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Questions and Answers
What is a primary purpose of the upper respiratory system?
What is a primary purpose of the upper respiratory system?
- Ventilation and gas exchange
- Nutrient absorption
- Warm and moisten air (correct)
- PH regulation
What structures are part of the lower respiratory system?
What structures are part of the lower respiratory system?
- Nose and pharynx
- Oral cavity and esophagus
- Trachea and bronchi (correct)
- Tonsils and adenoids
Which of the following is not a protective factor of the respiratory system?
Which of the following is not a protective factor of the respiratory system?
- Hemolysis (correct)
- Secretory immunoglobulin
- Nasal hair
- Mucus production
Which bacterium is usually part of the normal upper respiratory flora?
Which bacterium is usually part of the normal upper respiratory flora?
What role do defensins play in the respiratory system?
What role do defensins play in the respiratory system?
Which fungus is commonly found in the upper respiratory system?
Which fungus is commonly found in the upper respiratory system?
Which of the following bacteria are occasionally found in the upper respiratory tract?
Which of the following bacteria are occasionally found in the upper respiratory tract?
Which statement is true regarding the nasal hair in the respiratory system?
Which statement is true regarding the nasal hair in the respiratory system?
Which of the following pathogens is associated with producing toxins?
Which of the following pathogens is associated with producing toxins?
What is the cause for acute epiglottitis which may lead to life-threatening upper airway obstruction?
What is the cause for acute epiglottitis which may lead to life-threatening upper airway obstruction?
When are viral respiratory tract infections most commonly observed?
When are viral respiratory tract infections most commonly observed?
Which population groups are more likely to develop complications from respiratory tract infections?
Which population groups are more likely to develop complications from respiratory tract infections?
Why is mechanical clearance important in the respiratory tract?
Why is mechanical clearance important in the respiratory tract?
Which of the following is NOT listed as a primary pathogen for respiratory infections?
Which of the following is NOT listed as a primary pathogen for respiratory infections?
Which bacterium is an obligate intracellular pathogen causing pneumonia?
Which bacterium is an obligate intracellular pathogen causing pneumonia?
What is a common trait of Group A β-hemolytic streptococci?
What is a common trait of Group A β-hemolytic streptococci?
Which factor can lead to decreased clearance of respiratory secretions?
Which factor can lead to decreased clearance of respiratory secretions?
Which of the following is most commonly associated with sinusitis?
Which of the following is most commonly associated with sinusitis?
What distinguishes bronchiectasis from a normal bronchus?
What distinguishes bronchiectasis from a normal bronchus?
What is the preferred method of specimen collection for diagnosing pharyngitis?
What is the preferred method of specimen collection for diagnosing pharyngitis?
Which of the following infections is NOT listed under upper respiratory tract infections?
Which of the following infections is NOT listed under upper respiratory tract infections?
Which pathogen is most commonly linked to epiglottitis?
Which pathogen is most commonly linked to epiglottitis?
What is the primary consequence of pharyngitis caused by Group A Streptococci?
What is the primary consequence of pharyngitis caused by Group A Streptococci?
Which laboratory diagnostic method is used to confirm pertussis?
Which laboratory diagnostic method is used to confirm pertussis?
Which hemolysin is oxygen-labile?
Which hemolysin is oxygen-labile?
Which of the following pathogens is less common in causing otitis media?
Which of the following pathogens is less common in causing otitis media?
What specific function does the M protein of Group A Streptococci perform?
What specific function does the M protein of Group A Streptococci perform?
Which of the following pathogens is less commonly associated with sinusitis?
Which of the following pathogens is less commonly associated with sinusitis?
Which upper respiratory tract infection can be caused by rhinovirus?
Which upper respiratory tract infection can be caused by rhinovirus?
What causes β-hemolysis in Group A Streptococci?
What causes β-hemolysis in Group A Streptococci?
What function does the capsule of the pneumococcal organism serve?
What function does the capsule of the pneumococcal organism serve?
Which of the following represents the result of a pneumococcal infection?
Which of the following represents the result of a pneumococcal infection?
Which diagnostic test involves the use of antiserum to cause capsule swelling?
Which diagnostic test involves the use of antiserum to cause capsule swelling?
Why is blood drawn during the diagnosis of a pneumococcal infection?
Why is blood drawn during the diagnosis of a pneumococcal infection?
Which organisms are commonly seen in a smear from a pneumococcal infection?
Which organisms are commonly seen in a smear from a pneumococcal infection?
What is the primary specimen collection method for diagnosing pharyngitis due to streptococci?
What is the primary specimen collection method for diagnosing pharyngitis due to streptococci?
What medium is used for culture when diagnosing pneumococcal infection from sputum samples?
What medium is used for culture when diagnosing pneumococcal infection from sputum samples?
Which pathogens are commonly associated with pharyngitis in adults?
Which pathogens are commonly associated with pharyngitis in adults?
Which toxins are involved in the adhesion and colonization of ciliated epithelial cells in the trachea?
Which toxins are involved in the adhesion and colonization of ciliated epithelial cells in the trachea?
What specific function does the tracheal cytotoxin perform in the pathogenesis of upper respiratory tract infections?
What specific function does the tracheal cytotoxin perform in the pathogenesis of upper respiratory tract infections?
During which stage of whooping cough is the patient highly infectious but not very ill?
During which stage of whooping cough is the patient highly infectious but not very ill?
What is the most sensitive diagnostic method for pertussis?
What is the most sensitive diagnostic method for pertussis?
Which substance causes necrosis of the epithelium and contributes to peribronchial inflammation and interstitial pneumonia?
Which substance causes necrosis of the epithelium and contributes to peribronchial inflammation and interstitial pneumonia?
What causes the frequency of convulsions in infants with whooping cough?
What causes the frequency of convulsions in infants with whooping cough?
What type of inflammation is associated with pertussis and may result from necrosis of epithelial cells?
What type of inflammation is associated with pertussis and may result from necrosis of epithelial cells?
What chemical substances are NOT involved in the pathogenesis of upper respiratory tract infections caused by Bordetella pertussis?
What chemical substances are NOT involved in the pathogenesis of upper respiratory tract infections caused by Bordetella pertussis?
Which of the following tests is NOT mentioned as useful for the laboratory diagnosis of Streptococcus pyogenes pharyngitis?
Which of the following tests is NOT mentioned as useful for the laboratory diagnosis of Streptococcus pyogenes pharyngitis?
What is the typical medium used for culturing Bordetella pertussis?
What is the typical medium used for culturing Bordetella pertussis?
Which characteristic is associated with virulent Bordetella pertussis?
Which characteristic is associated with virulent Bordetella pertussis?
Which antibiotic is recommended for the treatment of Streptococcus pyogenes pharyngitis?
Which antibiotic is recommended for the treatment of Streptococcus pyogenes pharyngitis?
What type of bacterium is Bordetella pertussis?
What type of bacterium is Bordetella pertussis?
Which of the following is a key diagnostic differentiation mentioned for Bordetella pertussis?
Which of the following is a key diagnostic differentiation mentioned for Bordetella pertussis?
What capability does the IgG binding protein have?
What capability does the IgG binding protein have?
How is pharyngitis most commonly transmitted?
How is pharyngitis most commonly transmitted?
Which test is most important for the serologic diagnosis of Streptococcus pyogenes infections?
Which test is most important for the serologic diagnosis of Streptococcus pyogenes infections?
What is used to prevent recurrences of Acute Rheumatic Fever (ARF) in susceptible ages?
What is used to prevent recurrences of Acute Rheumatic Fever (ARF) in susceptible ages?
What does Group A streptococci sometimes produce that can interfere with opsonization?
What does Group A streptococci sometimes produce that can interfere with opsonization?
Which age group is most affected by Group A streptococci causing pharyngitis?
Which age group is most affected by Group A streptococci causing pharyngitis?
Which indirect method is used to diagnose Streptococcus beta hemolytic -group A strains?
Which indirect method is used to diagnose Streptococcus beta hemolytic -group A strains?
What kind of procedures should patients with a history of Acute Rheumatic Fever receive antimicrobial prophylaxis for?
What kind of procedures should patients with a history of Acute Rheumatic Fever receive antimicrobial prophylaxis for?
Which antigens are included in most acellular pertussis vaccines?
Which antigens are included in most acellular pertussis vaccines?
Bordetella parapertussis can cause a disease similar to which condition?
Bordetella parapertussis can cause a disease similar to which condition?
Which characteristic helps differentiate Streptococcus pneumoniae from viridans streptococci?
Which characteristic helps differentiate Streptococcus pneumoniae from viridans streptococci?
What is the function of the polysaccharide capsule in Streptococcus pneumoniae?
What is the function of the polysaccharide capsule in Streptococcus pneumoniae?
What distinguishes the cell wall of Streptococcus pneumoniae?
What distinguishes the cell wall of Streptococcus pneumoniae?
Which of the following infections can be caused by Streptococcus pneumoniae?
Which of the following infections can be caused by Streptococcus pneumoniae?
What is the range of communicability for patients in the early catarrhal stage of pertussis?
What is the range of communicability for patients in the early catarrhal stage of pertussis?
Why does Streptococcus pneumoniae rapidly become gram-negative with age?
Why does Streptococcus pneumoniae rapidly become gram-negative with age?
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Study Notes
Upper Respiratory Tract Infections
Pathogenesis of Pneumococcal Infection
- Pneumococcal infection causes an outpouring of edema fluid into the alveoli, followed by red blood cells and leukocytes, resulting in consolidation of portions of the lung.
- Many pneumococci may reach the bloodstream via lymphatic drainage of the lungs.
Diagnostic Laboratory Tests for Pneumococcal Infection
- Blood is drawn for culture; CSF and sputum are collected.
- Stained smears of sputum show typical organisms, many PMNs, and many RBCs.
- Capsule swelling tests (quellung reaction) are used to identify the organism.
- Culture is created by sputum cultured on blood agar and incubated in CO2 or a candle jar.
Quellung (Swelling) Reaction
- The quellung reaction is used to identify pneumococci.
- When pneumococci of a certain type are mixed with specific antipolysaccharide serum of the same type or with polyvalent antiserum, the capsule swells.
Primary Pathogens in the Respiratory Tract
- Streptococcus pneumoniae
- Group A β-hemolytic streptococci
- Neisseria meningitidis
- Neisseria gonorrhoeae
- Bordetella pertussis
- Mycobacterium tuberculosis
- Legionella pneumophila
- Toxin-producing Corynebacterium diphtheriae
- Mycoplasma pneumoniae
- Chlamydia trachomatis
- Chlamydophila pneumoniae
Host Risk Factors for Infection
- Immune status of the host
- Infection-induced airway obstruction
- Age (infants and the elderly are more susceptible to certain respiratory tract infections)
- Reduced clearance of secretions
Seasonal and Community Trends in Infections
- Certain types of respiratory tract infections have peak seasonal incidences and may occur in epidemics in the community.
Normal Nasopharyngeal and Oropharyngeal Organisms
- Streptococcus mitis and other alpha-hemolytic streptococci
- Non-group A beta-hemolytic streptococci
- Streptococcus pneumonia
- Streptococcus salivarius
- Veillonella spp.
- Bacteroides spp.
- Fusobacterium spp.
- Prevotella spp.
- Coagulase-negative staphylococci
- Neisseria spp.
- Nonhemolytic streptococci
- Diphtheroids
- Micrococcus
- Eikenella spp.
- Capnocytophaga spp.
- Haemophilus influenzae
- Haemophilus parainfluenzae
- Peptostreptococcus
- Actinomycetes
- Staphylococcus aureus
- Mycoplasma
- Candida spp.
- Herpes simplex
Bordetella pertussis
Morphology and Identification
- Gram-negative, aerobic, pathogenic, encapsulated coccobacillus
- Bipolar metachromatic granules can be demonstrated
Culture
- Bordet-Gengou medium (potato-blood-glycerol agar)
- Nonmotile
Growth Characteristics
- Oxidase and catalase positive
- Hemolysis is associated with virulent B. pertussis
Prevention
- Multiple acellular pertussis vaccines are licensed
- The vaccines have at least two of the following antigens: inactivated pertussis toxin, filamentous hemagglutinin, fimbrial proteins, and pertactin
Epidemiology and Control
- The source of infection is usually a patient in the early catarrhal stage of the disease
- Communicability is high, ranging from 30-90%
Streptococcus pyogenes
Morphology and Identification
- Spherical or ovoid cells in chains
- Hemolysis is caused by either of two hemolysins, Streptolysin S and the oxygen-labile Streptolysin O
Structure
- M protein itself is a fibrillar coiled-coil molecule
- M protein has antigenicity and the capacity to bind other molecules such as fibrinogen, serum factor H, and Fc part of IgG
Pharyngitis
- Group A streptococci are the most common bacterial cause of pharyngitis in school-age children
- Transmission is person to person from the large droplets produced by infected persons during coughing, sneezing, or even conversation
- Asymptomatic carriers (1%) may also be the source, particularly if colonized in the nose as well as the throat
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