PurposeTo investigate the distribution characteristics of conjunctival sac flora and assess the susceptibility of commonly used topical antimicrobial agents in normal children under the age of 18 in East China.MethodsIn 2019, a study was conducted at Qingdao Eye Hospital of Shandong First Medical University to analyze the microorganism cultures of conjunctival sac in 1258 normal children (2516 eyes; average age, 6.21 ± 3.78 years) in East China. Exclusion criteria included children with ocular surface diseases and those who had used any topical antimicrobial agents recently. The microorganism species in the conjunctival sac were analyzed using the M-38A protocol (microdilution method; investigators read the minimum inhibitory concentration [MIC] values) by the Clinical and Laboratory Standards Institute to determine drug susceptibility.ResultsThe incidence of conjunctival sac microorganism in children was 32.87% (827/2516), a total of 541 cases (male 293, female 248). Children with conjunctival sac flora in a single eye were 255 and in both eyes were 286 (no statistical difference,P> 0.05). The concordance rate of children with binocular conjunctival sac flora was 32.16% (174/541; male 84, female 90). A total of 42 species of bacteria were detected. Children with Gram-positive cocci accounted for the highest proportion, 91.54% (757/827). The top three bacteria with the highest detection rates wereStaphylococcus epidermidis(S. epidermidis; 52.12%),Streptococcus(12.09%), andStaphylococcus aureus(S. aureus; 10.76%).Streptococcus mitis(5.20%) accounted for the highest proportion ofStreptococcus.S. epidermidishad the highest proportion in all age groups and was positively correlated with age (r= 0.89,P= 0.03). Before six years of age, the streptococcal proportion(mainly S. mitis) was greater than that of Staphylococcus aureus. The drug susceptibility analysis showed thatS. epidermidiswas most sensitive to gatifloxacin (98.61%), while it had the highest resistance rate to erythrocin (87.94%).S. aureushad the highest susceptibility to moxifloxacin (100%).Streptococcuswas most sensitive to moxifloxacin (96.97%) and had the highest resistance rate to tobramycin (92.93%).ConclusionsConjunctival sac flora in children was dominated by Gram-positive cocci, mainlyS. epidermidis,S. aureus, andStreptococcus.S. epidermidisincreased with age; the proportion ofStreptococcuswas higher thanS. aureusamong children aged 0–6 years. The typical conjunctiva sac flora was generally sensitive to quinolones, such as moxifloxacin and gatifloxacin;Streptococcusdisplayed high resistance to tobramycin antibiotics; and the female children had higher resistance to tobramycin than the male children.