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Methicillin-resistant Staphylococcus epidermidis
Abstract:
Staphylococcus epidermidis is frequently associated with infection of prosthetic heart valves, prosthetic orthopedic devices, and neurosurgical shunts. Penicillinase-resistant semisynthetic penicillins, such as methicillin, have been the therapeutic and prophylactic agents of choice for S epidermidis infection. However, more S epidermidis isolates are now resistant to methicillin and other penicillins. In our laboratory 41% of S epidermidis isolates were resistant to methici-lin. All of the methicillin-susceptible isolates and 82% of the methicillin-resistant isoates were susceptible to cephalothin. Cephalothin should replace methicillin as the prophylactic and therapeutic agent of choice in institutions with a high percentage of methicillin-resistant S epidermidis.
Insights
Methicillin resistance is increasing in Staphylococcus epidermidis infections. Cephalothin shows high susceptibility against both methicillin-susceptible and resistant strains, making it a potential replacement for methicillin.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Staphylococcus epidermidis commonly causes infections related to medical devices like prosthetic heart valves, orthopedic implants, and neurosurgical shunts.
- Penicillinase-resistant penicillins, notably methicillin, have historically been the primary treatment and preventative drugs for S. epidermidis infections.
- A growing concern is the increasing resistance of S. epidermidis isolates to methicillin and other penicillin-based antibiotics.
Purpose of the Study:
- To evaluate the susceptibility of Staphylococcus epidermidis isolates to cephalothin, particularly in the context of rising methicillin resistance.
- To determine if cephalothin can serve as an effective alternative prophylactic and therapeutic agent for S. epidermidis infections.
Main Methods:
- Antimicrobial susceptibility testing was performed on clinical isolates of Staphylococcus epidermidis.
- The study assessed the resistance rates to methicillin among the isolates.
- Susceptibility to cephalothin was determined for both methicillin-susceptible and methicillin-resistant S. epidermidis strains.
Main Results:
- In the laboratory setting, 41% of Staphylococcus epidermidis isolates exhibited resistance to methicillin.
- All methicillin-susceptible S. epidermidis isolates demonstrated susceptibility to cephalothin.
- A significant majority, 82%, of methicillin-resistant S. epidermidis isolates were also susceptible to cephalothin.
Conclusions:
- Cephalothin demonstrates broad-spectrum activity against Staphylococcus epidermidis, including methicillin-resistant strains.
- Given the high prevalence of methicillin resistance, cephalothin should be considered as a replacement for methicillin.
- Institutions experiencing high rates of methicillin-resistant S. epidermidis should prioritize cephalothin for prophylaxis and treatment.