The Genetic Basis of S. epidermidis’ Resistance to Oxacillin

1. Introduction

Staphylococcus epidermidis are tiny bacteria (approximately one micrometer in diameter), gram-positive cocci. The cocci are visualized individually under the microscope. The name of this species was given because it was commonly found on the skin surface (epi-dermis). However, S. epidermidis is now known to be a major cause of nosocomial infections. It is part of the normal human flora and can be found in the nose, skin, and gastrointestinal tract. S. epidermidis is thought to play a role in protecting the body against other pathogenic organisms.

2. The prevalence of S. epidermidis and its relatedness to other staphylococcal species
S. epidermidis is the most common CoNS isolated from clinical specimens worldwide (Kloos and Bannerman, 1995). The organism is frequently isolated from blood, skin, and soft tissue infections (Dajani et al., 1989; Kloos and Bannerman, 1995). It has also been recovered from joint fluid, cerebrospinal fluid, and intraperitoneal fluid (Dajani et al., 1989). S. epidermidis is part of the normal human flora and can be found in the nose, skin, and gastrointestinal tract (Kloos and Bannerman, 1995). This bacterium is considered commensal because it does not cause disease in healthy individuals (Kloos and Bannerman, 1995). However, S. epidermidis is opportunistic and can cause serious infections in immunocompromised individuals (Kloos and Bannerman, 1995).

3. The genetic basis of S. epidermidis’ resistance to oxacillin

The mechanism of resistance to oxacillin in S. epidermidis has been studied extensively and is now well-understood. Resistance to oxacillin in S. epidermidis is mediated by the production of an altered penicillin-binding protein (PBP 2a) that has reduced affinity for beta-lactam antibiotics (Holt et al., 1994). PBP 2a is produced by a mecA-encoded gene that is located on a mobile genetic element called the Staphylococcus cassette chromosome mec (SCCmec) (Holt et al., 1994; DeLeo et al., 1999). To date, six different types of SCCmec have been described, each with different antibiotic resistance profiles (DeLeo et al., 1999).

4. Implications of the findings

The findings of this study have several implications for the treatment of S. epidermidis infections. First, they underscore the importance of using an antibiotic that can penetrate the biofilm and reach the target bacteria. Second, they highlight the need for new drugs that can target PBP 2a or other proteins involved in resistance mechanisms. Finally, they suggest that combination therapy may be necessary to treat infections caused by multidrug-resistant strains of S. epidermidis.

5. Conclusion

In conclusion, S. epidermidis is a common cause of nosocomial infections. The mechanism of resistance to oxacillin in S. epidermidis is mediated by the production of an altered penicillin-binding protein (PBP 2a) that has reduced affinity for beta-lactam antibiotics. The findings of this study have several implications for the treatment of S. epidermidis infections. First, they underscore the importance of using an antibiotic that can penetrate the biofilm and reach the target bacteria. Second, they highlight the need for new drugs that can target PBP 2a or other proteins involved in resistance mechanisms. Finally, they suggest that combination therapy may be necessary to treat infections caused by multidrug-resistant strains of S. epidermidis.

FAQ

Oxacillin resistance in Staphylococcus epidermidis is the bacteria's ability to grow in the presence of the antibiotic oxacillin.

This resistance develops because some strains of S. epidermidis have acquired a gene that makes them resistant to the effects of oxacillin.

The consequences of this resistance include the ability of these resistant strains to cause infections that are difficult to treat with antibiotics.

To prevent or treat infections caused by resistant strains of S. epidermidis, it is important to use other antibiotics that are effective against these strains (such as vancomycin).

There are no other known risks associated with oxacillin resistance in S. epidermidis at this time.