Duration
The length of time bacteria are in the blood can vary greatly. If a small amount of bacteria is introduced into the blood, they are usually eliminated immediately by the body. This can happen during a visit to the dentist, for example.
Bacteria often enter the bloodstream from a local source of infection. This can be gum or tonsillitis, for example. If this focus of inflammation persists over a longer period of time, bacteria can repeatedly enter the bloodstream. In this case, bacteria can remain detectable in the blood until the original focus of infection has been successfully treated.
Cause
The presence of bacteria in the blood is not necessarily associated with symptoms, let alone a serious clinical picture. If bacteria are present in the blood, this can range from a symptom-free picture to a life-threatening condition of blood poisoning (sepsis) with multi-organ failure. The entry of bacteria into the bloodstream is in principle possible via different pathways.
Above all, it is important to consider whether the bacteria enter the blood of the affected person directly or first settle in a tissue. In general, bacteria can enter a person’s blood through a direct opening of a blood vessel, for example in the case of an open injury, or through a conscious vascular puncture during a medical procedure. A typical example of the direct penetration of bacterial pathogens into the bloodstream is the uptake of Clostridium tetani as a result of an accident.
This infection occurs when the open wound comes into contact with contaminated soil. In addition, bacteria, but also primarily ingested via other routes (food, respiration), can colonise a tissue and cause a disease, such as pneumonia, in the course of which the pathogens can also enter the bloodstream. This complication usually occurs when the patient is very weakened by the preceding illness and his immune system is “overtaxed” with the triggering pathogens, so that this process is feared.
The transfer of bacteria from the oral flora after or during brushing is normally harmless, but can also lead to the triggering of heart valve inflammation. This usually harmless example illustrates how the detection of bacteria in the patient’s blood is to be interpreted in a differentiated way. E. Coli is a bacterium which is also part of the natural intestinal flora in healthy people.
In some studies E. Coli was the most common bacterium detectable in the blood. E. Coli is a common cause of urinary tract infections or diarrhoea. There are a number of different strains of E. Coli.
While many are relatively harmless to humans and do not leave the bowel, others can cause serious diseases. If E. coli enters the bloodstream, it can cause life-threatening sepsis. But the bacteria do not always have to reach the bloodstream.
Often, only toxins produced by E. coli enter the bloodstream, not the bacterium itself. After surgery, the risk of infection with bacteria in the blood is increased. Every surgical procedure carries the risk of a nosocomial infection (hospital infection) due to foreign material introduced and injury to certain body structures.
It is therefore a so-called postoperative complication. For example, bacteria that are actually present in the intestine, such as E. coli, can enter the bloodstream after an operation in the abdominal cavity. This is known as an endogenous infection, in which the bacteria in the patient’s own body move to a different location.
Every postoperative wound has an increased potential for infection, from where the pathogens can spread into the blood. Such an infection can also be caused by endogenous, but also by exogenous (coming from outside) germs. Besides Enterococci, the most common pathogens include Staphylococcus aureus (especially MRSA) and Enterobacteriaceae.
In particular, implants, for example knee joint prostheses, as well as interventions in the abdominal cavity or heart are associated with an increased risk of sepsis. Sepsis as a result of a surgical intervention usually occurs within 24 hours. In the best case, the occurring symptoms are recognized a short time later and treated with an antibiotic that covers as broad a spectrum as possible.
Every further hour that passes decreases the chances of survival. If the focus of the infection is identified, further surgical intervention may be necessary to remove the focus. The likelihood of the occurrence of bacteria in the blood is increased after chemotherapy.
The majority of chemotherapeutic drugs (cytostatics), which are intended to combat the growth of malignant cells, are directed not only against tumour cells, but unfortunately also against the body’s own cells. Other, rapidly dividing cells of the immune system and blood formation in the bone marrow are also affected. During chemotherapeutic treatment, the blood count must be checked regularly.
A special focus is placed on the leukocytes, the white blood cells that are responsible for the smooth functioning of our immune system. As the number of white blood cells decreases, the risk of infection increases. This is often initially announced by a fever.
A bacterial infection can progress more quickly into sepsis due to a weakened immune system. If the white blood cells are likely to be affected, antibiotics against the most common pathogens can be used as a precaution. Patients with acute leukaemia or those receiving high-dose chemotherapy are usually admitted to hospital during treatment. This is a particularly high risk of infection. In this way, incipient sepsis is detected as early as possible.
