Microbial Spectrum and Resistance Patterns in Ocular Infections: A 15-Year Review in East China

Chunhong Liu,1,2,* Baixing Ding,3,* Jian Ji,1 Zhujian Wang,1 Huiwen Chen,1 Wenjun Cao1,2 1Clinical Laboratory, Eye & ENT Hospital, Fudan University, Shanghai, People’s Republic of China; 2Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, People’s Republic of China; 3Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Wenjun Cao Email wgkjyk@aliyun.comPurpose: To report antibiotic resistance rates and trends of common ocular isolates collected over a 15-year period.Methods: We collected 3533 isolates from July 1, 2005 to July 31, 2020. Antibiotic sensitivity was determined according to the guidelines of the Clinical and Laboratory Standards Institute. Chi-squared (χ2) test was used to analyze changes in antibiotic susceptibility over 15 years.Results: Among the 3533 isolates, the predominant pathogens were the staphylococcal species. Methicillin resistance was observed in 381 Staphylococcus aureus (S. aureus) isolates (46.4%) and 1888 coagulase-negative staphylococci (CoNS) isolates (61.1%), and methicillin-resistant (MR) isolates had a high probability of concurrent resistance to fluoroquinolones and aminoglycosides. The mean percentage of resistance in staphylococcal isolates did not reach statistical significance across patient age groups (P = 0.87). Methicillin resistance did not increase in the CoNS (P = 0.546) isolates, and resistance to methicillin slightly decreased among S. aureus (P = 0.04) isolates over 15 years. Additional exploratory analysis revealed a small decrease in resistance to tobramycin (P = 0.01) and chloramphenicol (P < 0.001) among the CoNS isolates. All staphylococcal isolates were susceptible to vancomycin.Conclusion: Staphylococci were the most common microorganisms responsible for causing ocular infections. Antibiotic resistance was high among staphylococci, with nearly half of these isolates were resistant to methicillin and these had a high probability of concurrent resistance among MR staphylococci to other antibiotics. Overall, ocular resistance did not significantly change during the 15-year study period. We conclude that continued surveillance of antibiotic resistance provides critical data to guide antibiotic selection.Keywords: methicillin, antibiotic resistance, ocular isolate, staphylococc