Lecture 16- Bacterial Diseases Of The Respiratory System

Question 1

Common diseases of the upper respiratory system

Answer 1

*laryngitis- streptococcus pneumoniae

*tonsillitis- s.pneumoniae

*epiglottitis- haemophilia influenzae

*sinusitis- general bacteria

Question 2

Scarlet fever

Answer 2

Caused by streptococcus pyogenes

Erythrogenic; redness producing toxin produces symptoms
Childhood disease- 2+8 years
Easily treated with antibiotics

Fever, rash, sore throat, swollen tongue + flushed cheeks; peeling skin when rash fades
^sometimes confused with measles
Highly contagious + is spread by close contact
Incubation; 2-5 days

Question 3

Scarlet fever- complications

Answer 3

Can develop into a more serious infection if untreated

Can develop into; ear infection, throat abscess, pneumonia, inflammation of the sinuses, skin/soft tissue infection, joint inflammation, septicaemia, meningitis

Later complications; bone/joint problems, liver, kidney/heart damage

Question 4

Diphtheria

Answer 4

Highly dangerous disease
Corynebacterium diphtheriae; gram + rod

Characterised by pseudo-membranes at the back of the throat
Membrane of fibrin, dead tissue + bacteria

D toxin produced by= lysogenized C.diptheriae
Prevented by= vaccine
Cutaneous diphtheria- infected skin wound leads to slow healing ulcer

Question 5

Pertussis; whopping cough

Answer 5

Bordetella pertussis; gram- coccobaccilus
Capsule
Tracheal cytotoxin; damages walls of ciliated cells
Pertussis toxin; prevented by vaccine
Cell fragments
3 stages;
1. Catarrhal stage; like common cold
2. Paroxysmal stage; violent coughing sieges
3. Convalescence stage

Question 6

Complications in infants + young children

Answer 6

Usually most severely affected + likely to develop severe complications;
- pneumonia
- temporary pauses in breathing due to difficulty breathing
- weight loss due to excessive damage
- seizures/ brain damage
- encephalitis - acute inflammation of the brain

Question 7

Immunity against pertussis

Answer 7

Vaccination- does not give life long immunity
Individuals can become re-infected + spread infection
Risk for children too young to be vaccinated

Question 8

Tuberculosis

Answer 8

Caused by mycobacterium tuberculosis
Rod shaped bacilli
Acid fast; resistant to most conventional microbiological staining techniques
PCR diagnosis

Question 9

Mtb infection, membrane + targets

Answer 9

Spread like common cold
Tb occurs- bacteria inhaled by human host
Primary defence; tracheal + brachial epithelium

Mtb membrane;
-waxy impermeable barrier
-unusual complex membrane lipids; mycolic acids
-slow growing
-adaptive- can hide in body

Drugs + targets;
Front line drugs; isoniazid, rifampicin, pyrazinamide + ethambutol

Question 10

Decline in TB

Answer 10

Slides 25-30

Question 11

Pneumonia + pneumococcal pneumonia

Answer 11

Inflammation of the tissues in the lungs
Alveoli= become inflamed and fill with fluid
Symptoms= cough, difficulty with breathing; oxygen deficit

Fatal in some cases; babies, young children + elderly, smokers

PP;
Streptococcus pneumoniae; gram + encapsulated diplococci
Diagnosis- culturing bacteria
Penicillin = drug choice

Question 12

Haemophilus influenzae pneumonia

Answer 12

Gram - coccobacillus
Alcoholism, poor nutrition, cancer or diabetes
Second gen cephalosporin

Question 13

Mycoplasmal pneumonia

Answer 13

Mycoplasma pneumoniae; pleomorphic, wall-less bacteria
Known as primary atypical pneumonia/ walking pneumonia
Common in= children/young adults
Diagnosis; PCR / igM antibodies

Question 14

Legionellosis

Answer 14

Legionellosisl legionella pneumophila= gram - rod
- found in water
- transmitted by inhaling aerosols; not transmitted from human to human
Diagnosis= culturing bacteria
Treatment= erythromycin

Question 15

L.pneumophila

Answer 15

Gram - , motile, aerobic rod
Considered to be intracellular parasites
Optimum growth temp; 20-45 degrees
Not culturable with standard microbial media- unusual nutritional requirements high iron conc

Question 16

Infection

Answer 16

Begins with the inhalation of the legionella pneumophila bacterium
Not transmitted from human to human
Legionella reach alveoli + come into contact with alveolar macrophage
^ takes bacteria into food vacuole inside the cell
Bacteria divide within vesicle- becomes studded with ribosomes + eventually kill macrophage

Question 17

Lung damage

Answer 17

Caused by;
- attracting phagocytes and T cells to the infected area
^ lungs become damaged because these cells release cytokines + other toxic products which do not kill the bacteria but damage the lung
- legionella survives= releases enzymes
- legionella pneumophila = damage lung tissue is by producing extracellular proteases -> lesion formation in lung tissue

Question 18

Psittacosis; ornithosis

Answer 18

Chlamydophila psittaci; gram - intracellular bacterium
Transmitted to humans by elementary bodies from bird droppings
Reorganises into reticulate body after being phagocytized
Diagnosis= culturing bacteria in eggs/cell culture
Treatment= tetracycline

Question 19

Fungal pneumonias

Answer 19

Rare in UK healthy individuals; immune-compromised
Associated with travelling
Examples; histoplasmosis, pneumocystis, coccidiodomycosis + blastomycosis

Question 20

Opportunistic fungi involved in respiratory disease

Answer 20

Aspergillus
Rhizopus
Mucor