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MD3001 Respiratory > Respiratory Tract Infections 2 > Flashcards

Respiratory Tract Infections 2 Flashcards

1
Q

What is the definition of pneumonia?

A

inflammation of the substance of the lungs

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2
Q

Describe pneumonia in children and adults

A

Children:

  • mainly viral
  • neonates can develop it from chlamydia trachomatis from their mother during birth

Adults:

  • mainly bacterial
  • aetiology varies with age, underlying disease, occupational and geographical risk factors
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3
Q

What are the common causes of viral pneumonia?

A
  • influenza virus
  • measles
  • coronavirus
  • parainfluenza virus
  • respiratory syncytial virus (RSV)
  • cytomegalovirus (CMV)
  • adenovirus
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4
Q

What are the common causes of bacterial pneumonia?

A
  • streptococcus pneumoniae
  • mycobacterium tuberculosis
  • haemophilus influenzae
  • pseudomonas aeruginosa
  • staphylococcus aureus
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5
Q

What is atypical pneumonia and the common causes of this?

A
  • failure to respond to treatment
  • mycoplasma pneumoniae
  • legionella pneumophilia
  • chlamydia pneumoniae
  • coxiella burnetii
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6
Q

What are the different anatomical classifications of pneumonia?

A
  • lobar pneumonia: involvement of distinct region of lung
  • bronchopneumonia:
  • diffuse, patchy consolidation
  • associated with bronchi and bronchioles
  • interstitial pneumonia:
  • invasion of lung interstitium
  • usually viral
  • necrotising pneumonia: lung abscesses and destruction of parenchyma
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7
Q

Describe the early and following clinical features of streptococcus pneumoniae

A

initially:

  • abrupt onset
  • rigors
  • fever
  • malaise
  • tachycardia
  • dry cough

followed by:

  • productive cough with rusty sputum
  • spiky temperature
  • lobular consolidation
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8
Q

Describe the clinical features of mycoplasma pneumoniae

A
  • fever
  • dry cough
  • dyspnoea
  • lymphadenopathy
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9
Q

What are the clinical features of haemophilus influenzae?

A
  • mainly occurs in children
  • consolidation or patchy bronchopneumonia
  • persistent purulent sputum and malaise
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10
Q

What causes Leigonnaire’s disease and what is it?

A
  • legionella pneumophila
  • gram negative bacillus that secretes protease causing lung damage
  • transmitted by aerosol (but not person-person)
  • severe systemic infection with pneumonia
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11
Q

What are the clinical features of legionella pneumophila?

A
  • tachypnoea
  • purulent sputum
  • CXR shows consolidation
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12
Q

How would you diagnose legionnaire’s disease in the lab?

A
  • gram stain sputum
  • recognition of antigen with serotype-specific fluorescent antibody
  • culture of legionella on cystine yeast extract agar
  • detection of antigen in urine
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13
Q

What are the clinical features and complications of mealses?

A

clinical features:

  • fever
  • runny nose
  • Koplik’s spots
  • characteristic rash

complications:

  • neurological complications
  • can cause ‘giant cell’ (Hect’s) pneumonia in immunocompromised - fatal
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14
Q

What are the important features of the measles virus?

A
  • paramyxovirus
  • spread by aerosol
  • affects multi-system
  • replicates in LRT
  • incubation 10-14 days
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15
Q

How would you diagnose, treat and prevent measles?

A

diagnosis:

  • serology for measles- specific IgM
  • virus isolation
  • virus RNA detection

treatment:

  • if severe, ribavirin
  • antibiotics for secondary bacterial infections

prevention:
- immunisation with highly effective, live, attenuated MMR vaccine

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16
Q

What are the risk factors of pneumonia?

A
  • bird contact (c. psitacci)
  • travel, air conditioning (L. pneumophila)
  • cystic fibrosis
  • immigration (pseudomonas)
  • farming (M. tuberculosis)
  • recent influenza (coxiella burnetti, S. pneumoniae, S. aureus)
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17
Q

What are the symptoms of pneumonia?

A
  • cough
  • breathlessness
  • sharp chest pain
  • purulent sputum
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18
Q

What are the clinical signs of pneumonia?

A
  • pyrexia
  • purulent sputum
  • rapid respiration
  • signs of consolidation
  • shock
  • cyanosis
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19
Q

Describe the process of diagnosing pneumonia

A
  • history
  • examination
  • radiology
  • sputum
  • serology
  • histopathology
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20
Q

Describe a CURB score

A
  • used to assess severity of pneumonia
  • 5 features each worth 1 point
  • C: confusion of new onset (AMTS of 8 or less)
  • U: blood urea greater than 7 mmol/l
  • R: respiratory rate of 30 breaths/min or more
  • B: blood pressure less than 90mmHg systolic/diastolic 60mmHg or less
  • age 65 or more
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21
Q

CURB 0

A
  • low severity
  • home treatment
  • antibiotics (amoxicillin/doxycycline)
22
Q

CURB 1-2

A
  • moderate severity
  • consider hospital referral
  • microbiological investigations
  • antibiotics given (amoxicillin/doxycyline)
23
Q

CURB 3-4

A
  • urgent hospital admission
  • empirical antibiotics if life-threatening (co-amoxiclav and clarithromycin)
  • microbiological investigations
  • urgent senior review
  • if 4-5: consider transfer to critical care unit
24
Q

Define endemic, epidemic and pandemic

A
  • endemic: present in community at all times, low to medium frequency at steady-state
  • epidemic: sudden severe outbreak within region or group
  • pandemic: occurs when epidemic becomes widespread and affects whole region/continent/world
25
Q

Describe the features of the influenza virus

A
  • orthomyxovirus
  • single stranded RNA
  • segmented

3 types:
A: epidemics/pandemics, animal reservoir
B: epidemics, no animal hosts
C: minor respiratory illness

26
Q

What are the type-specific antigens on the surface of the influenza virus?

A
  • haemagglutinin (H)
  • neuaminidase (N)
  • reassortment gives rise to new combinations of H and N antigens
27
Q

What are the different genetic changes that the influenza virus undergoes during spread through the host?

A

Antigenic drift:

  • point mutations in H and N antigens constantly
  • allows virus to multiply in individuals with immunity to preceding strains
  • new sub-type can affect community
  • occurs with all types

Antigenic shift:

  • sudden major change based on recombination between 2 different virus strains when they infect same cell
  • produces virus with novel surface glycoproteins
  • new strain can spread through previously immune populations (new pandemic)
28
Q

What things can risk a pandemic?

A
  • antigenic shift
  • if most people have no immunity
  • if attack rate is high - spreads rapidly
  • mortality can be high
29
Q

What virus causes swine flu and describe its infection

A
  • H1N1 virus
  • many older people had been infected with older virus in childhood
  • vaccine contained H1N1 components
  • infection limited to people under 40
  • attack rate high but mortality low because many had degree of immunity
30
Q

What is the diagnosis and treatment of influenza?

A

diagnosis:

  • nasopharyngeal aspirate
  • direct immunofluorescence
  • culture
  • NAAT detection
  • serum serology

treatment:

  • amatadine
  • zanamavir
  • oseltamivir
31
Q

What is the management and prevention of influenza?

A

management:

  • rest, warmth, hydration, analgesia
  • antiviral treatment within 48hrs to reduce duration of fever
  • antibiotics not given unless secondary bacterial infection suspected

Prevention:

  • vaccine
  • different strains of antigen used in anticipation of latest strain to emerge
32
Q

Describe the influenza vaccine

A
  • new vaccine based on predicted strains
  • trivalent vaccine
  • new recombination methods speeds up process of developing new vaccine
  • those at risk (elderly, immunosuppressed etc) require annual vaccine
33
Q

What is SARS?

A
  • outbreak of severe respiratory disease with no identifiable cause
  • China Nov 2002
  • 10% fatality rate
34
Q

What are the SARS symptoms?

A
  • high fever
  • cough
  • shortness of breath
  • CXRs consistent with pneumonia
35
Q

How is SARS transmitted and the incubation period?

A
  • transmitted via droplets, faeces and infected animals

- incubation period of 2-7 days

36
Q

How would you identify SARS-associated coronavirus?

A
  • virus isolation in cell culture
  • electron microscopy
  • molecular techniques
37
Q

What are the characteristics of the SARS-associated coronavirus?

A
  • enveloped
  • RNA virus
  • characteristic halo
  • receptor for spike protein is ACE2
38
Q

What is the treatment of SARS?

A
  • no specific anti-viral treatment:
  • ribavirin
  • corticosteroids
  • interferons
  • anti-retroviral therapies (eg. PI)
  • whole inactivated virus vaccines
  • recombinant vaccine
39
Q

What things are associated with TB?

A
  • AIDS
  • increased use of immunosuppressive drugs
  • decreased socio-economic conditions
  • increased immigration from areas of high endemicity
  • multiple drug resistance
  • overcrowding and poor nutrition
40
Q

What are the different clinical features of TB?

A

Primary TB:

  • usually symptomless
  • may be associated with cough and wheeze
  • small transient pleural effusion may occur

Miliary TB:

  • results from acute diffuse dissemination of bacillus
  • fatal without treatment

Post-Primary TB:

  • onset of symptoms over weeks/months
  • malaise
  • fever
  • weight loss
  • mucoid, purulent or blood stained sputum
  • pleural effusion
41
Q

What are the symptoms of TB?

A
  • poor appetite
  • night sweats
  • weakness
  • fever
  • dry cough
  • weight loss
  • GI symptoms
42
Q

Describe the features of mycobacterium tuberculosis and the disease itself

A
  • neither gram positive or negative
  • acid-fast bacilli
  • human pathogen
  • obligate anaerobe (found in well- aerated upper lobes of lungs)
  • spread by inhalation of organisms from dust/aerosols
  • primarily disease of lungs but can spread to other sites
43
Q

Describe the Mantoux test

A
  • used to detect latent TB infection
  • tuberculin injected intradermally
  • immune response if individual previously exposed to bacterium
  • induration (palpable hardened area) measured after 48-72 hrs
44
Q

Describe the importance of bacterial load on diagnostics

A
  • symptoms differ at different bacterial loads
  • patients present at different bacterial loads
  • diagnostic tests become positive at different bacterial loads
  • reducing the bacterial load can delay diagnosis
45
Q

Describe the diagnosis methods of TB

A
  • visualisation of acid-fast bacilli in sputum smears
  • auramine:
  • positive organisms fluoresce yellow
  • more sensitive than Z/N for initial diagnosis as whole smear can be examined under low power magnification
  • shows presence/absence
  • Ziehl-Neelsen (Z/N)
  • carbol fuschin stain and methylene blue counter stain
  • 100 fields examined under 100x objective
  • semi-quantification
46
Q

What are the solid and liquid culture options for tuberculosis and the timing you would need to culture for?

A

Solid:

  • Lowenstein-Jensen slopes: 6 weeks
  • Middlebrook agar plates: 2-3 weeks

Liquid:
- mycobacteria growth indicator tube: 5-15 days
(* allows continuous monitoring of positive cultures)

47
Q

How does bacteria show up in culture?

A
  • bacterial growth measured by consumption of oxygen in media
  • tubes contain fluoresence compound sensitive to presence of oxygen
  • actively respiring bacteria consume oxygen from media allowing fluoresence to be detected
48
Q

What is the treatment and prevention of TB?

A

treatment:

  • combination therapy:
  • isoniazid, rifampicin, ethambutol, pyrazinamide
  • to prevent resistance
  • prolonged therapy
  • minimum 6 months
  • eradicates slow growing organisms

prevention:

  • childhood immunisation
  • live attenuated BCG vaccine
  • prophylaxis with isoniazid for 1 year
49
Q

What are some examples of fungal infections?

A
  • aspergillus fumigatus

- pneumocystis jiroveci

50
Q

What are some examples of parasitic infections?

A
  • ascaris
  • strongyloides
  • echinococcus granulosus

MD3001 Respiratory (38 decks)

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