Microbes-L11- Bacterial Respiratory Pathogens

what are respiratory tract infections classified to?

1. upper respiratory tract infection- nasal, pharynx, nose

2. lower respiratory tract infection-larynx, trachea, bronchi and lungs

what are upper respiratory tract infections caused by and what do they include?

• acute infection

• tonsilitis

• sinusitis

• common cold

what are lower respiratory tract infections caused by and what do they include?

• inflammation of air passages within the lungs

• trachea, large and small bronchi within lungs become inflamed

• bronchitis and pneumonia

what are some common defences in respiratory tract and why?

most common place for infectious agents to gain access to the body

• nasal hair

• cilia

• mucus

• coughing/sneezing/swallowing

• macrophages

• secretory IgA antibodies

normal microbiota of the respiratory tract

• gram positive bacteria- streptococci and staphylococcus are common

• get ill when immunocompromised

• normal: acintobacteria, firmucites

describe an upper respiratory tract disease-s!

• common caused by allergy or infections

• follows a bout of the common cold

• naal congestion, pressure above nose and forehead, headache- facial swelling

• discharge is opaque green/yellow- bacteria

• treated with antibiotics

describe another upper respiratory tract disease-a

acute otitis media- an ear infection

• viral infection can lead to inflammation of Eustachian tube- middle ear build up of fluid where bacteria can multiple

• bacteria can migrate along Eustachian tube from upper respiratory tract- make pu

• pain, hearing loss- can lead to eardrum rupture

describe an upper respiratory tract disease-chary

• inflammation of the throat- reddened mucosa, swollen tonsils, white packets of inflammatory

• bad smelling breath

• penicillin etc

describe an upper respiratory tract disease-diph

diphtheria

• sore throat, lack of appetite and fever

• - pseudomembrane forms on tonsils or pharync

• diphtheria has a toxin- 3 regions- C, T and R domain

• A fragment-active part- inhibits protein synthesis

diseased caused by microorganisms affecting upper and lower respiratory tract

whopping cough- by RSV and influenza- caused by bordetella pertussis toxin

1. catarrhal stage- 3-21 days, bacteria cause symptoms that look like a cold

2. paroxysmal stage- uncontrollable coughing- spasms that can cause burst blood vessel and vomiting

pertussis toxin- suppresses antibodies, stops neutrophil recruitment, inhibits phagocytosis

what are lower respiratory tract infections caused by bacteria? what parts do they effect?

• affect bronchi, bronchioles and lungs

• pneumonia and TB

pneumonia- how is it diagnosed? what are symptoms

• diagnosed based on anatomical features- inflammation of alveolar wall and fluid filled space

• begin with upper respiratory tract symptoms- runny nose, congestion

• headache/fever- then chest pain/fever/cough

what are the common bacteria that cause pneumonia?

gram negative organisms

• streptococcus pneumonia, staphlococcus aurea, strepcoccus Klebsiella

discuss klebsiella pneumonia features

• gram negative

• rod shape, non motile

• anerobic

• lactose fermenting

• polysaccharide capsule- mucoid colonies on plates

discuss klebsiella pneumonia- where it can be found

• in nature- soil, plants, water

• in the human microbiota

• mouth, nasopharynx, skin and intestinal tract

• spreads easily but not through the air

• can cause pneumonia, meningitis, urinary tract infections

discuss klebsiella pneumoniae- in a hospital setting

• cause human nosocomial infections

• high risk patients are those requiring catheters/ventilators, this eon antibiotics as microbiota is disrupted

• can spread via respiratory tract- pneumonia

• from contaminated hands and person to person contact

discuss klebsiella virulence factors

• has an O antigen

• capsular polysaccharide-K antigen

• both contribute to pathogenicity

• capsule- whole cell surface- increases its virulence

• creates a physical barrier to evade hosts immune system

• protects cell from desiccation

discuss pseudomas aeruginosa

• gram negative

• rod shaped

• can cause disease in different species

• non spore forming

• type IV pili

• LPS and outer membrane proteins

• flagellins

• type VI secretion systems

what is pseudomas aerugina associated with and what makes it so virulent?

• cycstic fibrosis

• has efflux pumps for antibiotic resistance, and extracellular polysaccharide for biofilm formation

• exotoxin A

• also associated with nosocomial hospital cases of ventilator and hospital acquired pneumonia