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Week 5 Learning Objectives
Respiratory Tract Infections:
Compare and contrast the clinical features (symptoms and signs) and natural history of viral and
bacterial respiratory tract infections
Viral infections of the respiratory system will most likely affect the upper respiratory tract. Bacterial
infections on the other hand, are responsible for most cases of pneumonia and are generally involved
further down the respiratory tract. As a result, the symptoms for both can quite often be distinguishable
as generally affect two different sections of the respiratory system. Viral infections include Acute Coryza
(common cold) and Influenza (flu) and will usually affect passages of the upper airways. Clinical features
of a viral respiratory tract infection commonly include but not limited to (can vary depending on virus):
 Unproductive Cough
 Fever
 Sore Throat
 Nasal Blockage
 Nasal Discharge usually green/yellow
 Vomiting
Patients will usually present with a general feeling of sickness including one or more of the
aforementioned symptoms. Viral infections of the upper respiratory tract will often have very rapid
onset. Most of these types of infections will not require treatment, though Paracetamol is commonly
used to relieve symptoms.
Bacterial infections are the most common cause of community and hospital acquired pneumonia. These
infections can be a secondary infection caused by a preceding viral infection in the upper respiratory
tract. For example, a patient may present with pneumonia after they have just immediately had or is still
having a severe case of influenza. The history of the presenting illness will often show a common cold or
flu that has progressively worsened. Symptoms of the bacterial induced pneumonia include, but are not
limited to:
 Systematic features
o Fever
o Rigors
o Shivering
 Vomiting
 Painful Unproductive Cough (at first)
 Cough with Mucosporulent Sputum (later)
 Pleuritic Chest Pain
 Upper Abdominal Tenderness
Antibiotic Resistance
Briefly describe the consequences of antibiotic resistance at the individual and population health levels
Antibiotic resistance poses a considerable threat to the population at large. Since the discovery of
Penicillin, antibiotics have been heavily used to control bacterial infections. Bacterial resistance to
antibiotics would severely hinder the capability to control these infections. The population of greatest
concern would be hospital patient, particularly those who have impaired immune systems.
Immunosupressed individuals will have very little resistance to infections and rely heavily on antibiotics.
If they were to be infected by a drug-resistant microorganism such as MRSA, antibiotic treatment will
not be effective, limiting the physician’s capacity to assist.
A large problem also lies with the development of more antibiotic resistant organisms. We currently
have a range of drugs that can help combat bacterial infections but the rapid rate of evolution and
adaptation that microorganisms undergo increases their ability to build resistance to these drugs. We
may potentially run out of effective agents, eliminating the advantage of antibiotics altogether.
Outline measures to reduce its occurrence
The most common error that leads to antibiotic resistance is the inappropriate use of the drug.
Antibiotics should only ever be used in situations that have been deemed appropriate. Every time a
bacterium encounters one of these drugs, there is a very small chance that it can develop an immunity
though mutation, natural selection or by acquiring it from another microorganism. Prolific overuse of a
drug will increase the chances of an organism developing resistance to it, as is the case with the original
Penicillin. Limiting these chances is paramount to preventing resistance. As a result, antibiotics should
only be prescribed under these circumstances:
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The target organism must be fully susceptible to the effects of the agent.
An appropriate target route and administration must be given to ensure no dose is “wasted”.
Prescription must acknowledge of current local patterns of antimicrobial resistance.
A dose must be effectively calculated and delivered.
These measures will ensure that inappropriate dosages are given, minimizing the opportunity for
microorganisms to develop resistance. These also ensure that whatever organism is exposed to the drug
is eliminated, preventing the re-growth and re-culture of a drug resistant form of the same organism.