Microbiology
Infections
Question 8 of 77
A 45 year old lady presents to ED with malaise and severe breathlessness on exertion and lying down. About 2 weeks ago she suffered from a flu-like illness. Chest x-ray demonstrates cardiomegaly and interstitial oedema. Inflammatory markers are raised. A diagnosis of myocarditis is made. Which of the following pathogens is the most likely infective agent:
Answer:
Viral infection is the most common cause of acute myocarditis and coxsackievirus is the most common viral cause in Europe and the USA.Myocarditis
Microbiology / Infections
Last Updated: 21st April 2019
Infective Agents
- Viral
- Coxsackievirus (most common cause)
- Parvovirus B19
- Herpesviridae
- Echovirus
- Adenovirus
- Rubella
- Bacterial
- Mycoplasma pneumoniae
- Staphylococcus aureus
- Corynebacterium diphtheriae (toxin-mediated)
- Immune-mediated
- Group A streptococcal infection (rheumatic fever)
Clinical Disease
- Flu-like symptoms associated with fatigue, exertional dyspnoea, palpitations and precordial pain
- Tachycardia, dysrhythmia or cardiac failure may be present
- ECG may show T-wave inversion, prolongation of the PR or QRS interval, extrasystoles or heart block
- Chest x-ray may show cardiomegaly
- Cardiac enzymes may be elevated
Diagnosis
Viruses may be detected in faecal, nasopharyngeal and throat specimens in nucleic acid amplification tests (NAATs).
Treatment
Treatment is supportive.
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- 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 |
