In vitro antibacterial activity of Aqueous, ethanol and methanol flower extracts of chamomile alone and in combination with tetracycline by the use of agar well diffusion method against Staphylococcus aureus as gram positive bacterium and Escherichia. coli, Proteus sp. and Klebsiella sp. as gram negative bacteria was studied. It was found that chamomile aqueous extract has no inhibitory effects against gram positive and gram negative bacteria. Ethanolic and methanolic extracts exhibited antibacterial activity against S. aureus at the concentration 1000mg/ml. The diameter of the inhibition zones of S. aureus was 15 mm for Ethanol extract and 12mm at for methanol extract. No antibacterial effect on E. coli, Proteus and Klebsiella for the two extracts. The synergistic effect between the combination of tetracycline with chamomile extracts (ethanol and methanol) (vol./vol.) on S. aureus was studied. It was found that all the combinations proved strong inhibitory effect against S. aureus with different inhibition zone diameters ranged from 23 mm to 35 mm.

The effects of plants aqueous extracts (Myrtle, Harmal, Henna, Thyme and Fenugreek) against some clinical species of microorganisms were studied. These isolates included: Pseudomonas sp., Klebseilla sp., Escherichia coli, Proteus sp., Staphylococcus aureus and Candida albicans. The susceptibility of these isolates was tested against plants aqueous extracts by the agar well diffusion method. The results showed that the aqueous extract of Myrtle inhibited the growth of all tested microorganisms at concentration 5%, followed by Harmal when all tested bacteria were inhibited at concentration 10% except C. albicans inhibited at 20%. Compare with Henna when all bacteria were inhibited at concentration 20% except C. albicans was resistant, followed by Thyme which only two bacteria (Klebsiella sp. & Staphylococcus aureus) were inhibited at 20% while the remaining microorganism were resistant. On other hand all tested microorganisms were resistant to Fenugreek even at high concentration.