Respiratory Infections

Respiratory

• sinus, nasal cavities, and hair prevent microbial entry

• normal microbes suppress pathogens by competing for nutrients and prod. inhibitory substances

• ciliary escalator - pushes particles to the throat with ciliary action

• alveolar macrophage - no microbes in lung

• Respiratory mucus protects mucosal surfaces

• lower respiratory tract is nearly sterile

Streptococal Pharyngitis (Strep throat)

• caused by GAS

• fever, tonsilitis, enlarged lymph nodes

Scarlet Fever

• erythrogenic toxin produced by lysogenized S. Pyogenes

• was introduced from a virus

• complication of GAS

Diphtheria

Cause: Corynebacterium

• forms tough grayish membrane (throat)

• no passage of air to lung

• diphtheria toxin can damage

• exotoxin produces only by lysogenized bacteria

• can circulate in the blood ; damage heart and kidneys

• Prevent by DTP vax (form of toxoid vax)

Common cold (Rhinovirus)

• no vax

• endemic

• no fever

• no treatment - must treat symptoms

Otitis Media

• middle ear; cause many bacteria at S. pneumoniae

• common in childhood due to smaller auditory tube

Lower Respiratory Sys: Pertussis

• whooping cough

• cause: Bordetella pertussis

• starts mild, then becomes aggressive coughing and gasping for air

• prod. capsule

  • attach to ciliated cells in trachea, destroys ciliated cells and shut down the ciliary escalator

• Pertussis toxin damages ciliated cells

• toxin may enter blood stream

• prevent with DTaP vax

• treat with erythromycin

TB

Mycobacterium

• acid fast rod; trans. inhaling

• thick waxy (rich in lipids

  • will not dry out and resists microbials

• inhaled TB is phagocy. by alvelor macrophages but resists killing

• mycolic acid in the cell wall stimulates inflammation. response

• macrophages isolate/wall off turbercule

• tubercles then heal, and calcify (Ghon’s complex)

  • The tubercle can break down and release bacteria into the lungs/cardio sys. (disseminated infection / miliary TB)

TB skin test

• positive reaction means current or previous infection

• X ray, CT, acid fast staining of sputum

• culturing (TB grows very slow, culturing is hard)

• New rapid blood test for IRN-y and PCR test

• 1/3 of world has latent TB

• leading cause of death for people with HIV

• BCG vax- live culture of avirulent M.Bovis (not in US, can affect TB test results, not very effective)

Treatment of TB

• min of 6 months on drug therapy due to slow growht and dormancy

• first line - isxoniazid, rifampin,. ehtnambutol, pyrazanamide

• second line used if first line doesnt work

• multidrug resistant - resist first line

• extensively drug resistant - resists second line too

Bacterial Pneumonia

• Pneumococcal

• cause: Strep. Pneumoniae

• capsule resisting phago.

Haemophiles Influenzae Pneumonia

• similar symptoms to pneumonia

• HIB vax. very young and old at risk

• atypical - caused by mycoplasma

• mild symptoms are common in young adults

Legionellosis

• associate with cooling towers and AC systems

• grows in H20 and forms biogilm

• viral pneumonia - complications of flue and meales, but less severe than bacterial pneumonia

Viral pneumona

• complication of influenza, measles, chicken pox

• few labs are equipped to test clinical samples properly for viruses

• SARS - associated with coronavirus (from Asia 2003)

• MERS-COV (saudi arabia 2012)

• COVID 19

Respiratory Synctial Virus

most common in infants and life threatening pneumonia in older adults

• cause: cell fusion in cell culture

• coughing and wheezing for longer than a week

• diagnosis: serological test for viruses and antibodies

• Treat: palivizumab

Viral Pneumonia - Influenza

• segmented RNA virus with envelop and spikes

• chills, fever, headache, muscle aches

Hemagglutinin (HA) spikes

• attach to host

Neuraminidase (NA) spikes

• help virus spread

vax avaliable

Treatment with Tamiflu and Relenza (inhibits neuraminidase)

• cells have H and N identification

• Antigenic drift - H will change to N, allowing virus to stop host immunity

  • Antigenic shifts - MAJOR CHANGES - causes pandemics

Fungal - Histoplasmosis

• lung infaction - spread by bat droppings

• limited geographical range in US

• endemic in appalacian area

Pneumocystis Pneumonia

• immunocomp. people ; lung infection

• primary indicator of AIDs

Aspergillosis

lung infection

• fungi grows in compost piles