OVERVIEW
Severe infections are the first cause of death in acute leukemia, accounting for about 70% of deaths. In addition to the use of intense chemotherapy and hematopoietic stem cell transplantation to treat the disease, the prevention and treatment of infectious complications is also of great importance and requires great attention and practical measures.
Causes
1. The bone marrow “crowding out effect” of leukemia itself and the cytotoxic effect of chemotherapy make the neutrophils, which are responsible for the main defense of the patient’s body, decrease significantly, and the frequency of infection increases significantly when <1×109/L, and serious infections are inevitable when <0.5×109/L, and fatal infections are very likely to happen when <0.1×109/L. lethal infections occur. At the same time, the duration of neutropenia is closely related to the chance and severity of infection.
2. In acute leukemia, not only is the number of neutrophils significantly reduced, but their function is also severely damaged. The chemotaxis, phagocytosis and killing functions of neutrophils in patients with acute leukemia are inhibited to different degrees, which is also an important reason why patients with acute leukemia are prone to infections.
3. Other immune functions of the patient, including cellular and humoral immunity (production of various antibodies) undertaken by lymphocytes, phagocytosis of macrophages, and the ability to produce various cytokines to fight infections, are all reduced, which makes the patient very susceptible to bacterial, fungal and viral infections.
Symptoms
1. Respiratory tract infection
In mild cases, only upper respiratory tract infection is manifested, with symptoms such as nasal congestion, runny nose, sore throat, cough and sputum. If the tonsils are involved, the tonsils may be enlarged, but due to neutropenia, purulent secretions and pus plugs are rare (common signs in normal people with tonsillitis). Involvement of all sinuses (including both maxillary sinuses, sieve sinuses and frontal sinuses), of which maxillary sinusitis is the most common, especially due to nosebleeds prolonged gauze filling the nasal cavity is most likely to be complicated. Patients present with pain in one or both upper teeth or cheeks, often with pressure in the cheeks. To confirm sinusitis, localized X-rays may be taken or a CT scan may be performed.
Lung infections are the most common type of respiratory infection and a more serious one. Cough, sputum, chest pain, and even dyspnea are the main symptoms. Also due to the lack of neutrophils, the local inflammatory reaction may not be typical, sometimes there is no sputum, or only a small amount of white sputum, without typical yellow pus sputum; chest auscultation may be no rales, or only a small amount of dry rales, and may be the lack of the typical vesicular sounds (wet rales); chest X-ray or CT examination may show inflammatory shadows, but sometimes there may be no abnormal changes. Repeated sputum culture is very important to clarify the nature of the bacteria.
2. Skin and soft tissue infection
It often occurs in various puncture sites, such as intramuscular injection, venous blood sampling or infusion, bone marrow and lumbar vertebrae puncture, with redness, swelling, pain, heat and localized pressure pain. It can also occur at non-puncture sites, similar to cellulitis. In the case of fever of unknown origin, a careful physical examination should be performed to detect limited skin and soft tissue infections. Because the patient’s neutrophils are reduced, the local inflammatory reaction of redness, swelling, heat and pain of the infection is atypical, which should be paid special attention to.
3. Perianal infection
Patients who have suffered from hemorrhoids, anal fissure and anal fistula before suffering from leukemia are prone to perianal infections, and a few of them can form perianal abscesses. Sometimes local inflammatory reaction is easy to miss the diagnosis, in case of fever of unknown cause should be carefully asked about the history of perianal diseases, and carefully check the local abnormalities.
4. Urinary tract infection
Typical urinary tract infection patients have urinary pain, urinary frequency, urinary urgency and other signs of urinary tract irritation, but patients with leukemia sometimes may not have the above typical symptoms, only the routine examination of urine shows more leukocytes, and some patients have completely normal routine, while urine culture has pathogenic bacteria growth.
5. Septicemia
Typically, chills and chills appear before the onset of fever, followed by a rapid rise in body temperature to 39 ℃ or more, and daily temperature fluctuations, flaccid fever type. Such high fever can last for several days to weeks, and the prognosis is poor without strong antimicrobial treatment. In some patients, bacteria in the blood can form a bacterial plug, blocking the small terminal arteries, forming a disseminated concave rash with a black crust in the center. This is a specific sign of sepsis in leukemia patients, especially gram-negative bacillus sepsis, and the smear and culture of the scabs can detect pathogenic bacteria.
Clinically suspected sepsis requires repeated blood sampling for bacterial culture, and the time of blood sampling should be chosen before daily infusion of antibacterial drugs, otherwise it will affect the growth of bacteria in the specimen, resulting in false-negative results.
Treatment principles
1. Respiratory tract infection
It is very important to identify the pathogenic bacteria of the infection, and the culture of tonsil and nasal swabs can be done respectively to select targeted and sensitive antibiotic treatment. Lung infections, such as strong antibiotic treatment for 3 to 5 days still no improvement (at least a drop in temperature), should be considered with or without fungal (mycobacterial) infections, or rare infections such as Pneumocystis carinii, Nucella, etc., to make every effort to obtain the evidence of these rare infections, and then select the targeted drug therapy, otherwise the condition of the dangerous, high mortality.
2. Perianal infection
All patients with acute leukemia should pay attention to smooth bowel movement, and routinely use 1:1000 potassium permanganate solution (commonly known as gray manganese oxygen water) sitz bath once a day to keep the perianal area clean. Once infection is suspected, local swab culture should be done as soon as possible to clarify the pathogenic bacteria of infection.
3. Septicemia
Clinically suspected sepsis requires repeated blood sampling for bacterial culture, and the time of blood sampling should be selected before daily infusion of antibacterial drugs, otherwise it will affect the growth of bacteria in the specimen, resulting in false-negative results. In some patients, despite repeated blood cultures, the presence of bacteria in the blood circulation cannot be confirmed. As long as the clinical suspicion is high, powerful broad-spectrum antibiotics should be used in a timely manner, and once positive bacterial culture results have been obtained, the corresponding antibacterial drugs should be adjusted according to the drug susceptibility test data of the pathogenic bacteria.