Microbiology
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Pathogens
A patient presents to ED complaining of a 3 day history of progressive muscle weakness and paraesthesia which started in both feet and appears to be spreading up his legs. He is now finding it difficult to walk. On further questioning, you determine that about 2 weeks ago he had a few days illness of bloody diarrhoea following a take away from a chicken shop. Which of the following is the most likely causative pathogen:
Answer:
These clinical features are suggestive of Guillain-Barre syndrome; an acute, ascending progressive peripheral neuropathy, characterised by weakness, paraesthesia and hyporeflexia. About 75% of cases have a history of preceding infection, usually of the respiratory and gastrointestinal tract. Campylobacter jejuni is the most commonly implicated gastrointestinal pathogen, which fits with the history of bloody diarrhoea following contaminated poultry.Campylobacter Jejuni
Microbiology / Pathogens / Gram-negative Gastrointestinal Disease
Last Updated: 23rd May 2023
| Microorganism | Campylobacter Jejuni |
|---|---|
| Gram stain | Gram negative |
| Shape | Rod (spiral flagellate) |
| Oxygen requirements | Microaerophilic |
| Oxidase | Positive |
| Reservoir | Multiple animals and fowl - contaminated food |
| Transmission | Oral-faecal route |
| Diseases | Acute bloody diarrhoea (dysentery), Guillain Barre syndrome |
Campylobacter spp. are a common cause of acute infective gastroenteritis, particularly in children, with Campylobacter jejuni responsible for 90% of Campylobacter gastroenteritis.
Transmission
Campylobacter spp. are found in human and animal gastrointestinal tracts. Infection typically follows ingestion of contaminated meat (most frequently undercooked poultry), unpasteurised milk or contaminated water, following which the microorganism invades and colonises the mucosa of the small intestine.
Clinical Disease
Clinical features typically include:
- Fever
- Flu-like illness
- Abdominal pain/cramps (children may be misdiagnosed with acute appendicitis or intussusception)
- Profuse and occasionally bloody diarrhoea
- Nausea and vomiting
Diagnosis
Diagnosis is made from culture of a stool specimen.
Treatment
Diarrhoea is usually self-limiting and treatment supportive but antibiotics may be indicated in severe infection or in immunocompromised patients; first line is clarithromycin (or azithromycin or erythromycin), ciprofloxacin is an alternative.
Complications
Immune-mediated complications include (typically occurring 1 - 2 weeks after onset):
- Reactive arthritis (usually of the ankles, knees and wrists, may be associated with conjunctivitis and urethritis)
- Guillain-Barre syndrome (an autoimmune ascending peripheral neuropathy)
Prevention
Prevention of Campylobacter infection is dependent on good animal husbandry and abattoir practices, proper sewage disposal and good food and personal hygiene in shops, dairies and at home.
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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 |
