Bacterial liver abscess

Introduction to bacterial liver abscess Bacterial liver abscess refers to the intrahepatic purulent infection caused by the invasion of suppurative bacteria into the liver. The disease can be caused by biliary diseases (16% to 40%) and portal vein infection (8% to 24%). basic knowledge Sickness ratio: 0.1% Susceptible people: no specific population Mode of infection: non-infectious Complications: biliary bleeding

Cause of bacterial liver abscess

(1) Causes of the disease

Bacterial liver abscess is an intrahepatic suppurative infection caused by purulent bacteria, also known as suppurative liver abscess. The liver receives a double blood supply from the hepatic artery and the portal vein, and passes through the biliary-rich blood supply and mononuclear-macrophages. The system's powerful phagocytosis can kill invading bacteria and prevent it from growing. Therefore, bacterial liver abscess does not occur often. When the body's resistance is weak, the invading purulent bacteria can cause liver infection and form abscess, causing bacteriality. The most common pathogens of liver abscess in the adult are Escherichia coli, Proteus, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus in children, followed by Friedländer Klebsiella, the pathogen enters the liver, Via the following channels:

Biliary system

This is the most important infection route in our country. In cases with biliary obstruction and secondary infection, such as common bile duct stones, biliary tract worm or clonorchiasis, acute suppurative choledochitis, bacteria can go up the biliary tract. Infected the liver to form a liver abscess.

2. Portal system

Abdominal infection (such as gangrenous appendicitis, suppurative pelvic inflammatory disease, etc.), intestinal infection (such as ulcerative enteritis, bacillary dysentery, etc.), sputum nucleus infection, etc. can cause thrombophlebitis of the portal vein branch, its septic embolus It can then enter the liver along the portal system, causing liver abscesses. Due to the widespread use of antibiotics, infections in this pathway are rare.

3. Lymphatic system The adjacent parts of the liver such as purulent lesions such as cholecystitis, underarm abscess and stomach, duodenal perforation, etc., bacteria can invade the liver through the lymphatic system.

4. Blood infection

In the case of suppurative infections in any part of the body, such as respiratory infections, acute osteomyelitis, subacute endocarditis, sputum and sputum, the pathogens can enter the liver from the hepatic artery.

5. Direct intrusion

When the liver has an open injury, the bacteria can directly invade through the wound, and sometimes the closed injury of the liver forms a subcapsular hematoma of the liver, and the original bacteria in the liver can transform the hematoma into an abscess.

6. Other ways of unknown reasons

There are no obvious causes of liver abscess, such as occult liver abscess, there may be some infectious lesions in the body. When the body's resistance is weakened, accidental bacteremia causes liver inflammation and abscess. It is reported that occultity 25% of liver abscesses are associated with diabetes.

Due to the extensive and effective application of antibiotics and the advancement of surgical treatment in recent years, cases of bacterial liver abscess caused by other abdominal infections have been rare. Peking Union Medical College Hospital has earlier and nearly 10 years of bacterial liver abscess cases, biliary system. Stones and tumors are the main cause of the disease. Diabetic patients are more likely to have this disease (8.3%), and cases with negative bacterial culture have increased (52.1%). Currently, biliary liver abscess accounts for about half or more, combined with stones. Or cancerous biliary obstruction is more likely to occur, and biliary aphids are still reported in some grassroots units.

As for the so-called unexplained liver abscess, it is speculated that it is most likely caused by bacteremia that is not obvious in the primary lesion; mild liver injury or ischemia may also be its direct cause, and diabetes is also a bacterial liver abscess. The cause of the disease, sometimes the bacterial culture of the liver abscess is negative, and it is not excluded due to the inappropriate culture technique for anaerobic bacteria.

(two) pathogenesis

Bacterial liver abscess is mostly mixed infection, often detecting a variety of bacteria, mainly endogenous bacteria, more than 60% of the intestinal Gram-negative bacilli, the most common in the past is Escherichia coli, late Cray white Bacillus has risen to the first place. The most common positive cocci are Staphylococcus aureus. Klebsiella, Proteus and Pseudomonas aeruginosa are important pathogens for abscesses in patients hospitalized for long-term hospitalization and antibiotic treatment. About half of the liver Anaerobic bacteria can be detected in the pus of patients with abscess. The most commonly isolated anaerobic bacteria are Bacteroides fragilis, Clostridium megai, etc., biliary liver abscess and portal vein bloody infectious liver abscess pathogen Escherichia coli Bacillus is the main pathogen, and the pathogen of hepatic arterial bloodstream infectious liver abscess is Staphylococcus aureus.

After the bacteria invade the liver, it causes an inflammatory reaction of the liver. When the body has strong resistance or after a certain treatment, the inflammation can be absorbed by itself, and even some small abscesses that have formed can be absorbed after being effectively treated. Healing, on the other hand, when the body's resistance is low and the treatment is not timely, the inflammation will spread and spread further, especially in the concentrated part of the lesion. Due to the destruction of the liver tissue, multiple small abscesses can be gradually expanded and merged into one or several A large abscess, so liver abscess is mostly single, but it can also be multiple, in general, blood-borne infections are often multiple, the lesion is mainly right liver or involving the whole liver, the origin of biliary-derived liver abscess In multiple small abscesses, its distribution is consistent with the distribution of intrahepatic bile duct lesions, located on one side of the liver, one leaf or one segment, the abscess often communicates with the bile duct, and the bile duct is also filled with pus. Some people think that acute obstructive suppuration The late stage of cholangitis is essentially a manifestation of acute liver abscess. Abscess and cryptogenic abscess caused by hematoma infection after liver trauma are mostly single, due to Dirty blood circulation is abundant. Once an abscess is formed, a large amount of toxin is absorbed into the blood, and severe sepsis appears in the clinic. When the abscess turns chronic, granulation tissue growth and fibrosis appear on the wall of the abscess. It gradually reduces or disappears. If the liver abscess is not properly controlled, it can be worn to the underarm, abdominal cavity, and thoracic cavity. Liver abscess caused by biliary infection may also be associated with biliary bleeding.

Bacterial liver abscess prevention

The prevention of bacterial liver abscess involves two aspects:

1. Improve the health of the body, enhance the body's ability to prevent disease and disease, and at the same time avoid factors that may induce the body's resistance to reduce, such as high-dose chemotherapy, radiotherapy and long-term use of immunosuppressive agents.

2. For diseases that are prone to induce bacterial liver abscess, we should pay close attention to treatment, such as hepatolithiasis, acute suppurative obstructive cholangitis, abdominal infection, intestinal infection, etc., after controlling these causes, it can prevent bacterial liver abscess. The occurrence, in fact, due to the early use of powerful and effective antibiotics, the incidence of bacterial liver abscess has been greatly reduced.

Bacterial liver abscess complications Complications biliary bleeding

Complications of bacterial liver abscess often exacerbate the condition and confuse clinical signs, leading to misdiagnosis.

Common complications are abscess rupture, perforation to adjacent organs, penetration into the chest to produce empyema and pleural bronchospasm, or penetration into the abdominal cavity, pericardial cavity; sometimes can also penetrate the stomach, duodenum, colon, kidney, pancreas A small number of cases can be inserted into the vena cava, hepatic vein, thoracic duct or abdominal wall, etc., embolism, thrombosis and other parts of the formation of abscess, causing intrahepatic vascular rupture by the biliary tract, that is, biliary bleeding is rare.

Symptoms of bacterial liver abscess Common symptoms Liver enlargement Peritonitis Pulse rate Increased ascites Hepatomegaly Painful liver function Impaired Lung infection Infection Abdominal pain Nausea

Bacterial liver abscess has no typical clinical manifestations. The acute inflammatory phase is often concealed by the primary disease. The disease is generally more acute. Due to the rich blood supply of the liver, once the suppurative infection occurs, a large amount of toxins enter the blood circulation, causing the whole body. Toxic reaction, clinically followed by some pioneering diseases (such as biliary ascariasis), sudden chills, high fever and pain in the liver area, the main clinical manifestations are as follows:

1. chills and high fever

Most of the earliest symptoms, but also the most common symptoms, patients in the early stage of the onset of sudden chills, followed by high fever, fever is more relaxation type, body temperature is 38 ~ 40 ° C, up to 41 ° C, cold and heat with a lot of sweating, pulse The rate increases, several times a day, repeated attacks.

2. Liver pain

Inflammation causes enlargement of the liver, resulting in acute expansion of the liver capsule, persistent dull pain in the liver area; the time of occurrence may occur before or after other symptoms appear, or may occur simultaneously with other symptoms, severe pain often prompts a single abscess The abscess is persistently dull and painful in the early stage. It is often sharp and severe pain in the later stage. The abdomen of the liver is often indicated with the aggravation of the abdomen. Sometimes the pain can be radiated to the right shoulder. The left liver abscess can also be radiated to the left shoulder.

3. fatigue, loss of appetite, nausea and vomiting

Due to systemic toxicity and sustained consumption, fatigue, poor appetite, nausea and vomiting are common gastrointestinal symptoms, a small number of patients in the short-term manifestations of mental dysfunction and other serious morbidity, and a small number of patients with diarrhea, bloating or more intractable Hiccups and other symptoms.

4. Signs

Hepatic tenderness and hepatic enlargement are the most common; there is snoring pain in the right lower chest and liver area; sometimes there is right responsive pleurisy or pleural effusion; if the abscess is located on the liver surface, the intercostal skin of the corresponding part is red, full, Touch pain and depressed edema; if the abscess is located in the lower right part, it is common to have a right rib or a right upper abdomen full, or even a localized bulge, often touching the enlarged liver or undulating mass, and has obvious tenderness and abdomen Muscle tension, etc.; left liver abscess, the above signs are confined to the xiphoid process, advanced patients may have ascites, which may be due to portal vein inflammation and peripheral abscesses affect the portal vein and liver function damage, long-term consumption caused malnutrition and Low protein, secondary to biliary obstruction, are associated with jaundice, other reasons for suppurative liver abscess, once jaundice, it indicates serious condition, poor prognosis, the above is a typical liver abscess performance, it is worth pointing out Due to the advancement of current medical treatment technology and the early application of antibiotics, the above typical performances are rare, and often suffer from abdominal pain, fatigue and night sweats. .

Examination of bacterial liver abscess

Laboratory inspection

1. The total number of white blood cells and neutrophil counts are increased, 50% have anemia, more than 90% have accelerated erythrocyte sedimentation rate, and liver function has certain damage. In most patients, alkaline phosphatase is significantly increased, and transaminase is only moderately elevated. Half of the bilirubin is elevated, and the prognosis of patients with hypoproteinemia is poor.

2. Liver puncture can puncture the most obvious intercostal space at the tender point. After the needle enters the skin and muscle layer, let the patient take a big breath, then exhale and hold the breath as much as possible, puncture the needle into the liver and immediately withdraw the inner core. The liver contents were aspirated, and the extracted pus was used for bacterial culture (high positive rate), and blood culture was performed when needed, but the positive rate was low.

3. The detection rate of bacteria in liver pus culture is 20% to 50%. The pathogenic bacteria are related to the infection route. Most of the cells invaded from the biliary tract and portal vein are Escherichia coli or other Gram-negative bacilli; most of the bacteria invaded from the hepatic artery are cocci. In particular, Staphylococcus aureus, 85.2% of 532 cases of liver pus in the country, including Staphylococcus aureus accounted for 38.6%, E. coli accounted for 27.4%, others have Streptococcus mutans and hemolytic streptococcus, Pseudomonas aeruginosa, Proteus, feces Alcaligenes, gas-producing bacilli, etc., and some are mixed infections. Domestic reports, more than 60% of liver pus cultures are gut-negative bacilli, and common positive cocci are Staphylococcus aureus, post-traumatic and immunosuppressed patients. Liver abscesses Streptococcus and Staphylococcus aureus are more common, reported that 36% to 45% of bacterial liver abscesses are anaerobic infections, about 25% of patients are aerobic, anaerobic mixed infections, previous sterility Most of the abscesses are caused by anaerobic bacteria. If the anaerobic culture technique is used routinely, the positive rate of culture can be improved. The common anaerobic bacteria are Bacteroides fragilis, Fusobacterium megasus, and Microaerobacteria.

4. Blood culture at the same time blood culture can have pathogenic bacteria growth, and some are the same as the pathogens in pus culture. Negative blood culture may be caused by bacteria without blood infection or with antibiotics.

Film degree exam

X-ray inspection

X-ray examination can be found that the liver shadow is enlarged. If the abscess is located in the right hepatic lobe, obstruction of the diaphragm can be observed, movement is limited, the angle of the rib is blurred or a small amount of fluid in the chest, right lower lung inflammation or atelectasis, etc. There may be a gas-liquid plane in the abscess area. It is suggested that the abscess is caused by gas-producing bacterial infection. The abscess of the left lobe of the liver may cause gastric cardia and small curvature of the stomach. The diaphragmatic muscle is restricted, the cost of the rib is disappeared, and a small amount of fluid in the chest cavity. When the situation is equal, it is also necessary to consider whether there is an underarm abscess.

2. Ultrasound examination

It can be found that there is a typical liquid echo dark area or an abscess inner liquid level in the abscess. In addition to assisting the clinical diagnosis, this test can also help to understand the location, size and depth of the abscess to determine the best abscess. Puncture point and needle direction and depth, or provide a choice for surgical drainage, but ultrasound for multiple liver abscess less than 1cm, often difficult to find, should be noted in clinical diagnosis, from the perspective of ultrasound, but also with other Identification of cystic lesions. Under normal circumstances, the cyst wall of the hepatic cyst is neat and clear, the density inside the capsule is uniform, and the wall of the liver abscess is irregular and the boundary is unclear. The cavity often contains multiple echo zones.

3. CT examination

CT examination can find the size and shape of the abscess, showing the exact location of the abscess in the liver, providing clear and intuitive image data for the clinician to perform abscess puncture and surgical drainage, mainly as a low-density area in the liver, with a slightly higher CT value. In hepatic cysts, most of the borders are not clear, and sometimes there may be blocky shadows in the low-density area. The contrast is enhanced after the contrast agent is injected, and the boundary is more clear. The typical manifestation of the enhanced scan is the annular enhancement of the abscess wall (target sign). The appearance of the "target" sign indicates that an abscess has formed.

4. MRI examination

Liver abscess is due to edema in the early stage, so it has long T1 and T2 relaxation time characteristics on MRI examination, and it shows a low signal intensity area with unclear boundary on T1 weight image, and the signal intensity increases on T2 weight image, when abscess After the formation, the abscess is a low-intensity signal zone on the T1 weight image; the abscess wall is an inflamed granulosus connective tissue, and its signal intensity is also lower, but slightly higher than the abscess; the inflammatory edema around the wall of the abscess is slightly lower than that of the liver tissue. The ring-shaped signal intensity of the abscess wall, on the T2 weight image, the tissue signal intensity of the abscess and edema increased significantly, and there was a ring-shaped abscess wall with a slightly lower signal intensity.

Diagnosis and identification of bacterial liver abscess

diagnosis

Diagnosis is generally not difficult. Anyone with suppurative disease will suddenly have obvious chills and fever, liver pain with sputum tenderness, hepatomegaly, and increased white blood cells suggest bacterial infection. Bacterial liver abscess should be considered. Clear liquid occupancy, diagnosis can be established, such as ultrasound guided percutaneous puncture to obtain pus can be diagnosed, pus can still be cultured to guide treatment.

Due to the rich blood supply to the liver, once a suppurative infection occurs, it can quickly lead to obvious systemic symptoms, and it will be aggravated in a short period of time. Clinically, there are some pioneering purulent infections, such as biliary tract inflammation, suppurative appendicitis, and then chills and fever. Liver area pain, rapid liver enlargement, increased white blood cells, accompanied by fatigue, anorexia, nausea, vomiting, severe systemic sepsis symptoms, liver pain is a more localized symptom, mostly due to rapid liver enlargement, liver capsule Swelling, so it is more dull and painful, but it is persistent; but it also shows pain, burning, jumping pain, or even colic; if the abscess stimulates the right ankle, the right shoulder, back pain, fever is often a relaxation type. Moderately high, more with chills sweating but also about 15% no fever, multiple abscess symptoms are often more serious than a single abscess, severe cases can appear jaundice, liver abscess can still wear into the adjacent cavity leading to the chest or lungs Infection, underarm abscess, peritonitis, pelvic abscess, etc., such as complications have often been confused at the time of diagnosis, right upper chest pus liver appears right chest reactive effusion is not seen.

Bacterial hepatic abscess signs: severe disease, may have mild jaundice, hepatomegaly and tenderness or cramps, such as abscess located above the liver upper elevation, or right pleural effusion, liver abscess Local skin may have depressed edema, or even local uplift, and the white blood cells are significantly increased in the test. The neutral ratio is about 90%, and even the left shift.

Differential diagnosis

The differential diagnosis of bacterial liver abscess is difficult. Because of the clinical inflammatory reaction, leukocytosis and other inflammatory reactions, and the liver enlargement, the liver pain is not only a kind of liver abscess. Here are the following common diseases. It differs from a swollen abscess:

1. Gallbladder and biliary tract disorders Gallbladder and biliary tract disorders often have a history of acute attacks, such as simple cholelithiasis, systemic response is not significant and nausea and vomiting is often prominent; and liver abscess is generally not accompanied by nausea and vomiting, acute cholecystitis Often there are obvious local pain and tenderness, and often can get swollen gallbladder; while liver abscess is mainly manifested as upward swelling of the liver, gallbladder can not be touched, common bile duct stones with severe cholangitis, sometimes with clinical Liver abscess is very similar, but bile duct stones are often accompanied by nausea and vomiting and jaundice. In the early stage, the liver enlargement and tenderness are often not obvious, but there is no increase in the diaphragm and activity limitation.

2. The diagnosis of subarachnoid abscess and bacterial liver abscess is more difficult. The correct diagnosis before surgery is almost impossible. Generally speaking, the systemic reaction of bacterial liver abscess is especially serious compared with the underarm abscess; The chills and intermittent high fever are not as good as the liver abscesses. On the contrary, the chest wall pain is more pronounced in the underarms. The phenomenon of radiation to the shoulders is more frequent, and the pain during breathing is more obvious. Before the underarm abscess formation There are almost always precursor lesions such as perforation of acute appendicitis and perforation of ulcer disease; however, the above lesions can also cause liver abscess.

X-ray examination can sometimes identify the above two types of lesions. Generally, the simple axillary abscess can be seen on the anterior and posterior slices. The rib angle is blurred. The lateral flank can be seen on the posterior side of the rib angle blurred, while the liver abscess has subgingival abscess. In the anterior and posterior slices, the palpebral angle is blurred, and the anterior rib angle is blurred on the lateral slice. The B-mode ultrasound examination is more helpful for diagnosis. When the ultrasound and CT scan are difficult to identify, the magnetic resonance coronal image can be diagnosed.

3. Amoebic liver abscess Generally speaking, multiple bacterial liver abscess and single bacterial liver abscess have different clinical manifestations. The former has sudden chills, high fever and sweating, liver enlargement and tenderness. Obviously, the increase of white blood cells is more significant, and jaundice is more common. The single performance of bacterial liver abscess is mild or mild. Similarly, the clinical manifestations of amebic liver abscess are more than that of multiple bacterial liver abscess. More moderate, the identification between the two is not difficult, but the symptoms of amebic liver abscess and single bacterial liver abscess are quite similar, the identification of the two is sometimes very difficult.

The most important point of identification in the amoebic liver abscess often has a history of amebic enteritis and pus and bloody stools, such as the discovery of amoebic trophozoites in the patient's stool, more diagnostic, in addition, amebic liver abscess The symptoms are mild, the white blood cell increase is not significant, and the eosinophilic is more, the course is longer, but the anemia is more obvious; the liver is obvious, intercostal edema, local uplift and tenderness are more obvious, the actual diagnosis is often only in the puncture After the pus, according to the nature of the pus and the results of the bacterial examination, the final conclusion can be made.

4. Other portal vein thrombophlebitis sometimes needs to be differentiated from liver abscess. Simple thrombophlhritis is often caused by poor portal vein blood flow (mainly due to cirrhosis and liver cancer) and lesions in the portal vein wall, or blood components. Changes (mainly erythrocytosis or increased platelets) and other causes, thrombosis in the portal vein after the onset, patients may also have mild chills and fever and other symptoms, sometimes confused with liver abscess, but thrombotic portal phlebitis sometimes There is ascites; while the liver is not significantly swollen, no tenderness, and no jaundice. The general identification is not difficult.

Liver cancer is sometimes difficult to distinguish from liver abscess. Although liver cancer patients are mostly nodular, hard, local pain and tenderness are not obvious, and there is no obvious inflammatory reaction in the whole body, but sometimes with a single liver abscess. It is difficult to identify, serum alpha-fetoprotein is often positive, B-mode ultrasound is helpful for identification.

Right lower lobe pneumonia may also be confused with liver abscess. The latter shows chills, fever, right chest pain, shortness of breath, cough, lung snoring, and increased white blood cells, all of which can be suspected of having lower lobe pneumonia. Abscess usually has no signs of consolidation in the lungs, and there is an increase in the diaphragm. The liver is swollen and tender, and can be identified.

In recent years, with the continuous advancement of medical equipment and clinical diagnosis and treatment technology, many favorable conditions have been provided for the clinical diagnosis of this disease. It is important that clinicians should consider the existence of this disease because early diagnosis is to improve the disease and The key to prognosis.

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