

Question 15

Discuss Diphtheria:

• What is the main associated microorganism?
• _______ tends to be mild, but the infected discharge is important in the spread of disease among children.
• Pathogenesis:
  
  • ______ inhibits protein synthesis
  • Obstruction of _____ and ______

Answer 15

Diphtheria

• Associated microorganism = Corynebacterium diphtheriae
• Nasal diphtheria tends to be mild, but the infected discharge is important in the spread of disease among children
• Pathogenesis:
  
  • Diphtheria toxin - inhibits protein synthesis
  • Obstruction of airways and pharyngeal diphtheria

Question 16

Discuss Vincent’s angina:

• Predisposing factors?
• Microorganisms?
• Clinical features?

Answer 16

Vincent’s angina

Predisposing factors: poor dental health and poor oral hygiene, recurring periodontal disease, advance age, smoking or chewing tobacco and immunodeficiency

Microorganism: Borrelia vincenti in association w/ fusiform bacilli

Clinical features: soreness of mouth and gums (painful gingiva), halitosis, bleeding gums

• Progression: periodontium might be destroyed (ANUG)
• Involves all gingival margin which become covered by a necrotic pseudo membrane

Question 17

Discuss Ludwig’s angina:

• Originates from?
• Predisposing factors?
• Associated microorganisms?
• Clinical features?

Answer 17

Ludwig’s angina

Originates from an odontogenic infection (tooth abscess), especially from the 2nd or 3rd lower molars

Predisposing factors: dental caries, recent dental tx, systemic illnesses, alcoholism, AIDS, jawbone fracture, oral piercings

Associated microorganisms: S. viridans and S. aureus

Clinical features: tooth pain, fever, difficulty in swallowing and increasing stridor

• examination shows a bull-neck appearance w/ tenderness of the neck and throat

Question 18

Poor oral hygiene, recurring periodontal disease, advanced age, smoking or chewing tobacco and immunodeficiency are predisposing factors of which of the following?

A. Vincent’s angina

B. Ludwig’s angina

Answer 18

A. Vincent’s angina

Question 19

Which of the following is associated w/ Fusiform bacilli?

A. Diphtheria

B. Vincent’s angina

C. Ludwig’s angina

Answer 19

B. Vincent’s angina

Vincent’s angina = Borrelia vincenti + Fusiform bacilli

Ludwig’s angina = S. Viridans + S. aureus

Question 20

Which of the following is associated w/ S. viridans and S. aureus?

A. Diphtheria

B. Vincent’s angina

C. Ludwig’s angina

Answer 20

C. Ludwig’s angina

Vincent’s angina = Borrelia vincenti + Fusiform bacilli

Ludwig’s angina = S. Viridans + S. aureus

Question 21

Dental caries, recent dental tx, systemic illness, alcoholism, AIDS, jawbone fracture and oral piercings are predisposing factors of which of the following?

A. Vincent’s angina

B. Ludwig’s angina

Answer 21

B. Ludwig’s angina

Vincent’s angina = poor oral health and recurring periodontal disease

Ludwig’s angina = dental caries, recent dental tx

Question 22

Which of the following is associated with ANUG?

A. Vincent’s angina

B. Ludwig’s angina

Answer 22

A. Vincent’s angina

Question 23

Discuss the Common Cold Syndrome:

• Associated viruses?
• Effect in the oral cavity?

Answer 23

Common Cold Syndrome

Associated viruses: Rhinoviruses

Effect in the oral cavity: sinus pressure can hurt teeth and cause xerostomia

Question 24

Discuss Infectious mononuleosis “Mono”:

• Associated virus?
• Symptoms?

Answer 24

Infectious Mononucleosis

Associated virus = Epstein-Barr virus (EBV)

Symptoms: fever, sore throat and swollen lymph nodes and abnormal lymphocytes in blood. Tonsillitis and fatigue are common. Splenomegaly

Question 25

Discuss Enteroviral pharyngitis: * Associated virus? * What are the 3 examples of enteroviral pharyngitis and common pathologies?

Answer 25

Enteroviral pharyngitis Associated virus: **Enteroviruses (coxsackievirus or echovirus)** Examples of enteroviral pharyngitis and common pathologies: * **Herpangina = coxsackievirus type A 2-6** * **Acute lymphonodular pharyngitis = coxsackievirus type A10** * **Hand-foot and mouth disease = coxsackievirus A5, 9, 10 and 16**

Question 26

(T/F) The normal upper respiratory tract is **bacteriologically sterile**.

Answer 26

FALSE correct statement: The normal **_lower_** respiratory tract is **bacteriologically sterile**

Question 27

Discuss Bronchitis: * Associated microorganisms? * Acute bronchitis vs Chronic bronchitis:

Answer 27

**_Bronchitis_** Associated microorganisms: **influenza** and **parainfluenza** * bacterial infection is secondary after viral **Acute bronchitis**: shorter illness that commonly follows a cod or viral infection (Flu) **Chronic bronchitis**: a persistent productive cough for at least 3 consecutive months in at least 2 consecutive years * common among cigarette smokers * progress to COPD

Question 28

Discuss Chronic Obstructive Pulmonary Disease (COPD): * Associated microorganisms? * Symptoms? * Pathogenesis? * Diagnosis?

Answer 28

**_COPD_** Associated microorganisms: **S. pneumonie, H. influenza, Chlamydia pnemonie, Mycoplasma pneumonie** Symptoms: excessive mucus production and poor clearance of bronchi Pathogenesis: emphysema and chronic bronchitis **Diagnosis: sputum is always colonized with mixed upper respiratory tract flora and may contain neutrophils**

Question 29

Discuss Cystic Fibrosis: * Associated microorganisms? * Characteristics? * Oral cavity manifestation?

Answer 29

**_Cystic Fibrosis_** Associated microorganisms: **S. aureus, S. pneumoniae, Hemophilus influenzae, Pseudomonas aeruginosa** Characteristics: thick mucus that blocks the respiratory 'tubes' and traps microorganisms **Oral cavity manifestations: possible enamel defect due to antibiotic use**

Question 30

Discuss Pertussis (whooping cough): * Associated microorganism? * Who is most commonly affected? * What are the 3 stages? * Pathogenesis?

Answer 30

**_Pertussis (whooping cough)_** Associated microorganism: **Bordetella pertussis** * **Affects infants** Stages: * Catarrhalis stage * Paroxysmal stage * Convalescent stage Pathogenesis: * colonizing of the bronchial epithelium and decrease phagocytic killing * The toxin porduced by B. pertussis **paralyzes the cilia, thus impairing an important pulmonary defense**

Question 31

Discuss Pneumonia: * Infection in one or both lungs, characterized by _______ of the alveoli in the lungs. * Transmission? * Bacterial pneumonia vs Viral pneumonia:

Answer 31

**_Pneumonia_** * Infection in one or both lungs, characterized by inflammatioin of the alveoli in the lungs * Transmission: droplets **Bacterial pneumonia:** * **S. pneumonia, S. aureus, H. influenza, Legionella pneumophilia and MRSA** **Viral pneumonia:** * **Coronavirus, influenza A and B, Rhinovirus, Adenovirus and Respiratory syncytial virus**

Question 32

What are the 5 **bacteria** associated with **bacterial pneumonia**?

Answer 32

1. S. pneumonia 2. S. aureus 3. H. influenza 4. Legionella pneumophilia 5. MRSA (methicillin resistant S. aureus)

Question 33

What are the 5 viruses associated with Viral pneumonia?

Answer 33

1. Coronaviruses (MERS-CoV and SARS) 2. Influenza A and B 3. Rhinovirus 4. Adenovirus 5. Respiratory syncytial virus

Question 34

Do you expect to find bacteria or any type of microorganisms in the **lower** respiratory tract?

Answer 34

NO

Question 35

**Possible enamel defect due to antibiotic use** is an oral manifestation of which of the following? A. Bronchitis B. Cystic fibrosis C. Pertussis D. Pneumonia

Answer 35

B. Cystic fibrosis

Question 36

Discuss Severe Acute Respiratory Syndrome (SARS): * Associated microorganism? * Pathogenesis?

Answer 36

**_SARS_** Associated microorganism: SARS coronavirus Pathogenesis: virus spreads by the airborne route through droplets or aerosols. Infectivity of the virus is high during the febrile period

Question 37

Discuss Croup (laryngotracheobronchitis): * Associated microorganism: * Symptoms? * Pathogenesis? * Who is it common in?

Answer 37

**_Croup_** Associated microorganism: **parainfluenza viruses** type 1 and 2 Symptoms: harsh barking coughs, noisy breathing, restlessness and tachycardia increase as respiratory obstruction develops Pathogenesis: the virus invades epithelial cells of the tracheobronchial tree, via the binding of haemagglutinin and neuraminidase * Common in **infants**

Question 38

Discuss Influenza: * Associated microorganisms? * which one ONLY infects humans? * which one infects humans and animals? * Pathogenesis? * Symptoms?

Answer 38

Influenza: Associated microorganisms: influenza viruses type A and B * Influenza type B = ONLY humans * Influenza type A = humans and animals * type A is the major cause of pandemic and epidemic influenza infections Pathogenesis: direct person-to-person spread through acute infections * viruses favor bacteria colonization in the lung by acting on the epithelial cells of the upper respiratory tract: * removing the physical barrier which opposes the lung bacterial colonization and reducing the ciliary mucus clearance Symptoms: tracheobronchitis w/ some involvement of small airways

Question 39

What two diseases do not yet have a vaccine available for?

Answer 39

**Common cold** (Rhinovirus) and **SARS** (Coronavirus)

Question 40

(T/F) Periodontal bacteria may potentially disseminate into the lower respiratory tract causing infections.

Answer 40

True

Question 41

What are the 3 possible mechanisms of oral bacteria to promote respiratory infections?

Answer 41

**1. Aspiration of oral bacteria or pathogen into the lungs** (anaerobic bacteria in sputum) **2. Periodontal disease associated bacterial enzymes:** enzymes in saliva may alter mucosal surfaces to promote colonization and adhesion of respiratory pathogens **3. Cytokines released at the oral cavity during inflammatory response**: mediated alteration in respiratory epithelium

Question 42

What are the 5 pathogens associated to periodontal disease that may be found in infected lung fluids? * Which of these 5 pathogens may participate in initiation or progression of pneumonia?

Answer 42

1. P. gingivalis 2. Actinobacillus actinomycetemocomitans 3. Actinomyces 4. Fusobacterium nucleatum 5. S. viridans may participate in initiation or progression of pneumonia