Respiratory Infections

Respiratory Infections

1. upper respiratory tract

   • adults
     • sore throat + tonsillitis
       • common viral cause
         • majority due to viruses
           • antibiotics usually unnecessary
         • enteroviruses
         • Epstein-Barr
         • adenoviruses
       • common bacterial cause
         • strep pyogenes
       • management
         • probs nothing
         • if severe/persistant
           • oral penicillan V
       • investigations
         • blood/serology tests
         • nasal swab
         • viral culture
         • throat swab
           • gram stain
     • common cold
       • Rhinoviruses
       • adenoviruses
       • coronaviruses
     • infectious mononucleosis
       • effects adolescents + young adults
       • causes
         • HIV infection
         • toxoplasmosis
         • cytomegalo virus
         • Epstein-Barr virus
           • glandular fever
             • investigations
               • blood film
               • serology
                 • raised IgM
                 • IgG in previous infection
               • IM test/ monospot
             • treatment
               • aspirin gargles
               • avoid penicillin esters eg ampicillin
   • children
     • tonsillitis/pharyngitis
       • viral or bacterial
       • treatment
         • nothing or 10 days penicillin
       • throat swab
     • infective agents
       • bacterial
         • H influenzae
         • Moxarella catterhalis
         • mycoplasma
         • staph aureus
         • beta haemolytic
           • strep pyogenes
         • non-haemolytic
           • strep pneumoniae
         • streptococci
       • viral
         • Rhinovirus
         • RSV
         • paraflu 1+3
         • influenza A + B
         • adenovirus
     • croup/epiglottitis
       • bacterial
       • rare
       • intubation + antibiotics
       • can swell to obstruct trachea
       • stridor due to narrowing of airways
       • oral steroids
     • otitus media
       • antibiotic treatment usually doesn't help
       • ear infection
       • secondary infection
         • pneumococcus
         • haemococcus influenzae
       • spontaneous rupture of ear drum
     • Rhinitis
       • self limiting
         • limits own growth by its actions
       • prodome to other illnesses
         • pneumonia
         • bronchiolitis
         • meningitis
         • septicaemia

2. lower respiratory tract

   • pneumonia
     • CURB 65
       • Confusion
       • Urea
       • Respiratory Rate
       • diastolic BP
       • over age 65
       • severity scale
     • affects lung parenchyma
       • solid alveoli
     • symptoms
       • pleuritic chest pain
       • breathlessness
       • cough
         • shadowing on chest X-ray
       • infected sputum
     • signs
       • reduced chest expansion
       • dull percussion note
       • bronchial breathe sounds
       • increased vocal resonance
       • crackles
     • classification
       • community acquired
       • hospital acquired
       • recurrent
       • aspiration
       • in immunocompromised
     • bacterial
       • common
         • staph aureus
         • strep pneumoniae
       • uncommon
         • legionella pneumophilia
     • treatment
       • pneumococcus
         • IV benzyl penicillin
         • oral ampi/amoxycillin
       • staphylocoocal
         • IV flucloxacillan, gentamicin, vancomycin
       • mycoplasma
         • tetracycline or clarithromycin
       • chlamydial
         • tetracycline, erythromycin, larithromycin
   • bronchiectasis
     • dilation of bronchi produces chronic sepsis in chest
     • caused by
       • severe childhood measles
       • prolonged whooping cough
       • immunoglobulin deficiencies
       • CF
       • severe pneumonia or TB
     • symptoms
       • daily cough
         • sputum production
       • chest infections
     • signs
       • lung crackles on inspiration + expiration
       • finger clubbing
     • treatment
       • occasionally prophylactic antibiotics
       • daily autogenic drainage by physios
     • can't be cured
   • in children
     • viral causes
       • respiratory syncytial virus
       • parainfluenzae 3
       • influenza A + B
       • adenovirus
     • bronchiolitis
       • infection of bronchioles
         • in infants, peaks at 3 months
       • usually caused by RSV
       • symptoms
         • crackles +/- wheeze
         • nasal stuffiness
         • tachypnoea
           • shortness of breathe
         • poor feeding
       • management
         • maximal observation, minimal intervention
     • commnity acquired pneumonia
       • not treated if symptoms mild
       • if vomiting
         • oral amoxycillin or macrolide
     • empyaema
       • complication of pneumonia
       • symptoms
         • chest pain
         • unwell
       • extension of infection into pleural space
       • treatment
         • drainage
         • Enter text here

3. microbiological diagnosis of chest infections

   • diagnostic tehniques
     • microscopy + culture of sputum + blood
     • antigen detection methods
       • detect specific antigen immunologically
         • agglutination
           • latex particles coated with monoclonal antibodies (single clone of plasma cells), clumping visible
             • changes in colour if enzyme present
         • virus detected innasopharyngeal secretions
         • legionella + pneumoncoccal antigen can be detected in urine
         • immunofluorescence
         • ezyme immunoassay
           • enzyme-labelled antigens + antibodies to detect biological molecules
     • TB
       • ZN or aranine phenol stain
       • AAFB
       • extended culture for mycobateria
     • bronchio-alveolar lavage
       • lower airway samples collected by bronchoscopy
         • more accurate diagnosis as less liable to contamination
           • used for diagnosis of ventilator associated pneumonia
             • many patients have bacteraemia (bacteria in blood)
     • PCR
       • primers bind to target DNA sequence
         • multiple copies of target sequence produced
           • amplified copies of DNA dectected
     • organisms not easily cultured
       • coxiella burnetti
       • legionella pneumophilia
       • chlamydia psittaci
       • mycoplasma pneumoniae

4. pathology of pulmonary infection

   • lung infections are multifactorial
     • microorganism pathogenicity
       • opportunistic
         • immunocompromised patients
       • primary
       • facultative
     • capacity to resist infection
       • age of patient
       • state of host defence mechanisms
         • decreases with age
     • population at risk
       • exposure
   • acute epiglottitis
     • haemophilus influenzae type B
     • rarely caused by parainfluenza virus type 4
     • inflammation + infection can rapidly block airwway
   • viral infection
     • can damage respiratory epthelium
       • can be completely lost
         • no clearance of fluids or microorganisms from lungs
   • recurrent lung infection
     • local bronchial obstruction
     • local pulmonary damage
     • generalised lung disease
     • non-respiratory disease
   • alveolar hypoventilation
     • increases PACO2
       • leads to increase in PaCO2
     • insufficient amount of air moved in + out of lungs
     • decrease in PAO2
       • decrease in PaO2
         • corrected by raising FIO2
   • outcome/complications of pneumonia
     • most resolve
     • pleurisy
       • inflammation
     • pleural effusion
       • fluid collected in pleural space
     • pleural empyema
       • pus in pleural space
         • fibrous wall develops around it
     • mass lesion
       • fibrous tissue
     • cryptogenic organising pneumonia
     • chronic bronchiolitis obliterans
     • lung abscess
       • tissue destruction
         • accumulation of inflammatory exudate
       • obstructed bronchus
       • staph aureus
         • metastatic pyaemia
           • necrotic lung
           • infection arrives via bloodstream
       • Klebsiella
       • pneumococcus
     • bronchiectasis
       • dilatation of bronchi
         • lung parenchymal destruction
         • severe infective episode
         • recurrent infection
         • proximal bronchial obstruction
   • patterns of pneumonia
     • aspiration
       • vomiting,oesophageal lesions
     • obstrutive
     • endogenous lipid
     • segmental
     • hypotatic
       • underlying/pulmonary CV disease
         • build up of fluid
     • lobar
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   • host defences in lower respiratory tract
     • alveolar macrophages
     • mucociliary escalator
     • cough reflex
     • deposition on terminal bronchioles/proximal alveoli
       • clearance by alveolar macrophage phagocytosis
         • interstitial pathway via lymph to lymph nodes
           • exit lung to bloodstream
         • deposition on conducting airways
           • clearance via mucociliary escalator
             • mucous carried out of lungs with macrophages in it