SMI summary - throat related specimen

To investigate for:

Pharyngitis, Tonsillitis, Epiglottitis, Laryngitis.

Specimen types:

Throat swab, posterior pharyngeal swab, nasopharyngeal swab, pharyngeal washings, pus aspirate, oropharyngeal swab, throat gargle.

Target organisms - which organisms could cause following infections?

Pharyngitis (sore throat)

  • Viral (commonest),

  • Group A Streptococcus

  • Group C/G Streptococcus

  • Streptococcus anginosus group,

  • Corynebacterium – C diphtheriae, C. ulcerans,

  • Vincent’s angina – Borrelia vincentii and Fusobacterium species,

  • Arcanobacterium haemolyticum,

  • Fusobacterium necrophorum.

  • Neisseria gonorrhoeae.

Rare:

  • Francisella tularensis, Yersinia enterocolitica, Mycoplasma pneumoniae and Chlamydophila pneumoniae.

Other:

  • To test for carriage – Neisseria meningitidis, Staph aureus.

Epiglottitis

  • H. influenzae type b,

  • Group A Streptococcus

  • Pseudomonas species and

  • Mycobacterium tuberculosis.

In immunocompromised patients:

  • Candida species and Aspergillus

Tonsillitis

  • Viral infection,

  • Some bacterial infection – Group A Streptococcus.

  • Quinsy (peritonsillar abscess):
    1. Streptococcus anginosus group,
    2. Group A Streptococci,
    3. Fusobacterium
    4. Anaerobes (Prevotella, Porphyromonas and Peptostreptococcus species),
    5. S. aureus

Laryngitis

  • Viral infection,

  • Corynebacterium diphtheriae (rare),

  • MRSA,

  • Group A streptococci,

  • Streptococcus pneumoniae,

  • Haemophilus influenzae and

  • Mycobacterium tuberculosis or

  • Fungal (Candida species, Blastomyces species)

  • Parasite infections.

Non-infectious aetiology:

  • smoking, alcohol misuse, voice overuse, gastroesophageal reflux disease (GERD), allergies, inhalation of irritants or chemicals.

When to test for Corynebacterium diptheriae/ Corynebacterium ulcerans?

  • Membranous or pseudomembranous pharyngitis/tonsillitis

  • Contact with a confirmed case within the last 10 days

  • Travel abroad to high risk area within the last 10 days

  • Contact with someone who has been to a high risk area within the last 10 days

  • Contact with any animals (including household pets, visiting a farm or petting zoo) within the last 10 days

  • Recent consumption of any type of unpasteurised milk or dairy products

  • The patient works in a clinical microbiology laboratory, or similar occupation, where Corynebacterium species may be handled

Processing specimen

Gram stain

Stain for Vincent’s organisms: report on Vincent’s organisms detected.

Plate selection

  • Organisms should be isolated up to species level, except yeast – which can be left at yeast level.

  • Beta-haemolytic Streptococcus should be tested by Lancefield grouping.

  • Any C diphtheriae/ C ulcerans should be referred to the reference lab for toxigenicity test ASAP.

  • H influenza should be referred to the reference lab for grouping if it is epiglottitis.

Safety, infection control and public health - C diphtheriae/ C ulcerans

Corynebacterium diphtheriae, Corynebacterium ulcerans

C. diphtheriae and C. ulcerans are in Hazard group 2. Suspected and known isolates of C. diphtheriae /C. ulcerans should always be handled in a microbiological safety cabinet. Sometimes the nature of the work may dictate that full containment Level 3 conditions should be used eg for the propagation of C. diphtheriae/C. ulcerans in order to comply with COSHH 2004 Schedule 3 (4e).

Diphtheria is a notifiable disease in the UK.

  • Lab should immediately inform microbiologists

  • Infection control team should be notified ASAP.

  • UKHSA should be notified on suspicion, on an urgent basis for management of the case, contacts and outbreak.

  • In the healthcare setting, appropriate infection control measures should be taken.

  • All isolates should be referred to the reference lab for toxigenicity test.