Potential Changes in the Conjunctival Microbiota of Middle-aged and Elderly Chinese Population at Current Stage

Abstract

Abstract Background The conjunctiva, as an exposed ocular tissue, harbors microbial colonization. Changes in ocular surface microenvironment and overall health status can lead to ocular infectious diseases. During the Covid-19 pandemic, the probability of experiencing ocular discomfort has gradually increased after wearing masks. Therefore, this study aims to isolate and identify the conjunctival microbiota of cataract patients at the present stage and analyze the associated influencing factors. Methods This study recruited 216 participants (216 eyes) from April 2022 to July 2022. Under the condition of no antibiotic use prior to cataract surgery, sterile swabs were used to collect samples from the lower conjunctival sac. Bacterial cultures were then conducted, followed by species identification through 16S rDNA gene sequencing. Clinical factors associated with positive or negative bacterial isolation rates were analyzed, including age, gender, meibomian gland dysfunction (MGD), history of hypertension, history of diabetes, history of cancer, history of infectious diseases and the habit of wearing masks. Results Among the 216 eyes, 78 eyes yielded isolates, with an isolation rate of 36.11%, detecting a total of 122 strains. Gram-positive rods accounted for 49.18% (60 strains), Gram-positive cocci accounted for 45.08% (55 strains), Gram-negative bacteria accounted for 4.92% (6 strains), and fungi accounted for 0.82% (1 strain). This study found that the most abundant genera in the conjunctival sac were Corynebacterium (52%), Staphylococcus (38%), Micrococcus (9.84%), Acinetobacter (4.10%) and Bacillus (3.28%). Furthermore, age (P = 0.006), gender (P = 0.039), diabetes (P = 0.003), history of infectious diseases (P = 0.02), and duration of mask replacement (P < 0.001) were important factors influencing the positive bacterial culture of the conjunctival microbiota. Although hypertensive patients exhibited a higher isolation rate of conjunctival bacteria, it did not reach statistical significance, and the history of cancer did not affect the isolation rate of the conjunctival microbial community in cataract patients before surgery. Conclusion The composition of the conjunctival microbiota in middle-aged and elderly Chinese individuals may have undergone changes at the present stage, with an increased isolation rate of Corynebacterium and Micrococcus, which warrants attention from ophthalmologists. Advanced age, female gender, MGD, diabetes, recent history of infectious diseases, and poor mask-wearing habits may be important factors to consider in preventing perioperative infections in cataract patients.