Pyogenic LRT Infections
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
drjonahp@yahoo.com
Introduction
Lower Respiratory Tract Infection (LRTI) is the infection that occurs below the level of the larynx.
1) Laryngo-trachea-bronchitis (LTB)
2) Bronchitis
3) Bronchiolitis
4) Pneumonia
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Introduction
Essentially, it is the inflammation of the airways/pulmonary tissue, which may be due to viral or bacterial infections of the lung tissue, below the level of the larynx.
Gastro-esophageal reflux may cause a chemical pneumonitis in the lungs.
Smoke and chemical inhalation may also cause pulmonary inflammation
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Etiology
• Viral
• Bacterial
• Mycobacterial
• Fungal
• Protozoal
• Others like smoke, chemicals, dust and pollen.
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Etiology
Viral causes:
Influenza A virus
Respiratory syncytial virus (RSV)
Varicella-zoster virus (VZV)
Chickenpox
Secondary bacterial infection commonly follows viral upper or lower respiratory tract infection (URTI or LRTI).
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Etiology
Bacterial causes :
Streptococcus pneumoniae (the majority of bacterial pneumonias)
Hemophilus influenzae
Staphylococcus aureus
Klebsiella pneumoniae
Escherichia coli
Anaerobes
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Etiology
Atypical bacterial causes:
Mycoplasma pneumoniae
Legionella pneumophila,
Chlamydophila pneumoniae
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Etiology
Fungal causes:
• Endemic fungi
–Histoplasmosis
–Blastomycosis
–Cryptococcosis
• Aspergillus
• Candida
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Clinical Presentation
Typical viral Upper Respiratory Tract Infection presentation with fever.
Bacterial pneumonia in children presents with persistent or repetitive fever > 38.5°C with chest recession and a raised respiratory rate.
Audible wheezing is not seen very often in LRTI but more common with diffuse infections caused by M pneumoniae and bronchiolitis.
Stridor or croup suggests URTI, epiglottitis or foreign body inhalation.
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Clinical Presentation
Newborn and neonates present with:
Poor feeding, irritability or lethargy
Grunting, tachypnoea, cyanosis (in severe infection) and cough.
Fever (±Hypothermia)
In this age group beware of streptococcal sepsis and pneumonia in the first 24 hours of life and Chlamydial pneumonia, which may be accompanied by chlamydial conjunctivitis (presents in the second or third week of life)
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Clinical Presentation
Infants present with:
Cough (the most common symptom after the first four weeks)
Tachypneic (according to severity), grunting
Chest indrawing, feeding difficulties, irritability and poor sleep
Breathing, which may be described as 'wheezy' (but usually upper airway noise)
History of preceding URTI (very common) with atypical and viral infections (especially pneumonia) may have low-grade or no fever.
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Clinical Presentation
Toddlers/pre-school children:
Preceding URTI and cough is the most common symptom with vomiting (post-tussive vomiting).
Fever occurs most noticeably with bacterial organisms.
Pain (chest and abdominal)
Lower lobe pneumonias can cause abdominal pain.
Older children will present with additional symptoms to those above. Atypical organisms are more likely in older children
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Differential diagnosis
Asthma
Inhaled foreign body
Pneumothorax
Cardiac dyspnoea
Pneumonitis from other causes:
Extrinsic allergic alveolitis
Smoke inhalation
Gastro-esophageal reflux
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Investigations
White cell count is often elevated.
Microbiological studies:
Blood cultures are seldom positive in pneumonia (fewer than 10% are bacteraemic in pneumococcal disease).
Sputum culture
Chest radiography (CXR) is not routinely indicated in outpatient management.
CXR cannot reliably differentiate between bacterial and viral infections.
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Prevention
Prevention of pneumococcal pneumonia and influenza by vaccination, for high-risk individuals with pre-existing heart or lung disease.
Smoking in the home is a major risk factor for all childhood respiratory infections.
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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Thank you
Dr. J. Y. Peter (BM BCh, MSc, FMCPath, MRCPath)
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