flu and respiratory tract infections Flashcards
what are the clinical presentations of influenza?
- fever
- malaise (generally unwell)
- myalgia (muscle pain)
- headache
- cough
- prostration (weakness)
what are the types of ‘flu’?
- classical; influenza A and B
- flu-like illnesses; parainfluenza viruses and many others
- haemophilus influenza; bacterium, not a primary cause of flu, may be secondary invader
how is influenza transmitted?
-droplets or through direct contact with respiratory secretions
when are infection control precautions used?
Intubation, extubation and related procedures, for example manual ventilation and open suctioning.
Cardiopulmonary resuscitation.
Bronchoscopy.
Surgery and post mortem procedures in which high-speed devices are used.
Dental procedures.
Non Invasive Ventilation (NIV) e.g. Bilevel Positive Airway Pressure Ventilation (BiPAP) and Continuous Positive Airway Pressure Ventilation (CPAP).
High Frequency Oscillatory Ventilation (HFOV).
Induction of sputum.
what are complications of ‘flu’?
- primary influenza pneumonia (pandemics, can be of young people, high mortality)
- secondary bacterial pneumonia (infants, elderly and debilitated, pre-existing disease and pregnant women)
- bronchitis
- otitis media (?)
- influenza during pregnancy may be associated with perinatal mortality, prematurity, smaller neonatal size and lower birth rate
what is the therapy for flu?
- treating symptoms e.g. bed rest, fluids, paracetemol
- antivirals - oseltamivir, zanamivir
- monitor for complications
why might pandemics occur?
-influenza A only
-antigenic shift
segmented genome
-animal reservoir/mixing vessel
how do we confirm influenza?
-PCR is done on; nasopharyngeal swabs, throat swabs or other respiratory samples
what are the types of flu vaccines?
- killed vaccine = grown in hens eggs or cell culture then inactivated and combine with an adjuvant, contains 2 influenza A viruses and one or two influenza B viruses, given annually to at risk groups.
- live attenuated vaccine = more effective in children aged 2-17, administered intra-nasally.
can antivirals be used as prophylaxis?
- yes but rarely done
- see NICE guidelines
which flu like virus is prevalent in the summer?
parainfluenza virus 1
what are common causes of community acquired pneumonia?
(microbiological causes)
- mycoplasma pneumonia
- coxiella burnetii
- chlamydia
Describe mycoplasma, coxiella and chlamydia psittaci
- all respond to tetracycline and macrolides (clarithromycin)
- generally lower mortality than classical bacterial pneumonia
- often referred to as atypical pneumonia
- confirmed by serology (sputum), and virus detection by PCR
Describe mycoplasma pneumonia.
- often community acquired
- children and young adults have highest incidences
- person to person spread
Describe coxiella burnetti.
- cause diseases such as pneumonia and pyrexia of unknown origin (Q fever)
- uncommon, sporadic zoonosis (?)
- from sheep and goats
- complications include culture negative endocarditis
Describe chlamydia and respiratory disease.
- chlamydophilia psittaci causes psittacosis (chlamydia psittaci)
- uncoomon, sporadic zoonosis
- caught from pet birds (parrots, budgies and cockatiels)
- usually presents as pneumonia
what are the clinical presentations of bronchiolitis?
- 1st or 2nd year of life
- fever, coryza (inflammation of mucus membrane in nose), cough, wheeze
- severe cases; grunting, decreased Pa02, intercostal/sternal indrawing
what complications can come form bronchiolitis and how is it controlled?
- respiratory and cardiac failure (due to prematurity or pre existing conditions)
- NICE and SIGN guidelines on treatment
- up to 80% caused by respiratory syncytial virus (RSV)
- epidemics every winter
- stop spread in hospital wards by cohort nursing, handwashing, gowns, gloves etc.
Describe metapneumonovirus.
- most children antibody positive by 5
- highest incidence in winter
- may be second only to RSV in bronchiolitis
- similar symptoms to RSV
- range of severity from mild to requiring ventilation
- confirmed by PCR
what are alternative types of chlamydia?
- chlamydia trachomatis = STI which can produce infantile pneumonia when carried in mother
- chlamydophilia pneumonia = person to person, mostly mild respiratory infections, may be picked up by psittascosis tests
what is MERS CoV?
- middle eastern respiratpry syndrome coronavirus
- most prevalent in Saudi Arabia
- in camels
what are types of upper respiratory tract infections?
- common cold = coryza
- pharyngitis
- sinusitis
- epiglottitis
- strep throat
- tonsillitis
- rhinovirus
what are the types of lower respiratory tract infections?
- acute bronchitis
- acute exacerbation of chronic bronchitis
- pneumonia
- influenza
Describe coryza.
(common cold)
- acute viral infection of nasal passages often accompanied by a sore throat
- sometimes a mild fever
- spread by droplets and fomites
- complications include sinusitis and acute bronchitis
what is acute sinusitis?
- preceeded by a common cold
- purulent nasal discharge
- frontal headache, retero orbital pain, maxillary sinus pain, tooth ache, discharge
- most effective treatment is nasal decongestant, some need antibiotics, usually resolves within 10 days
what is quinsy?
= complication of tonsillitis leading to a peri-tonsillar abscess which needs drained or can obstruct the airway
-needs antibiotics
what is diphtheria?
- life threatening due to toxin production
- produces a characteristic pseudo membrane
- not seen in UK due to vaccination
what is acute epiglottitis?
- damage to the epiglottis leading to swelling and obstruction
- can be caused by influenza B but is unlikely due to vaccines
- mostly caused by strep. pyrogenes and strep. pneumonia
- common in children
- life threatening due to obstriuction
what is acute bronchitis?
- cold which ‘goes to the chest’
- productive cough. fever, normal chest X-ray and exam, may have transient wheeze
- not life threatening and usually self limiting
- antibiotics are not needed in normal people
- can be severe in patients with chronic lung disease
what are the incubation times for upper respiratory tract infections?
- Rhinoviruses: 1-5 days
- Group A streptococci: 1-5 days
- Influenza and parainfluenza viruses: 1-4 days
- RSV: 7 days
- Pertussis (whooping cough): 7-21 days
- Diphtheria: 1-10 days
- Epstein-Barr virus (glandular fever): 4-6 weeks
how are acute exacerbation of COPD managed?
- antibiotics = amoxicillin or doxycycline
- bronchodilator inhalers
- steroids
- refer to hospital if; evidence of respiratory failure, not coping at home
Describe pneumonia.
-most common in older people but more people under 50 die of pneumonia than any other infection
-can become bactearamic =in blood stream
- has consolidation (exudate)
-symptoms; malaise (tiredness), anorexia, sweats, rigors, myalgia, headache, confusion, cough, pleurisy, haemopysis, dyspnoea, preceding URTI, abdominal pain, diarrhoea, arthralgia
signs; fever, rigors (shaking), herpes labialis, trachpnoea, crackles, rub, cyanosis, hypotension
-investigated by blood cultures, serology, arterial gases, blood count , chest X-ray etc.
what is the curb 65 score?
- indicator of severity of pneumonia
- C -new onset of confusion
- U - urea>7
- R - respiratory rate >30/min
- B blood pressure systolic <90 or diastolic <61
- 65 - age 65 or older
why can the CURB65 score be misleading?
- young people with pneumonia will compensate very well for being unwell so will have a relatively good CURB65 score until they rapidly decline
- the opposite is true for older people in that they may already have a few of the points and may be over treated
what are factors indicating severe pneumonia other than the CURB65 score?
- temperature below 35 or above 40
- cyanosis, Pa02 <8kPa
- WBC <4or >30
- multi-lobar involvement
which pathogens are most prevalent in causing pneumonia?
-s. pneumpniae
-H. influenzae
(not worthwhile finding out the type of pathogen as around 50% comes back fasley negative)
Describe mycoplasma pneumonia.
- peaks every 4 years
- wide range of pathologies; pneumonia, hepatitis, autoimmune haemolytic anemia, arthritis
- cant use B-lactamases or cephalosporins as antibiotics as it has no cell wall
why are macrolides not good for pneumonia?
- 1 in 10 have resistance
what things should u ask about lifestyle when looking for respiratory disease?
-HIV (PCP)
-PWID (people who inject drugs), staph. Aureus
-Alcohol/ homeless – TB, klebsiella
-Frequently hospitalised – pseudomonas
-Returning traveller – legionella, TB
Indian sub-continent – TB
Eastern Europe – MDR TB (multi drug resistant TB), XDR TB (extended drug resistant TB)
what are complications of pneumonia?
- respiratory failure
- pleural effusion
- empyema
- death
what are the special cases of pneumonia?
- hospital acquired (need extended gram negative cover, no longer give anaerobic cover routinely, amoxicillin and gentamicin)
- aspiration pneumonia(need anaerobic cover, amoxicillin and metronidazole)
- legionella (chest symptoms may be minimal, GI disturbance is common, confusion, levofloxacin)
what organisms cause pneumonia?
- viruses - influenza, parainfluenza, measles, varicella-zoster, respiratory syncytial virus (RSV)
- bacteria
- chlamydia, mycoplasma
- fungi
what is lobar pneumonia?
- confluent consolidation involving a complete lung lobe.
- most often due to streptococcus pneumonia
- can be seen with other organisms (klebsiella, legionella)
what is the acute inflammatory response in lobar pneumonia?
- exudation of fibrin-rich fluid
- neutrophil infiltration
- macrophage infiltration
- resolution
what are complications of pneumonia?
- organisations (fibrous scarring)
- abscess
- bronchiectasis
- empyema
what is bronchopneumonia?
- infection starting in airways and spreading to adjacent alveolar lung
- most often seen with pre-existing disease (COPD, cardiac failure, viral infection, aspiration of gastric contents)
- caused by strep. pneumonia, haemophilus influenza, staphylococcus, anaerobes, coliforms
what are lung abscesses?
- localised collection of pus
- tumour-like
- chronic malaise and fever
- can be from aspiration
what is bronchiectasis?
- abnormal fixed dilation of the bronchi
- usually due to fibrous scarring following infection
- also seen with chronic obstruction (tumour)
- dilated airways accumulate purulent secretions
Describe TB
- mycobacterial infection
- chronic infection described in many sites (lung, gut, kidneys, lymph nodes, skin)
- pathology characterised by delayed hypersensitivity
- m. tuberculosis/ m. bovis main pathogens
- other organisms may cause atypicak infections especially in immunocompromised hosts (avoid phagocytosis, stimulates a host T cell response)
Describe T cell response immunity and hypersensitivity.
-T-cell response to organism enhances macrophage ability to kill mycobacteria
this ability constitutes immunity
-T-cell response causes granulomatous inflammation, tissue necrosis and scarring
this is hypersensitivity (type IV)
-Commonly both processes occur together
why do diseases re-activate?
- decreased T-cell function (age , coincidence disease -HIV- immunosuppressive therapy)
- reinfection at high dose or with more virulent organism
