Chronic Respiratory Infections
Normal Flora of the Respiratory Tract
Upper respiratory tract
i.




Mouth
Streptococci (particularly Streptococcus mutans and Streptococcus salivarius)
Lactobacilli spp.
Staphylococcus epidermidids
Spirochetes
ii.




Nose
Staphylococci (most common in noses, especially Staphylococcus epidermidids and
Staphylococcus aureus)
Streptococci (particularly Streptococcus pneumoniae)
Virdans streptococci
Corynebacterium spp.
iii.






Throat (Larynx and pharynx)
Staphylococci
Streptococci
Neisseria spp.
Haemophilis spp.
Corynebacterium spp.
Branhamella
Lower respiratory tract
• There should be NO normal flora present in the lower respiratory tract. Sputum can be
contaminated by organisms in the mouth on its passage out of the respiratory tract.
Common Upper Respiratory Tract Infections
Infection
Acute Coryza
(Common Cold)
Pharyngitis/tonsillitis
Acute Laryngotracheobronchitis
Sinusitis
Epiglottitis
Acute otitis media (middle ear
infection via Eustachian tube)
Agent
> 70% viral – rhinovirus,
coronavirus
Resp synctial virus (RSV)
As above + haemolytic
streptococci, EBV
Parainfluenza viruses, influenza
virus, RSV
Strep. Pneumoniae, Haemophilus
influenza
Haemophilus Influenzae
Strep. Pneumoniae, Haemophilus
influenza, Moraxella catarrhalis
but can also be viral
Clinical Features
Rapid onset. Sneezing, sore throat,
watery nasal discharge, cough
More severe sore throat, hoarse or
loss of voice, painful cough
Sudden attack of cough with
stridor and breathlessness. Can
lead to cyanosis and asphyxia in
small children
Fever, Unilateral pain over sinuses,
purulent nasal discharge
Mostly affect young children.
Fever, sore throat, progressing to
stridor and dysphagia
Fever, ear pain, and associated
symptoms such as runny nose and
cough
Common Lower Respiratory Tract Infections
Infection
Bronchiolitis (mainly affects babies
and little children)
Acute Bronchitis
Agent
RSV, parainfluenza virus,
adenovirus
Rhinovirus, adenovirus, influenza
virus, RSV
Whooping cough
Bordetella pertussis
Chronic bronchitis exacerbation
Strep. Pneumoniae, Haemophilus
influenza, Moraxella catarrhalis
Acute typical pneumonia
Strep. Pneumoniae, Haemophilus
influenza, Moraxella catarrhalis,
Staph. Aureus, Legionella + many
others
Atypical pneumonia
Mycoplasma pneumoniae,
Chlamydia pneumoniaeS
Clinical Features
Cough, runny nose, dyspnoea
Often follows common cold. Initially
dry, painful cough. Then chest
tightness, wheeze and
breathlessness. May have fever
Features of the common cold but
also persistent cough and sticky
mucous develops in RT making
breathing difficult
When breathing suddenly becomes
more difficult for a person with
chronic bronchitis (due to
narrowing or airway and secretion
of large amounts of mucous)
Fever, shivering, vomiting,
breathlessness, cough (at start
short, painful + dry but later
accompanied by sputum), chest
pain
Symptoms much milder than acute
typical pneumonia
Planktonic vs Sessile Organism
• Bacteria in the environment are described as planktonic or sessile
• Planktonic organism = organisms (bacteria) that remain suspended (float) in a fluid environment
 They have surfaces that are hydrophilic (water loving), do not have a surrounding sugar coat,
so are very susceptible to antibiotics
 They are also easily detected and dealt with by the host immune system
• Sessile organisms = organisms bound within or to a surface structure
 More resistant to antibiotic action than planktonic organisms
 This is because sessile organisms firstly form colonies and due to higher numbers, those in
the centre are less susceptible to being affected by antibiotics
 But the main reason for sessile organisms higher resistance is due to the biofilm produced by
the organism, which protects them from antibiotic action. It is thought that the biofilm
produces antibiotic-degrading enzymes and also has the ability to “pump” out antibacterial
agents (from the biofilm) before they can have an effect on the bacteria itself