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Staphylococcus Epidermidis Characteristics

Staphylococcus epidermidis causes a large number of hospital-acquired infections. Treating infections caused by S. epidermidis often proves difficult because of the bacterium's genetic characteristics and growing resistance to high-powered antibiotics. At the same time, treating patients with antibiotics before they become infected with S. epidermidis often proves effective in blocking the bacterium.

  1. Description

    • S. epidermidis is closely related to the better-known bacterium Staphylococcus aureus. A genetic analysis of S. epidermidis reported in the May 23, 2005, issue of the journal Microbial Drug Resistance revealed that the bacterium mutates often, making it difficult to target exactly with antibiotics. Another overview of S. epidermidis appearing in the July 2001, Journal of Medical Microbiology notes that the bacterium is among the most frequently found pathogens on human skin and mucous membranes and becomes virulent (i.e., disease-causing) when it develops binding sites on its cell wall that it normally lacks. Unlike many kinds of staphylococci, S. epidermidis does not contain a coagulation-inducing enzyme, such as thrombin or renin. Lacking these enzymes, S. epidermidis bacteria must be able to produce a slime-like substance on its outer surface that allows it to bind with tissue and infect it.

    Diseases Caused

    • S. epidermidis bacteria cause a large percentage of infectious diseases in hospital patients and people receiving medical treatments that require the placement of catheters or the implantation of medical devices such as hip replacements. Open wounds and burns are also susceptible to S. epidermidis infections. Authors of different peer-reviewed journal articles have identified S. epidermidis as the cause of encephalomeningitis, toxic shock syndrome, bacteremia, endocarditis, sepsis/septicemia and ventriculitis.

    Incidence of S. Epidermidis Infection

    • Recently compiled statistics on hospital-acquired infections caused specifically by S. epidermidis do not exist. The authors of the 2001 Journal of Medical Microbiology did note that between 48 percent and 67 percent of hospital-acquired infections result from S. epidermidis, S. aureus or other staphylococci that lack coagulation-inducing enzymes. An older study reported in the Oct. 1, 1982 Annals of Internal Medicine states that for every 1,000 days patients with acute leukemia spent in the hospital, 14 patients picked up an S. epidermidis infection. Currently, nearly 10 percent of all patients who spend time in a hospital acquire bacterial infections they did not come to the hospital with, according to an Emerging Infectious Diseases article (see Resources).

    Infection Treatment

    • Like its cousin S. aureus, S. epidermidis has developed broad resistance to methicillin. Vancomycin-resistant strains of S. epidermidis have also emerged. Rifampin (e.g., Rifadin from sanofi aventis) has proven to be the most consistently effective antibiotic for treating S. epidermidis infections.

    Infection Prevention

    • Following cleaning, hand-washing and disinfection protocols does not always protect patients from S. epidermidis infections. Having patients take antibiotics before and after surgical procedures can help prevent infections, and German surgeons even reported during a presentation at the 1999 meeting of the Orthopaedic Research Society that they had success in preventing S. epidermidis infections by mixing bone cement with tobramycin. Patients at risk for S. epidermidis infections have also received protection from taking doses of cefazolin (e.g., Kefzol), gentamicin and cefuroxime (e.g., Ceftin).

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