Inhibitory effect of green tea extract on bacteria isolated from respiratory tract infections

Abstract

Inhibitory effect of green tea extract on bacteria isolated from respiratory tract infectionsM. S. Abbas I. J. Lafta A. I. ModaferColl. of Vet. Med./ Unive of BaghdadAbstractThe sensitivity of 20 gram-positive and gram- negative bacterial isolates obtained from patients suffered from respiratory diseases were studied. Gram- positive bacteria included: 4 isolates of both Staphylococcus aureus and Streptococcus pneumoniae and one isolate of Corynebacterium spp., while gram- negative bacteria consisted of Klebsiella pneumoniae (1 isolate), Klebsiella oxytoca (1 isolate), Escherichia coli (2 isolates), Pseudomonas aeruginosa (6 isolates) and Neisseria meningitidis (1 isolate). Camellia sinensis Linn leaf ethanolic extract antimicrobial activity was studied. We compared the mean zone of growth inhibition produced by green tea extract with that of the eight antibiotics used in this study. Green tea was effective against all tested gram- positive bacteria and some gram- negative bacteria, in which mean zone of growth inhibition of 14.66 mm in S. aureus, 14.5 mm in S. pneumoniae and 14 mm in Corynebacterium spp. was observed. As far as gram- negative bacteria, green tea extract produced the highest zone of growth inhibition of 15 mm against N. meningitidis and the lowest growth inhibition zone (8.5 mm) in case of E. coli and it was not effective in inhibition of P. aeruginosa, K. pneumoniae and K. oxytoca.The antimicrobial activity of green tea extract was similar to that of Neomycin when testing the sensitivity of N. meningitidis, while it was similar to oxytetracycline when testing S. aureus. The green tea extract gave low growth inhibition zones, but was higher than that reported by 5 antibiotics: (cefaclor, clindamycin, oxytetracycline, neomycin and cefotaxime) when studying S. Pneumoniae sensitivity. P. aeruginosa revealed wide antibiotic resistant, in which it resisted 7 antibiotics, followed by E. coli and S. aureus, as both of them resisted 6 antibiotics.