BIOL2100 Ch 21 Respiratory Tract Infections PDF

**BIOL2100 Ch 21 Respiratory Tract Infections** **Nester 10th** **Questions** - Who was Rebecca Lancefield and what were her accomplishments as discussed in the Power Point? - Describe the anatomy and function of the upper vs. lower respiratory tract. - What is the function of gob...

**BIOL2100 Ch 21 Respiratory Tract Infections** **Nester 10th** **Questions** - Who was Rebecca Lancefield and what were her accomplishments as discussed in the Power Point? - Describe the anatomy and function of the upper vs. lower respiratory tract. - What is the function of goblet cells? - What is the mucociliary escalator, and how does it protect from lower respiratory tract infections? - What is the function of the tonsils? - Do healthy people carry *Staphylococcus aureus*? - What is rhinitis, sinusitis, pharyngitis, laryngitis, epiglottitis, conjunctivitis? - Why may epiglottitis be life-threatening? - What is otitis media? - What is the function of the eustachian tubes, and why are children more susceptible to otitis media due to the shape of their eustachian tubes? - What is pneumonia and why may it be life-threatening? - What are some causative agents of conjunctivitis, otitis media and sinusitis? - What bacterium causes Strep Throat? - Describe the characteristics of *Streptococcus pyogenes*. - What is M-protein and how does it trick the immune system? - What is the function of streptokinase? - What is the function of Protein G? - What are the functions of streptolysin O and S? - What are the results of streptococcal pyrogenic exotoxins (SPEs)? - Describe possible post-streptococcal sequelae and how they arise? - Describe the symptoms of diphtheria. - Describe the *Corynebacterium diphtheriae* bacterium. - What is a palisade arrangement? - What type of toxin is diphtheria toxin and what does it do? - Where in the bacterium is the diphtheria toxin gene located? - What is the reason of the formation of a pseudomembrane and what could be the consequence? - Explain why a lower respiratory tract infection generally is more serious. - What serious infections could result from an upper respiratory tract infection? - Give examples of upper vs. lower respiratory tract infections. - What causes most cases of the common cold? - Why does rhinovirus cause respiratory infection, but not digestive system infection? - How are respiratory infections spread? - What stands in the way of manufacturing a vaccine against common cold? - What bacterium causes pneumococcal pneumonia? How can it be prevented? - What other diseases are associated with pneumococcus infection? - What pathogen often causes walking pneumonia? Describe the pathogen. - What pathogen causes Pertussis? Describe the pathogen. - How can pertussis be prevented? - What type of toxin is the pertussis toxin? - What pathogen causes T.B.? Describe the pathogen. - Describe the disease progression of T.B. from the initial infection to the development of latent disease and active disease. - What is miliary T.B.? - What immune cell is infected by *M. tuberculosis?* - What is a granuloma /tubercle and how does it form? - What is the skin test that detects T.B. called? - What pathogen causes Legionnaire's Disease? Describe the pathogen. - What pathogen causes anthrax? Describe the pathogen. - What pathogen causes influenza? - What are hemagglutinin and neuraminidase? - Describe antigenic drift vs. shift and explain the differences and consequences of each. - How is hantavirus transmitted? **Notes:** Rebecca Lancefield was a microbiologist who created the **"Lancefield Grouping"** of streptococci, allowing for a better prediction of pathogenic potential than hemolysis assays. One important example of a Group A streptococcus (GAS) is *Streptococcus pyogenes*. She also discovered the M-protein that plays an important role in its virulence. Respiratory Tract Anatomy: Upper Respiratory Tract: Nose, Nasal Cavity, Pharynx, Larynx, Epiglottis Lower Respiratory Tract: Trachea, Bronchi, Bronchioles, Alveoli Mucus is produced by specialized cells -- goblet cells. The mucociliary escalator is the mechanism of cilia of the ciliated epithelium removing impurities the lungs. The tonsils are lymphoid tissue. A two-way illustration shows the Lateral view of the upper respiratory tract. (b) Frontal view of the upper and lower respiratory tracts. *Staphylococcus aureus* is carried by about 30% of individuals. - Conjunctivitis, Otitis media and ***Haemophilus influenzae*** (Gram-negative rod) and ***Streptococcus pneumoniae*** (Gram-positive encapsulated diplococcus) - Conjunctivitis is less commonly caused by ***Staphylococcus aureus*, *Neisseria gonorrhoeae, and Chlamydia trachomatis*** - Approximately one third of otitis media, sinusitis caused by respiratory **viruses.** - ***S. pyogenes:* Causes strep throat** - Gram-positive; grows in chains - β-hemolysis of blood agar (clear area forms due to complete lysis) - Group A Streptococcus (GAS) from Lancefield grouping - Different strains within GAS distinguished by M protein. - M-protein **prevents opsonization** - **Streptolysins** make holes in membranes of erythrocytes and leukocytes. - **Protein G** is an **Fc receptor**; binds Fc portion of IgG, **prevents IgG mediated phagocytosis** - **Streptococcal pyrogenic exotoxins (SPEs) -- superantigens** leading to **scarlet fever, streptococcal toxic shock syndrome (STSS)**, or necrotizing fasciitis "**flesh-eating disease**" - - **Post-streptococcal sequelae** - Complications that develop after streptococcal infections due to cross reactive antibodies - **Acute rheumatic fever (ARF)** - **Carditis** - damage of the heart valves - **Acute post-streptococcal glomerulonephritis** (immune complexes and complement) **Diphtheria** ***Corynebacterium diphtheriae*** (Pleomorphic, Gram-positive rod) - Club-shaped, grow side by side in "**palisades**" or attached on one end in "**V" formation** - **Diphtheria A-B toxin causes cell death -** may be released into blood stream causing **organ damage.** It's coded by a prophage integrated into the *C. diphtheriae* bacterial chromosome. - **Pseudomembrane**: formed in throat from dead cells and may obstruct airways - Treated with **antiserum** or prevented by **toxoid vaccine (DTaP)** Lower Respiratory Tract Infection: Generally more serious than upper respiratory tract infection -- can cause oxygen deprivation if lungs become inflamed. However, upper respirator infections can sometimes cause infection in the Central Nervous System (ex. Meningitis). Upper Respiratory Tract: Common cold (rhinitis) -- caused by rhinoviruses (100+ different types), - Low infectious dose -- only a few virions needed to infect - Many other viruses (adenovirus, coronavirus), some bacteria also produce cold signs and symptoms Lower Respiratory Tract: **Pneumonia** is disease of lower respiratory tract caused by bacterial, viral, or fungal infection of the lungs - Alveoli fill with fluids like pus and blood - Inflammatory response to microbial infection - **Leading cause of death due to infectious disease in the U.S.** - **Pneumococcal pneumonia** - *Streptococcus pneumoniae* - Gram-positive diplococcus known as **pneumococcus** - Vaccines available - **Capsule blocks phagocytosis** - **Exotoxin** damages ciliated epithelium - **Pneumococci may cause sepsis**, **endocarditis** (heart valve infection), **meningitis** (infection of brain, spinal cord membranes) - **Mycoplasma** **pneumonia caused by *Mycoplasma pneumoniae*** - **Generally mild**; often called "**walking pneumonia**" or **atypical pneumonia** - Small bacterium **lacking cell wall** - Slow, aerobic growth - Colonies on agar look like **fried eggs** - **Pertussis ("whooping cough")** - **DTaP (Diptheria, Tetanus, acellular Pertussis) vaccine** - ***Bordetella pertussis* (Gram-negative rod)** - **Exotoxin damages cilia of the respiratory epithelium causing severe cough (paroxysms)** - **Tuberculosis** - **Latent tuberculosis infection (LTBI),** may **become active tuberculosis (TB disease)** if carrier becomes immunocompromised. - **Form tubercles** - Primarily **infects alveolar macrophages** of the lungs - **Miliary TB:** Bacteria travel through bloodstream to other organs. - *Mycobacterium tuberculosis* - **Acid-fast** bacterium - Cell wall contains **mycolic acid -- makes cells resistant to** drying, disinfectants, chemicals **Legionnaires' Disease** (*Legionella* Pneumonia) - Fatal in many cases - Causative Agent: ***L. pneumophila*** - Spread via aerosolized water - Bacteria survive by preventing phagosome-lysosome fusion and multiply within macrophages - No direct person-to-person spread - Also causes "Pontiac Fever" (milder, flu-like symptoms) **Inhalation Anthrax** - ***Bacillus anthracis*** is also a **Category A bioterrorism agent** - **Anthrax meningitis** occurs in about half the cases - **Endospore**-forming, **Gram-positive** bacterium - Toxin-producing, **encapsulated** cells enter bloodstream, damage endothelial cells; this leads to **vascular leakage** and **pulmonary edema** - **Untreated, case-fatality rate is near 95%** **Influenza:** Influenza A virus - 8 **segments of single-stranded RNA** - Glycoprotein **spikes** embedded in envelope: **hemagglutinin antigen (HA) and neuraminidase antigen (NA)** - **Antigenic drift**: minor mutations in HA and NA genes; responsible for **seasonal influenza** - Immunity developed from previous year less effective - **Antigenic shift**: uncommon; concurrent infection allows mixture of 8 RNA segments; causes **pandemic influenza** - Human strain can gain novel HA and/or NA antigens to which humans have no immunity -  **COVID-19, SARS, and MERS:** - Enveloped, **single-stranded RNA viruses** with spikes on their surface that create a **crown-like** appearance - *Coronaviridae* family **Hantavirus Pulmonary Syndrome:** - Caused by a **hantavirus** called the **Sin Nombre virus** (SNV) - Is transmitted to **humans from rodents** via **inhalation of contaminated dust** - **Case fatality rate is high** (40%) **Fungal Infections of the Lower Respiratory System:** **Coccidioidomycosis (Valley Fever, S.W. U.S.) and Histoplasmosis** (associated with caves) **can occur in healthy individuals** - Those fungi are **dimorphic** - Grow in soil as **molds** - Differentiate into **yeast** form in the body ***Pneumocystis* pneumonia (PCP)** is a widespread **opportunist** fungus - Can cause serious disease in HIV patients and other immunocompromised individuals