Infection in total joint replacements. Why we screen MRSA when MRSE is the problem?

Area of Science:

• Microbiology
• Infectious Diseases
• Surgical Infections

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen, necessitating effective screening protocols.
• Coagulase-negative staphylococci (C-NS), particularly Staphylococcus epidermidis, are common skin flora and frequent causes of surgical site infections.
• Current pre-operative screening primarily focuses on MRSA, potentially overlooking other resistant staphylococcal species.

Purpose of the Study:

• To evaluate the prevalence of MRSA in pre-operative screenings.
• To determine the rate of methicillin resistance among Staphylococcus aureus and coagulase-negative staphylococci (C-NS) isolated from surgical tissue samples.
• To assess the clinical relevance of screening for methicillin-resistant C-NS, including Staphylococcus epidermidis.

Main Methods:

• Retrospective review of 8911 pre-operative patient screenings conducted between May 1996 and February 2001.
• Analysis of 844 surgical tissue samples for Staphylococcus aureus and C-NS, with subsequent testing for methicillin resistance.
• Microbiological culture and susceptibility testing.

Main Results:

• Only 0.9% of pre-operative screenings yielded MRSA.
• Among surgical tissue samples, 13.6% grew Staphylococcus aureus, with only 0.01% being MRSA.
• A substantial 43.4% of tissue isolates were C-NS, and 55.1% of tested C-NS were methicillin-resistant, predominantly Staphylococcus epidermidis.

Conclusions:

• Pre-operative MRSA screening identified a low prevalence.
• Methicillin-resistant C-NS, especially Staphylococcus epidermidis, are prevalent in surgical tissues and warrant consideration for screening.
• Expanded screening protocols may be necessary to encompass methicillin-resistant Staphylococcus epidermidis to better manage surgical site infections.