What Is Bacteremia?

Bacteremia refers to the presence of microorganisms in the blood. Most of the bacteria enter the blood from local lesions. Mainly in the early stages of inflammation, macrophages of the liver, spleen, and bone marrow can form a line of defense to remove bacteria. It means that external bacteria enter the blood system through the entrance of the body surface or the entrance of infection, and then multiply in the human blood and spread with the blood flow throughout the body. The consequences are very serious.

Basic Information

English name

bacteremia

Visiting department

Internal medicine, surgery, oncology

Multiple groups

Patients with immunocompromised and severe illness

Common causes

Bacteria enter the blood from local lesions

Common symptoms

High fever, headache, dizziness, nausea, vomiting, may have conscious disturbances; fast heart rate, shortness of breath or difficulty

Causes of Bacteremia

Surgical or routine dental procedures for infected oral tissue, infected lower urinary tract, incision and drainage of abscesses, and bacterial growth of internal devices, especially intravenous and intracardiac catheters, urinary catheters and ostomy Both organs and catheters can cause transient bacteremia. Typical Gram-negative bacteremia is intermittent and opportunistic. Although this bacteremia may not affect healthy people, it is useful for patients with immunocompromised and severe illness, patients after chemotherapy, and severe malnutrition. Can have serious consequences. The initial site of infection is usually in the lungs, urogenital tract, gastrointestinal tract, or soft tissues, including skin with pressure ulcers and ulcers. It can also occur in dangerous people, especially with heart valve disease, artificial heart valves, or other blood vessels After dental surgery for prosthetic patients.

Gram-negative bacteremia is more common in chronic and immunocompromised patients, but the bloodstream of these patients can also be infected by aerobic bacteria, anaerobic bacteria and fungi. Bacteroides can be complicated by abdominal and pelvic infections, especially when the female reproductive tract is infected.

Metastatic infections of the meninges or pericardium or serosal cavity of the large joints can be caused by transient or persistent bacteremia, especially when the pathogenic bacteria are enterococci, staphylococci, or fungi. Endocarditis can also occur . However, endocarditis rarely occurs in Gram-negative bacteremia. Staphylococcal bacteremia is common in intravenous drug users. Staphylococci are also the main pathogenic bacteria of Gram-positive bacterial endocarditis that can involve tricuspid valves.

Clinical manifestations of bacteremia

1. Suddenly onset of high fever, can reach 40 -41 , or low temperature, rapid onset, severe illness, rapid development;

2. headache, dizziness, nausea, vomiting, and conscious disturbance;

3. Increased heart rate, fine pulse, shortness of breath or difficulty;

4. Liver and spleen can be enlarged, severe cases can be jaundice, subcutaneous bleeding spots, and so on.

Unless the patient is at risk of persistent or high levels of bacteremia, transient and low levels of bacteremia are asymptomatic. It is typically manifested by signs of systemic infection, including shortness of breath, chills, increased body temperature, and gastrointestinal symptoms (abdominal pain, nausea, vomiting, diarrhea). In the early stages of the disease, hypotension is often not found if blood pressure is not measured. Some patients have late onset of hypotension.

Bacteremia test

Pus or body fluids should be obtained from all infected sites, including infected body cavities, joint spaces, soft tissues, and damaged skin for Gram staining and culture. Blood culture should include aerobic and anaerobic cultures, and two blood cultures should be performed at an interval of 1 hour. Blood should be collected from different sites each time. In addition, sputum, catheterization sites, and wound specimens can be cultured.

Bacteremia diagnosis

Those who meet two or more of the objective indicators of the examination items can be considered to be the formerly called septic syndrome, which is now the systemic inflammatory response syndrome: body temperature> 38 ° C or <36 ° C; heart rate> 90 beats / minute; Rate> 20 times / minute or arterial carbon dioxide partial pressure (PaCO ₂ ) <32mmHg; blood white blood cell count> 12000 / l or <4000 / l, or immature white blood cell> 10%, the typical white blood cell count is initially reduced to <4000 / l, then rose to> 15000 / l in 2-6 hours, and the immature form increased significantly.

Differential diagnosis of bacteremia

Sepsis

Bacteria invade the bloodstream and grow rapidly, causing systemic infection symptoms. The onset is characterized by the beginning of a severe chill, followed by a high fever of 40 ° C to 41 ° C, accompanied by sweating, headache, and nausea.

2. Toxemia

Bacterial toxin enters the blood circulation from the local infection lesion, and produces systemic persistent high fever, accompanied by a large amount of sweating, weak pulse or shock. Because bacterial toxins in the blood can directly damage blood cells in the blood, anemia often occurs. No bacteria were found in blood culture. It is worth paying special attention to that although serious injuries, vascular embolism, intestinal obstruction and other diseases, although there is no bacterial infection, toxins produced by large-scale tissue destruction can also cause toxemia.

3. Sepsis

Symptoms of purulent lesions in the body are caused by the spread of blood to other parts of the body through blood circulation to produce new purulent lesions. The onset characteristics are similar to sepsis, but multiple purulent lesions can be found on the body, and even many abscesses.

Bacteremia complications

Common complications of this disease: secondary empyema; purulent pericarditis; peritonitis; meningitis; acute endocarditis.

Bacteremia treatment

Surgical or internal venous catheterization or catheter-related transient bacteremia is often difficult to detect and generally does not require treatment. However, if patients have valvular heart disease, endovascular prostheses, or receive immunosuppressive drugs, prophylactic antibiotics should be used to prevent endocarditis.

The prognosis of more severe bacteremia depends on two determinants: first, the rapid and thorough identification of the source of the infection; and second, the original disease and its accompanying dysfunction. Traumatic implants, especially intravenous and urinary catheters, should be removed quickly. After obtaining test specimens such as Gram stain and bacterial culture, antibiotic treatment should be given empirically. Certain cases (such as ruptured viscera, myometritis with abscess, gangrene of the intestine or gall bladder) must be treated surgically, large abscesses must be opened for drainage, and necrotic tissue should be removed. Those with persistent bacteremia due to pulmonary, biliary, or urinary tract infections are usually successfully treated with antibiotics without obstruction and abscess formation. In the case of multiple organ failure, multiple bacteria (polybacterial bacteremia) are often found and the prognosis is poor. Delays in antibiotic or surgical treatment significantly increase mortality.

Bacteremia prevention

If all obvious or hidden suppurative lesions can be removed early, the incidence of bacteremia can be reduced. Common childhood infectious diseases such as measles, influenza, whooping cough, etc., are often prone to secondary respiratory bacterial infections, which can cause bacteremia. For such children, protection must be strengthened. No matter how small the skin trauma must be paid attention to, appropriate treatment early.