Staphylococcus aureus Keratitis in Taiwan: Genotyping, Antibiotic Susceptibility, and Clinical Features

Abstract

Staphylococcus aureus is an important pathogen for keratitis, a vision-threatening disease. We aimed to investigate the genotyping, antibiotic susceptibility, and clinical features of S. aureus keratitis, and to explore the possible role of Panton–Valentine leucocidin (PVL), a major virulence factor of S. aureus. We recruited 49 patients with culture-proven S. aureus keratitis between 2013 and 2017 at Chang Gung Memorial Hospital, Taiwan. PVL gene, multilocus sequence type (MLST), staphylococcal cassette chromosome mec (SCCmec), and pulsed-field gel electrophoresis (PFGE) were performed. Antibiotic susceptibility was verified using disk diffusion/E test. There were 49 patients with S. aureus keratitis; 17 (34.7%) were caused by methicillin-resistant S. aureus (MRSA) and 9 (18.4%) isolates had PVL genes. The predominant genotyping of MRSA isolates was CC59/PFGE type D/SCCmec VT/PVL (+). All methicillin-sensitive S. aureus (MSSA) and approximately 60% MRSA were susceptible to fluoroquinolones. No significant differences in clinical features, treatments, and visual outcomes were observed between MRSA/MSSA or PVL(+)/PVL(−) groups. In Taiwan, approximately one third of S. aureus keratitis was caused by MRSA, mainly community-associated MRSA. Although MRSA isolates were more resistant than MSSA, clinical characteristics were similar between two groups. Fluoroquinolones could be good empiric antibiotics for S. aureus keratitis.

Molecular and Phenotypic Characterization of Ocular Methicillin-Resistant Staphylococcus epidermidis Isolates in Taiwan

“…This percentage is similar to our previous report on MRSA, where approximately 60% of MRSA isolates were susceptible to fluoroquinolones. 44 Therefore, fluoroquinolones are still reasonable options for empirical antibiotics to treat MRSE infections and for perioperative prophylactic use. However, it is important to note that fluoroquinolones may not be effective in certain circumstances, particularly in cases involving ST59, the most common MRSE lineage, which shows particularly low susceptibility to fluoroquinolones ( Fig.…”

“…Despite these limitations, this study contributes to our current knowledge about staphylococci in Taiwan, complementing our previous studies about the clinical and microbiological characteristics of S. aureus ocular infections. 44 , 49 Through our clinical, genotypic, and phenotypic characterization of ocular S. epidermidis isolates, we were able to identify certain pathogenic clonal lineages and their relevant virulence factors.…”

Staphylococcus aureus and Pseudomonas aeruginosa infectious keratitis: key bacterial mechanisms that mediate pathogenesis and emerging therapeutics

“…However, interestingly, there is still debate about the clinical importance of PVL as a more recent study on human subjects by Hsaio et al. found similar clinical features, including ulcer location, ulcer size and presence of hypopyon, as well as antibiotic susceptibility between PVL-positive and PVL-deficient strains ( Hsiao et al., 2022 ). It should be noted that there are several other identified homologous protein components such as LukM, LukS-R, LukE, LukF-R and LukD that can combine with each other to form multiple unique toxins.…”