21 Respiratory System Infections

5-6

Respiratory system infections are most prevalent as they are easy to transmit

• inanimate objects

• respiratory droplets

  • sneezing (nasal sprays) have an area of effect of [__] feet

Varies from annoying (eg. common cold)

to deadly diseases (eg. pneumonia)

Upper respiratory

½ ways respiratory infections are divided by

[__] » refers to the head and neck region, diseases here are:

• very common

• uncomfortable but not life-threatening

• contains normal microbiota in nose and throat

  • Streptococci in throat

  • S. aureus in nose (~30% of healthy individuals)

Sterile sites:

• conjunctiva (eye)

• sinuses

• tear ducts

• middle ear

Lower Respiratory

2/2 ways respiratory infections are divided by

[__] » refers to the chest area. Diseases here are:

• more serious; can be life-threatening

» lacks normal microbiota in this region

• defenses: IgA, macrophages, mucociliary escalator

Streptococcus pneumoniae

[__] alongside Haemophilus influenzae are the common causative agents for the common secondary infections in the upper respiratory tract:

• conjunctivitis (pink eye)

• otitis externa / media » infection of inner / outer ear

• sinusitis » sinus infection

Conjuctivitis

Upper respiratory infection

Pink eye. Can be caused by bacteria or viruses

Symptoms: tears, redness of conjunctiva, swollen eyelids, pus

» more pus produced in bacterial [__] than viral [__]

» bacterial [__] is highly contagious as people tend to touch their eyes and transmit the largely bacterial pus to their hands and everything else they touch

Otitis

Upper respiratory infection

Infection in the ears

[__] externa: infection of outer ear by normal microbiota

» typically caused by S. aureus, C albicans (yeast), & other Gram-negative opportunistic pathogens

Otitis media: infection of middle ear (which is sterile)

» common infection in young children; kids tend to tug their ear

Symptoms: mild fever, severe earache due to fluids in eardrum, inability to hear, pressure build up that may cause eardrum rupturing

Sinusitis

Upper respiratory infection

Infection in the usually sterile sinus → inflammation causes its many symptoms

Symptoms: facial pain, pressure, headaches, malaise, and thick green nasal discharge

» yellow discharge still indicates milder symptoms while green indicates definite need for antibiotics

Streptococcus pyogenes

“Strep throat” or Streptococcal pharyngitis

Symptoms: painful swallowing

Causative agent is [__]: gram-positive streptococci

• belongs to Group A streptococcus (GAS)

• has hemolysin → beta-hemolytic

» when systemic, cause severe hemolytic anemia (deadly)

• virulent due to:

adhesins that help them attach to surfaces and avoid host defenses

» capsule → resistant to getting phagocytized

» M proteins

exotoxins that are pyogenic: pus-producing

Streptococcal Pharyngitis

[__] is characterized by

• sore throat, difficulty swallowing, fever

• red throat with pus patches

Spread by: respiratory droplets or contaminated food

Confirmed by:

» rapid antigen test → uses antibiotics to detect bacteria

» throat culture (growing and isolating for the bacteria Streptococcus pyogenes)

Treatment:

prompt antibiotic needed as it moves fast and can become systemic and lead to more deadly sequelae

» 10 days of antibiotics (Penicillin or erythromycin)

Glomerulonephritis

Post-Streptococcal sequelae

(i.e, long-term complications post-strep throat)

[__] : kidney disease that destroys its cells by infection and inflammation of the glomerulus

Rheumatic fever

Post-Streptococcal sequelae

(i.e, long-term complications post-strep throat)

[__] : inflammatory disease that affects the heart (damages heart valves) and joints, skin, and brain