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Chapter 22 Lecture 3 (Rhinosinusitis and Otitis Media (Pathogenesis and…
Chapter 22 Lecture 3
Rhinosinusitis and Otitis Media
Bacteria resident in the pharynx can infect the nose and sinuses or even the middle ears via the connections in the throat
Signs and symptoms
Malaise accompanied by headache and inflamed nasal passages
Otitis media results in severe pain in the ears which could end abruptly when/if the eardrum ruptures (releases pressure)
Pathogen and virulence factors
Caused by various respiratory microbiota
Streptococcus pneumonia, staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis
May be due to damage to upper respiratory system and auditory tube resulting from viral infections, cigarette smoke, and other irritants that allows normal microbiota to become opportunistic infections
Pathogenesis and epidemiology
Bacteria in the pharynx spread to the sinuses via the throat
Same with middle ears being infected via the auditory tubes
S/S is caused by the inflammation which is triggered by the infection
Rhinosinusitis is more common in adults
Otitis media is more common in children because the auditory tubes are more horizontal and have smaller diameters
Diagnosis, treatment, and prevention
Symptoms are often diagnostic; however, studies indicated that that bacteria cause fewer than 10% of cases
An infection is more likely if acute rhinosinusitis lasts more than 10 days, with a high fever and pus filled nasal discharge or if it worsens after a brief period of improvement be placed on amoxicillian
No known way to prevent rhinosinusitis
Flushing nasal and sinus cavities with saline solution can reduce duration of symptoms (Neti pot)
Treatment of otitis media
Amoxicillin
Lancing the eardrum of the infected ear to release pressure
Installing plastic tubes to allow drainage of fluid and pus
Removing the tonsils
Epidemiologists calculate that immunizations against influenza and S. pneumonia could reduce the number of childhood cases of otitis media by 1 million per year
Common Cold Viral Diseases of the Upper Respiratory System
Average adult will have two colds per year
Signs and symptoms
Sneezing, runny nose, congestion, sore throat, malaise, and cough
Fever does not occur unless a secondary bacterial infection is present
Signs & symptoms last about a week but the mild cough could go on for several weeks
Pathogens and virulence factors
Over 200 different serotypes(strains)
Enteroviruses (rhinoviruses) are the most common cause (115)
Numerous other viruses cause colds
Cold viruses replicate at the lower temperature of the nasal cavity
Pathogenesis
After attaching to cells of the nasal mucous membrane, cold viruses cause the cells to create many more viruses, then kill the cell. The new viruses are released to infect more cells
When cold symptoms are at their worst, over 100,000 viruses/ml of nasal mucous is present. Can remain infected for hours outside the body.
Infected cells lose ciliary action and slough off when they die. This triggers the release of inflammatory chemicals and stimulates nerve cells triggers mucus production, sneezing, & congestion
Epidemiology
Rhinoviruses are highly infective- a single virus is good enough to cause a cold in 50% of infected people
Spread by coughing/sneezing, fomites, or person-to-person contact
Self inoculation by touching the mucous membranes of your eyes. Explosive sneezes rarely transmit colds.
Develop some immunity to serotypes over time
Children ~6-8 colds per year
Young adults~2-4
Adults older than 60~1 or fewer
Diagnosis, treatment, and prevention
Signs and symptoms are usually diagnostic
Antihistamines, decongestants, and pain relievers reduce the symptoms but not the duration Pleconaril, taken on the onset can reduce duration of symptoms and the seriousness
Hand antisepsis is important preventive measure
Bacterial Pneumonias
Lung inflammation accompanied by fluid-filled alveoli and bronchioles
Fluid can be pus –empyema
When pleurae become inflamed- pleurisy
Described by affected region or organism causing the disease
Lobar pneumonia- entire lobes of lungs
Mycoplasma pneumonia- (bacteria called Mycoplasma Health-care Associated pneumonia
Healthcare-associated pneumonia one significant infection is the ventilator –associated pneumonia Bacterial biofilms set up house in the tubes which cause VAP
Bacterial pneumonias are the most serious and the most frequent in adults
Bacterial Diseases of the Lower Respiratory System
Lower respiratory organs are usually axenic. This means that the lower respiratory system is normally devoid of microorganisms
Bacterial infection of the lower respiratory system can cause life-threatening illness.
Bacterial pneumonias
Legionnaires disease
Pertussis
Whooping cough
Pneumoccocal pneumonia
Most common & community acquired usually lobar
Signs and symptoms
Fever, chills, congestion, cough, and chest pain
Results in short, rapid breathing
Blood enters the lungs, causing rust-colored sputum
Pathogen and virulence factors
Caused by Streptococcus pneumoniae
Virulence factors
Adhesins
Polysaccharide capsules that protect from lysis by phagocytes
Pneumolysin cytotoxin that is secreted by pneumococci suppresses the digestion of phagocytized bacteria by interfering with the action of lysosomes
Pathogenesis and epidemiology
Infection occurs by inhalation of bacteria
Phosphorylchloirine triggers endocytosis by lung cells, the capsule protects the bacterium and the pneumococci (that has been protected) will eventually kill lung cells. From the bacteria’s hiding place, the bacteria can pass into the blood, and brain to cause bacteremia and meningitis
Bacterial replication causes damage to the lungs because they are damaging the alveoli. Fluid will fill the alveoli, gas exchange is exchange is poor, leukocytes will attack the bacteria, causing the inflammatory response to occur, along with a fever, which adds to the disease
The body wants to limit migration of bacteria so it tries binding the microbes with the active sites of secretory IgA. The rest of the antibody molecule will bind to mucus (coughing it out with the ciliated action) but the Pneumococcus counteracts this defense by secreting Pneumococcal IgA protease which destroys host secretory IgA
Accounts for most cases of bacterial pneumonia
Diagnosis, treatment, and prevention
Diagnosed by identifying diplococci in sputum smears
Penicillin is drug of choice for treatment
Some strains are now penicillin resistant (1/3 are)
Substitute Vancomycin
Vaccination is method of prevention ages 2, 4, 46 and 12-15 months of age and for all who are over the age of 65 or who are at risk.
Primary atypical (mycoplasmal) pneumonia
Leading type of pneumonia in children and young adults
Signs and symptoms
Fever, malaise, HA, sore throat, and excessive sweating
Symptoms may last for weeks. Body responds to infection with a persistent, unproductive cough in an attempt to clear the lungs of the pathogen and mucus
Not severe enough to require hospitalization or to cause death (usually called “walking pneumonia”
Pathogen and virulence factors
Caused by Mycoplasma pneumoniae theses lack cell walls, so they have a variety of shapes (pleomorphic)
They also are free-living microbes which means they can grow and reproduce independently of other cells
Virulence factors include an adhesion protein that attaches specifically to receptors located at the bases of cilia that lines the respiratory tracts
Capsule which provides protection against phagocytosis
Pathogenesis
Bacteria colonize and kill epithelial cells because they attach to the cilia and causes the cilia to stop beating- this type of colonization ends up killing the epithelial cells
Mucus buildup due to the cilia cells are not doing their job (ciliary escalator) and colonization by other bacteria causes a build up of the mucus that irritates the respiratory tract.
Epidemiology
Bacteria spread by nasal secretions among people who are in close contact like classmates, and family members
Most common pneumonia in teenagers and young adults
Diagnosis, treatment, and prevention
Difficult to diagnose because mycoplasmas are small and difficult to detect in specimens or tissue samples & they grow slowly in culture (2-6 weeks)
Treated with erythromycin or doxycycline
Prevention difficult since infected individuals may be asymptomatic
Frequent handwashing, avoiding contaminated fomites and proper coughing etiquette
No vaccine