Increased incidence of teicoplanin-non-susceptible Staphylococcus epidermidis strains: a 6-year retrospective study

Area of Science:

• Microbiology
• Infectious Diseases
• Antimicrobial Resistance

Background:

• Glycopeptide antibiotics like vancomycin and teicoplanin are crucial for treating Staphylococcus epidermidis infections, especially those with oxacillin resistance.
• Recent years have seen a concerning increase in S. epidermidis strains exhibiting reduced susceptibility to teicoplanin.
• This trend necessitates an investigation into the characteristics and drivers of teicoplanin non-susceptibility.

Purpose of the Study:

• To characterize teicoplanin-non-susceptible (Teico-NS) S. epidermidis strains isolated at a specific hospital.
• To analyze the potential relationship between the increasing incidence of Teico-NS strains and historical teicoplanin usage patterns.

Main Methods:

• Retrospective analysis of 328 S. epidermidis clinical isolates collected between January 2016 and December 2021.
• All isolates were confirmed to be susceptible to vancomycin (MIC ≤ 4 mg/L).
• Teicoplanin susceptibility was assessed using minimal inhibitory concentration (MIC) breakpoints.

Main Results:

• The annual incidence of S. epidermidis strains with elevated teicoplanin MIC (8 mg/L) ranged from 22.2% to 28.9%.
• A significant surge in strains with teicoplanin MIC ≥ 16 mg/L was observed in 2021 (32.5%).
• While teicoplanin use increased until 2019, a 2020 decrease due to COVID-19 prevented establishing a clear correlation with rising resistance.

Conclusions:

• There is a clear increase in the incidence of teicoplanin-non-susceptible S. epidermidis in recent years.
• The study could not establish a direct correlation between teicoplanin usage and the observed rise in teicoplanin resistance.
• Further research is essential to elucidate the underlying mechanisms and identify risk factors contributing to teicoplanin resistance in S. epidermidis.