StatsDirect version 3. The effect of human tear samples against bacterial growth was evaluated and compared with the standard. The letters A, B, C, and D were used to differentiate bacteria treated with tear samples on agar plates and are given as follows:.
In comparison to negative control, all tear samples significantly inhibited the growth of Escherichia coli. As indicated in Figure 1 , inhibition in E. The standard ampicillin showed maximum bacterial inhibiting property, with a zone of inhibition 6 mm Figure 1.
The effect of tear samples on the growth of Shigella sonnei is presented in Figure 2 , showing significant inhibition of bacterial growth as compared to the negative control. The standard ampicillin showed maximum bacterial inhibiting property with a zone of inhibition 6 mm.
The inhibition in Shigella sonnei growth was as 4. As indicated in Figure 3 , all the tear samples exerted maximum antibacterial activity against Staphylococcus aureus.
The standard drug ampicillin showed significant antibacterial activity with a zone of inhibition zone 6 mm, after 24 hours of inoculation. The inhibitory activity of tear samples was 4. The effect of tear samples on the growth of Salmonella Typhi is presented in Figure 4. The standard ampicillin showed maximum bacterial inhibiting property, which was 6 mm zone of inhibition. The detail zones of inhibition were as 5. The comparative analysis of bacterial inhibition has been made on the basis of the mean value of all bacteria against tear samples.
As presented in Figure 5 , the concentration of lysozyme in the children tear samples was found in the range of 1. In the young group, lysozyme concentration was 1. In adult tear samples, the concentration of lysozyme was from 2.
In the present study, sixteen different tear samples of different age groups were evaluated for their antibacterial activities against four different strains of bacteria. Tear samples were collected from children, young, adult, and old persons. All these samples were categorized in four groups as described above. The results showed that these tear samples possess potential antibacterial activities against gram positive and gram negative bacterial strains.
The standard ampicillin showed maximum antimicrobial activity, which was used as a reference. In literature the antibacterial and antifungal spectrum of tears has been investigated.
However, the antibacterial spectrum of human tear with respect to age has not been evaluated, and this is the first report of antibacterial activity of tears with respect to age. According to Blaker et al. Human tear lipocalin acts as a scavenger for oxidative-stress-induced lipid peroxidation products in a cell culture system [ 20 , 21 ]. The tear samples from children showed significant inhibition against gram negative bacteria Salmonella Typhi.
The children tear samples also showed inhibition against Escherichia coli , Staphylococcus aureus , and Shigella sonnei. Moreover, the lysozyme concentration in children tear samples was 1. The young tear samples showed maximum inhibition against gram positive bacteria, Staphylococcus aureus , Escherichia coli , Salmonella.
Typhi and Shigella sonnei. The adult tear samples showed significant inhibition against gram positive bacteria Shigella sonnei and zone of inhibition was found almost similar to standard drug ampicillin. Moreover, the adult tear samples also showed significant inhibition against other bacterial strains such as, Salmonella Typhi, Staphylococcus aureus and Escherichia coli.
The lysozyme concentration in adult tear samples was 2. The tear samples from old showed significant inhibition against gram negative bacteria Salmonella Typhi, Staphylococcus aureus , Escherichia coli and Shigella sonnei.
The tear samples from old have lysozyme concentration 1. The lower antibacterial activity of tear samples from old as compared to other groups was due the less concentration of lysozyme in old tear samples.
According to Seal et al. In our study, the maximum concentration of lysozyme was found in adult tears samples, followed by tear samples of the young group. The concentration of lysozyme was higher in children tear samples as compared to old aged person. It has been reported that the tear lysozyme level is not affected by sex, but affected slightly with age. Scanning electron microscopy showed similar cell morphology for control and treated cells except that there was loss of aggregation in the treated cells in case of Staphylococcus aureus Conclusions : In spite of its abundance in tears, lysozyme in not an efficient antimicrobial of the ocular surface by itself.
This suggests that other proteins either individually or in combination with lysozyme might be more effective in protecting the ocular surface from pathogens. This will be tested in further investigations to understand the role of different proteins in tear defence. Purchase this article with an account.
Support None. Alerts User Alerts. The chemical substrate selected for this assay was p-nirrophenyl penta-N-acetyl B-chitopentaoside PNP. The free p-nitrophenol can then be accurately quantitated with a simple colorimeter.
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