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O Staphylococcus epidermidis, or S. epidermidis, is a gram-positive bacterium that is naturally present on 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, the Staphylococcus epidermidis it is not widely considered in clinical practice, since most of the time it is isolated in the laboratory means contamination of the sample. However, this microorganism is able to grow easily in medical devices, in addition to having been reported to be resistant to various antibiotics, which makes it difficult to treat the infection.
How to identify infection by S. epidermidis
The main type of infection by S. epidermidis it is sepsis, which corresponds to infection in the blood, since this bacteria can easily enter the body, especially when the immune system is compromised, in addition to being associated with endocarditis. Thus, infection by S. epidermidis can be identified by analyzing the symptoms, the main ones being:
- High fever;
- Excessive tiredness;
- Headache;
- General malaise;
- Decreased blood pressure;
- Shortness of breath or difficulty breathing.
O S. epidermidis it is normally associated with infections in a 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 the S. epidermidis of Staphylococcus aureus. O S. epidermidis it does not have this enzyme and, therefore, it is said to be coagulase negative, and it is considered the coagulase negative staphylococcus of greatest clinical importance, since it is associated with sample contamination, opportunistic infections and colonization of medical devices.
To differentiate from other coagulase-negative staphylococcus species, the novobiocin test is usually performed, which is done with the aim of checking the resistance or sensitivity to this antibiotic. O S. epidermidis it is usually sensitive to this antibiotic, and is usually the treatment 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 it does not necessarily mean infection, because since it is on the skin, during the blood collection process, bacteria may enter the circulation, being considered contamination of the sample in many cases. Therefore, the diagnosis of infection by S. epidermidis it is done from the analysis of two or more blood cultures, which are usually collected in different places to avoid false results.
Thus, the diagnosis of infection by S. epidermidis it 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.
Which is S. epidermidis resistant
Often contamination of the sample by S. epidermidis it is misinterpreted by the laboratories and indicated as infection in the test result, which makes the doctor indicate the use of antibiotics against "infection". The inappropriate use of antibiotics can favor the formation of resistant bacteria, making treatment difficult.
Currently, infection by S. epidermidis have been frequent in hospitalized patients and, therefore, have gained clinical importance not only due to the indiscriminate use of antibiotics, but also to their ability to form biofilm in medical equipment, which favors the proliferation of this bacterium and resistance to treatments.
How the treatment is done
Treatment for infection by Staphylococcus epidermidis it 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 it is only indicated when the infection is confirmed. In case of suspected contamination of the sample, new samples are collected to check 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 prevent the formation of biofilm and development of the Staphylococcus epidermidis, preventing infection.