Pathogenesis of gonococcal eye infection

Ophthalmia neonatorum is a term for conjunctivitis occurring in new-borns during the first 28 days of life, also called neonatal conjunctivitis. Infection is caused by transfer of bacteria from the mother to the eyes of the infant during passage through the birth canal. Infection causes inflammation of the eye with yellowish discharge and swelling of the eyelids. If it is not treated, or if standard treatment is ineffective, corneal scaring and perforation can occur, ultimately leading to permanent blindness.

The aim of this study is to identify the underlying pathogenesis mechanisms responsible for ocular damage, including perforation and corneal melt that occur during infection with Neisseria gonorrhoea. In addition, treatments that are in development for application to the eye to eliminate gonococcal eye infection were investigated to determine their potential for ocular damage.
An explanted corneal infection model using bovine eyes and cell culture-based models using human corneal and lens cells were used in this study with regards to irritation and tissue damage. Establishment and maintenance of infection for one week on explanted corneas and for 24 hours on cell culture resulted in no corneal melting or cell damage which suggested that the clinical illness that results in corneal melt during keratitis is not caused by the microbial replication on the cornea or within corneal cells but rather by the persistence of the microbes, which causes the host immune system to be stimulated.

N. gonorrhoeae has developed resistance to numerous antibiotic substances including the first-line dual therapy; ceftriaxone and azithromycin-resistant strains are becoming more prevalent. Natural oils were investigated for their antigonococcal effects as novel therapeutic options to uncover widely available and affordable choices. Coconut oil that has been lipase-treated and oregano essential oil showed strong bactericidal activity against N. gonohorroeae and caused no irritation to the bovine corneas nor cytotoxicity to the human lens epithelial cells. Results suggested that theses oils could be possible sources of novel antibacterial compounds that can topically fight N. gonorrhoeae ocular infection.

Bioinformatics and sequence analysis were used to mine alleles and variation of isolates from different geographical locations, with a focus on DNA/protein sequences from IgA1 protease in all N. gonorrhoeae isolates deposited in the PubMLST database. Sequences of 2 3 IgA1 protease are highly similar between N. gonorrhoeae isolates, however there are two distinct types of IgA1 protease, which differ by 62 amino acids.