1. Microbial Diseases of the Respiratory System
Chapter 24
Microbial Diseases of the Respiratory System

2. Q&A
How do these bacteria, by growing on these particular body cells, cause the disease pertussis?

3. The Respiratory System
Learning Objectives
24-1 Describe how microorganisms are prevented from entering the respiratory system.
24-2 Characterize the normal microbiota of the upper and lower respiratory systems.

4. The Upper Respiratory System
Nose
Pharynx (throat)
Middle ear
Eustachian tubes

5. Structures of Upper Respiratory System
Figure 24.1

6. The Lower Respiratory System
Larynx
Trachea
Bronchial tubes
Alveoli
Pleura

7. Structures of Lower Respiratory System
Figure 24.2

8. Normal Microbiota of Respiratory System
Suppress pathogens by competitive inhibition in upper respiratory system
Lower respiratory system is sterile

9. What is the function of hairs in the nasal passages? 24-1
Normally, the lower respiratory tract is nearly sterile. What is the primary mechanism responsible? 24-2

10. Upper Respiratory System Diseases
Learning Objectives
24-3 Differentiate pharyngitis, laryngitis, tonsillitis, sinusitis, and epiglottitis.
24-4 List the causative agent, symptoms, prevention, preferred treatment, and laboratory identification tests for streptococcal pharyngitis, scarlet fever, diphtheria, cutaneous diphtheria, and otitis media.
24-5 List the causative agents and treatments for the common cold.

11. Upper Respiratory System Diseases
Pharyngitis
Laryngitis
Tonsillitis
Sinusitis
Epiglottitis: H. influenzae type b

12. Streptococcal Pharyngitis
Also called strep throat
Streptococcus pyogenes
Resistant to phagocytosis
Streptokinases lyse clots
Streptolysins are cytotoxic
Diagnosis by enzyme immunoassay (EIA) tests
Figure 24.3

13. Scarlet Fever Streptococcus pyogenes Pharyngitis
Erythrogenic toxin produced by lysogenized S. pyogenes

14. Diphtheria Corynebacterium diphtheriae: Gram-positive rod
Diphtheria toxin produced by lysogenized C. diphtheriae
Figure 24.4

15. Diphtheria Diphtheria membrane: Fibrin, tissue, bacterial cells
Figure 24.5

16. Diphtheria Prevented by DTaP vaccine Cutaneous diphtheria
Diphtheria toxoid
Cutaneous diphtheria
Infected skin wound leads to slow-healing ulcer

17. Otitis Media S. pneumoniae (35%) H. influenzae (20–30%)
M. catarrhalis (10–15%)
S. pyogenes (8–10%)
S. aureus (1–2%)
Incidence of S. pneumoniae reduced by vaccine
Figure 24.6

18. The Common Cold
Rhinoviruses (50%)
Coronaviruses (15–20%)

19. Which one of the following is most likely to be associated with a headache: pharyngitis, laryngitis, sinusitis, or epiglottitis? 24-3
Among streptococcal pharyngitis, scarlet fever, or diphtheria, which two diseases are usually caused by the same genus of bacteria? 24-4
Which viruses, rhinoviruses or coronaviruses, cause about half of cases of the common cold? 24-5

20. Diseases in Focus: Diseases of the Upper Respiratory System
A patient presents with fever and a red, sore throat. Later, a grayish membrane appears in the throat. Gram-positive rods were cultured from the membrane.
Can you identify infections that could cause these symptoms?

21. Lower Respiratory System Diseases
Learning Objectives
24-6 List the causative agent, symptoms, prevention, preferred treatment, and laboratory identification tests for pertussis and tuberculosis.
24-7 Compare and contrast the seven bacterial pneumonias discussed in this chapter.
24-8 List the etiology, method of transmission, and symptoms of melioidosis.

22. Lower Respiratory System Diseases
Bacteria, viruses, and fungi cause
Bronchitis
Bronchiolitis
Pneumonia

23. Pertussis (Whooping Cough)
Bordetella pertussis
Gram-negative coccobacillus
Capsule
Tracheal cytotoxin of cell wall damaged ciliated cells
Pertussis toxin
Prevented by DTaP vaccine (acellular Pertussis cell fragments)
Figure 24.7

24. Pertussis (Whooping Cough)
Stage 1: Catarrhal stage, like common cold
Stage 2: Paroxysmal stage—violent coughing sieges
Stage 3: Convalescence stage

25. Q&A
How do these bacteria, by growing on these particular body cells, cause the disease pertussis?

26. Tuberculosis Mycobacterium tuberculosis
Acid-fast rod; transmitted from human to human
Figure 24.8

27. Tuberculosis
M. bovis: <1% U.S. cases; not transmitted from human to human
M. avium-intracellulare complex infects people with late-stage HIV infection

28. Tuberculosis
Clinical Focus, p. 144

29. Tuberculosis
Figure 14.10c

30. Worldwide Distribution of Tuberculosis
Figure 24.11a

31. U.S. Distribution of Tuberculosis
Figure 24.11b

32. The Pathogenesis of Tuberculosis
Figure 24.9

33. The Pathogenesis of Tuberculosis
Figure 24.9

34. The Pathogenesis of Tuberculosis
Figure 24.9

35. The Pathogenesis of Tuberculosis
Figure 24.9

36. The Pathogenesis of Tuberculosis
Figure 24.9

37. Treatment of Tuberculosis
Treatment: Prolonged treatment with multiple antibiotics
Vaccines: BCG, live, avirulent M. bovis; not widely used in United States

38. A Positive Tuberculin Skin Test
Figure 24.10

39. Diagnosis of Tuberculosis
Tuberculin skin test screening
Positive reaction means current or previous infection
Followed by X-ray or CT exam, acid-fast staining of sputum, culturing of bacteria

40. Pneumococcal Pneumonia
Streptococcus pneumoniae
Gram-positive encapsulated diplococci
Figure 24.12

41. Pneumococcal Pneumonia
Symptoms: Infected alveoli of lung fill with fluids; interferes with oxygen uptake
Diagnosis: Optochin-inhibition test or bile solubility test; serological typing of bacteria
Treatment: Penicillin, fluoroquinolones
Prevention: Pneumococcal vaccine

42. Haemophilus influenzae Pneumonia
Gram-negative coccobacillus
Predisposing factors: Alcoholism, poor nutrition, cancer, or diabetes
Symptoms: Resemble those of pneumococcal pneumonia
Diagnosis: Isolation; special media for nutritional requirements
Treatment: Cephalosporins

43. Mycoplasmal Pneumonia
Primary atypical pneumonia; walking pneumonia
Mycoplasma pneumoniae
Pleomorphic, wall-less bacteria
Common in children and young adults
Figure 24.13

44. Mycoplasma pneumoniae
Figure 11.20

45. Mycoplasmal Pneumonia
Symptoms: Mild but persistent respiratory symptoms; low fever, cough, headache
Diagnosis: PCR and serological testing
Treatment: Tetracyclines

46. Legionellosis Legionella pneumophila Found in water
Gram-negative rod
Found in water
Transmitted by inhaling aerosols; not transmitted from human to human
Clinical Focus, p. 691

47. Legionellosis
Symptoms: Potentially fatal pneumonia that tends to affect older men who drink or smoke heavily
Diagnosis: Culture on selective media, DNA probe
Treatment: Erythromycin

48. Psittacosis (Ornithosis)
Chlamydophila psittaci
Gram-negative intracellular bacterium
Transmitted to humans by elementary bodies from bird droppings
Reorganizes into reticulate body after being phagocytized

49. Psittacosis (Ornithosis)
Symptoms: Symptoms, if any, are fever, headache, chills
Diagnosis: Growth of bacteria in eggs or cell culture
Treatment: Tetracyclines

50. Psittacosis (Ornithosis)
Figure 11.24a

51. Chlamydial Pneumonia Chlamydophila pneumoniae
Transmitted from human to human
Figure 11.24b

52. Chlamydial Pneumonia
Symptoms: Mild respiratory illness common in young people; resembles mycoplasmal pneumonia
Diagnosis: Serological tests
Treatment: Tetracyclines

53. Q Fever Causative agent: Coxiella burnetii Reservoir: Large mammals
Tick vector
Can be transmitted via unpasteurized milk

54. Coxiella burnetii, the Cause of Q Fever
Figure 24.14

55. Q Fever
Symptoms: Mild respiratory disease lasting 1–2 weeks; occasional complications such as endocarditis occur
Diagnosis: Growth in cell culture
Treatment: Doxycycline and chloroquine

56. Melioidosis Causative agent: by Burkholderia pseudomallei
Reservoir: Soil
Mainly in southeast Asia and northern Australia
Symptoms: Pneumonia, or tissue abscesses and severe sepsis
Diagnosis: Bacterial culture
Treatment: Ceftazidime

57. Diseases in Focus: Common Bacterial Pneumonias
A 27-year-old man with a history of asthma was hospitalized with a 4-day history of progressive cough and 2 days of spiking fevers. Gram-positive cocci in pairs were cultured from a blood sample.
Can you identify infections that could cause these symptoms?

58. Another name for pertussis is whooping cough
Another name for pertussis is whooping cough. This symptom is caused by the pathogens’ attack on which cells? 24-6
What group of bacterial pathogens causes what is informally called “walking pneumonia”? 24-7
The bacterium causing melioidosis in humans also causes a disease of horses known as what? 24-8

59. Lower Respiratory System Diseases
Learning Objective
24-9 List the causative agent, symptoms, prevention, and preferred treatment for viral pneumonia, RSV, and influenza.

60. Viral Pneumonia
Viral pneumonia occurs as a complication of influenza, measles, or chickenpox
Viral etiology suspected if no other cause is determined

61. Respiratory Syncytial Virus (RSV)
Common in infants; 4500 deaths annually
Causes cell fusion (syncytium) in cell culture
Symptoms: Pneumonia in infants
Diagnosis: Serological test for viruses and antibodies
Treatment: Ribavirin, palivizumab

62. Influenza (Flu) Symptoms: Chills, fever, headache, and muscle aches
No intestinal symptoms
1% mortality, very young and very old
Treatment: Zanamivir and oseltamivir inhibit neuraminidase
Prophylaxis: Multivalent vaccine

63. The Influenza Virus
Hemagglutinin (HA) spikes used for attachment to host cells
Neuraminidase (NA) spikes used to release virus from cell
Figure 24.15

64. The Influenza Virus Antigenic shift Antigenic drift
Changes in HA and NA spikes
Probably due to genetic recombination between different strains infecting the same cell
Antigenic drift
Point mutations in genes encoding HA or NA spikes
May involve only 1 amino acid
Allows virus to avoid mucosal IgA antibodies

65. Influenza Serotypes Type Antigenic Subtype Year Severity A H3N2 H1N1
1889
1918
1957
1968
1977
Moderate
Severe
Low B
None
1940 C
1947
Very mild

66. Is reassortment of the RNA segments of the influenza virus the cause of antigenic shift or antigenic drift? 24-9

67. Lower Respiratory System Diseases
Learning Objective
24-10 List the causative agent, mode of transmission, preferred treatment, and laboratory identification tests for four fungal diseases of the respiratory system.

68. Histoplasmosis
Histoplasma capsulatum, dimorphic fungus
Figure 24.16

69. Histoplasmosis Distribution
Figure 24.17

70. Coccidioidomycosis Causative agent: Coccidioides immitis
Reservoir: Desert soils of Southwest U.S.
Symptoms: Fever, coughing, weight loss
Diagnosis: Serological tests
Treatment: Amphotericin B

71. The Life Cycle of Coccidioides immitis
Figure 24.18

72. U.S. Endemic Area for Coccidioidomycosis
Figure 24.19

73. Pneumocystis Pneumonia
Causative agent: Pneumocystis jirovecii
Reservoir: Unknown; possibly humans or soil
Symptoms: Pneumonia
Diagnosis: Microscopy
Treatment: Trimethoprim

74. Figure 24.20

75. Blastomycosis Causative agent: Blastomyces dermatitidis
Reservoir: Soil in Mississippi valley area
Symptoms: Abscesses; extensive tissue damage
Diagnosis: Isolation of pathogen
Treatment: Amphotericin B

76. Other Fungi Involved in Respiratory Disease
Systemic
Predisposing factors:
Immunocompromised state
Cancer
Diabetes
Aspergillus fumigatus
Mucor
Rhizopus

77. The droppings of both blackbirds and bats support the growth of Histoplasma capsulatum; which of these two animal reservoirs is normally actually infected by the fungus? 24-10

78. Diseases in Focus: Diseases of the Lower Respiratory System
A worker was hospitalized for acute respiratory illness. He had been near a colony of bats. The mass was surgically removed. Microscopic examination of the mass revealed ovoid yeast cells.
Can you identify infections that could cause these symptoms?