Antibiotic-Associated Dysbacteriosis

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Also known as: Antibiotic-Associated Enterocolitis — Clostridial Enteropathy — Antibiotic Toxicity — Antibiotic-Associated Enterotoxaemia

Introduction

This condition may occur in different rodent species and other animals following administration of certain antibiotics, often by the oral route.

Hamsters and guinea-pigs are particularly susceptible, and the disease is characterised by profuse diarrhoea with a high mortality which develops 1-5 days after antibiotic administration.

The bacterial flora of most rodents is Gram positive with organisms such as streptococci and lactobacilli.

When a narrow-spectrum antibiotic with activity against Gram positive organisms such as penicillin, ampicillin, amoxicillin, clindamycin is administered, the normal bacterial flora is killed and there is overgrowth of abnormal flora, particularly E. coli and Clostridium species. Clostridium difficile is one of the organisms linked to the condition.

These bacteria multiply, produce toxins which are absorbed and can lead to a potentially fatal enterotoxaemia.

This is particularly the case if the antibiotic is administered by the oral route. Parenteral administration can also lead to problems due to certain antibiotics such as ampicillin and penicillin being excreted in the bile.

Clinical Signs

There will have been a history of recent antibiotic treatment and the development of profuse, watery diarrhoea.

This might be the only sign, but if enterotoxaemia is developing, the animal may experience systemic signs such as: lethargy, inappetance, pyrexia, weakness, coma and death.

Diagnosis

Diagnosis should be provisionally made on the basis of the history and clinical signs.

Bacteriology can be performed on the faeces and gut contents of affected animals, including an assay for the C. difficile toxin.

Post-mortem changes include: atonic and dilated caecum with an oedematous and haemorrhagic mucosa. Mucosal hyperplasia in the terminal ileum.

Treatment

Treatment is supportive. Antibiotics should be immediately stopped.

Warmed fluids should be administered via the intravenous or intraosseus route.

Analgesics help prevent abdominal discomfort.

Nutritional support is important, and high-fibre diets should be syringe-fed to help prevent ileus.

Transfaunation may be considered to replace normal bacterial flora.

Balanced appropriate antibiotic therapy, metronidazole, motility modifiers and antiendotoxin therapy may also be indicated.

If the enterotoxaemia is severe this is a life-threatening condition and the prognosis is guarded.

Prevention

Antibiotics which should be avoided in rodents, especially by the oral route, follow the PLACE mnemonic:

P: Penicillin
L: Lincomycin
A: Ampicillin, Amoxicillin
C: Clindamycin, Cephalosporin
E: Erythromycin

Antibiotics that have been used safely in rodents include: chloamphenicol, trimethoprim-sulpha and enrofloxacin.


Antibiotic-Associated Dysbacteriosis Learning Resources
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References

Harkness, J. (2010) Harkness and Wagner's Biology and Medicine of Rabbits and Rodents John Wiley and Sons

Mitchell, M. (2009) Manual of exotic pet practice Elsevier Health Sciences

Hagan, W. (1988) Hagan and Bruner's Microbiology and infectious diseases of domestic animals Cornell University Press

Percy, D. (2007) Pathology of laboratory rodents and rabbits John Wiley and Sons




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