Original Publication Date: 27 July, 2017
Publication / Source: Future Microbiology
Authors: Michael Otto
Blood infection (sepsis) causes millions of deaths worldwide and is the most frequent cause of death in hospitalized patients. Sepsis is most commonly due to bacteria . In addition to symptoms related to the specific bacterial infection, symptoms of sepsis include fever, tachycardia and tachypnea. The definition of sepsis is clinical, with the sepsis-related organ failure assessment score, a combination of scores for the respiratory, cardiovascular, hepatic, coagulation, renal and neurological conditions, giving an understanding of the severity of sepsis in terms of the prediction for a fatal outcome.
Sepsis develops from bacteria being present in the blood (bacteremia) when the immune system launches an overwhelming responsive defense . While sepsis is well defined clinically, the molecular immunological mechanisms that underlie the development of sepsis are poorly understood. Long believed to be predominantly due to Gram-negative bacteria, during the second half of the 20th century, Gram-positive bacteria, in particular Staphylococcus aureus, have become leading causes of sepsis and sepsis-related deaths . [/userpro_private]Coagulase-negative staphylococci (CNS), with the major species S. epidermidis, are also often reported as frequent causes of sepsis, particularly among neonates [3,4]. However, the fact that they are ubiquitous commensals on the human skin makes the microbiological diagnosis of a true CNS blood infection difficult, as the detection of CNS in blood samples is often due to contamination rather than a true infection. The precise percentage of how many positive blood cultures are due to contamination varies considerably among the many studies that have attempted to estimate that number. Nevertheless, there is agreement that S. epidermidis is among the most frequent bacterial sources underlying bacteremia and sepsis .
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