Micro Chapter 21: Upper and Lower Respiratory system

Outline the components of the upper respiratory tract

Nose and nasal cavity, pharynx (throat), and epiglottis

describe the mucociliary escalator

• propels mucus, trapped particles out of the respiratory tract

  • Normally keeps lower respiratory tract (trachea, bronchi, lungs) free of microbes

  • Cilia of epithelial cells beat synchronously

How to respitory infections progress

• Initiates as Nasopharyngeal (Nose, throat (pharyngitis) and progresses to Ears (otitis media), Sinuses (sinusitis)

Describe tonsils and their functions

• secondary lymphoid organs

• come into contact with microbes entering

• important for immune response but can become infected

describe the normal flora of the respiratory system and its function

Nasal cavity, nasopharynx and pharynx colonized by numerous bacteria = competitive exclusion

Outline Streptococcal Pharyngitis S/S

S/S

• red itchy throat + patches of pus + tiny hemorrhages

• inflammation of mucous membranes

• high fever, coughing, sneezing

• swollen lymph nodes

What is the causative agent for Streptococcus pyogenes

• Gram-positive, grows in chains

• Beta-hemolysis of blood agar

• Group A streptococcus (GAS)

Post-streptococcal sequelae

scarlet fever, rheumatic fever, glomerulonephritis

Explain the Pathogenesis of Streptococcal Pharyngitis

• hyaluronic acid capsule

• streptococcal pyrogenic exotoxins (SPEs)

  • can lead to high fever, toxic shock, and flesh-eating fasciitis

• Protein G prevents IgG-mediated phagocytosis

• M protein important adhesin

• Protein F adheres to fibrin of epithelial cells

Explain the Epidemiology of Streptococcal Pharyngitis

• naturally only infects humans

• spread by respiratory droplets or contaminated food

• Nasal carriers more likely to spread than pharyngeal, anal carriers

• Individuals can be asymptomatic carriers for weeks

Explain the treatment and prevention of streptococcal pharyngitis

• no vaccines, confirmation via diagnostic tests and throat cultures

• A sore throat in presence of fever should be cultured for prompt treatment

• Treatment with penicillin or erythromycin about 90% effective, preventing post-streptococcal sequelae

what is the causative agent for a common cold

There are more than 100 serotypes of human rhinovirus

What are the S/S of the common cold

• malaise

• scratchy mild sore throat

• runny nose

• cough and hoarseness

• nasal secretion symptoms

  • initially profuse and watery

  • later, thick and purulent

  • no fever

    • unless complicated with secondary infection

• symptoms disappear in about a week

Describe the pathogenesis for the common cold

Rhinovirus

• attach to receptors on respiratory epithelial cells, infect

• infection can spread to ears, sinuses, lower respiratory tract

• infection is halted by inflammatory response, interferon release immune response

What is the epidemiology for the common cold

• humans are only source for cold virus

• close contact with infected person or secretions usually necessary transmission

  • high concentrations are found in nasal secretions during first 2 or 3 days of a cold

• young children transmit cold virus easily

  • due to lack of good hygiene

Describe the preventions of the common cold

• no vaccine

  • too many different types of rhinovirus

    • makes vaccination impractical

• hand washing

• keep hands away from face

• avoid crowds during cold season

What is the treatment for the common cold

• Antibiotic therapy is ineffective

• Certain antiviral medications show promise

  • must be taken at first onset of symptoms

• Treatment with over the counter medications may prolong duration due to inhibition of inflammation

explain the causative agent Tuberculosis

• causative agent

  • Mycobacterium tuberculosis

  • Gram-positive

  • acid-fast due to mycolic acid in cell wall

    • this contributes to its resistance

explain the pathogenesis of tuberculosis

• pulmonary macrophage causes death of lung tissue resulting in formation of cheesy material

explain the epidemiology of tuberculosis

• factors important in transmission

• frequency of coughing, adequacy of ventilation, degree of crowding

• immunocompromised

tuberculosis diagnosis

1. Tuberculin skin test- Mantoux test

2. Chest X-rays

Describe the treatment of tuberculosis

• 1st line of drugs

  • Rifampin

  • isoniazid

  • pyrazinamide

  • ethambutol

• Isoniazid- mycolic acid inhibitor

describe the difference between antigenic variation, drift, and shift

antigenic variation: 2 glycoproteins projecting from the viral envelope - new virus strains

Antigenic drift: minor mutations

Antigenic shift: major changes that may cause pandemic