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What is meant by Pneumonia?
Pneumonia is a common illness and means infection in the lung. This infection mainly affects the alveoli of the lungs. These are tiny air sacs in the lung. They take oxygen from the air you breathe in. They send this oxygen to the blood stream, which then travels around the body. When there is an infection in the lung, the alveoli fill up with mucus. This prevents the lungs from taking up enough oxygen from the breathed-in air. This leads to shortness of breath. The mucus may be coughed up as phlegm (or sputum). Inflammation caused by the infection can cause a fever and pain on the side of the affected lung.
A patient will notice increased cough, phlegm, breathlessness, wheeze and chest pain) with the cardinal signs on inflammation fever, rigors and sweats.
Occasionally a patient might have vomiting and diarrhea. Note elderly patients, young patients and immunocompromised patients might not demonstrate classic signs of a pneumonia.
What investigations do I need?
Based on a history of increased respiratory symptoms a patient should be referred for a CXR. A diagnosis of pneumonia should not be made without a CXR.
Blood tests like a C-reactive protein and full blood count (FBC) can also support the diagnosis.
Sputum should be sent for culture through a family doctor or within a hospital setting.
Bronchoscopic sampling of the airways is only indicated in refractory pneumonias or other complicated pneumonias, like a nosocomial (originated in hospital) pneumonia, immunocompromised pneumonia or when there is any doubt of a non-bacterial organism like fungi, mycobacterium or pneumocystis.
Should I stay in a hospital or should I rest at home?
Assess the patient’s severity with the CRB-65 or CURB-65 score. The CRB-65 score can be used in a primary care setting without checking the blood urea level.
Respiratory rate ≧ 30/min
BP ≤ 90/60
Age ≧ 65
If using the CRB-65 score in a primary care setting without bloods;
Score 0: Patient is suitable for home antibiotics
Score 1-2: Consider hospital referral
Score 3-4: Urgent hospital admission
The CURB-65 or CRB-65 should always be interpreted in conjunction with clinical judgement and reassessed at each review if there is insufficient improvement. If no clear response within 48 hours, a patient should be considered for admission, or add a macrolide e.g. clarithomycin or a tetracycline to cover mycoplasma infection.
Compliance with antibiotics and Resistance Patterns
Patients should always finish the entire course of antibiotics prescribed to them. Numerous studies have repeatedly shown that current full compliance with an antibiotic course is approximately 50%. This is frequently due to good symptomatic resolution before the full course of antibiotics is done.
Unfortunately, antibiotic resistance is on the rise and likely leading to an increase in initial treatment failure at a primary care setting.
What happens after the patient gets a pneumonia
Patient should notice subjective improvement in their original symptoms within 3 to 5 days. Symptoms like cough can take 2 weeks to 2 months to settle. Co-morbid diseases like diabetes, ischaemic heart disease and cancer affect the rate of resolution from a pneumonia. This along with age, severity of the original pneumonia and etiology can lead to either slow recovery or complete treatment failure.
It is very important for a patient to get a follow-up CXR at 6 weeks after a pneumonia to ensure non-pneumonic conditions are highlighted. A main concern is underlying lung cancer where a non-resolving consolidation or shadow on a CXR will require a CT of the lung.
Separate issues are the increased risk of bleeding with warfarin when taken with antibiotics, plus interactions with medications like statins, amiodarone and QT prolonging medications.
What are alarm symptoms or signs after a pneumonia?
Approximately 10% -15% of patients might not respond to empirical antimicrobial therapy.
Persistence of original symptoms beyond 5 days of commencing antibiotics is suggestive of a pneumonia refractory to original therapy. A more detailed history will be necessary looking for other risk factors for atypical organisms and non-infectious causes. The initial worry is whether a resistant organism is involved. There is also a smaller chance there could be a super-infection with a nosocomial or hospital-acquired organism if patient was admitted. Occasionally the pneumonia was caused by fungi, mycobacterium or Pneumocystis.
At this stage, a thoracic CT can be considered after a repeat CXR. If a patient notices swinging temperatures, drenching sweats and worsening malaise, a lung abscess or empyema will have to be out ruled as a sequestrated pneumonia may inadequately get adequate amounts of antibiotic therapy.
An empyema is when a parapneumonic pleural effusion becomes infected and leads to pus formation in the pleural space.
A consolidation on CXR might not be a pneumonia
Non-resolving pneumonias might not be a pneumonia at all. A combination of repeat thoracic imaging, bloods, bronchoscopic evaluation or tissue sampling might lead to a host of other differential diagnoses.
Consider if the patient has
• Neoplastic causes like lung cancer, lymphoma or pulmonary metastases
• Vascular diseases like a pulmonary embolism and resulting pulmonary infarction or congestive cardiac failure
• Drug-induced e.g. hypersensitivity pneumonitis
• Inflammatory conditions like cryptogenic organizing pneumonia (previously BOOP), sarcoidosis or granulomatous polyangitis
At this stage, a respiratory specialist referral is appropriate.