Antimicrobial Effects of Black Tea (Camellia sinensis) on Pseudomonas Aeruginosa Isolated from Eye Infection
Keywords:
Keratitis, ., Pseudomonas aeruginosa , Contact lenses, Antibiotic Sensitivity test, , Virulence factors, , Adhesion, Camellia sinensis, Agar-well diffusion method, Synergistic ActivityAbstract
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 <5×10P
6
P 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).
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