Micro 21

• includes nose and nasal cavity, pharynx (throat) and epiglottis
• Ciliated cells line much of respiratory tract and remove microorganisms constantly propelling mucus out of respiratory system

• includes larynx, trachea, bronchi, and lungs
• Pleural membranes surround lungs
• Viruses & microbes normally absent from lower respiratory system

• Streptococcal pharyngitis (strep throat)
• Diphtheria
• Conjunctivitis (pinkeye), otitis media (ear ache) and sinus infection (often occur together)

• Bacterial species that can infect upper respiratory
• cause sore throat
• no treatment required as immune system will quickly eliminate it

• Causes strep throat (streptococcal pharyngitis)
• Enters by nose or mouth
• Results in Pharyngitis and other S/S
• Symptoms go away, exits by nose and mouth

• Late complications appear:
• Glomerulonephritis
• Rheumatic fever
• Neurological abnormalities

Complications subside

Damaged heart valves leak, heart failure developes

• S/S: Sore, red throat w pus & tiny hemorrhages, enlargement/tenderness of lymph nodes on neck.
• Less frequent: abscess formation involving tonsils, occasionally rheumatic fever and glomerulonephritis
• Incubation: 2-5 days
• Cause: Streptococcus pyogenes, Lancefield group A β-hemolytic streptococci

• Virulence associated with hyaluronic acid capsule and M protein, both which inhibit phagocytosis
• Protein G binds Fc segment of IgG, interfering with opsonization
• Protein F is responsible for mucosal attachment
• Has enzymes that lyse WBC, RBC, and degrade tissue which enhances spread of bacteria

• Spread by direct contact and droplet infection, also by contaminated food
• Tx is 10 days of penicillin or erythromycin
• *must be distinguished from viral, as can't be treated w antibiotics
• Prevention: avoid crowds, adequate vent, daily penicillin to prevent recurrent infection w hx of rheumatic heart disease

• Streptococcal pyrogenic exotoxins
• Superantigens responsible for scarlet fever, toxic shock, and "flesh-eating" gasciitis

• Includes rheumatic fever and glomerulonephritis
• may follow strep throat, due to immune response

• Toxin-mediated disease of the upper respiratory tract
• Can be prevented by immunization
• Caused by Cornyebacterium diphtheriae

• Enters by inhalation
• Infection established in nasal cavity and/or throat
• Toxin released, pseudomembrane forms
• Toxin cares paralysis, damages heart muscle, kidneys and nerves
• Membrane may become loose and obstruct breathing
• Exit from body by respiratory secrections

S/S: sore throat, fever, fatigue. pseudomembrane forms on tonsils and throat or in nose; paralysis, heart and kidney failure

Caused by: Corynebacterium diphtheriae, an A-B toxin-producing, non-spore forming Gram pos rod

• Infection in upper respiratory tract
• Exotoxin released and absorbed by bloodstream
• Toxin kills cells by interfering with protein synthesis
• Effect is on cells that have receptors for toxin - mainly heart, kidney, and nerve tissue

• Inhalation of infection droplets
• Direct contact with patient or carrier
• indirect contact with contaminated articles

Tx: antitoxin: erythromycin to prevent transmission

• Prevent: immunization with diphtheria toxoid
• Given to children at 6 wk, 4 months, 6 months, 18 months, and 4-6 yrs in DTaP
• boosters every 10 yrs

• "conjunctivitis" = pinkeye
• These often run together and have the same causative agent

Increased tears, redness, swollen eyelids, sensitivity to light, pus

Antibacterial eyedrops or ointments

• Hand Washing, avoid rubbing/touching eyes particularly with shared towels
• Highly contagious

• Manifests with severe earache, may or may not have fever
• Kids who use pacifiers beyond age 2 are increased risk

• Generally, amoxicillin is effective
• During flu season, giving flu vaccine is helpful
• Tubes can also help

Facial pain and pressure, HA and malaise. Thick green nasal discharge may contain pus/blood sometimes as well

Generally, amoxicillin is effective

• 1) Haemophilus influenzae - tiny gram-neg rod
• 2) Streptococcus pneumoniae - Gram + encapsulated diplococcus

• Common cold
• Adenoviral pharyngitis

Viral upper respiratory infection

S/S: scratchy throat, nasal discharge, malaise, HA, cough

Causative: Mainly rhinoviruses; more the 100 types; many other viruses, some bacteria

• Viruses attach to respiratory epithelium, start infection that spread to adjacent cells
• Ciliary action ceases and cells slough
• Mucus secretion increases, and inflammatory reaction occurs
• Infection stopped by interferon release, cell-mediated and humoral immunity

• Inhalation of infected droplets
• Transfer of infectious mucus to nose or eye by contaminated fingers
• Children initiate many outbreaks in families due to lack of care with nasal secretions

No generally accepted tx except control of symptoms

Handwashing, avoiding people with colds and touching face

Viral upper respiratory infection

Resemble common cold or strep, sx varying from mild to severe

• S/S: Fever, very sore throat, severe cough, swollen lymph nodes of neck, pus on tonsils and throat
• Sometimes conjunctivitis, less frequently, pneumonia
• Causative agent: Adenoviruses - more than 45 types

• Virus multiplies in host cells
• Cell destruction and inflammation occur
• Different types produce different sx

Spread by infected droplets, possible spread from GI tract

• No tx except for relief of sx
• No vaccine
• Avoided by hand washing, avoid people w symptoms

• Pneumococcal pneumonia
• Klebsiella Pneumonia
• Mycoplasmal pneumonia ("walking pneumonia")
• Pertussis ("Whooping cough")
• TB
• Legionnaires' disease

"Please Keep My Test Percent Low"

Bacterial Lower Respiratory tract infect

• S/s: Cough, fever, chill, rust sputum, SOB
• Inc: 1-3 days
• Cause: Pneumococcus, Streptococcus Pneumoniae; encapsulated strains

• Inhalation of encapsulated pneumococci
• Colonization of alveoli incites inflammation
• Plasma, blood and inflammatory cells fill alveoli
• pain results from involvement of nerve endings

• Higher carrier rates for S. Pneumoniae
• Risk of pneumonia increased with conditions such as alcoholism, narcotic use, chronic lung disease, and viral infection that impair mucociliary escalator
• Other predisposing factors are chronic heart disease, diabetes, and cancer

Treat with penicillin, erythromycin

• Capsular vaccine available contains 23 capsular antigens
• conjugate vaccine for infants

• Bacterial Lower respiratory infection
• S/S: chills, fever, cough, chest pain, grossly bloody mucoid sputum

Incubation 1 to 3 days

Caused by Klebsiella Pneumoniae, an enterobacterium

• Aspiration of colonized mucus droplets from throat
• Destruction of lung tissue and abscess formation common
• Infection spreads via blood to other body tissues

• Often resistant to antibiotics, and colonize individuals who are taking them
• Klebsiella sp. and other Gram-neg rods are common causes of fatal healthcare-associated pneumonias

Treated with cephalosporin with an aminoglycoside

No vaccine available

*IS MOST DANGEROUS OF 3 PNEUMONIA'S

• Bacterial Lower Respiratory infection
• ("Walking Pneumonia")
• S/s: Gradual onset of cough, fever, sputum production, HA, fatigue, muscle aches
• Incubation: 2 - 3 weeks
• Causative agent: Mycoplasma pneumoniae; lacks cell wall

• Cells attach to specific receptors on the respiratory epithelium
• Inhibition of ciliary motion and destruction of cells follow

• Inhalation of infected droplets;
• mild infections common and foster spread of disease

• Treated with tetracycline or erythromycin
• No vaccine available
• Avoid crowding in schools and military facilities advisable

• Bacterial LOWER respiratory infection
• Whooping cough
• S/S: runny nose followed after a # of days by spasms of violent coughing; vomiting and possible convulsions
• Incub: 7-21 days
• Cause: Bordetella pertussis, a tiny gram neg rod

• Colonization of the surfaces of the upper respiratory tract and tracheobronchial system
• Ciliary action slowed
• Toxins released by B. pertussis cause death of epithelial cells and increased cAMP
• Fever, excessive mucus output, and rise in lymphocytes in blood result

Inhalation of infected droplets; older children and adults have mild symptoms

Tx: erythromycin, somewhat effective if given before coughing spasms start, eliminates B. pertussis

Acellular vaccine (DTaP), for immunization of infants and children

Bacterial lower respiratory infection

• 1-Inhaled through lungs
• 2-Bacteria phagocytized by lung macrophages and multiply within them, protected by lipid-containing cell walls and other mech.
• 3-Infected macrophages are carried to various parts of body: kidney's, brain, lungs, lymph nodes; release of M. tb occurs
• 4-Delayed hypersensitivity develops; wherever infected M.tb has lodged, intense inflammation reaction develops
• 5-Bacteria surrounded by macrophages & lymphocytes, growth ceases
• 6-Intense inflammatory reaction & release of enzymes can cause caseation necrosis & cavity formation
• 7-W uncontrolled or reactive infection, M.tb exits body through mouth by coughing

• S/S: Chronic fever, weight loss, cough, sputum production
• Incubation: 2-10 weeks
• Cause: Mycobacterium tuberculosis; unusual cell wall with high lipid content

• Colonization of alveoli incites inflammatory repsonse
• Ingestion by macrophages follows
• Organisms survive ingestion and are carried to lymph nodes, lungs, and other body tissues
• Tubercle bacilli multiply, granulomas form

Inhalation of airborne organisms, latent infections can reactivate

Small enuf to go into alveoli

• Tx: Two or more antitubercular meds given simultaneously long term, such as isoniazid (INH) and rifampin
• DOTS
• BCG vaccination preventive but not used in US
• TB (Mantoux) skin test for detection of infection, allows early therapy of cases

Tx: All high-risk cases including young people with pos tests and individuals whose skin test converts from neg to pos

Bacterial Lower Respiratory Infection

• S/S: Muscle aches, HA, fever, cough, SOB, abd pain, diarrhea
• Incub: 2-10 days
• Cause: Legionella pneumophila , a gram neg bacterium that stains poorly in clinical specimens

• Organism multiplies with phagocytes
• Released with death of cell
• Necrosis of cells lining alveoli
• inflammation and formation of microabscesses

Originates mainly from warm water contaminated with other microorganisms, such as found in air-conditioning systems

Tx: Erythromycin and rifampin

• Avoidance of contaminated water aerosols
• Regular cleaning and disinfection of humidifying devices

• Influenza
• RSV
• Hantavirus

• Flu
• Widespread epidemics are characteristic of influenza A viruses
• Antigenic shifts and drifts are responsible
• Deaths are usually but not always caused by secondary infection
• Reye's syndrome may rarely occur during recovery from flu and other viral infections but is probably not caused by virus itself

• Caused by minor mutations in genes that code for Ha and Na antigens & are responsible for yearly occurrence of flu outbreaks (seasonal influenza)
• Happen during normal viral replication and often cause change in only single amino acid in HA or NA spikes
• Enuf to make immunity developed previous year less effective
• Strain names are given indicating year and location they are isolated
• VERY SLOW CHANGE

• Is uncommon but more dramatic change resulting of viral genome reassortment, cause of pandemic flu
• When 2 different flu viruses infect cell at same time, progeny produced can have TNA segments from either virus
• One can be from human and one can be from animal... or whatever. Various mutations occur
• VERY FAST CHANGE

• 1. Inhaled and carried to lungs
• 2. Viral hemagglutinin attaches to specific receptors on ciliated epithelial cells, with viral envelope fuses with cell, and virus enters by endocytosis
• 3. Host cell synthesis diverted to synthesize new virus
• 4. Newly formed virions bud from infected cells; released and infect ciliated epithelium, mucus-secreting and alveolar cells
• 5. Infected cells ultimately die and slough off; recovery of mucociliary escalator may take weeks
• 6. Secondary bacterial infection of lungs, ears, and sinuses is common
• 7. Virus exits with coughing

• S/S: fever, muscle aches, lack of energy, HA, sore throat, nasal congestion, cough
• Inc: 1-2 days
• Cause: Influenza virus, an orthomyxovirus

• Infection of respiratory epithelium
• Cells destroyed and virus released to infect 
• Secondary bacterial infection results from damaged mucociliary escalator

Epi: Antigenic drift and shift prevent immunity

• Tx: Amantadine and rimantadine are sometimes effective for preventing type A but not B virus disease
• Neuraminidase inhibitors effective against both A & B
• These meds somewhat effective for tx if given early in disease
• Vaccines usually 80-90% effective

• Respiratory syncytial virus
• S/S: runny nose, cough, fever, wheezing, diff breathing, dusky color
• Cause: RSV, a paramyxovirus that produces syncytia

• Sloughing of respiratory epithelium and inflammatory response plug bronchioles, cause bronchiolitis
• Pneumonia results from bronchiolar and alveolar inflammation, or secondary infection

Yearly epidemics during cold months; readily spread by otherwise healthy older children & adults who often have mild symptoms. No lasting immunity

• Tx: No satisfactory antiviral tx. No vaccine
• Preventable by injections of immune serum globulin or a monoclonal antibody

• S/S: fever, muscle aches, V/D, SOB, shock
• Inc: 3 days to 6 weeks
• Cause: Sin Nombre and related hantaviruses of bunyavirus family

Viral antigen localizes in capillary walls in lungs, causes inflammation

Zoonosis likely to involve humans in proximity to increasing mouse populations. Generally no person-to-person spread

• Avoid contact with rodents
• Seal access to houses, food supplies
• Good ventilation, avoid dust
• Use disinfectant in cleaning rodent-contaminated areas
• No proven antiviral tx

• Valley fever
• Spelunkers disease

• (Valley Fever)
• Fungal infection of respiratory tract
• S/S: Fever, cough, loss of appetite. most are asymptomatic
• Less frequently: painful nodules on extremities, pain in joints; skin, mucus membranes, brain, and internal organs sometimes involved
• Incubation: 2 days to 3 weeks
• Cause: Coccidioides immitis, a dimorphic fungus

• Valley Fever
• After lodging in lung, arthrospores develop into spherules that mature and discharge endospores, each of which then develops into another spherule
• Inflammatory response damages tissue
• Hypersensitivity to fungal antigens causes painful nodules and joint pain

• Valley Fever
• Inhalation of airborne C. Immitis spores with dust from soil growing the organism
• Occurs only in certain semi-arid regions of Western hemisphere (california)

Tx: amphotericin B and fluconazole or itraconazole

Prevention by dust control methods such as grass planting and watering

• Fungal infection of respiratory tract, of cave goers
• S/S: mild respiratory sym; less frequently fever, cough, chronic sores. most are asymptomatic
• Incub: 5-8 days
• Cause: Histoplasma capsulatum, a dimorphic fungus

• Spores inhaled, change to yeast phase & multiply in macrophages
• granulomas form
• disease spreads in individuals with AIDS or other immunodeficiencies

• The fungus prefers to grow in soil contaminated by bird or bat poop, especially in Ohio and Mississippi River valleys, and US southeast
• Spotty distribution in other countries
• Spelunkers are at risk (cave goers)

Amphotericin B and itraconazole for serious infections

Prevention by avoiding soils contaminated with chicken, bird or bat droppings