In vivo antibacterial activity of Plocamium rigidum extract on Escherichia coli O157:H7 in experimentally infected Balb/c mice

Abstract

Despite the large pharmaceutical potentials of natural products from marine algae as antibiotics, there is a scarcity of scientific research on their safety and efficacy.This study evaluated the in vivo acute toxicity and therapeutic efficacy of the crude extract of Plocamium rigidum in infected Balb /c mice.Acute toxicity of Plocamium rigidum extract and antibacterial activity against Escherichia coli OH157:H7 was assessed in Balb/c mice. Acute toxicity was determined by single oral extract gavage, ranging from 2500 mg/kg to 4250 mg/kg body weight. In vivo antibacterial activity was evaluated on 24 mice infected with E. coli O157:H7 and Pseudomonas aeruginosa by intravenous injection and subcutaneous methods respectively. Following incubation and disease development, groups of mice were subjected to various treatments which included gentamycin, ampicillin and different concentrations of Plocamium rigidum extract over a period of five days. The E. coli O157:H7 and Pseudomonas aeruginosa cell loads in faeces of test mice were quantified daily.The calculated LD50 was 3512 mg/kg body weight. Plocamium rigidum extract dosage of 355 mg/kg body weight cleared the load of E. coli O157:H7 in mice on the fifth day of treatment. No significant changes in Pseudomonas aeruginosa loads in mice faeces were recorded at any of the extract dosages used.Plocamium rigidum extract can be classified as a low toxicity substance with therapeutic efficacy in E. coli OH157:H7 infected Balb/c mice at an oral dosage of 355 mg/kg body weight and may be an alternative drug lead for bacterial infections. We can also conclude that halogenated monoterpenes are safe in animal models as none of the test mice treated with Plocamium extract died during the experiment.