Effect of anti-lysozyme and IgA antibodies of tear film on microorganisms causing eye corneal infection

             The study aimed to investigate the effect of anti-lysozyme and IgA antibodies in tear film on the occurrence and growth of microorganisms (bacteria and/or fungi) causing eye keratitis infection. For this purpose (105) corneal scraping samples were taken from patients suffering of microbial keratitis referred to Ibn Al-Haitham Eye Teaching Hospital in Baghdad. After culturing on the related selective media, results showed that 73 of the samples were positive for occurrence of microorganisms; of these, 68 (64.76%) were belonged to bacterial and 5(4.76%) to fungi. After the bacterial isolates were identified by cultural, microscopic and biochemical examinations, the following species and percentages were recorded: Pseudomonas aeruginosa 29 (39.73%), Staphylococcus aureus 22 (30.14%) and Staphylococcus epidermidis 17 (23.28%). While the fungal isolates were belonged to Aspergillus niger 3 (4.12 %) and Alternaria spp. 2 (2.73 %) according to their identification through the cultural and microscopic examinations, addition to the types and shapes of fungal spores. Upon such findings, P.aeruginosa was the predominant bacteria and A.niger the prevalent fungi. Regarding to the patients gender, it was found that cases of microbial keratitis in the samples were more abundant in males 41 (56.16%) than in females 32 (42.85%). Patients group of age (41-59) years was the most microbial keratitis infected group with a percentage of (30.20 %), while the lowest infected group was (≥ 60) year with a percentage of (17.80 %). The IgA levels were found to be increased with the corneal ulcer infection. The mean IgA levels were significantly higher than the matched controls (t = 2.04 for 40 df ,P< 0.05) in the age group of  ≤ 20 years. In the group age (21-40), the mean IgA levels were also significantly higher than those of the matched controls (t = 4.46 for 54 df, P<0.001).Moreover, in the age groups (41-59)and (≥ 60)  years significantly higher means of IgA levels (t = 4.04 for 42 df, P<0.001,and t = 2.58 for 59 df, P<0.001) were
recorded in comparison to respective matched controls. Low levels of tear anti-lysozyme were observed in patients with infective corneal ulcers, when compared with the controls. The decrease in the level of lysozyme in tears for age group ≤ 20 to (21–40) years was statistically significant (P<0.001). Again, the fall in the level of tear lysozyme from the age group (41-59) to ≥ 60 years was statistically significant
(P<0.001). Regarding gender factor, there were no significant differences detected among the two sexes.