Chapter 22Respiratory system infections

Medgar Evers College

Biology 261

Prof. Santos

Anatomy and physiology of the respiratory system

• Upper respiratory system includes the moist lining of the eyes (conjunctiva), nasolacrimal duct, middle ears, sinuses, mastoid air cells, nose, and throat.

• Functions include temperature and humidity regulation and removal of microorganisms.

• Lower respiratory system includes the trachea, bronchi, bronchioles, and the lungs.

• The alveoli are the air sacs located in the lungs where gas exchange occurs.

• Pleural membranes cover the lungs and line the chest cavity.

• Ciliated cells line the respiratory tract and filter and remove germs by constantly propelling mucus out of the respiratory system.

Microbiota of the respiratory system

• A wide variety of microorganism colonize parts of the upper respiratory system, including S. aureus.

• Viruses and microorganisms are normally absent from the lower respiratory system.

Infections of the upper respiratory system

1- strep throat * bacterial

2- diphtheria * bacterial

3- pink eye, earache, sinus infection

* Bacterial and viral

4- the common cold * viral

5- adenoviral pharyngitis * viral

Infections of the lower respiratory system

Bacterial infections include

• Pneumococcal pneumonia

• Klebsiella pneunomia

• Mycoplasmal pneumonia

• Whooping cough (pertussis)

• Tuberculosis

• Legionnaire’s disease

Viral infections of the lower respiratory system

• Influenza• Respiratory syncytial viral infection• Hantavirus pulmonary syndrome

Fungal infections of the Respiratory system

• Histoplasmosis (Spelunker’s disease) • Coccidiodomycosis (Valley fever)

Viral infections of upper respiratory system

disease cause Incubation period

symptoms Pathogenesis/epidemiology

treatment

Common cold

rhinovirus 1 to 2 days

Scratchy throat, nasal discharge, malaise, headache, and a mild cough

Viruses attach to the respiratory epithelium, inhalation of infected droplets containing the virus

No general accepted treatment, bed rest, hand washing, cold medication to alleviate symptoms

disease cause Incubation period

symptoms Pathogenesis/epidemiology

treatment

Adenoviral pharyngitis

Adenovirus (more than 45 types)

5 to 10 days

Fever, sore throat, severe cough, swollen lymph nodes, pus on tonsils, sometimes pink eye

Viral replication in host cells, inhalation of infected droplets

No treatment just medication to alleviate symptoms

Bacterial infections of upper respiratory system

disease cause Incubation period

symptoms Pathogenesis/epidemiology

treatment

Strep throat S. pyogenes 2 to 5 days Sore and red throat, with pus and hemorrhages, enlarged and tender lymph nodes

Includes c5a peptidase, hyluronic acid capsule, M protein, protein F, Protein G, exotoxins, streptolysins O and S, tissue degrading enzymes

10 days of penicillin or erthromycin

Diphtheria Corynebacterium diphtheriae

2 to 6 days Sore throat, fever fatigue, paralysis and heart and kidney failure

Exotoxins released and absorbed by bloodstream

Antitoxin and erythromycin to prevent transmission

• Very little invasive ability by pathogen.

• Formation of pseudomembrane on tonsils from the result of dead epithelial cells, leukocytes, and fibrin. This membrane may loosen up and cause suffocation.

Post streptococcal complications

1- acute rheumatic fever

2- acute post streptococcal glomerulonephritis

Acute rheumatic fever

• Inflammatory disease

• Develops as a complication to Strep infections.

• Usually affects children 5 to 15 years old

• Can cause permanent damage to heart and valves

• Rare in the U.S.A

Symptoms of rheumatic fever

• Fever

• Painful and tender joints — most often the ankles, knees, elbows or wrists; less often the shoulders, hips, hands and feet

• Pain in one joint that migrates to another joint

• Red, hot or swollen joints

• Small, painless nodules beneath the skin

• Chest pain

• Sensation of rapid, fluttering or pounding heartbeats (palpitations)

• Fatigue

• Shortness of breath

acute post streptococcal glomerulonephritis

• Post-streptococcal glomerulonephritis. Glomerulonephritis may develop a week or two after recovery from a strep throat infection. An overproduction of antibodies stimulated by the infection may eventually settle in the glomeruli, causing inflammation.

acute post streptococcal glomerulonephritis symptoms

• Symptoms usually include swelling, reduced urine output and blood in the urine. Children are more likely to develop post-streptococcal glomerulonephritis than are adults, and they're also more likely to recover quickly.

disease cause Incubation period

symptoms Pathogenesis/epidemiology

treatment

Conjunctivitis otitis media and sinus infections

Most common pathogens for all three all Haemophilus influenzae and Streptococcus pneumoniae

Red swollen eyes, pus discharge, earache, pain and pressure in the sinus area

antibiotics

Viral infections of lower respiratory system

disease cause Incubation period

symptoms pathogenesis

treatment

Influenza Influenza A virus, an orthomyxovirus

1 to 2 days

Fever, muscle ache, lack of energy, headache, sore throat, nasal congestion, cough

Antigenic drift and shift allow for variations, virus infects respiratory epithelium and destroys the cells

Vaccine is 80 to 90 % effective, drugs such as amantadine and rimantadine are effective against type A

Influenza

• Influenza A has 8 segments of ss RNA, has an envelope.

• The envelope has 2 types of spikes; HA and NA

• HA hemagglutinin

• NA neuraminidase antigen

• HA allows the virus to attach

• NA allows virus to be released

• There are subtypes of HA (16) and NA (9). For example; H1, H2, N1, and N2.

• Swine flu 2009 H1N1

• Avian flu 1997 H5N1

• * H1, H2, H3, N1 and N2 spread among us!

• Antigenic drift- minor mutations in the genes that encode for HA and NA. this is responsible for the yearly outbreaks of influenza called seasonal influenza.

• A/Texas/77 (H3N2) vs A/Bangkok/79 (H3N2)

• Antigenic shift- a sudden major change in the spike proteins because the virus has acquired new genome.

• Antigenic shift is the cause of pandemic influenza

disease cause Incubation period

symptoms pathogenesis

treatment

Respiratory syncytial viral infection

RSV, a paramyxo-virus

1 to 4 days Runny nose, cough, fever, wheezing, difficulty breathing, dusky color due to lack of oxygen

Inhaling infected droplets, virus enters the respiratory tract and causes death and sloughing of the cells

No vaccine available, no effective anti viral medication exist!

disease cause Incubation period

symptoms pathogenesis

treatment

Hanta virus pulmonary syndrome

Sin Nombre and other hantaviruses of the bunyavirus family

3 days to 6 weeks

Fever, muscle ache, vomiting, diarrhea, cough, shortness of breath

Viral antigen localizes in the capillary walls in the lungs.

No proven anti viral treatment

Good hygiene, good ventilation, avoid contact with rodents

Bacterial infections of the lower respiratory system

disease cause Incubation period

symptoms pathogenesis

treatment

Pneumococcal pneumonia

Streptococcus pneumoniae

1 to 3 days

Cough, fever, shaking chills, rust color sputum from degraded blood, shortness of breath, chest pains

Inhalation of virus into the alveoli, rapid multiplication, inflammatory response, and pain due to nerve ending involvement

Penicillin, erythromycin, and others as prescribed by your doctor

disease cause Incubation period

symptoms pathogenesis

treatment

Klebsiella pneumonia

Klebsiella pneumoniae

1 to 3 days

Chills, fever, chest pain, gross bloody sputum

Aspiration of colonized droplets from the throat, destruction of lung tissue.

A member of the cephalosporin antibiotics with an aminoglycoside.

disease cause Incubation period

symptoms pathogenesis

treatment

Mycoplasmal pneumonia

Mycoplasma pneumoniae

2 to 3 weeks Gradual cough, fever, sputum production, headache, fatigue, muscle ache

Cells attach to specific receptors on the respiratory tract inhibiting cilia motion and destruction of ciliated cells

Tetracycline and erythromycin

Some key differences

1- pain associated mostly with pneumococcal pneumonia due to involvement of nerve endings

2- klebsiella pneumonia involves bloody and gelatin-like sputum and involves rapid destruction of lung tissue and lung abscess formation.

Mycoplasmal pneumonia is resistant to penicillin due to the fact that the pathogen has no cell wall.

disease cause Incubation period

symptoms pathogenesis

treatment

Whooping cough

(pertussis)

Bordella pertussis

7 to 21 days

Runny nose, spasms of violent cough, vomiting and possible convulsions

Toxins secreted by pathogen destroys epithelial cells

Vaccination and erythromycin if given early is effective.

Some facts

• Disease has three stages

1- catarrhal- inflammation of mucous membrane

2- paroxysmal- violent cough followed by forceful attempts to inhale

3- convalescent- period of recovery

disease cause Incubation period

symptoms pathogenesis

treatment

Tuberculosis Mycobacterium tuberculosis * cell wall has lots of lipids

2 to 10 weeks

Chronic fever, weight loss, cough, sputum production

2 or 3 medications given together for a long period of time such as Isoniazid and rifampin.

Pathogenesis

1- pathogen enters the lungs

2- alveolar macrophages ingest the pathogen

3- the pathogen survives inside the macrophage

4- additional macrophages and lymphocytes are recruited to the site.

5- foamy macrophages are formed.

6- fibrous capsule surrounds macrophages =tubercle

7- some infected macrophages die releasing the pathogen into airway

8- within the tubercle T cells secrete cytokines that trigger macrophages to destroy the pathogen.

disease cause Incubation period

symptoms pathogenesis

treatment

Legionnaires’ disease

Legionella pneumophila

2 to 10 days

Muscle ache, headache, fever, cough, shortness of breath, chest and abdominal pain

Warm water contaminated with pathogen, pathogen multiplies within the phagosome, destroys cell and then inflammation follows.

Rifampin and erythromycin

Fungal infections of the Lungs

disease cause Incubation period

symptoms pathogenesis

treatment

Valley fever

*Only in semi arid regions of the western hemisphere.

Coccidioides immitis

2 to 3 weeks

Fever, cough, chest pain, loss of appetite, pain in joints,

Spores form in the lungs, inflammatory response to damage, inhalation of airborne pathogen spores.

Antimicrobial medications such as

Amphotericin B, and fluconazole.

disease cause Incubation period

symptoms pathogenesis

treatment

Spelunker’s disease

Histoplasma capsulatum

5 to 8 days

Slight fever, chest pain, cough and chronic sores in mouth

Inhalation of spores, they change to yeast, forming granulomas

Amphotericin B, itraconazole for serious infections.

Virulence factors of Streptococcus pyogenes.

Includes

• C5a peptidase destroys the C5a complement component

• Hyluronic acid capsule helps the bacteria attach to the epithelial cells

• M protein helps destroy the C3b Complement component preventing opsonization

• Protein F helps the bacteria attach to host

• Protein G is an Fc binding receptor

• Exotoxins responsible for scarlet fever, toxic shock and flesh eating fasciitis

• Streptolysins O and S lyse wbc’s and rbc’s.

• Tissue degrading enzymes helps pathogen spread by destroying DNA, Proteins, blood clots.