Respiratory infections Flashcards
What is coryza? viral or bacterial? spread by? what organisms?
Common cold:mild fever/sore throat
- viral infection nasal passages: adenovirus, rhinovirus, RSV
- spread by droplets and formites
What is acute sinusitis usually preceded by? what does it cause? viral or bacteral? treatment?
- Preceded by a common cold
- purulent nasal discharge
- viral aetiology
- self limiting: 10 days
What is diptheria? caused by? what is characteristic? other clinical features?
- infection caused by bacterium Corynebacterium diphtheriae.
- Signs and symptoms may vary from mild to severe
- life threatening due to toxin production
- characteristic ‘pseudomembrane’
- sore throat/fever/barking cough/swollen neck due to lymph nodes
- vaccination in UK
Acute bronchitis:
- preceded by?
- clinical features?
- treatment?
- preceded by common cold
- productive cough, minority have fever, may have transient wheeze
- supportive tx
What are the clinical features (5) of an acute exacerbation of COPD? What clinical signs are seen?(5)
Usually preceded by upper respiratory tract infection
Increased sputum production
Increased sputum purulence
More wheezy
Breathless
OE: Respiratory Distress Wheeze Coarse crackles May be cyanosed In advanced disease – ankle oedema
What is the management for an acute exacerbation of COPD? when to admit?
- Antibiotic: 1st line amox. 500mg TDS for 5 days, 2nd line Doxy. 200mg OD for 1st day and then 100mg OD for further 4 days
- Bronchodilator inhalers
- Short course of steroids in some cases
Admit if:
- evidence resp. failure
- not coping at home
What is the CURB65 severity score?
C New onset of confusion U Urea >7 R Respiratory rate >30/min B Blood pressure Systolic <90 OR Diastolic <61 65 age 65 years or older
Score 1 for each
What is the treatment for community acquired pneumonia?
CURB65:
0-2: amox. 1g TDS IV/PO 5days or doxy 200mg day 1 then 100mg OD (IV clarith. if NBM)
3-5 (severe): Co-amox IV 1.2mg TDS + doxy. 100mg PO BD
if in ICU:
Co-amoxiclav IV 1.2g tds + Clarithromycin IV 500mg bd
Severe - If penicillin allergic: IV Levofloxacin 500mg bd
Step down to Doxycycline 100mg bd for all
patients with severe CAP
What are 3 clinical complications of pneumonia?
- respiratory failure
- pleural effusion
- empyema
What are the aetiology for:
Classical flu
Flu-like illnesses
Bacterial cause - is this a primary cause for flu?
Classical:
- influenza A
- influenza B
Flu-like:
- parainfluenza
- many others
Haemophilus influenza:
-not a primary cause of flue but may be a secondary invader
What is the transmission of flu?
Droplets/resp. secretions
What are the four complications of flu?
Primary influenzal pneumonia:
- seen most during pandemic years
- can be disease of young adults
- high mortality
Secondary bacterial pneumonia:
-more common in infants/elderly disabled/pre-existing disease/pregnant women
bronchitis
otitis media
What is influenza infection during pregnancy assoc. with? (4)
- perinatal mortality
- prematurity
- smaller neonatal size
- lower birth weight
Flu treatment
supportive, paracetamol, fluid, bed rest
How can you detect influenza virus?
PCR:
-nasopharyngeal swabs in virus transport medium
Antibody detection:
- other hospitals
- often retrospective
- may need paired acute and convalescent bloods
What are the main differences between the killed flu vaccine and the live attenuated vaccine:
- what do they contain?
- who recieves either vaccine?
- administered?
Killed vaccine
currently contains 2 different influenza A viruses and one influenza B virus
given annually to adult patients at risk of complications
given to health care workers
Given to children aged 6 months to 2 years at risk of complications
Live attenuated vaccine
Also contains 3 viruses
More effective than killed vaccine in children aged 2-17
Offered this year to ALL children aged 2-5, and all primary school children
Administered intra-nasally
How effective is flu vaccine?
no more than 70% effective at preventing clinical disease
Are antivirals ever used after a contact with flu?
-rare
What are the usual bacterial organisms found for:
- mild/moderate pneumonia
- severe pneumonia
What is important to remember for pneumonia post flu?
Mild/moderate:
- strep. pneumoniae
- haemophilus influenzae
- staph. aureus
Severe pneumonia:
as above but possible coliforms and atypicals such as:
m. catarrhalis, Mycoplasma pneumoniae, Legionella pneumophilia, Chlamydophila pneumoniae & Chlamydophila psittaci
Remember Staph aureus
pneumonia post influenza and the PVL producing strains of Staph aureus that can produce severe pneumonia in children and young adults especially
What bacterial organisms can be seen in hospital acquired pneumonia?
-strep. pneumoniae,
Haemophilus influenzae
and coliforms.
Legionella can be hospital acquired.
What coliforms can cause pneumonia? what are the risk factors for this?
Klebsiella
Escherichia coli
Enterobacter
Proteus
Pseudomonas aeruginosa
- debilitated
- chronically ill
- alcoholism
What type of pneumonia is seen in those with immune defects and anatomical abnormalities (4)
Opportunistic pathogens
-Fungal pneumonia: Candida spp. causing candidiasis.
Aspergillus spp. causing aspergillosis.
Mucor spp. causing mucormycosis.
Cryptococcus neoformans causing cryptococcosis.
recurrent pneumonia
Pneumocystis jiroveci pneumonia (PJP), formerly known as Pneumocystis carinii pneumonia (PCP) - one of the most frequent and severe opportunistic infections in people with weakened immune systems.
Protozoa:
cryptosporidia, toxoplasma
Virus:
cytomegalovirus - CMV
Opportunistic bacteria (as well as virulent infection with common organism e.g. TB): Mycobacterium avium intracellulare
How can you diagnose community acquire pneumonia?
Sputum culture - purulence/viral PCR
Which viruses can cause community acquire pneumonia?
Flu A/B Rhinovirus RSV Human metapneumovirus (hMPV) Parainfluenza 1-4 Adenovirus Coronaviru
Describe the clinical features of legionella pneumonia
Flu like illness which may progress to a severe pneumonia, with mental confusion, acute renal failure and GI symptoms.
Mortality 5-30%
How is legionella spread?
water droplets
What are the risk factors for legionella (2)?
- exposure of contaminated aerosolised water
- impaired immunity: >55yo, diabetes, smoking, malignancy, altered immunity
How is legionella pneumonia diagnosed?
-Legionella urinary antigen
Detects serogroup 1 only
-Culture
Slow on selective media
-Paired serology
Rise in titres
Now PCR available direct from Sputum
What is the antibiotic treatment for legionella pneumonia?
- clarythromycin, erythromycin
- quinolones (e.g. levofloxacin)
What is the treatment for severe vs non-severe aspiration pneumonia?
Severe:
-IV amox + met + gent
(if penicillin allergic change amox to co-trimoxazole)
step down to:
PO co-trim. + metronidazole (total IV/PO 7 days)
Non-severe:
-PO amox + metronidazole 5 days
What organisms can cause exac. of COPD?
Haemophilus influenzae & Moraxella catarrhalis (gram -ve coccus), Streptococcus pneumoniae (gram +ve diplococci), Gram-negatives & others
What is the treatment for COPD exac.?
Only treat if increase in sputum purulence or new CXR changes or pneumonia
Empiric treatment as per NHST policy
1st line Amoxicillin 500 mg TDS (5 days)
2nd line Doxycycline 200mg D1 > 100 mg D2-5
Aim to cover in 1st instance H. influenzae, M. catarrhalis & S. pneumoniae
What is the diagnosis for pneumocystis pneumonia?
BAL > Sputum > Gargle
Microscopy: Immunofluorescence
PCR
What is the difference between pneumocystis pneumonia in a patient with HIV vs non-HIV
General: fever, dry cough, shortness of breath, and fatigue
HIV: sub-acute, low grade fever > severe pneumonia
Non-HIV: more acute, higher fever
What is the treatment for pneumocystis pneumonia?
co-trimoxazole
what is the difference of aspergillus pneumonia in immunocompromised vs immunocompetent patients?
Immunocompromised/suppressed patients
Severe pneumonia and invasive disease.
Immunocompetent patients:
Localised pulmonary infection
Aspergilloma (fungus ball) in pre-existing chest cavities
what is the diagnosis and treatment of aspergillus pneumonia?
Diagnosis
BAL ideally: Fungal culture (PCR)
Tissue: Histopathology
Treatment
- Amphotericin B
- Voriconazole
- Surgery
What type of organism is tuberculosis?
-acid alcohol fast bacilli with a thick waxy coat
TB clinical features respiratory (7)
LT cough Chest pain Sputum +/- haemoptysis Weakness or fatigue Weight loss Fever & chills Night sweats
What is the diagnosis of TB?
Microscopy of sputum/tissue Culture on selective media - slow PCR - fast (1-2hrs) but expensive (immune reaction) Ziehl-Neelson stain: dye red - cheap
What is formed when someone is exposed to TB? Do patients remain well or not?
Granuloma is formed - host walls off infection (type IV hypersensitivity)
- 90% remain well
- 50% clear TB spontaneously
- 5% active TB
- 5% reactivity of latent disease
What is heard on auscultation in TB infection?
-upper zone crackles
TB clinical features: Meningeal GI Spinal Pericardial Renal Joints Adrenal other?
Meningeal:
- headache
- drowsy
- fits
GI:
- pain
- bowel obstruction
- perforation
- peritonitis
Spinal:
- pain
- deformity
- paraplegia
Pericardial:
-tamponade
Renal:
-renal failure
Septic arthritis:
-cold monoarthritis of large joints (never inject steroids into a solitary arthritic joint)
Adrenal:
-hypoadrenalism
Other:
- lymphadenopathy
- cold abscess (collections of pus without pain and acute inflamm.)
What is seen on histology for TB?
- Multinucleate giant cell granulomas
- Caseating necrosis
- Sometimes visible mycobacteria
What are they characteristics on x-ray for TB? (5)
Upper lobe predominance Cavity formation Tissue destruction Scarring and shrinkage Heals with calcification
What is the treatment for TB?
RIPE then drop the PE
Two months of Rifampicin Isoniazid Pyrazinamide Ethambutol
Then four months of
Rifampicin
Isoniazid
side effects rifampicin?
Colours urine and all bodily fluids orange
Is a potent inducer of cytochrome enzymes
Rapid breakdown of all steroid molecules including hormonal contraception.
Similar breakdown of opiate analgesics and many other drugs
Side effects ethambutol?
Ethambutol can cause optic neuritis
What is the criteria for latent TB?
No evidence of active TB
- Symptoms
- X-ray
- Culture
Evidence of previous TB infection
- History of TB prior to 1960
- Calcification on x-ray
- Exposure to High Prevalence area
What are the two tests for previous TB exposure?
Interferon Gamma Release Assay
( Blood test )
Detects previous exposure to TB
Mantoux ( tuberculin ) test.
( Skin test )
Detects previous exposure to TB and BCG
What are the differences between IGRA and mantoux test?
Visit number
sensitivity/specificity
Does it require immunocompetence?
TST: 2 visits Operator dependent False negatives False positives Type 4 hypersensitivity reaction - has to be immunocompetent
IGRA 1 visit Laboratory environment High sensitivity Ignores BCG
What is the treatment for latent TB?
Treat or leave it alone
However if you want to give anti-TNF drugs (as this can cause reactivation)
6 months of isoniazid
or
3 months rifampicin + isoniazid
Caution: both drugs are associated with disturbance of liver function. This is more frequent in women.
What can cause reactivation TB?
-HIV
(all TB cases offered HIV test, all HIV cases offered CXR)
-steroids
-immunosupressant drugs
Risk factors for pleural infection (6)
diabetes mellitus immunosuppression including corticosteroids gastro-oesophageal reflux alcohol misuse intravenous drug abuse
What are the three different types of pleural infection?
Simple parapneumonic effusion
Complicated parapneumonic effusion
Empyema- pus in the pleural space
What is a complicated parapneumonic effusion?
+ve G stain, pH <7.2, low glucose, septations, loculations
Treatment for pleural infection
Simple effusion = none of the above may be treated with antibiotics alone but may need drainage later on if things change Large effusion = chest drainage V small (<1cm) effusions may be left untapped
What are the four pathological complications of pneumonia?
- organisation (fibrous scarring)
- Abscess
- Bronchiectasis
- Empyema (susupect if slow to resolve pneumonia)
What is bronchopneumonia?
Infection starting in airways and spreading to adjacent alveolar lung
Most often seen in the context of pre-existing disease
-COPD
-Cadiac failure (elderly)
-complication of viral infection (flu)
-aspiration pneumonia
What does abscess cause and when is this usually seen?
Localised collection of pus
Tumour-like
Chronic malaise and fever
Context - aspiration (vomiting/lowered conscious level/pharyngeal pouch)
What is bronchiectasis?
- Abnormal fixed dilatation of the bronchi
- Usually due to fibrous scarring following infection (pneumonia, tuberculosis, cystic fibrosis)
- Also seen with chronic obstruction (tumour)
- Dilated airways accumulate purulent secretions
- involved bronchi are dilated, inflamed and easily collapsable
- airflow obstructions
- impaired clearance of secretions
What are the primary and secondary tissue changes seen in TB?
Primary
- Small focus (Ghon focus) in periphery of mid zone of lung
- Large hilar nodes (granulomatous)
Secondary
-Fibrosing and cavitating -apical lesion (cancer an important differential diagnosis
What are the risk factors for developing chronic pulmonary infection?
Abnormal host response:
- immunodeficiency: congenital/acquired
- immunosuppression: drugs/malignancy
Abnormal innate host defence:
- damaged bronchial mucosa
- abnormal cilia
- abnormal secretions
Repeated insult:
- aspiration (NG feeding/poor swallow/pharyngeal pouch)
- indwelling material (NG tube in wrong place/chest drain/foreign body)
What are 4 reasons for immunodeficiency?
Immunoglobulin deficiency:
- IgA deficiency (common, increased risk of acute infections, rarely chronic infections)
- Hypogammaglobulinaemia(rare, increased risk of acture and chronic infections)
- CVID (commonest cause of immunodeficiency, recurrent infections)
- Specific polysaccharide antibody deficiency
Hypo-splenism
immune paresis:
-myeloma/lymphoma/metastic malig.
HIV
what are 3 reasons for damaged bronchial mucosa?
- smoking
- recent pneumonia/viral infection
- malignancy
What are 2 reasons for abnormal cilia?
- kartenagers syndrome
- youngs syndrome
What are 2 reasons for abnormal secretions?
cystic fibrosis
channelopathies
What are 5 forms of chronic infection?
- intrapulmonary abscess
- empyema
- chronic bronchial sepsis
- bronchiectasis
- cystic fibrosis (and other rare conditions)
Intrapulmonary abscess
- clinical features (6)
- when does it occur?
Clinical features:
- indolent presentation
- wt loss
- lethargy
- tiredness
- weakness
- cough +/- sputum
Usually occurs after a preceding illness of some sort:
- pneumonic infection
- post viral
- foreign body
REMEMBER: flu -> staph pneumonia -> cavitating pnuemonia -> abscess
what bacterial and fungal pathogens cause intrapulmonary abscess?
Bacteria:
- streptococcus
- staphylococcus (esp. post flu)
- E-coli
- Gram -ves
Fungi:
-aspergillus
What is a septic emboli?
Right sided endocarditis •Infected DVT •Septicaemia •Intravenous drug users Inject into groin / DVT/ Infection /PE + Abscesses
What pathogens cause empyema?
Gram +ve
Gram -ve
Gram +ve:
- strep. milleri
- staph. aureus (usually post op or nosocomial or immunocompromised)
Gram -ve:
- e-coli
- pseudomonas
- h. influenzae
- klebsiella
Anaerobes in 13% of cases (usually in severe pneumonia or poor dental hygeine)
How do: -CXR -USS -CT help with the diagnosis of empyema?
CXR:
- persisting effusion, particularly if loculations visible
- D sign
- remember lateral (retrodiaphragmatic collections)
USS:
- PREFERRED Ix
- simple/bedside/targetted sampling
CT:
-differentiating between empyema and abscess
What is the treatment for empyema?
IV antibiotics:
Amox and met initially
Oral:
directed against cultured bacteria - AT LEAST 14 days
What is the presentation of bronchiectasis? (4)
- recurrent ‘chest infections’
- recurrent abiotic prescriptions
- no/short lived response to abiotics
- persistent sputum production
How is bronchiectasis diagnosed?
Clinically:
- cough productive of sputum
- chest pain
- recurrent LRTI’s
Radiological:
-high resolution CT
what is chronic bronchial sepsis?
- All hallmarks of bronchiectasis but no bronchiectasis on HRCT
- confirmed positive sputum results
- same work up as bronchiectasis
What demographic of patients get chronic bronchial sepsis?
- often younger patients, mainly women, often involved in childcare
- others are older with COPD or airways disease
What are the treatment options for bronchiectasis?
- Stop smoking
- Flu vaccine
- Pneumococcal vaccine
- Reactive antibiotics - get sputum culture and sensitivities from lab
What are the treatment options for bronchiectasis when it is colonised with persistent bacteria?
- prophylactic abiotics
- neb. gentamicin/colomycin
- pulsed IV abx
- alternating oral abx
Low dose macrolide antibiotics have been shown to reduce exacerbation rates in bronchiectasis
–Clarithromycin 250 mg OD
–Azithromycin 250mg Three Times a Week
•Particularly effective in pseudomonas colonised
individuals
