Microbiology
Pathogens
Question 118 of 180
A patient presents with a progressive symmetric descending flaccid paralysis following a 2 day history of diarrhoea and vomiting. He initially noticed blurred vision and dysphagia and is now complaining of weakness of his upper limbs. He is apyrexial and his observations are all normal. You suspect Clostridial infection. Which of the following Clostridium spp. is most likely responsible for this picture:
Answer:
Botulism is an acute neurologic disorder that causes potentially life-threatening neuroparalysis due to a neurotoxin produced by Clostridium botulinum. Food borne botulism symptoms typically develop 12-36 hours after ingestion of food containing the toxin, and may initially include nausea and vomiting, abdominal pain and diarrhoea. The typical neurological pattern is an acute onset of bilateral cranial neuropathies associated with symmetric descending weakness. Other key features include: absence of fever, no cognitive defects, normal heart rate and blood pressure and no sensory defects.Clostridium Spp.
Microbiology / Pathogens / Clostridial Infection
Last Updated: 23rd April 2020
Clostridial toxins
Clostridia produce the largest number of toxins of any bacterial class. The common source of entry in humans is the gastrointestinal tract or trauma.
Species-specific toxin expression:
- Botulism (C. botulinum)
- Colitis (C. difficile)
- Tetanus (C. tetani)
- Septic abortion (C. sordellii)
- Gas gangrene (C. perfringens, C. novyi, C. septicum, C. sordellii, C. histolyticum)
- Clostridial food poisoning (C. perfringens)
Clostridium Perfringens
| Microorganism | Clostridium Perfringens |
|---|---|
| Gram stain | Gram positive |
| Shape | Rod |
| Oxygen requirements | Obligate anaerobe |
| Additional features | Spore-forming, Produces exotoxin |
| Reservoir | Soil & intestinal flora |
| Diseases | Gas gangrene, food poisoning |
Clostridium Tetani
| Microorganism | Clostridium Tetani |
|---|---|
| Gram stain | Gram positive |
| Shape | Rod |
| Oxygen requirements | Obligate anaerobe |
| Additional features | Spore-forming, Produces tetanospasmin |
| Reservoir | Soil, dust & intestinal flora |
| Diseases | Tetanus |
Clostridium Difficile
| Microorganism | Clostridium Difficile |
|---|---|
| Gram stain | Gram positive |
| Shape | Rod |
| Oxygen requirements | Obligate anaerobe |
| Additional features | Spore-forming, Produces Toxin A (enterotoxin) and Toxin B (cytotoxin) |
| Reservoir | Intestinal flora & environment |
| Diseases | Pseudomembranous colitis |
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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 |
