Synergistic antimicrobial activity of black pepper extract with some antibiotics combination on Escherichia coli isolated from chickens

Antimicrobial activity of methanol piper nigrum extract in combination with some antibiotics was investigated againstEscherichia coli isolated from chicken samples. The in-vitro antimicrobial sensitivity pattern of these isolates was doneand the intermediate isolates were checked for combination with methanol piper nigrum extract after detecting theirantimicrobial activities against these isolates by both disc diffusion test and MIC and the obtained data showed thatantimicrobial activities of amoxicillin, doxycycline, gentamicin, erythromycin and cefotaxime were enhanced incombination with methanol piper nigrum extract. The obtained data showed that enhancement by both disc diffusion testand MIC for methanol piper nigrum extract and each of the mentioned antibiotics in decimal assay of additivity ratio was(0.5 for amoxicillin, cefotaxime and 0.5 for extract and 0.4 for doxycycline, gentamicin, and erythromycin and 0.6 forextract) against E. coli isolates.