Microbiology
Infections
A 14 year old boy is brought into ED complaining of a sore throat, fever, painful swallowing and tender lymph nodes. An image of his throat is shown below. You determine that he requires antibiotic treatment, what is the first line antibiotic for this condition:
![By James Heilman, MD (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons](https://primary-cdn.frcemsuccess.com/wp-content/uploads/2016/12/Tonsillitis-254x300.jpg)
(Image by James Heilman, MD (Own work) [CC BY-SA 3.0 , via Wikimedia Commons)
Answer:
Streptococcus pyogenes is the most common cause of bacterial tonsillitis. If it is decided that antibiotics are appropriate, the first line choice is a 10 day course of phenoxymethylpenicillin (penicillin V). In penicillin allergy, clarithromycin is the agent of choice.Acute Tonsillitis
Microbiology / Infections
Last Updated: 5th August 2019
Tonsillitis is inflammation due to infection of the tonsils. It is a very common condition, most frequent in children aged 5 – 10 years and young adults between 15 – 25 years.
Clinical Features
Patients may complain of pain in the throat, pain on swallowing, pain referred to the ears, headache and a high temperature. Nausea, vomiting, and abdominal pain are common in children. On examination, the throat is red, the tonsils are swollen and may be coated or have white flecks of pus on them (exudative). Patients are usually pyrexial and may have swollen and tender anterior cervical glands.
Causes
The most common bacterial cause of tonsillitis is group A beta-haemolytic streptococcus (GABHS), also called Streptococcus pyogenes (15 – 30% of sore throats in children and 10% in adults).
Common viral causes of a sore throat include:
- Rhinovirus, coronavirus, parainfluenza virus: the common cold (25% of sore throats)
- Influenza types A and B: influenza
- Adenovirus: pharyngoconjunctival fever (4% of sore throats)
- Epstein-Barr virus: infectious mononucleosis (< 1 % of sore throats)
- Herpes simplex virus type 1 (and more rarely type 2): acute herpetic pharyngitis (2% of sore throats)
Investigations
Investigations are not performed routinely.
Management
Pain and fever should be treated with paracetamol or an NSAID such as ibuprofen. In most patients, no or delayed antibiotic prescribing is recommended. Sore throat due to a viral or bacterial cause is a self-limiting condition. Symptoms resolve within 3 days in 40% of people, and within 1 week in 85% of people, irrespective of whether or not the sore throat is due to a streptococcal infection
The NICE guidelines suggests that indications for immediate antibiotics include:
- Features of marked systemic upset secondary to the acute sore throat
- Unilateral peritonsillitis
- A history of rheumatic fever or valvular heart disease
- An increased risk of severe infection or developing complications (such as a child with diabetes mellitus or immunodeficiency)
- Acute tonsillitis with three or four Centor criteria present (i.e. likely bacterial infection)
The likelihood of the presence of bacterial infection is based on the Centor Criteria:
- History of fever
- Tonsillar exudate
- No cough
- Tender anterior cervical lymphadenopathy
Patients with one or none of these criteria are unlikely to have GABHS. Consideration of antibiotic prescription should be limited to patients with three or four criteria.
If antibiotics are to be used, first line is a 10 day course of phenoxymethylpenicillin. Amoxicillin or ampicillin should be avoided if there is a possibility of glandular fever. If penicillin-allergic, a 5 day course of clarithromycin is recommended.
Complications
Complications of streptococcal pharyngotonsillitis include:
- Local extension:
- Otitis media
- Acute sinusitis
- Peritonsillar abscess (quinsy)
- Peritonsillar cellulitis
- Parapharyngeal abscess
- Retropharyngeal abscess
- Mastoiditis
- Streptococcal pneumonia
- Systemic
- Metastatic infection (e.g. brain abscess, endocarditis, meningitis, osteomyelitis or liver abscess)
- Streptococcal toxic shock syndrome
- Scarlet fever
- Rheumatic fever
- Post-streptococcal glomerulonephritis
Report A Problem
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Loading Form...
- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
