Case 7- pneumoniae Flashcards
Which conditions make you more susceptible to LRTI’s?
COPD and asthma
Types of LRTI’s
Pneumonia, Bronchitis (mianly viral), Bronchiolitis, Exacerbation of chronic obstructive pulmonary disease/ asthma.
What causes Bronchiolitis?
The RSV virus
Difference between bronchitis and pneumonia?
Bronchitis is mostly caused by virus’s. It causes inflammation in the bronchial airways
Pneumonia
Pneumonia is an infection of the lung tissue in which the air sacs of the lungs become filled with microorganisms, fluid and inflammatory cells affecting the function of the lung. Tends to be more serious then Bronchitis. You will see consolidation in an x-ray
Incidence of pneumonia
Occurs more in autumn and winter. Annual incidence of CAP is 5-10 per 1000, for those who get it hospital admission is 22-42%
What classes of organisms cause pneumoniae?
Viruses, bacteria or fungi
How can you prevent pneumonia
Immunization, adequate nutrition and addressing environmental factors
Most common cause of CAP
S.pneumoniae (streptococcus)
Most common cause of CAP in COPD
H.influenzae
Most common cause of CAP secondary to influenza
S.aureus
Cause of atypical pneumonias
Mycoplasma pneumoniae and Legionella spp (causes sporadic outbreaks)
Symptoms of pneumonias
Acute illness, Cough, Fever, Purulent sputum (smells), sometimes Haemoptysis (blood streaks in sputum), Breathlessness, Wheeze, Pleuritic pain, Abnormal (consolidation) CXR and Confusion (especially in the elderly).
Risk factors for pneumonia
- Younger than 16, older than 65.
- Co morbidities= HIV, Diabetes mellitus, Renal disease, Malnutrition, recent viral respiratory infections, immunosuppressant therapy.
- Other respiratory infection= COPD, CF, Bronchiectasis, neoplasms.
- Lifestyle: Cigarette smoking, Alcohol misuse, IDVU (intravenous drug usage).
Mycoplasma pneumoniae
Small bacteria which is rod shaped. Transmission is through airborne droplets through close contact. Onset can be gradual and sub-acute, slowly progressing to a high fever and persistent cough. It is frequently mild and self resolving. It is a mild self-limiting disease ‘Walking Pneumonia.’
Legionella spp- pneumonia
Gram negative bacteria. Infection is caused by inhalation of contaminated aerosols. Precense is particularly associated with cooling towers, air conditioning units, fountains, hot-tubs and shower heads. There are local and sporadic outbreaks. Legionnaires disease is 2 to 5 times more common in men. Mortality 10-15%.
CAP examination
Focal chest signs present such as dullness to percussion, course crepitation and vocal fremitus
Temperature above 38 degrees, respiratory rate above 20 beats per minute, heart rate above 100 beats per minute, new confusion. Consolidation in the X-ray
Lab diagnostics for CAP
You can use a culture from sputum or bronchioalveolar lavage and a blood culture.
• Antigens in the urine for pneumococci, legionella.
• Antibodies in the blood- for Staphylococci.
• Enzyme linked immunosorbence (ELISA) or polymerase chain reaction / detection of IgM antibodies for M.pnuemioniae.
CURB-65 score
Used to test for CAP and measure its severity
• C: confusion present (mental test score <8/10)
• U: plasma urea level >7mmol/L
• R: respiratory rate >30/min
• B: Systolic BP <90mm Hg / diastolic <60mm Hg.
• 65: older than 65.
You get 1 point for each category you qualify. 0-1 outpatient treatment. 2 admit to hospital. Higher then 3 and you should be admitted to ICU.
HAP - hospital acquired pneumonia
Defined as new onset of cough with purulent sputum in patients beyond 2 days after initial admission. Second most common type of nosocomial (originating in hospital) infection after a UTI. Significant mortality risk in elderly with co-morbidities. Caused by different types of organisms from CAP, can be linked to antibiotic resistance
Causes of HAP
- Gram -ve rods: E.coli, Klebsiella spp, Pseudomonas spp.
- Anaerobic bacteria: Enterobacter
- S.aureus (MRSA)
- Acinectobacter spp.
Treatment for CAP
- Mild disease: Amoxicillin.
- Moderate disease: Amoxicillin and Clarithromycin (if atypical suspected) or Doxycycline.
- Severe disease: Co-amoxiclav, it is a mixture of Amoxicillin and Clavulanic acid which is a beta lactamase inhibitor
Treatment for atypical pneumonias
Clarithromycin
Treatment for HAP
Co-amoxiclav
Causes of endemic fungal pneumonias
- Histoplasma capsulatum causing histoplasmosis- endemic in mid central and the eastern half of USA. From bat and bird faeces.
- Coccidioides immitis causing coccidioidomycosis- Central America, Mexico, S.America. It is found in the soil.
- Paracoccidioides brasiliensis causing paracoccidiodomycosis- found in Mexico, central and S.America. It is water borne.
Causes of opportunistic fungal pneumonia
- Candida spp. Causing candidiasis.
- Aspergillus spp. Causing asperillosis- seen in the UK a lot. Causes localised pulmonary infection in people with underlying lung disease, allergic bronchopulmonary disease, allergic sinusitis and allergic alveolitis.
- Mucor spp. Causing mucormycosis
- Cryptococcus neoformans causing cryptococcosis.
Aspergillus spp
A.fumigatus, A.flavus and A.niger. Can cause necrotising inflammation of the lungs. Leads to infarction -> necrosis -> oedema -> bleeding. Granulomas will form (immune complexes which try to restrict the movement of infection) and there will be a cavity wall invasion. This may cause damage to the lung tissue.
