Infection Flashcards
What is the clinical presentation of flu?
High fever of abrupt onset Malaise Myalgia (sore muscles) Headache Cough Prostration (flat on back, unable to do anything) - £10 note test
Which organisms are the cause of classical flu?
Influenza A and influenza B virus
Which virus is most likely to cause a pandemic?
Influenza A
Which organisms are the cause of flu-like illnesses?
Parainfluenza (among others)
What is the difference between classical flu influenza and homophiles influenza?
Classical flu is a virus and homophiles influenza is a bacteria
What is the management of flu?
- Bed rest, fluids and paracetamol - Antivirals: oseltamivir, zanamivir
Endemic
Naturally occurs in the population (e.g. flu)
Epidemic
Outbreak of unexpected size to a given area, country or population • E.g. obesity or winter epidemic of flu pretty much every year
Pandemic
Global distribution of disease - rare and serious
Antigenic drift
Antigen has slightly changed from what it was before - Enough that the antibodies don’t quite recognise the antigen, but enough of a response that you don’t get too ill (occurs in endemics)
Antigenic shift
Antigens have completely changed
What are the phases of pandemics?
• Phases 1-3: stages where you don’t really need to worry - Flu is starting to mutate but hasn’t been transmitted to anyone else yet • Phase 4: Sustained human-human transmission • Phase 5-6: Widespread human infection • Post peak phase: Possibility of recurrent of events. Another peak, which can even be more serious than the original peak • Post pandemic: Disease resumes normal levels within a population
Pneumonia
Infection involving the distal airspaces usually with inflammatory exudation (“localised oedema”). Fluid filled spaces lead to consolidation.
In which group of people is CAP classically seen?
Otherwise healthy young adults
What are the complication of pneumonia?
- Organisation (fibrous scarring) - Abscess - Bronchiectasis - Empyema – spread of inflammation to the pleural cavity.
Bronchopneumonia
Infection starting in airways and spreading to adjacent alveolar lung. Occurs in people who can’t clear organisms.
Lung abscess
Cavitating lesion in the lung with localised collection of pus. Associated with chronic malaise and fever.
Bronchiectasis
Abnormal fixed dilatation of the large airways (bronchi) due to fibrous scarring after infection in the lung (pneumonia, tuberculosis, cystic fibrosis)
What is the pathophysiology of bronchiectasis?
Infection organises rather than resolves, scar tissue is formed, airway is pulled open and the dilatation becomes fixed. Once the airways are larger than a certain diameter, they begin to produce secretions and these will accumulate. Static secretions are a fertile ground for infections.
What condition is bronchiectasis often associated with?
Cystic fibrosis
What kind of reaction is TB?
Delayed (Type IV) hypersensitivity - granulomas with necrosis
What is the pathophysiology of TB?
Inhaled organism phagocytosed and carried to hilar lymph nodes. Immune activation (few weeks) leads to a granulomatous response in nodes (and also in lung) usually with killing of organism. In a few cases infection is overwhelming and spreads
Where does secondary TB tend to be localised?
Apices of lung
What are the signs and symptoms of TB?
Weight loss, night sweats, cough, haemoptysis, breathless, upper zone crackles, headache, drowsy, peritonitis
What is the treatment for TB?
2 months of 4, 4 months of 2: RIPE: Rifampicin, Isoniazid, Pyrazinmide, Ethambutol
Which respiratory infections can occur in the URT?
Common cold (coryza) Pharyngitis Sinusitis Epiglottitis
Which respiratory infections can occur in the LRT?
Acute bronchitis Acute exacerbation of chronic bronchitis Pneumonia Influenza
What is the common cold (coryza) and how is it spread?
Acute viral infection of the nasal passages often accompanied by sore throat. Spread by droplets and fomites.
Which viruses are associated with the common cold?
Rhinoviruses, coronaviruses and adenoviruses
What is sinusitis?
Viral (or bacterial/fungal) infection of paranasal sinuses, usually preceded by coryza.
What is rhinitis and what are the different types?
Sneezing attacks, nasal blockage/discharge occurring >1hr on most days. Can either be seasonal/intermittent (hay fever or perennial/persistent.
What is pharyngitis?
Endemic adenovirus infection, causing reddened oropharynx and soft palate and inflamed tonsils. (sore throat)
What is acute epiglottitis?
Life-threatening airway obstruction in children aged 2-7yrs caused by H. influenzae.
What is influenza?
Flu symptoms caused by Influenza A (pandemics) and Influenza B (localised outbreaks). Not a cold!
What is bronchitis?
“Cold which goes to the chest” – acute infection of bronchi causing them to become inflamed. Usually arises from Strep. pneumoniae/H. influenzae infections, or in people with COPD
What should you not use in epiglottitis?
Don’t use a laryngoscope in acute epiglottitis, because exacerbate the swelling
What is diphtheria and what is it characterised by?
Potentially fatal contagious bacterial infection that mainly affects the nose and throat. Characterised by pseudo membrane forms which can cut off the airways
What is the incubation time for rhinovirus?
1-5 days
What is the incubation time for group A strep?
1-5days
What is the incubation time for influenza and parainfluenza?
1-4 days
What is the incubation time for influenza and Ebstein barr virus?
4-6 weeks
What is pertussis and what is its incubation time?
Whooping cough - 7-21 days
What are the clinical features of acute exacerbation of COPD?
Green sputum is key • Increased sputum production • Increased sputum purulence • More wheezy • Breathless
What is the management of acute exacerbation of COPD?
• Antibiotic. e.g. doxycycline or amoxicillin • Bronchodilator inhalers • Short course of steroids in some cases • Refer to hospital if • Evidence of respiratory failure or not coping at home
Red hepatisation of the lung
When the lung turns a darker red and looks like liver. With pneumonia, RBCs are released into the interstitium
What are the symptoms of pneumonia?
• Cough • Pleurisy • Haemoptysis • Dyspnoea • Preceding URTI • Abdominal pain • Diarrhoea • Malaise • Anorexia • Sweats • Rigors • Myalgia (muscle pain) • Arthralgia (joint pain) • Headache • Confusion
What is the definition of pneumonia?
Signs and symptoms of a lower respiratory tract infection, with a new infiltrate on a CXR
What is the CURB 65 score?
C - New onset of confusion U - Urea >7 R - Respiratory rate >30/min B - Blood pressure Systolic
What are the complications of pneumonia?
• Respiratory failure • Pleural effusion • Empyema • Death
What is different about the management of HAP?
Need extended gram negative cover
What is different about the management of aspiration pneumonia?
Need anaerobic cover
What is different about legionella pneumonia?
• Chest symptoms may be minimal • GI disturbance is common • Confusion common
In what group of people does klebsiella pneumonia occur?
elderly/diabetics/alcoholics
In what group of people does pneumocystis pneumonia occur?
The immunosuppressed
What is the most common organism causing pneumonia?
Strep pneumonia
What investigations would you do for pneumonia?
Bloods (WCC, CRP) Sputum and blood cultures Atypical serology eg. mycoplasma or legionella CXR
Which type of pneumonia are you primarily considering with 23 year old asthmatic women who has been feeling ‘under the weather’ for 2 week with lethargy and dry cough with central burning chest pain on coughing?
Mycoplasma pneumonia
Which type of pneumonia are you primarily considering with 26 year old nursery nurse with frequent chest infections and had lots of antibiotics over many months and productive sputum?
Haemophilus influenzae - common in those with bronchiectasis particularly nursery nurses
Which type of pneumonia are you primarily considering with IV drug users?
Staph aureus
What are examples of antivirals?
• oseltamivir • zanamivir
How is flu confirmed in the lab?
Direct detection of the virus via PCR or antibody detection
Which organism infection causes Q fever?
Coxiella burnetti
What are the 3 most common atypical pneumonias?
Mycoplasma, coxiella and chlaminphila psittaci
What is the treatment for Mycoplasma, coxiella and chlaminphila psittaci (3 most common atypical pneunomias)?
Tetracycline and macrolides (eg clarithromycin)
In what group of people does bronchiolitis most commonly present?
1-2 years children
Which virus most commonly causes bronchiolitis?
Respiratory Syncytial Virus
Which virus was first isolated in 2001 and associated with Acute Respiratory Tract Infections?
Metapneumovirus
What is the main way for detecting any virus?
PCR
Chlamydia trachomatis
STI which can cause infantile pneumonia - can be passed onto child during vaginal childbirth
Which are of the body is inflamed in rhinitis?
The nose
What is the treatment for acute epilglottitis?
Ceftriaxone
Which kinds of organisms colonise the upper respiratory tract?
Gram-positive • α-haemolytic streptococci, including Strep pneumonia • ß-haemolytic streptococci e.g. Strep progenies • Staphylococcus aureus Gram-negative, including • Haemophilus influenza • Moraxella catharalis
How does the conducting airway (trachea and bronchi) resist colonisation and infection?
• Mucociliary escalator • Cough • AMP’s • Cellular & humoral immunity
Which organism is associated with whooping cough (pertussis)?
Bordetella pertussis (gram positive coccobacillus)
How do you diagnose pertussis?
• Bacterial culture - Pernasal swab (charcoal) • PCR - Pernasal swab (
How does the respiratory zone (terminal airways and alveoli) remain sterile and avoid infections?
alveolar lining fluid containing surfactant, Ig, complement, FFA, AMP as well as alveolar macrophages and neutrophils
How is legionella pneumonia spread?
No person-to-person spread. Transmitted by inhalation of contaminated water droplets, therefore associated with factories or in unused shower heads in hotels etc
How can you detect legionella pneumonia?
• Legionella urinary antigen • Culture • Paired serology • Now PCR available direct from Sputum
What is the treatment for legionella pneumonia?
Clarithromycin or erythromycin
What poses the greatest risk for hospital acquired pneumonia?
Endotracheal intubation with mechanical ventilation, as this breaches airway defences, impairs cough & mucociliary clearance and facilitates microaspiration of secretions that pool above the endotracheal tube cuff
What are the most commonly associated organisms for CAP?
Strep pneumoniae, haemophylius influenzae, staph aureus and atypical
What are the most commonly associated organisms for HAP?
Gram-negative (including E. coli, Klebsiella spp. Pseudomonas spp), CAP organisms, S. aureus and anaerobes
Which group of people is - Pneumocystis jirovecii pneumonia (PCP) associated with?
Immunocompromised
What is the treatment for - Pneumocystis jirovecii pneumonia (PCP)?
Co-trimoxazole or pentamidine
Aspergillus
Chest infection resulting from the inhalation of fungal spores, usually aspergillum fumigatus
What is the treatment for aspergillus?
Amphotericin B, Voriconazole or Surgery
What is the test for TB?
Ziehl-neelson stain as it is a an acid alcohol fast bacilli, or PCR or culture
What are the advantages and disadvantages of each of the tests for TB?
Culture is the most sensitive but it is very slow. Mycobacterial PCR is fast but expensive. Ziehl-neelson is cheap and fast, but no indication of species of sensitivity
True or False: TB can infect almost any organ
True
Why do you need to treat TB for 6 months?
Because it continues to replicate
What are some of the causes of immunodeficieny than can result in chronic infection?
- Immunoglobin deficiency eg. IgA deficiency, hypogammaglobulinaemia, CVID - Hyposplenism - Immune paresis - HIV
What is the difference between immunodeficiency and immunosuppression?
Immunodeficiency is the results of specific diseases etc whereas immunosuppression is a form of treatment given by steroids, methotrexate, monoclonal antibodies etc
What conditions can result in abnormal cilia and thus result in chronic infections?
Kartagener’s syndrome (cilia can’t move) or Young’s syndrome (no cilia at all)
What conditions can result in abnormal secretion and thus result in chronic infections?
Cystic fibrosis or channelopathies
What is an intrapulmonary abscess and what causes it?
Localised suppuration assoc. with cavity formation on CXR/CT. Caused by aspiration, TB, Stap/Klebs cavitating pneumonia, septic emboli, foreign body inhalation
Bronchiectasis
Abnormal permanent dilatation of airways, resulting inflammation and thickening of walls. Mucociliary transport mechanism is impaired and thus recurrent bacterial infections ensue.
What is the most common cause of bronchiectasis?
Cystic fibrosis
What would you see on CXR of bronchiectasis?
Dilated and thickened bronchi
What are the symptoms of bronchiectasis?
• Recurrent infections/antibiotics • Productive cough (yellow-green sputum, can become haemoptysis) • Halitosis (bad breath) • Recurrent febrile episodes, malaise • Clubbing • Coarse crackles, pneumonic episodes
What is the management of bronchiectasis?
• Pneumococcal vaccine • Postural drainage! • Antibiotics (mild: cefaclor/ciprofloxacin, flucloxacillin if S. aureus; persistent: ceftazidime) • Bronchodilators + anti-inflammatory agents
Cystic fibrosis
Autosomal recessive disorder in which there is a defect in the CFTR gene, a critical chloride channel resulting in abnormally viscous mucous – blockages of many tubular structures including conducting airways & lungs.
What is the carrier rate of CF?
1 in 25
