Chapter 21 Infectious Diseases of the Respiratory System.

Chapter 21 Chapter 21

Infectious Diseases of the Infectious Diseases of the Respiratory System Respiratory System

Diseases of the Upper Diseases of the Upper Respiratory TractRespiratory Tract

A. Rhinitis (Common Cold)A. Rhinitis (Common Cold)

1. Most often caused by Rhinoviruses1. Most often caused by Rhinoviruses

A) Cause 30-50% of common coldsA) Cause 30-50% of common colds

B) There are more than 100 types of B) There are more than 100 types of rhinovirusesrhinoviruses

2. Unlike bacterial infections, there is 2. Unlike bacterial infections, there is typically no sign of fever but malaise, typically no sign of fever but malaise, scratchy throat, runny nose and scratchy throat, runny nose and cough are frequently exhibitedcough are frequently exhibited


3. Frequent hand-washing and avoiding 3. Frequent hand-washing and avoiding people with colds are the best people with colds are the best preventative measures; there is no preventative measures; there is no vaccine vaccine

4. Most treatments alleviate the 4. Most treatments alleviate the symptoms but don’t affect the virussymptoms but don’t affect the virus


B. Otitis Media & SinusitisB. Otitis Media & Sinusitis

1. Bacterial infections of the middle ear and 1. Bacterial infections of the middle ear and sinusessinuses

A) Very common, often occur togetherA) Very common, often occur together

B) Frequently have the same causative B) Frequently have the same causative agentagent

2. Causative agents include 2. Causative agents include Haemophilus Haemophilus aegyptius, Haemophilus influenzae, aegyptius, Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus Streptococcus pneumoniae, Streptococcus pyogenes, Neisseria gonorrhoeae, pyogenes, Neisseria gonorrhoeae, andand Staphylococcus aureusStaphylococcus aureus


3. Symptoms:3. Symptoms:

A) Otitis media: earache, fever, vomiting; A) Otitis media: earache, fever, vomiting; may lead to ruptured eardrummay lead to ruptured eardrum

B) Sinusitis: headache, severe malaise, B) Sinusitis: headache, severe malaise, and pain & pressure in the sinus region and pain & pressure in the sinus region with drainage that may be yellow or with drainage that may be yellow or greenishgreenish

4. Viral causes include the adenoviruses and 4. Viral causes include the adenoviruses and rhinovirusesrhinoviruses

A) Infections are generally milderA) Infections are generally milder


C. PharyngitisC. Pharyngitis

1. Streptococcal Pharyngitis (Strep throat)1. Streptococcal Pharyngitis (Strep throat)

A) Caused by A) Caused by Streptococcus pyogenesStreptococcus pyogenes

B) Results in redness, edema, swelling B) Results in redness, edema, swelling and tenderness of the tonsils and/or and tenderness of the tonsils and/or pharyngeal mucus membranespharyngeal mucus membranes

1) May also result in pus-filled nodules 1) May also result in pus-filled nodules on the tonsilson the tonsils

C) If untreated, may lead to scarlet fever C) If untreated, may lead to scarlet fever or rheumatic feveror rheumatic fever


2. Adenoviral Pharyngitis2. Adenoviral Pharyngitis

A) There are more than 45 types of A) There are more than 45 types of adenoviruses that infect humans adenoviruses that infect humans

B) These cause infections that vary B) These cause infections that vary from mild to severe often which from mild to severe often which resembles a common cold or strep resembles a common cold or strep throatthroat

C) Transmission is through inhalation C) Transmission is through inhalation of infected dropletsof infected droplets


D. DiphtheriaD. Diphtheria

1. A toxin-mediated disease caused by 1. A toxin-mediated disease caused by Corynebacterium diphtheriaeCorynebacterium diphtheriae

2. Produces an exotoxin that is absorbed 2. Produces an exotoxin that is absorbed into the bloodstream causing damage to into the bloodstream causing damage to the heart, nerves, and kidneysthe heart, nerves, and kidneys

3. Symptoms include inflammation, low-3. Symptoms include inflammation, low-grade fever, sore throat, vomiting, grade fever, sore throat, vomiting, enlargement of cervical lymph nodes, enlargement of cervical lymph nodes, and swelling of the neckand swelling of the neck


4. May also result in the formation of a 4. May also result in the formation of a pseudomembranepseudomembrane

A) A grayish film consisting of fibrous A) A grayish film consisting of fibrous cells and fluidcells and fluid

B) Can form over the pharynx and B) Can form over the pharynx and airways resulting is asphyxiationairways resulting is asphyxiation

5. Transmission is via direct contact with 5. Transmission is via direct contact with patient or carrier, or with indirect contact patient or carrier, or with indirect contact via fomites or inhaled infectious dropletsvia fomites or inhaled infectious droplets

Diseases of the Upper and Diseases of the Upper and Lower Respiratory TractLower Respiratory Tract

A. Whooping cough (Pertussis)A. Whooping cough (Pertussis)

1. Caused by 1. Caused by Bordetella pertussisBordetella pertussis

2. 2. BordetellaBordetella produces a pertussis toxin produces a pertussis toxin (Ptx) and filamentous hemagglutinin (Fha) (Ptx) and filamentous hemagglutinin (Fha)

A) These help the bacteria to attach to A) These help the bacteria to attach to and destroy the respiratory epithelium and destroy the respiratory epithelium resulting in a build-up of mucusresulting in a build-up of mucus

3. Following a 3-21 day incubation period, 3. Following a 3-21 day incubation period, the disease is characterized by three the disease is characterized by three stagesstages


A) Catarrhal stageA) Catarrhal stage

1) First stage1) First stage

2) Marked by nasal drainage & 2) Marked by nasal drainage & congestion, sneezing, and occasional congestion, sneezing, and occasional coughingcoughing

3) Lasts 1-2 weeks3) Lasts 1-2 weeks


B) Paraoxysmal stage B) Paraoxysmal stage

1) Characterized by fits of 10-20 1) Characterized by fits of 10-20 abrupt, hacking coughs followed by abrupt, hacking coughs followed by deep inspiration which gives off a deep inspiration which gives off a “whoop” sound“whoop” sound

a) Can occur up to 15 times/daya) Can occur up to 15 times/day

2) Usually lasts 1-6 weeks2) Usually lasts 1-6 weeks


C) Convalescence stageC) Convalescence stage

1) Coughing fits decrease in length 1) Coughing fits decrease in length and frequencyand frequency

2) Can last for weeks to months2) Can last for weeks to months

3) A secondary pneumonia infection is 3) A secondary pneumonia infection is sometimes seensometimes seen


B. Respiratory Syncytial Virus InfectionsB. Respiratory Syncytial Virus Infections

1. Caused by the respiratory syncytial 1. Caused by the respiratory syncytial virus (RSV) virus (RSV)

2. Primarily infects infants and young 2. Primarily infects infants and young childrenchildren

A) Most prevalent cause of respiratory A) Most prevalent cause of respiratory infection in newbornsinfection in newborns

3. The virus enters the tract and causes 3. The virus enters the tract and causes cells to fuse together creating a clump of cells to fuse together creating a clump of cells known as a cells known as a syncytiasyncytia


A) The cells will die and slough off A) The cells will die and slough off causing a clogging of the bronchicausing a clogging of the bronchi

1) Patients are often susceptible to 1) Patients are often susceptible to secondary infections because of thissecondary infections because of this

4. Symptoms include runny nose, cough, 4. Symptoms include runny nose, cough, fever, wheezing, dyspnea, and a dusky fever, wheezing, dyspnea, and a dusky skin colorskin color

5. An immunoglobulin vaccine is 5. An immunoglobulin vaccine is approved for use on preemiesapproved for use on preemies


C. Influenza (Flu)C. Influenza (Flu)

1. Most common and widespread 1. Most common and widespread epidemics of influenza are the result epidemics of influenza are the result of influenza Type A virus because of of influenza Type A virus because of its ability to undergo its ability to undergo antigenic drifts antigenic drifts and shiftsand shifts

A) Changes that allow the virus to A) Changes that allow the virus to evade host defensesevade host defenses


2. Its primary virulence factor is 2. Its primary virulence factor is hemagglutinin hemagglutinin

A) A component of the viral envelope A) A component of the viral envelope (protein spike)(protein spike)

B) Helps to attach the virus to host cells B) Helps to attach the virus to host cells

3. Symptoms include headache, chills, dry 3. Symptoms include headache, chills, dry cough, body aches, fever, stuffy nose, and cough, body aches, fever, stuffy nose, and sore throat sore throat

A) Extreme fatigue can last a few days or a A) Extreme fatigue can last a few days or a few weeksfew weeks


4. Deaths are typically not due to the 4. Deaths are typically not due to the influenza virus itself, but rather they are influenza virus itself, but rather they are most commonly attributed to secondary most commonly attributed to secondary infectionsinfections

A) Often caused by A) Often caused by S. aureusS. aureus and and S. S. pyogenespyogenes

5. Type B is less severe and not widespread 5. Type B is less severe and not widespread and Type C is even less significantand Type C is even less significant

6. Usually not treated with antivirals but 6. Usually not treated with antivirals but Tamiflu (oseltamivir) is the drug of choiceTamiflu (oseltamivir) is the drug of choice

Diseases of the Lower Diseases of the Lower Respiratory TractRespiratory Tract

A. TuberculosisA. Tuberculosis

1. Caused by the acid-fast (+) bacteria 1. Caused by the acid-fast (+) bacteria Mycobacterium tuberculosisMycobacterium tuberculosis

A) Humans are easily infected with A) Humans are easily infected with M. M. tuberculosistuberculosis but most are resistant but most are resistant to the diseaseto the disease

B) Only about 5% of infected people B) Only about 5% of infected people actually develop a clinical case of TBactually develop a clinical case of TB

C) Untreated TB progresses slowlyC) Untreated TB progresses slowly


2. Colonization of the alveoli follows 2. Colonization of the alveoli follows inhalation of the bacteriainhalation of the bacteria

3. The disease is usually confined to the 3. The disease is usually confined to the lungs where it manifests itself in two lungs where it manifests itself in two stagesstages


A) Primary tuberculosisA) Primary tuberculosis

1) Most individuals are asymptomatic but 1) Most individuals are asymptomatic but may have a mild fevermay have a mild fever

2) Macrophage aggressively attack the 2) Macrophage aggressively attack the bacteriabacteria

a) The mycolic acid in their cell walls a) The mycolic acid in their cell walls allows them to escape digestionallows them to escape digestion

b) The bacteria continues to multiply b) The bacteria continues to multiply within the macrophage and ultimately within the macrophage and ultimately destroys itdestroys it


c) This causes a Type IV (cell-mediated) c) This causes a Type IV (cell-mediated) hypersensitivity response attracting hypersensitivity response attracting lymphocytes and more macrophage to lymphocytes and more macrophage to the areathe area

d) These surround the bacteria essentially d) These surround the bacteria essentially “walling off” the bacteria and containing “walling off” the bacteria and containing it within a it within a tubercletubercle

i) Enlarged structure composed of i) Enlarged structure composed of bacteria surrounded by macrophage bacteria surrounded by macrophage and lymphocytesand lymphocytes


e) The bacteria can survive in the e) The bacteria can survive in the tubercle for many yearstubercle for many years

3) Most individuals recover completely 3) Most individuals recover completely from this infectionfrom this infection


B) Secondary tuberculosis B) Secondary tuberculosis

1) Results when dormant cells from primary 1) Results when dormant cells from primary infection become activeinfection become active

a) This is usually triggered by an a) This is usually triggered by an immunosupressed stateimmunosupressed state

2) The bacteria in the tubercles multiply and 2) The bacteria in the tubercles multiply and start to spread to other areas of the start to spread to other areas of the respiratory tractrespiratory tract

3) Symptoms include violent dry coughing, 3) Symptoms include violent dry coughing, greenish or bloody sputum, fever, weight loss, greenish or bloody sputum, fever, weight loss, extreme fatigue, night sweats, and chest pain extreme fatigue, night sweats, and chest pain


4. Disseminated tuberculosis 4. Disseminated tuberculosis

A) Infected macrophages then carry the A) Infected macrophages then carry the bacterium to various body parts where they bacterium to various body parts where they are releasedare released

1) Most often infect the urinary, 1) Most often infect the urinary, reproductive, nervous, and skeletal reproductive, nervous, and skeletal systemssystems

2) Results in the formation of tubercles in 2) Results in the formation of tubercles in the infected structuresthe infected structures

3) Symptoms depend on the system & 3) Symptoms depend on the system & structures infectedstructures infected


B. PneumoniaB. Pneumonia

1. Pneumococcal pneumonia 1. Pneumococcal pneumonia

A) Caused by A) Caused by Streptococcus pneumoniaeStreptococcus pneumoniae

1) Gram-positive, 1) Gram-positive, encapsulatedencapsulated diplococcusdiplococcus

2) Is the leading cause of bacterial 2) Is the leading cause of bacterial pneumonia (a.k.a. pneumococcus)pneumonia (a.k.a. pneumococcus)

3) The capsule is its primary virulence 3) The capsule is its primary virulence factor but some strains produce their factor but some strains produce their own antibodiesown antibodies


B) Symptoms include fever, painful B) Symptoms include fever, painful breathing, fluid collection in the air breathing, fluid collection in the air sacs, and sputum containing blood & sacs, and sputum containing blood & puspus

C) Common complications include: C) Common complications include: pleurisy (inflammation of pleural pleurisy (inflammation of pleural serosa), septicemia, endocarditis, and serosa), septicemia, endocarditis, and even meningitiseven meningitis


2. Klebsiella pneumonia2. Klebsiella pneumonia

A) Caused by A) Caused by Klebsiella pneumoniae Klebsiella pneumoniae

1) Typically an enterobacterium1) Typically an enterobacterium

2) It is a primary cause of 2) It is a primary cause of nosocomial infectionsnosocomial infections

B) Symptoms are similar to B) Symptoms are similar to pneumococcal pneumonia except pneumococcal pneumonia except patients experience chills and their patients experience chills and their sputum is red and gelatinoussputum is red and gelatinous


3. Mycoplasmal pneumonia3. Mycoplasmal pneumonia

A) Leading cause of pneumonia in college A) Leading cause of pneumonia in college students and is also common among students and is also common among military recruitsmilitary recruits

B) Generally mild disease and is often B) Generally mild disease and is often referred to as “walking pneumonia”referred to as “walking pneumonia”

C) Causative agent is C) Causative agent is Mycoplasma Mycoplasma pneumoniaepneumoniae

1) Small, deformed bacterium 1) Small, deformed bacterium lacking a lacking a cell wallcell wall


C. Legionnaires’ DiseaseC. Legionnaires’ Disease

1. Caused by 1. Caused by Legionella pneumophilaLegionella pneumophila

2. Symptoms include: head and muscle 2. Symptoms include: head and muscle ache, fever, cough, shortness of ache, fever, cough, shortness of breath, chest and abdominal pain, breath, chest and abdominal pain, and diarrheaand diarrhea

A) If untreated can cause A) If untreated can cause pneumonia and ultimately deathpneumonia and ultimately death


3. 3. L. pneumophilaL. pneumophila is found commonly in warm is found commonly in warm natural waters natural waters

A) Resists heating, cooling, and some A) Resists heating, cooling, and some chlorineschlorines

1) Allows the bacteria to survive in air 1) Allows the bacteria to survive in air conditioners, poorly treated pools, conditioners, poorly treated pools, showers, and even vegetable sprayers in showers, and even vegetable sprayers in supermarketssupermarkets

4. Pontiac Fever is a milder form of the disease 4. Pontiac Fever is a milder form of the disease which rarely causes pneumonia or deathwhich rarely causes pneumonia or death


D. Hantavirus Pulmonary SyndromeD. Hantavirus Pulmonary Syndrome1. Caused by the Sin Nombre (“no name”) 1. Caused by the Sin Nombre (“no name”)

virusesviruses2. Zoonosis likely to involve humans in 2. Zoonosis likely to involve humans in

proximity to booming mouse populations with proximity to booming mouse populations with no person-to-person transmissionno person-to-person transmissionA) Transmission via contact with fecesA) Transmission via contact with feces

3. Symptoms include inflammation of capillary 3. Symptoms include inflammation of capillary walls in the lungs, fever, muscle aches, walls in the lungs, fever, muscle aches, vomiting, diarrhea, cough, shortness of vomiting, diarrhea, cough, shortness of breath, and ultimately shock and death in 5-6 breath, and ultimately shock and death in 5-6 days (about 40% of the time)days (about 40% of the time)


E. CoccidiodamycosisE. Coccidiodamycosis

1. Also known as Valley Fever1. Also known as Valley Fever

A) Prevalent in dry, semi-arid desert A) Prevalent in dry, semi-arid desert areas seen in the Western U.S.areas seen in the Western U.S.

2. Caused by inhalation of spores from 2. Caused by inhalation of spores from Coccidioides immitisCoccidioides immitis

A) Commonly found in dust and soil A) Commonly found in dust and soil


3. Symptoms often mimic a common cold or 3. Symptoms often mimic a common cold or the flu; may also be aspymtomaticthe flu; may also be aspymtomatic

4. Rarely causes death in non-compromised 4. Rarely causes death in non-compromised individuals and is rarely chronicindividuals and is rarely chronic

F. HistoplasmosisF. Histoplasmosis

1. Also known as Spelunker’s Disease 1. Also known as Spelunker’s Disease

2. The most common fungal respiratory 2. The most common fungal respiratory diseasedisease

3. Causative agent is 3. Causative agent is Histoplasma Histoplasma capsulatumcapsulatum


4. Produces respiratory symptoms (cough, 4. Produces respiratory symptoms (cough, shortness of breath, dyspnea) but may shortness of breath, dyspnea) but may asymptomaticasymptomatic

5. Spores are more widespread and tend 5. Spores are more widespread and tend to be found in soils contaminated by bird to be found in soils contaminated by bird or bat droppingsor bat droppings

G. G. PneumocystisPneumocystis Pneumonia Pneumonia

1. A life-threatening form of pneumonia 1. A life-threatening form of pneumonia seen primarily in immunocompromised seen primarily in immunocompromised individualsindividuals


A) Once the leading cause of death in AIDS A) Once the leading cause of death in AIDS patientspatients

2. Caused by 2. Caused by Pneumocystis jiroveci Pneumocystis jiroveci (formerly (formerly known as known as P. cariniiP. carinii))

A) An opportunistic pathogen found in the A) An opportunistic pathogen found in the lungs of most individualslungs of most individuals

B) However, its natural reservoir and mode of B) However, its natural reservoir and mode of transmission are unknowntransmission are unknown

3. Symptoms include shortness of breath, rapid 3. Symptoms include shortness of breath, rapid breathing, non-productive cough, slight fever, breathing, non-productive cough, slight fever, and dusky skin colorand dusky skin color

Chapter 21 Infectious Diseases of the Respiratory System.

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Transcript of Chapter 21 Infectious Diseases of the Respiratory System.