Antimicrobial Effects of Black Tea (Camellia sinensis) on Pseudomonas Aeruginosa Isolated from Eye Infection

T. Flayyih, May; S. Yousif, Hanaa; M. Subhi, Israa

	Antimicrobial Effects of Black Tea (Camellia sinensis) on Pseudomonas Aeruginosa Isolated from Eye Infection
Iraqi Journal of Science
Article 1, Volume 54, Issue 2, 2013, Pages 255-265
Authors
May T. Flayyih; Hanaa S. Yousif; Israa M. Subhi
Abstract
This study was conducted to evaluate the effects of black tea on Pseudomonas aeruginosa isolated from eye infection. One hundred samples (corneal scrapings) were obtained. Approximately, 77% of the cases were due to contact lens wear followed by 15 % trauma and 8% with unknown history. The isolates identified as P. aeruginosa were 30% (23/77 CL) and 25% (2/8 Unknown). On the other hand, the Kirby-Bauer antibiotic sensitivity assay showed that 100% of the isolates were sensitive to Neomycin, Gentamicin and Amikacin. While 91.6% were sensitive to Carbenicillin and Ceftriaxone; 66.6% were sensitive to Cefotaxime and 0% were sensitive to Tertacycline. Only two isolates were found to be multidrug resistant. Screening for some Pseudomonas virulence factors such as hemolysin and protease showed that all the isolates had the ability to produce Beta hemolysin and digested casein due to protease secretion. For adhesion ability using Christensen’s method, 8.33% were recorded as strong (+++), 41.66% were moderate (++) while 50% were weak (+).In contrast black tea (Camellia sinensis) was examined for its antimicrobial activity. The agar-well diffusion method was used for the concentrations 100, 200, 300, and 400mg/ml respectively. Results showed that the minimum inhibitory concentration of tea alcohol extract was 400mg/ml with inhibition zone of 20mm. The extract decreased the bacterial viable count since it showed a visible decrease to <5×106 Colony Forming Unite (CFU)/ml after 24 hours of incubation. Black tea extract also had the ability to completely inhibit Pseudomonas growth on blood agar and inhibited protease activity and adhesion. There were also differences in Congo red binding seen in bacterial cell suspensions cultured in growth media that contained tea extract. The synergistic activity of tea extract with antibiotics has changed the resistance of P. aeruginosa (without the tea) to sensitive (in presence of tea extract).
Keywords
Keratitis; pseudomonas aeruginosa; Contact lenses; Antibiotic Sensitivity test; virulence factors; Adhesion; Camellia sinensis; Agar; well diffusion method; Synergistic Activity

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