Staphylococcus epidermidis: what it is, symptoms and treatment

Content:

Staphylococcus epidermidis , or S. epidermidis , is a gram-positive bacterium that is naturally present in the skin, causing no harm to the body . This microorganism is considered opportunistic, as it is capable of causing disease when the immune system is weakened, for example.

Because it is naturally present in the body, Staphylococcus epidermidis is not widely considered in clinical practice, since most of the time it is isolated in the laboratory, it means contamination of the sample. However, this microorganism is able to easily grow in medical devices, and it has been reported to be resistant to several antibiotics, which makes it difficult to treat the infection.

How to identify S. epidermidis infection

The main type of infection by S. epidermidis is sepsis, which corresponds to infection in the blood, since this bacterium can easily enter the body, especially when the immune system is compromised, in addition to being associated with endocarditis. Thus, S. epidermidis infection can be identified through the analysis of symptoms, the main ones being:

  • High fever;
  • Excessive tiredness;
  • Headache;
  • General malaise;
  • Decreased blood pressure;
  • Shortness of breath or difficulty breathing.

S. epidermidis is commonly associated with infections in the hospital environment due to its ability to colonize in intravascular devices, large wounds and prostheses, for example, managing to proliferate and resist treatment.

How the diagnosis is made

In the laboratory, the identification of this bacterium is done through tests, the main one being the coagulase test, which differentiates S. epidermidis from Staphylococcus aureus. S. epidermidis does not have this enzyme and, therefore, is said to be coagulase negative, and is considered the coagulase negative staphylococcus with the greatest clinical importance, since it is associated with sample contamination, opportunistic infections and colonization of medical devices.

To differentiate from other coagulase-negative staphylococci species, the novobiocin test is usually performed, which is carried out with the objective of verifying resistance or sensitivity to this antibiotic. S. epidermidis is normally sensitive to this antibiotic, and the treatment is usually indicated by the doctor . However, there are strains of S. epidermidis that already have a resistance mechanism against this antibiotic, which makes treatment difficult.

Often, the presence of S. epidermidis in the blood does not necessarily mean infection, because since it is found on the skin, during the blood collection process, the bacteria may enter the circulation, which is considered contamination of the sample in many cases. Therefore, the diagnosis of S. epidermidis infection is based on the analysis of two or more blood cultures, which are usually collected in different places to avoid false results.

Thus, the diagnosis of S. epidermidis infection is confirmed when all blood cultures are positive for this microorganism. When only one of the blood cultures is positive for S. epidermidis and the others are positive for another microorganism, it is considered contamination.

What is resistant S. epidermidis

Many times, sample contamination by S. epidermidis is misinterpreted by laboratories and indicated as infection in the test result, which causes the doctor to indicate the use of antibiotics against the "infection". The inappropriate use of antibiotics can favor the formation of resistant bacteria, making treatment difficult.

Currently, S. epidermidis infection has been frequent in hospitalized patients and, therefore, has gained clinical importance not only due to the indiscriminate use of antibiotics, but also to its ability to form biofilms on medical equipment, which favors the proliferation of this disease. bacteria and resistance to treatments.

How is the treatment done?

Treatment for infection by Staphylococcus epidermidis is usually done with the use of antibiotics, however, the antimicrobial of choice varies according to the characteristics of the bacteria, since many have resistance mechanisms. Thus, the use of Vancomycin and Rifampicin, for example, may be recommended by the doctor.

In addition, treatment for S. epidermidis is only indicated when the infection is confirmed. In case of suspected contamination of the sample, new samples are collected to verify if there was contamination or if it represents infection.

In the case of colonization of catheters or prostheses by S. epidermidis , it is usually recommended to change the medical device. Currently, some hospitals adopt the use of antiseptic equipment that prevents the formation of biofilm and the development of Staphylococcus epidermidis , preventing infection.