Community Based Medicine - Common microorganisms in upper respiratory tract infections Flashcards

1
Q

Common cold, pharyngitis (tonsilitis/quinsy), acute sinusitis, acute epiglottitis

A

The respiratory tract is the most common site of

infection by pathogens because its:

  • In direct contact with the physical/outer environment
  • Exposed to airborne microbes

The most pathogenic bacteria have developed

mechanisms to protect themselves:

  • A capsule that inhibits phagocytosis
  • Intracellular invasion of cells lining the
  • respiratory tract or alveolar macrophages to
  • escape the immune system

All surfaces of the respiratory tract are colonised by the

host microbiota:

  • Inhabitants of the respiratory tract and rarely, if ever,
  • cause disease
  • Most come from the oropharynx

Two main functions:

  • Compete with pathogenic organisms for potential

attachment sites

  • Produce substances that are bactericidal and

prevent infection by pathogen

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2
Q

The common cold?

A
  • Common microbe: Rhinoviruses are the main culprit (>80 strains exist). 1 - 4 day incubation
  • Characteristic symptoms: A self-limiting nasal discharge becoming mucopurulent over a few days
  • Complications: otitis media (6% of children), pneumonia, febrile convulsion
  • Treatment: Avoid treatment. If nasal obstructions in infants 0.9% saline nose drops
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3
Q

Pharyngitis/Tonsilitis/Quinsy

  • Pharyngitis: Inflammation of the pharynx
  • Tonsillitis: Inflammation of the tonsils
  • Quinsy: A peritonsillar abscess as a complication of tonsillitis
A

Common causative organisms:

Pharyngitis/tonsillitis Pharyngitis/tonsillitis

Mostly respiratory viruses:

Group A β-haemolytic streptococcus

Group C & G β-haemolytic streptococcus

Quinsy

Often polymicrobial

Group A

β-haemolytic Streptococcus

Staphylococcus aureus

Anaerobes

Haemophilus Infleunzae

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4
Q

Respiratory syncytial virus

A

Bronchiolitis

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5
Q

Parainfluenza Virus?

A

Croup

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6
Q

Rhinovirus?

A

Common Cold

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7
Q

Influenza virus?

A

The most common cause of community-acquired pneumonia

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8
Q

Haemophilus influenzae?

A

Community-acquired pneumonia
Most common cause of bronchiectasis exacerbations
Acute epiglottitis

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9
Q

Staphylococcusaureus

A

Pneumonia, particularly following influenza

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10
Q

Mycoplasma pneumoniae

A
  • Atypical pneumonia
  • Flu-like symptoms classically precede a dry cough.
  • Complications include haemolytic anaemia and erythema multiforme
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11
Q

Legionella pneumophilia

A
  • Atypical pneumonia
  • Classically spread by air-conditioning systems, causes dry cough.
  • Lymphopenia, deranged liver function tests and hyponatraemia may be seen
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12
Q

Pneumocystis jiroveci

A
  • Common cause of pneumonia in HIV patients.
  • Typically patients have few chest signs and develop exertional dyspnoea
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13
Q

Mycobacterium tuberculosis

A
  • Causes tuberculosis.
  • A wide range of presentations from asymptomatic to disseminated disease are possible.
  • Cough, night sweats and weight loss may be seen
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14
Q

Treatment

A

Pharyngitis/Tonsilitis

  • Group A,C&G Streptococcus - Ist Line Penicillin V 500mgs QDS
  • OR if not taking orally, Benzylpenicillin 1.2g ODS IV
  • If penicillin allergy - Clarithromycin 500mg BD PO (or IV if not taking orally)
  • 10 days for group A Streptococcus
  • 5 days for groups C&G streptococcus
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15
Q

Treatment

A

Quinsey

  • 1st line - Benzylpenicllin 1.2g QDS IV Plus Metronidazole 500mg TDS IV
  • if allergic to penicillin- Clarithromycin 500mg BD IV Plus Metronidazol 500mg TDS IV
  • Oral switch of Benzylpenicillin is penicillin V 500mg QDS
  • 5-7 days course
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16
Q

Acute Sinusitis:

inflammation of the paranasal sinuses with concurrent inflammation of the nasal cavity

A

Commons causative organism

  • Mostly respiratory viruses
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catarrhalis

Microbiological investigations

  • Nasal swabs are NOT recommended
  • Sinus aspirate ONLY for recurrent or
  • persistent infection
  • Blood cultures (if systemically unwell
17
Q

Treatment:

  • Topical treatment with 1% ephedrine drops and nasal douching may allow drainage of sinuses with mild disease without the need for antibiotics.
  • In chronic cases, topic steroid sprays are the mainstay of management with antibiotics reserved for acute flare up
A

Acute sinusitis

  • Moderate/severe disease - 1st - Amoxicillin 500mg-1g TDS po (5-7days)
    • Penicillin allergy - Clarithromycin 500mg BD po/Doxycycline 200mg stat then
18
Q

Acute Epiglottitis and supraglottitis

  • Inflammation of the epiglottis and supraglottic structures
  • Potential for life-threatening airway obstruction
  • History a disease of children beofe the introduction of Hib vaccine but now
  • prevalent in adults.
  • ENT review is essential
A

Common causative organisms

  • Haemophilus influenzae (type B)
  • Streptococcus pneumoniae
  • Staphylococcus aureus
  • Group A β-haemolytic streptococcus

Microbiological investigations

  • Blood culture
  • Epiglottal swab ONLY in intubated patients
19
Q

Treatment: airway management is vital

A