Septicemia and bacteremia are two technical terms often misunderstood even by doctors. These two terms are simply definition and do not have much influence on management decisions. Therefore, these two terms have slowly become limited to research. In any case, having a clear idea on these two conditions is worthwhile in case you ever hear it in a ward or while a doctor is explaining things to you.
Septicemia is actually an obsolete term. It used to mean the presence of live multiplying bacteria in the blood stream. As new research evidence continues appearing and understanding of infection and the systemic response grows, new terms have come into play. Sepsis, severe sepsis and septic shock are the three terms in practice now. A bit about SIRS also known as the systemic inflammatory response syndrome should be said before going into sepsis. When an infection enters the body, a lot of processes get jump started. The culminating total response is called SIRS. Body temperature above 38°C or below 36°C, heart rate above 90 beats per minute, respiratory rate above 20 or carbon dioxide partial pressure below 4.3Kpa, and white cell count above 12 X 109/L or below 4 X 10 9/L or >10% immature forms need to be demonstrated for SIRS to be diagnosed.
SIRS in the presence of infection is called sepsis. Severe sepsis is a condition where SIRS, infection and evidence of organ hypo-perfusion (altered conscious level, low urine output, hypoxia) coexist. Septic shock is where the blood pressure falls below 90mmHg despite fluid resuscitation, or there is a need to inotropic support to maintain blood pressure above 90mmHg in the presence of severe sepsis. Full blood count, blood culture, QHT, cardiac monitoring, respiratory support, antibiotic therapy and inotropic support may be given as needed.
Bacteremia is the presence of bacteria in the blood. Bacteremia suggests the presence of bacteria in the blood only; but, the condition of the patient is not described by it. It is important to understand that there are situations where there are bacteria in the blood without any outward sign of disease. These situations are collectively named as asymptomatic bacteremia. Entry of one virulent bacterium does not cause the disease. There is a minimum infective dose; a minimum number of bacteria that needs to be there in the body to cause outward manifestations of the disease. Some bacteria are so virulent; a small number leads to a huge systemic response while others need massive numbers to cause even mild forms of a disease.
Blood culture is the best way to detect a bacteremia. The concentration of bacteria in blood directly influences the outcome of the blood culture. When a high concentration of bacteria is present, the culture becomes positive easily.
What is the difference between Septicemia and Bacteremia?
• Septicemia is an obsolete term while bacteremia is not.
• Septicemia used to mean the presence of multiplying bacteria in the blood while bacteremia means the presence of bacteria in the blood.
• Septicemia was replaced by better terms that suggest the actual clinical condition of the patient but bacteremia is still around.