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Y2 Clinical Pathology > Respiratory Infections > Flashcards

Respiratory Infections Flashcards

1
Q

what are the 4 possible causes of an acute sore throat?

A
  1. pharyngitis
  2. acute tonsillar pharyngitis
  3. consider infectius mononucleosis (EBV)
  4. suspect epiglottitis
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2
Q

what are the key points in the history when differentiating the possible causes of an acute sore throat?

A
  • rapidity of onset of sore throat
  • difficulty breathing / speaking
  • ability to eat / drink / swallow
  • associated neck pain / swellings
  • symptoms of systemic infection - fever, chills, rigors, malaise
  • travel history
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3
Q

What is pharyngitis?

A

inflammation of the back of the throat (pharynx)

this results in sore throat and fever

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4
Q

What is acute tonsillar pharyngitis?

A

symmetrically inflamed tonsils and pharynx

(+/- fever and/or headache)

in severe infection, patient has marked systemic symptoms of infection and/or is unable to swallow

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5
Q

What would be seen in infectious mononucleosis?

A
  1. symmetrically inflamed tonsils
  2. soft palate inflammation
  3. posterior cervical lymphadenopathy
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6
Q

What would be seen in suspect epiglottitis?

A

sudden onset of a severe sore throat

no inflammation of the tonsils and/or oropharynx & systemic symptoms/signs of infection

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7
Q

What is pharyngitis and tonsillar pharyngitis caused by?

A

it is commonly caused by viruses, however in a third of people, no cause can be found

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8
Q

What are the common infectious causes of pharyngitis and tonsillar pharyngitis?

A

viruses:

  • rhinovirus
  • coronovirus
  • parainfluenzae
  • influenza A & B
  • adenovirus
  • viruses account for 50% of sore throat

bacteria:

  • group A beta-haemolytic streptococcus is the most common bacterial cause of sore throat
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9
Q

What are rarer causes of pharyngitis and tonsillar pharyngitis?

A
  • Neisseria gonorrhoeae (gonococcal pharyngitis)
  • HIV-1
  • Corynebacterium diptheriae (diptheria)
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10
Q

what is meant by the Centor criteria?

When are they used?

A

the Centor criteria give an indication of the likelihood of a sore throat being due to a bacterial infection

if 3 or 4 of the Centor criteria are met, the positive predicitive value is 40 - 60%

the absence of 3 or 4 of the Centor criteria has a fairly high negative predictive value of 80%

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11
Q

What are the 4 Centor criteria?

A
  • tonsillar exudate
  • tender anterior cervical lymphadenopathy
  • fever over 38oC
  • absence of a cough
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12
Q

What is involved in the investigations for outpatients and inpatients with acute sore throat?

A

outpatients (non-severe infection):

  • no routine investigations unless infectious mononucleosis is suspected

inpatients (severe infection):

  • throat swab for culture
  • blood cultures ( full blood count, U&Es, LFTs)
  • blood sample for monospot or EBV serology if infectious mononucleosis is suspected
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13
Q

What is involved in the management of acute sore throat?

A
  • oral analgesics (paracetamol, ibuprofen)

most acute sore throats DO NOT require antibiotics

  • consider antibiotics in non-severe acute tonsillar pharyngitis if symptoms present for 1 week and getting worse
  • give antibiotics in severe acute tonsillar pharyngitis, quinsy or epiglottitis
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14
Q

What causes infectious mononucleosis / glandular fever?

What age group tend to be affected and what are the symptoms?

A

caused by epstein-barr virus (EBV)

usually seen in teenagers and is asymptomatic

it is characterised by a triad of symptoms:

  • fever
  • tonsillar pharyngitis
  • cervical lymphadenopathy
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15
Q

How is infectious mononucleosis diagnosed?

Which treatment should be avoided?

A

blood for monospot +/- EBV serology

ampicillin should be avoided as it leads to development of maculopapular rash

there are some complications such as splenic rupture

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16
Q

What is epiglottitis?

What is it caused by?

A

inflammation of structures above the glottis

  • Haemophilus influenzae type B (Hib) was the commonest cause before the vaccine was introduced
  • also caused by Streptococcus pneumoniae and Group A streptococcus
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17
Q

What is involved in the investigations for epiglottitis?

A

blood cultures and epiglottic swabs

attempting to examine the throat may result in total airway obstruction, so should only be done when anaesthetic support is present

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18
Q

What is involved in the management for epiglottitis?

A

acute epiglottitis & associated upper airway obstruction has significant morbidity and mortality and may cause respiratory arrest and death within 24 hours

secure the airway & oxygenation is priority

  • IV antibiotics (usually 3rd generation cephalosporin)
  • analgesia
  • public health should be informed if it is Hib epiglottitis
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19
Q

What is otitis externa (OE)?

What is the difference between acute and chronic OE?

A

inflammation of the external ear canal presenting with a combination of otalgia, pruritis and non-mucoid ear discharge

acute OE - symptoms < 3/52

chronic OE - symptoms > 3/52

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20
Q

What are the risk factors associated with otitis externa?

A
  • swimming (or other water exposure)
  • trauma (e.g. ear scratching, cotton swabs)
  • occlusive ear devices (e.g. headphones, hearing aids)
  • allergic contact dermatitis (e.g. due to shampoos, cosmetics)
  • dermatological conditions
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21
Q

What is acute OE?

What is is caused by?

A

it ranges in severity - mild/moderate/severe + necrotising (malignant) OE

it is typically unilateral

90% of cases are bacterial and 2% are fungal

most commonly caused by Pseudomonas aeruginosa & Staphylococcus aureus

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22
Q

what is involved in the diagnosis and investigations for acute OE?

A

diagnosis:

  • history and otoscopic examination

investigations:

  • ear swab or pus sample for culture
  • in necrotising otitis externa, need CT temporal bone & bone biopsy
  • blood cultures if systemically unwell
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23
Q

What is involved in the non-antimicrobial and antimicrobial management of acute OE?

A

non-antimicrobial management:

  • remove / modify precipitating factors
  • remove pus & debris from ear canal
  • analgesia

antimicrobial managemet:

  • topical agents for mild-moderate
  • topical + systemic antibiotic (flucloxacillin) for severe AOE
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24
Q

what is malignant (necrotising) external otitis?

Who is usually affected?

A

it occurs when external otitis spreads to the skull base

(soft tissue, cartilage and bone of the temporal region & skull)

it can be life threatening

most commonly develops in elderly diabetic or other immunocompromised patients

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25
Q

What are the symptoms and treatments for malignant external otitis?

A
  • severe pain
  • otorrhoea
  • granulation tissue in the canal flooor
  • cranial nerve palsies

patients with these signs should be promptly referred to ENT

treatment for a minimum of 6 weeks

e.g. IV ceftazidime then po ciprofloxacin

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26
Q

What is chronic otitis externa?

How does it usually present?

A
  • pruritis
  • mild discomfort
  • erythematous external canal is usually devoid of wax
  • white keratin debris may fill the ear canal and over time the canal wall skin may become thickened, narrowing the external ear canal
  • often bilateral
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27
Q

What causes chronic OE?

How should it be treated?

A

a common cause of chronic OE is contact dermatitis

(e.g. from chemicals in cosmetics or shampoos)

generalised skin conditions such as atopic dermatitis or psoriasis can predispose to chronic OE

need to treat the underlying cause

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28
Q

what is otitis media (OM)?

Who tends to be affected?

A

middle ear inflammation involving fluid present in the middle ear

it is very common in children

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29
Q

What is the difference between uncomplicated acute OM and complicated acute OM?

A

uncomplicated acute OM:

  • mild pain < 72 hours duration and an absence of severe systemic symptoms
  • temperature < 39oC and no ear discharge

complicated acute OM:

  • presence of severe pain, perforated eardrum and/or purulent discharge, bilateral infection, mastoiditis
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30
Q

What causes otitis media?

How is it diagnosed and treated?

A

causes:

  • mainly caused by viruses
  • Streptococcus pneumoniae
  • Haemophius influenzaee
  • Moraxella catarrhalis

diagnosis:

  • swab any pus

treatment:

  • if not unwell, watch and treat symptomatically with analgesia & decongestant
  • if they are unwell, give amoxicillin
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31
Q

what is mastoiditis?

Who is often affected?

A

it is a complication of otitis media that involves infection of the mastoid bone and air cells

incidence is reduced with the use of antibiotics for OM

it is rare in adults but seen in < 1 in 1000 children with untreated AOM

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32
Q

What are the clinical features of mastoiditis?

What treatments are available?

A
  • fever
  • posterior ear pain and/or local erythema over the mastoid bone
  • oedema of the pinna
  • posteriorly and downward displaced auricle

treatment:

  • CT scan is always required
  • analgesia, IV antibiotics +/- mastoidectomy
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33
Q

What is pinna cellulitis (perichondritis)?

what is it associated with?

A

it is associated with trauma (including ear piercing & acupuncture), surgery and burns

perichondritis may be a complication of high ear piercing

(puncture thrugh the cartilage of the upper third of the pinna)

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34
Q

What usually causes pinna cellulitis?

How is it diagnosed and treated?

A
  • usual infective agent(s) in auricular perichondritis are:
    • Pseudomonas aeruginosa
    • and / or Staphylococcus aureus

Diagnosis:

  • a swab of the area and blood cultures should be obtained prior to starting antibiotics

Treatment:

  • empirical treatment - ciprofloxacin + flucloxacillin (or vancomycin in penicillin allergy)
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35
Q

What is pneumonia?

A

an infection affecting the most distal airways and alveoli

involves the formation of inflammatory exudate

36
Q

what are the 2 different anatomical patterns of pneumonia?

A

bronchopneumonia:

  • characteristic patchy distribution centred on inflamed bronchioles & bronchi then subsequent spread to surrounding alveoli

lobar pneumonia:

  • affects a large part of the entirety of a lobe
  • 90% due to S. pneumoniae
37
Q

What are the 4 different types of pnemonia?

A
  • community acquired pneumonia (CAP)
  • hospital acquired pneumonia (HAP)
  • ventilator acquired pneumonia (VAP)
  • aspiration pneumonia
38
Q

What is hospital acquired pneumonia?

what causes it?

A

pneumonia developing >48 hours after hospital admission

additional causative organisms to CAP, especially if it develops > 5 days after admission

e.g. enterobacteriaceae

39
Q

What is ventilator acquired pneumonia?

A

a subgroup of HAP

it is pneumonia developing > 48 hours after ET intubation & ventilation

Pseudomonas spp. may be implicated

40
Q

What is aspiration pneumonia?

A

pneumonia resulting from the abnormal entry of fluids into the lower respiratory tract

(e.g. food, drinks, stomach contents)

the patient usually has an impaired swallow mechanism

anaerobes may be implicated

41
Q

What is the epidemiology of CAP like?

What age does it affect and what time of the year is it more common?

A

incidence of 1 in 100 people per year (common)

20-40% of cases require hospitalisation

peak age of 50-70 years

peak onset from midwinter to early spring

42
Q

Where do people tend to acquire organisms from in CAP?

A
  • person-to-person or from a person’s existing commensals
    • S. pneumoniae , H. influenzae
  • from the environment
    • L. pneumophilia
  • from animals
    • ​C. psittaci
43
Q

How are the causative agents of CAP divided into 2 groups?

A

bacterial causes are divided into ‘typical’ and ‘atypical’

atypical organisms have no / atypical cell walls

the clinical presentation and treatment are slightly different

44
Q

What are examples of typical and atypical organisms which can cause CAP?

A

“typical” organisms (with cell wall):

  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Staphylococcus aureus
  • Klebsiella pneumoniae

“atypical” organisms (no / atypical cell wall):

  • Mycoplasma pneumoniae
  • Legionella pneumophilia
  • Chlamydophilia pneumoniae
  • Chlamydophilia psittaci
  • Coxiella burnetii
45
Q

What are the symptoms and signs of bacterial pneumonia?

A

symptoms:

  • usually rapid onset
  • fever / chills
  • productive cough
  • mucopurulent sputum
  • pleuritic chest pain
  • general malaise, fatigue, anorexia

signs:

  • tachypnoea, tachycardia, hypotension
  • examination findings consistent with consolidation
    • dull to percuss
    • reduced air entry, bronchial breathing
46
Q

Who tends to be affected by Mycoplasma pneumoniae?

what are the main symptoms, diagnosis and rare complications?

A

autumn epidemics every 4-8 years tend to affect children and young adults

main symptom is cough

diagnosis:

  • serology (difficult to culture)

rare complications:

  • pericarditis
  • arthritis
  • Guilliain-Barre
  • peripheral neuropathy
47
Q

What are outbreaks of Legionella pneumophilia associated with?

what are the symptoms like?

what would be seen on blood tests?

A

it colonises water piping systems so outbreaks are associated with showers, air conditioning units & humidifiers

symptoms:

  • high fevers
  • rigors
  • cough - dry initially but becomes productive
  • dyspnoea
  • vomiting & diarrhoea
  • confusion

blood tests:

  • deranged LFTs
  • SIADH (low sodium)
48
Q

Who tends to be affected by Chlamydophilia pneumoniae?

How do symptoms differ across the ages?

A

accounts for 3-10% CAP cases in adults

causes mild pneumonia or bronchitis in adolescents & young adults

incidence is highest in the elderly and they may experience more severe disease

49
Q

What is Chlamydophilia psittaci associated with?

What are other symptoms?

A

it is associated with exposure to birds

consider in those with pneumonia, splenomegaly & history of bird exposure

other symptoms:

  • rash
  • hepatitis
  • haemolytic anaemia
  • reactive arthritis
50
Q

What score is used to assess CAP disease severity?

What are the criteria?

A

CURB-65 score

Confusion

Urea > 7 mmol/L

Respiratory rate >/= 30

Blood pressure - systolic < 90 mmHg or diastolic < 60 mmHg

Age >/= 65 years

51
Q

What does the CURB-65 score show about severity of CAP?

A

CURB-65 score of 0 or 1 shows low severity CAP that can be treated at home

score of 2 shows moderate severity CAP that should be treated in hospital

score of 3-5 shows high severity CAP that should be treated in hospital and assess for ITU admission

52
Q

What are the investigations for inpatients with CAP?

A
  • chest X-ray (can take 6 weeks + radiological changes to resolve)

recommended for all moderate-severe CAP (CURB65 score >2):

  • sputum culture
  • blood culture
  • pneumococcal urinary antigen
  • legionella urinary antigen
  • PCR or serology for:
    • viral pathogens (influenza or COVID-19)
    • Mycoplasma pneumoniae
    • Chlamydophilia spp.
53
Q

What is the ABC approach used to treat CAP/HAP/VAP/aspiration pneumonia?

A

as with any unwell or septic patient:

A - airway:

  • ensure an open, patent and maintained airway

B - breathing:

  • assess respiratory rate and saturations
  • provide supplemental oxygen to reach prescribed target

C - circulation:

  • assess blood pressure and heart rate
  • gain IV access and give IV fluids if haemodynamically unstable
  • urinary catheter to monitor urine output

then prompt empirical antibiotic therapy

54
Q

What are the 3 main complications of pneumonia?

A

pleural effusion:

  • occurs in 3-5%
  • clear fluid +/- pus cells +/- organisms

empyema:

  • pus in the pleural space

lung abscess:

  • suppuration and destruction of lung parenchyma
  • single (aspiration) anaerobes - Pseudomonas
  • multiple (metastatic) - Staphylococcus aureus
55
Q

What viruses can cause lower respiratory tract infections (pneumonia) in the normal host and immunocompromised hosts?

A

pneumonia in the normal host:

  • influenza A and B
  • adenovirus
  • varicella zoster virus
  • COVID-19
  • parainfluenza and respiratory syncitial virus in children

pneumonia in the immunocompromised host:

  • measles
  • herpes simplex virus
  • cytomegalovirus
  • HHV-6
  • and all of the above
56
Q

what is the normal clinical presentation of influenza?

A

usually influenza produces uncomplicated disease

  • fever, headache, myalgia, dry cough, sore throat
  • convalescence takes 2-3 weeks
57
Q

What are the symptoms of primary viral pneumonia?

Who tends to get this?

What is it caused by?

A

it occurs more commonly in patients with pre-existing cardiac & lung disorders

caused by influenza virus

  • cough, breathlessness, cyanosis
  • secondary bacterial pneumonia may then develop after initial period of improvement
    • S. pneumoniae, H. influenzae, S. aureus
58
Q

How is influenza / primary viral pneumonia diagnosed?

A

viral antigen detection in respiratory samples using PCR

59
Q

What is VZV pneumonia?

Who tends to be affected and who is most at risk?

A

a complication of VZV (chickenpox) infection

it is rare in children but produces significant mortality and morbidity in adults

those at greatest risk are:

  • immunocompromised
  • adults with chronic lung disease
  • smokers
  • pregnant women
60
Q

What is the onset of VZV pneumonia like?

what tests are performed and how is it treated?

A

insidious onset 1-6 days after the rash has appeared with symptoms of progressive tachypnoea, dyspnoea and dry cough

tests:

  • chest X-ray to reveal diffuse bilateral infiltrates

treatment:

  • supportive & prompt administration of IV acyclovir
61
Q

What can rhinovirus cause?

How can it be tested for?

A

it is the agent responsible for most “common colds”

it can cause lower respiratory tract infections and trigger exacerbations of asthma

it is tested using a throat swab and PCR on NBA

62
Q

What are the consequences of CMV pneumonia?

What tests and treatment are available?

A

it is rarely seen in immunocompetent hosts

it can cause severe illness in transplant recipients and HIV patients

tests:

  • chest x-ray
  • broncho-alveolar lavage & viral load PCR

treatment:

  • supportive treatment
  • anti-viral (e.g. ganciclovir)
  • consider immunosuppression reduction in transplant patients
63
Q

What is bronchiectasis?

What are the typical symptoms?

A

acquired disorder of the major bronchi and bronchioles that is characterised by permanent abnormal dilatation & destruction of bronchial walls

symptoms:

  • chronic cough
  • mucopurulent sputum production
  • recurrent infections
    • S. aureus
    • H. influenzae
    • Pseudomonas aeruginosa
    • viruses
64
Q

What are the exacerbation investigations in bronchiectasis?

When are antibiotics recommended?

A

exacerbation investigations:

  • SpO2,
  • chest X-ray
  • FBC, LFTs, U&Es
  • CRP
  • preview previous sputum culture

antibiotics are recommended for exacerbations with acute deterioration with worsening symptoms

65
Q

What is involved in the non-antimicrobial management of bronchiectasis?

A
  • effective clearance of respiratory secretions
    • e.g. physiotherapy, postural drainage
  • nutritional support
  • identification and treatment of underlying cause
    • e.g. annual influenza vaccination
66
Q

What is cystic fibrosis?

A

an inherited disease caused by a genetic mutation on chromosome 7

this results in abnormal production and function of the cystic fibrosis transmembrane conductance regulator (CFTR)

the defective CFTR chloride channel function results in viscous secretions

67
Q

How do colonising organisms and resistance change over time in LRTIs in cystic fibrosis?

A
  • Staphylococcus aureus in childhood
  • Pseudomonas aeruginosa in childhood / early adolesence
  • Burkholderia cepacia is very resistant and transmissable
  • non-tuberculous mycobacteria & fungi
68
Q

What is involved in treatment of an acute exacerbation in cystic fibrosis?

A

use most recent sputum cultures to guide treatment

prolonged antibiotic courses (3 - 4 weeks)

general measures:

  • postural drainage
  • deep breathing, coughing & exercise
  • aerosolised DNAase + influenza and pneumococcal vaccinations
  • lung transplant
69
Q

Who should be given a pneumococcal vaccination (S. pneumoniae) to prevent LRTIs?

A
  • patients with chronic heart, lung and kidney disease
  • patients with splenectomy
  • part of infant vaccination schedule
  • may repeat after 5 years in certain populations
70
Q

Who should be given an annual influenza vaccination to prevent LRTIs?

A

vulnerable groups:

  • 2 - 17 year olds
  • over 65s
  • those with chronic disease and multiple comorbidities
71
Q

What is aspergillosis?

Who is most at risk?

A

an infection caused by Aspergillus

this is a common mold that lives indoors and outdoors

most people breathe in Aspergillus spores every day without getting sick

immunocompromised patients and those with lung disease are at a higher risk of developing health problems due to Aspergillus

72
Q
A
73
Q

who tends to be affected by allergic bronchopulmonary aspergillosis (ABPA)?

How does it present?

A

ABPA occurs in people with a background of atopy, asthma & cystic fibrosis

it presents with worsening asthma and lung function

74
Q

What are the diagnostic features of ABPA?

How is it treated?

A

diagnostic features:

  • high total IgE and specific IgE to Aspergillus
  • positive serum IgG to Aspergillus
  • CT imaging of thorax may demonstrate central bronchiectasis

treatment:

  • corticosteroids and antifungal therapy
75
Q

What is aspergilloma?

What causes it and what are common symptoms?

A

a mobile mass of Aspergillus within a pre-existing lung cavity

old cavities left by previous TB or sarcoidosis become colonised with Aspergillus spp.

symptoms:

  • cough
  • haemoptysis
  • weight loss
  • wheeze & clubbing
  • may be asymptomatic
76
Q

How is aspergilloma diagnosed?

A

can be seen on chest X-ray or CT thorax

diagnosis confirmed by a positive test for Aspergillus IgG antibody +/- Aspergillus antigen

sputum culture may be positive for Aspergillus spp.

77
Q

What is the treatment for aspergilloma?

What is an associated complication?

A

10% of cases resolve spontaneously

surgical resection may be perfomed or antifungals (injected into the cavity, or orally for symptom relief)

complication is massive haemoptysis

78
Q

What is different about Pneumocystis jiroveci pneumonia?

What are the symptoms?

A

it is a fungus but is not susceptible to many antifungals as it lacks ergosterol in its cell wall

principle mode of transmission is airborne route

symptoms:

  • insidious onset of fever
  • dyspnoea
  • non-productive cough & reduced exercise tolerance
  • exercise induced hypoxia is a classic finding
79
Q

What is involved in the diagnosis and treatment of Pneumocystis jiroveci pneumonia (PCP)?

A

diagnosis:

  • specimens are rarely isolated from expectorated sputum and are found in indued sputum
  • broncho-alveolar lavage increases diagnostic rate
  • PCR to detect P. jiroveci
  • blood tests for Beta-D-Glucan

treatment:

  • supportive care
  • antimicrobials (including co-trimoxazole)
  • steroids
  • some at risk groups (e.g. HIV patient with CD4 count <200) get primary prophylaxis
80
Q

what is Nocardia asteroides?

Who tends to be affected and what are the clinical features?

A

a genus of bacteria found in the environment

pulmonary nocardiasis is acquired through inhalation of the organism

mor common in immunosuppressed and those with pre-existing lung disease (esp. alveolar proteinosis)

presentaion and radiological findings are variable

81
Q

What is involved in diagnosis and treatment of pulmonary nocardiasis?

A

lung abscesses can develop

diagnosis:

  • specimens from sputum
  • or broncho-alveolar lavage or biopsy

treatment:

  • supportive treatment (ABC) then antibiotics for several months
  • co-trimoxazole is most commonly used
82
Q

How does Mycobacterium tuberculosis cause infection?

Who tends to be affected?

A

infection is acquired by inhalation of infected respiratory droplets

the bacilli lodge in the alveoli and multiply, leading to the formation of a Ghon focus

depending on the host’s immune response the infection will either become quiescent or progress and/or disseminate

it is more common in the developing world

83
Q

Who is at most risk from Mycobacterium tuberculosis?

What are the symptoms like?

A

risk of disease progression is highest at the extremes of age and in the immunocompromised

90% of primary infections are asymptomatic

reactivation of disease may occur in later life, particularly in the immunocompromised

84
Q

What is the most common presentation of Mycobacterium tuberculosis infection?

A

pulmonary tuberculosis

  • chronic productive cough and haemoptysis
  • weight loss
  • fever
  • night sweats

it can disseminate (miliary TB) and affect almost any other organ

85
Q

How is pulmonary tuberculosis diagnosed?

A

clincal features + supportive radiology + detection of acid-fast bacilli or culture of M. tuberculosis from clinical specimens

PCR-based tests may be used to detect MTB in clinical specimens

interferon gamma release assays +/- tuberculin skin test

86
Q

what is involved in the treatment and prevention of pulmonary tuberculosis?

A

Y2 Clinical Pathology (76 decks)

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