Assessment of Bacterial Profile of Ocular Infections among Subjects Undergoing Ivermectin Therapy in Onchocerciasis Endemic Area in Nigeria

Abstract

Bacteria are the major contributor of ocular infections worldwide. This can damage the structures of the eye with possible blindness and visual impairments, if left untreated. This study was undertaken   to determine bacterial agents of conjunctivitis among individuals from onchocerciasis endemic area in Anambra State, Nigeria. This was a cross-sectional study involving ninety-two (92) randomly recruited  test  subjects  undergoing ivermectin therapy aged between 11-80 years with signs and symptoms of  onchocerciasis infection and bacterial conjunctivitis at Isu-Anaocha community in  Anambra state between October and November, 2016. Ninety-two (92) apparently healthy subjects without signs and symptoms of onchocerciasis and bacterial conjunctivitis with normal vision, within the age of 11-80 years from the same community were used as control subjects, making a total of 184 participants. Visual acuity test was conducted on the participants using Snellen’s alphabet chart and illiterate E   chart.  Phenotypic   and antibiotic susceptibility tests of these isolates were   carried out according to  Kirby - Bauer disc diffusion method guidelines. In the test group, 22 out of 92 conjunctival samples yielded bacterial growth, giving percentage prevalence of 23.9%, with age group 41-50 years having the highest frequency 7(31.8%) among individuals co-infected with onchocerciasis infection whereas 72 out of 92 conjunctival samples in the control group yielded bacterial growth giving percentage prevalence of 78.3%, with age group 41-50 years having the highest frequency 35(37.2%) among individuals that had  no signs and symptoms of onchocerciasis infection. The predominant bacteria isolated was Staphylococcus   aureus 8(36%) in the test group and 20 (28%) in the control group, giving a total of 28 (30%). Other bacterial isolates were Streptococcus pneumoniae 17 (18%), Staph. epidermidis 15 (16%), Escherichia coli 13(14%), Pseudomonas aeruginosa 12(13%) and Salmonella spp. 9(9%). Antibiotic susceptibility testing showed that Gentamicin and fluoroquinolones are most active against Gram positive bacteria in conjunctivitis while Augmentin was found to be the most active against Gram negative organisms, therefore, recommended as first line drug. Visual acuity (VA) test done on the test group showed that 52 (57%) persons had   normal vision, 20 (22%) had mild visual impairment, 15 (16%) had moderate visual impairment, 5(5%) had severe visual impairment but none was blind. All forms of visual impairment are not wholly attributable to bacterial conjunctivitis as some could be due to ageing and uncorrected refractive errors.