Respiratory Tract Infections 2 Flashcards
What is pneumonia and how is it confirmed?
It is inflammation of the substance of the lungs. Confirmed using chest radiograph
Describe the difference in pneumonia in children and adults?
- Children - Mainly viral, neonates can develop it from chlamydia trachomatis from mother during birth.
- Adults - Mainly bacterial, the aetiology varies with age, underlying disease, occupational and geographic risk factors.
What are the common causes of viral pneumonia?
- Influenza virus,
- Measles,
- Coronavirus,
- Parainfluenza virus,
- Respiratory syncytial virus,
- Cytomegalovirus,
- Adenovirus
What are some bacterial causes of pneumonia?
- Streptococcus pneumoniae,
- Mycobacterium tuberculosis,
- Haemophilus influenza,
- Pseudomonas aeruginosa,
- Staphylococcus aureus
What are some of the atypical cause of pneumonia?
These are a failure to respond to treatment with penicillin, caused by;
- Mycoplasma pneumoniae,
- Legionella pneumophilia,
- Chlamydia psittaci/pneumoniae,
- Coxiella burnetii.
Describe the anatomical classification of pneumonia
- Lobar pneumonia,
- Bronchopneumonia,
- Interstitial pneumonia,
- Necrotising pneumonia (lung abscesses and destruction of parenchyma)
What are the clinical features of streptococcus pneumoniae infection?
Initially - Abrupt onset, rigors, fever, malaise, tachycardia, dry cough.
Followed by productive cough with rusty sputum, spiky temperature and lobular consolidation
What are the clinical features of mycoplasma pneumoniae?
Fever, dry cough, dyspnoea and lymphadenopathy.
What are the clinical features of haemophilus influenza infection?
Mainly occurs in children, it results in consolidation or patchy bronchopneumonia with persistent purulent sputum and malaise.
What are the clinical features of legionella pneumophila infections?
- It causes legionnaire’s disease
- Results in tachypnoea, purulent sputum and chest x-ray shows consolidation.
- Gram negative bacillus which secretes protease causing lung damage.
- Transmitted by aerosol, not person to person
How do you diagnose legionnaire’s disease?
Gram staining of sputum.
Recognition with serotype specific fluorescent antibody.
- Detection of antigen in urine
- 4-fold rise in antibodies.
Describe clinical features of measles?
Fever, runny nose, Koplik’s spots (only occur in measles) and a characteristic rash. It may cause neurological complications.
- May cause Hecht’s pneumonia
What is the prevention, diagnosis and treatment of measles?
Prevention - Immunisation with MMR vaccine.
Diagnosis - Serology for measles-specific IgM, viral isolation or viral RNA detection.
Treatment - If severe ribavirin or antibiotics for secondary bacterial infections.
What are some of the risk factors for pneumonia?
- Bird contact, Travel/air conditioning, cystic fibrosis, immigration, farming (sheep) and recent influenza.
What are the symptoms of pneumonia?
Cough, breathlessness, weakness and malaise, chest pain (pleural inflammation) and purulent sputum
What are the signs of pneumonia?
- Raised temperature
- Purulent sputum
- Rapid respiration
- Signs of lung consolidation
- Shock
- Cyanosis
How do you diagnose pneumonia?
- History,
- Examination,
- Radiology,
- Sputum,
- Serology,
- Histopathology.
Describe the CURB scores for pneumonia
- Confusion of new onset.
- Blood Urea nitrogen greater that 7mmol/l
- Respiratory rate over 30
- Blood pressure with systolic less than 90 or diastolic less than 60
- Age 65 or older.
Define endemic, epidemic and pandemic disease
endemic - Present in community at all times but at low levels.
Epidemic - Sudden severe outbreak within a region or group.
Pandemic - Occurs when epidemic becomes widespread and affects whole region/continent or world
What are the three types of influenza?
Type A - Epidemics and pandemics, animal reservoir.
Type B - Epidemics but no animal hosts
Type C - Minor respiratory illness
What are some of the type-specific antigens on the surface of influenza?
Haemagglutinin (H) and Neuraminidase (N)
What genetic changes does influenza virus undergo?
Antigenic drift - Small point mutations in the H and N antigens occurs constantly.
Antigenic shift - Sudden major change based on recombination between two different virus stains when they infect the same cell. (produces a virus with novel surface glycoproteins)
What makes a pandemic?
Antigenic shift, lack of immunity, attack rate is high and so it mortality
Describe features of swine flu
Influenza A virus H1N1. Since it was a H1N1 virus there was a high attack rate but low mortality due to a degree of immunity.
How do you diagnose influenza?
Nasopharyngeal aspirate - Direct immunofluoresence, culture and NAAT detection. Serology.
How do you treat influenza?
Amatadine, zanamavir and oseltamivir (very little effect)
What is the management of influenza?
Rest, warmth, hydration and analgesia. If given antiviral treatment in first 48 hours then it has some effect on fever duration. Antibiotics not given unless there is a secondary bacterial infection.
Describe features of the influenza vaccine
Antigenic variation means need for new one each year. It is based on the predicted strains. New recombination methods speed up the process of developing a vaccine
What are the symptoms of SARS
High fever, cough, shortness of breath and chest X-rays consistent with pneumonia
How is the SARS-associated coronavirus identified and what are its identifying features?
- Virus isolation in cell culture,
- Electron microscopy,
- Molecular techniques.
It is an enveloped RNA virus with a ‘halo’
What is the treatment for SARS?
Non specific anti-viral treatment available but can use ribavirin, corticosteroids, interferons and anti-retroviral therapies.
However inactivated virus vaccine developed.
What is tuberculosis associated with?
- AIDS,
- Increased use of immunosuppressive drugs,
- Decreased socio-economic conditions,
- Increased immigration from areas of high endemicity,
- Multiple drug resistance,
- Overcrowding and poor nutrition.
What are the clinical features of primary TB?
Usually symptomless but may be associated with a cough and wheeze. Small transient pleural effusions may occur.
What are the clinical features of miliary TB?
Results from acute diffuse dissemination of bacillus and can be fatal without treatment
What are the clinical features of post-primary TB?
Onset over weeks/months and symptoms are;
- Malaise,
- Fever,
- Weight loss,
- Mucoid, purulent or blood stained sputum,
- Pleural effusion
What are some of the symptoms for tuberculosis?
Poor apatite, night sweats, weakness, fever, dry cough, weight loss and GI symptoms
Describe features of mycobacterium tuberculosis
- Neither gram neg or positive.
- Acid-fast bacilli
- Spread by inhalation of organisms from dust/aerosols.
- Obligate aerobe (found in well aerated upper lobes of the lungs)
How can you detect latent TB infection?
Mantoux text - tuberculin is injected intradermally, there will be an immune response if an individual has previously been exposed to bacterium.
What is the importance of bacterial load on diagnostics?
Symptoms differ at different bacterial loads and diagnostic tests become more positive at different bacterial loads so reducing the bacterial load can delay the diagnosis
How can you detect M.tuberculosis?
Visualising acid-fast bacilli in sputum smears
What is the treatment for tuberculosis?
Combination therapy - (isoniazid, rifampicin etc) however multi-drug resistant TB is becoming a big issue.
Prolonged therapy of a minimum of 6 months to eradicate slow-growing organisms
How do you prevent TB?
Childhood immunisation, live attenuated BCG vaccine or prophylaxis with isoniazid for a year.
What are some pathogens that cause fungle infections?
Aspergillus fumigatus and pneumocystis jiroveci.
What are some pathogens that cause parasitic infections?
- Ascaris,
- Stringyloides
- Schistosoma
