The liver communicates with the intestinal tract through the biliary tract and receives a dual blood supply from the portal vein and hepatic artery, so it is prone to bacterial liver abscesses. As far as children are concerned, the pathogenesis of suppurative liver abscesses may be as follows: (1) bacteria invade the liver through the hepatic artery due to various suppurative infections combined with bacteremia in infancy; (2) during intestinal infections and umbilical infections, bacterial emboli fall off and enter the liver through the branches of the portal vein, resulting in abscesses; (3) biliary tract infections, and this route of infection can cause multiple abscesses, and it is common in older children3; (4) infections secondary to liver trauma; and (5) cryptogenic.4 In previous studies, the main pathogen of abscess cultures in children was aerobic Staphylococcus aureus. However, a pediatric study in Taiwan and several adult studies have found that the spectrum of pathogenic bacteria has changed, and Klebsiella pneumoniae and Escherichia coli have gradually become the main pathogens.2,5,6 The results of this study are similar to those in Taiwan. The possible reasons for this situation are that the incidence of Staphylococcus aureus is low in the author's area due to relatively good economic, medical and health conditions. Second, it may be that before obtaining pus and bacterial cultures, the children have been treated with antibiotics for a certain period of time, resulting in a decrease in the positive rate of cultures.7 In children, the cause of liver abscesses is usually unclear, and the proportion of cryptogenic liver abscesses is high. In this study, cryptogenic liver abscesses accounted for 52.6%, while a study of children in Taiwan showed that cryptogenic liver abscesses accounted for 70-80%.5,6
Fever and abdominal pain are the most common symptoms. This study suggests that the right lobe of the liver is the most common site of bacterial liver abscesses, so right upper abdominal pain is more common, and some children have symptoms such as cough, shortness of breath and chest pain caused by the liver abscess stimulating the diaphragm.6,7 However, the above clinical manifestations are not specific,8 and due to the widespread use of antibiotics and the children's own characteristics, early and timely diagnosis is difficult. In this study, 2 cases were misdiagnosed as atypical Kawasaki disease in the early stage and had symptoms of abdominal pain during the course of the disease, which were diagnosed by imaging examination.
The reasons for the misdiagnosis may be as follows: first, the incidence of Kawasaki disease in children is higher than that of bacterial liver abscesses, so it is easy to prioritize; second, there are similarities between the clinical symptoms and laboratory examination results. For example, repeated high fevers and elevated indexes of white blood cells, neutrophils and C-reactive protein in blood tests are shared by the conditions. Third, misdiagnosed children can have bayberry tongue and a rash at the same time, and the etiology of these patients may be Gram-positive cocci infection. Studies have confirmed that jaundice, diabetes, low immune status (tumors, use of immunosuppressants, malnutrition, etc.), sickle cell disease, abdominal trauma, some parasitic infections, appendicitis perforation and incorrect umbilical vein catheterization are high-risk factors for liver abscesses.2,5,7,9,10 Children with the above conditions, such as fever of unknown causes, abdominal pain, hepatomegaly, elevated white blood cells, C-reactive protein and neutrophils on laboratory examination, should be considered for the possibility of a liver abscess.
When a bacterial liver abscess is not ruled out clinically, it can be diagnosed by ultrasound or computed tomography (CT) or magnetic resonance imaging (MRI). Ultrasonic examination has the advantages of convenience and speed, ease of operation and a low price, so it is the most commonly used tool for the diagnosis of liver abscesses, and its sensitivity can reach more than 97%. However, because the imaging manifestation of early liver abscesses can be atypical and sometimes there is no obvious change under B-ultrasound, dynamic observation is needed.1,10 Combined with CT and MRI as a supplementary examination to confirm the ultrasound results in highly suspicious cases, and understanding the specific location of the abscess and the relationship between the abscess and the surrounding tissues is essential.
Early active anti-infective treatment of bacterial liver abscesses can delay the progression of liver abscesses that have not liquefied. Liver abscesses smaller than 3 cm have a good response to intravenous or oral anti-infective treatment. Empirically, metronidazole combined with third-generation cephalosporins (such as ceftriaxone or cefoxitin) or piperacillin-tazobactam is the first choice. The total course of antibiotic treatment is generally 4-8 weeks,11 but in the clinic, the actual use of antibiotics may be longer because of the lack of etiological results, the existence of a variety of basic diseases, hospital cross-infection and other complex situations. In addition, it should be noted that imaging abnormalities can last for a long time, and subsequent oral antibiotic treatment should be based on clinical symptoms and blood test results.7 When the abscess is large and liquefied, percutaneous liver aspiration or catheter drainage can greatly improve the cure rate of bacterial liver abscesses.5,7,12 However, the choice of percutaneous puncture or catheter drainage is still controversial, but a study by ZeremE suggests that for a multilocular abscess or for a single abscess larger than 5 cm, the effect of catheter drainage is better.9,12 When catheter drainage fails, the abscess is at high risk of rupture, and if the abscess is close to the pleura, surgical intervention should be considered.3 However, the decision between percutaneous puncture or surgical drainage is still controversial, so further evidence is needed about indications for surgical intervention in pediatric patients. In this study, only one case was treated with laparoscopic surgery and drainage because of severe clinical symptoms, poor effects after antibiotic treatment and obvious rapid enlargement of the abscess, and the rest were cured by simple antibiotics or antibiotics combined with percutaneous liver puncture. In addition, at the same time, other underlying diseases should be actively treated, and symptomatic supportive treatment should be given, including correcting hypoalbuminemia and treatments to protect the liver.