Bacterial infections

Introduction to bacterial infection Bacterial infections, bacilli, Gram-positive and negative bacteria, various organs of the body, bacterial infections can occur in all systems. Bacterial infection is an acute systemic infection caused by pathogenic bacteria or conditional pathogens invading the blood circulation, producing toxins and other metabolites. It is characterized by chills, fever, rash, joint pain and hepatosplenomegaly. Some may have septic shock and migratory lesions. An acute systemic infection caused by a pathogenic microorganism invading the blood from a wound or an infected lesion in the body. Clinically, some patients may also have irritability, cold limbs and purpura, rapid pulse rate, rapid breathing, and decreased blood pressure. Especially in the elderly, children, those with chronic diseases or immunocompromised, those who are not treated promptly and have complications, can develop sepsis or sepsis. basic knowledge Proportion of disease: According to different bacterial infections, the proportion of illness is different Susceptible people: no special people Mode of infection: non-infectious Complications: bacteremia, sepsis, septic shock

Cause of bacterial infection

Human factor

When the skin and mucous membranes are damaged or purulent inflammation, the bacteria are easy to invade the body. The immune response of the human body can be divided into two types: non-specific immune response and specific immune response. The latter can be divided into two aspects: cellular immunity and humoral immunity. . When the body's immune function declines, it can't fully exert its phagocytosis and kill bacteria. Even if the amount of invading bacteria is small, the pathogenicity is not strong, it can cause infection; the iatrogenic infection caused by the conditional pathogen is gradually increasing. .

Bacterial factors

Mainly related to the virulence and quantity of pathogens. Pathogenic bacteria with strong virulence or a large number enter the body, which is more likely to cause sepsis. Whether the bacteria cause infection after invading the human body is related to human defense, immune function, virulence and quantity of bacteria. Complete skin and mucous membranes are natural barriers that prevent bacteria from invading the body. After breakage, bacteria can easily invade the body from it, and the possibility of bacterial invasion is greater when the skin inflammation site or abscess is squeezed. In severe burns, the wound opens the door to bacteria. Skin necrosis and plasma exudation provide a good environment for bacterial growth, so it is highly susceptible to infection. After the urinary tract, biliary tract, gastrointestinal tract, and respiratory mucosa are damaged, if there is accumulation of content and increased pressure, the bacteria are more likely to enter the blood, retaining catheters such as catheters and veins, and intubating catheters when assisting breathing. Etc. also makes bacteria easy to invade. When the body's immune function is normal, the bacteria that enter the blood are quickly cleared by blood-defense cells such as monocytes and neutrophils, and those suffering from liver cirrhosis, diabetes, blood diseases, connective tissue diseases, etc. Due to metabolic disorders, humoral immunity and decreased cellular immune function, sepsis is easy to occur; the use of various immunosuppressive drugs and radiation therapy are also the reasons for the high incidence of sepsis. After the use of broad-spectrum antibacterial drugs, drug-sensitive bacteria are inhibited or killed, and some drug-resistant bacteria can also cause sepsis by multiplying.

Pathogenesis

(1) Patient factors: 1 Age: The age of good hair is younger and older, and their resistance is poor and the incidence is high. Newborns are more prone to this condition due to immature immune function. The smaller the birth weight, the higher the incidence rate, and there are statistics on bacterial infection in both domestic and foreign countries. Hidden bacteremia may also occur in infants and young children. In addition to the slightly higher body temperature, the child cannot find the source of the infected lesion. The incidence of such bacteremia is about 3% to 10%. 2 Pathways of pathogen invasion: Infant bacteremia originates from the skin, mucous membranes and umbilicus. The genitourinary tract and digestive tract infections are often Escherichia coli or Gram-negative bacteria, and anaerobic invasive pathways. Pneumococcal sepsis can occur in respiratory infections. Due to the development of diagnosis and treatment techniques, various punctures, endoscopy, various catheter intubation, drainage and dialysis therapy, and extracorporeal circulation make the bacteria easy to enter the bloodstream.

(2) Factors related to pathogens: 1 The number of pathogens is large, and the endocrine and exotoxin, enzymes and pathogenic factors are strong, and the invasiveness is strong, and the blood circulation of the invading portal is abundant, which is beneficial to the occurrence of sepsis. 2 The type of pathogenic bacteria changes with the age of the sick child and the development of the drug. In the past, the pathogens of childhood sepsis, in addition to the neonatal period may be E. coli, more common are streptococcus, staphylococcus and pneumococci, followed by meningococcal and influenza bacilli; typhoid and paratyphoid, Pseudomonas aeruginosa, etc. Rare. Since the widespread use of antibiotics in clinical practice, group A -hemolytic streptococcus and pneumococcal sepsis have been significantly reduced. Staphylococcus is more likely to cause sepsis due to the increased number of resistant strains. At present, Staphylococcus aureus and coagulase-negative Staphylococcus epidermidis are often the main pathogens of sepsis. However, the incidence of sepsis caused by bacterial infection of Gram-negative bacteria (mainly Escherichia coli) exceeds the trend of Staphylococcus aureus sepsis, Pseudomonas aeruginosa, Klebsiella pneumoniae and Azotobacter, Serratia, Proteus, etc. Bacterial sepsis with low pathogenicity can also occur. Group B -hemolytic streptococcus has become a common pathogen of neonatal sepsis. Tetracocci are also reported in neonatal and infant sepsis. Among the anaerobic bacteria, it is more common in Bacteroides fragilis. Multiple bacterial infections have also occurred.

Bacterial infection prevention

Always keep the skin and mucous membrane clean and intact, avoid trauma, avoid squeezing or picking up sores with needles, actively treat and control chronic diseases, rational use of immunosuppressants and antibiotics, burn wards should be strictly disinfected, etc. Prevention occurs. All obvious or insidious purulent lesions can be removed as soon as possible, and the incidence of infection can be reduced. Infectious diseases that are common in children, such as measles, influenza, and whooping cough, are susceptible to bacterial infections in the respiratory tract. For such children, protection must be strengthened. No matter how small the skin wounds must be taken seriously, it should be treated as appropriate. Environmental health, personal hygiene, nutritional status, and pediatric health care continue to improve, and the incidence of bacterial infections will inevitably decline.

Bacterial infection complications Complications bacteremia sepsis septic shock

In the case of low patient resistance, or the virulence and quantity of pathogenic microorganisms, pathogenic microorganisms can continuously multiply and spread directly to surrounding tissues and organs along the interstitial space, or spread to the whole body.

1. Locally spread inflammation Local pathogenic microorganisms can spread to surrounding tissues and organs through tissue gaps or natural conduits, or spread throughout the body. Such as tuberculosis, when the body's resistance is low, tubercle bacilli can spread along the interstitial space, so that the lesions expand; can also spread along the bronchus, forming new tuberculosis lesions in other parts of the lung.

2. Lymphatic disseminated pathogenic microorganisms invade the lymphatic vessels through the interstitial space, causing lymphangitis, and then enter the local lymph nodes with the lymph fluid, causing local lymphadenitis. Abdominal infection causes axillary lymphadenitis, and lower limb infection causes inguinal lymphadenitis. These changes in the lymphatics can sometimes limit the spread of infection, but when the infection is severe, the pathogen can enter the bloodstream through the lymph, causing the bloodstream to spread.

3, the bloodway spreads the pathogenic microorganisms in the inflammation foci to invade the blood circulation or its toxins are absorbed into the blood, which can cause bacteremia, toxemia, sepsis and sepsis.

(1) bacteremia: bacteria in the inflammatory lesions invade the bloodstream through blood vessels or lymphatic vessels. Bacteria can be found in the bloodstream, but no symptoms of systemic poisoning, called bacteremia. Some inflammatory diseases have bacteremia in the early stage, such as lobar pneumonia. At this time, blood culture or smear can be found to find bacteria. In the bacteremia phase, the phagocytic cells of the liver, spleen and lymph nodes can form a line of defense to remove pathogens.

(2) Toxemia: Toxins or toxic products of bacteria are absorbed into the blood, causing symptoms of systemic poisoning, called toxemia. Clinically, there are symptoms of high fever, chills and other poisoning, often accompanied by degeneration or necrosis of parenchymal cells such as heart, liver and kidney, but blood culture is negative, that is, no bacteria can be found. In severe cases, toxic shock can occur.

(3) septicemia: bacteria invading the blood grow and multiply, and produce toxins, causing systemic poisoning symptoms and pathological changes, called sepsis. In addition to the clinical manifestations of severe toxemia, patients often have multiple bleeding spots on the skin and mucous membranes, splenomegaly and systemic lymphadenopathy. At this time, blood culture can often find bacteria.

(4) pyemia (pyemia): sepsis caused by pyogenic bacteria further develops, bacteria with the blood flow to the body, multiple abscesses in the lungs, kidneys, liver, brain, etc., called sepsis or sepsis septicemia. These abscesses are usually smaller and more evenly distributed throughout the organ. Microscopically, bacterial colonies (emboli) are common in the center of the abscess and in the remaining capillaries or small blood vessels, indicating that the abscess is caused by the pyogenic bacteria embedded in the capillaries of the organ, so it is called embolic abscess. Or metastatic abscess.

Symptoms of bacterial infection Common symptoms Sore throat, increased heart rate, pharyngeal burning pain, high fever, shortness of breath, convulsions, joint pain, back, skin, redness, swelling, swelling of the elbow, dysfunction and dysfunction

Pediatric bacterial infectious stomatitis:

Sudden onset, accompanied by systemic reactions such as fever, headache, sore throat, crying, irritability, refusal to eat, submandibular lymphadenopathy, etc., lesions can occur in the oral mucosa, with more common tongue, lip and buccal mucosa. From the beginning, mucosal congestion and edema, followed by erosions or ulcers of varying sizes, scattered and gathered, and the surface was covered with a gray-white pseudomembrane, which was easy to wipe off, but the wound that left the hemorrhage was soon covered by a pseudomembrane. .

Bacterial vaginitis:

The typical clinical symptoms of this disease are markedly increased vaginal abnormal secretions, which are thin homogeneous or thin paste, grayish white, grayish yellow or milky yellow, with special fishy smell, due to alkaline prostatic fluid can cause amines Released, so the performance of sexual intercourse or sexual intercourse after the odor increased, menstrual period vaginal PH value increased, so the odor after menstruation or menstruation can also be aggravated, the patient's vulva has discomfort, including varying degrees of genital itching, generally no obvious Temporality, but the itch is more obvious in the state of rest and mood, there are different degrees of burning sensation in some cases, some patients have sexual pain, very few patients have lower abdominal pain, difficulty in sexual intercourse and abnormal urination, vaginal mucosa The epithelium showed no obvious hyperemia at the time of onset.

Bacterial enteritis:

Fever, diarrhea, mucus or pus in the stool, odor in the stool, and some have a sense of urgency, even if there is still a feeling of unfinished afterwards.

Bacterial skin disease:

1, the onset is more urgent, there are general symptoms such as general malaise, chills, high fever, headache, nausea, vomiting.

2, after a few hours, local edematous erythema appears in the local area, the surface is tense and bright, and rapidly expands to the surrounding area. Sometimes the blisters may appear on the surface of the skin lesions, the blister wall is thick, the contents are clear or turbid, and the sensation is hot and painful. Lymphangiitis and lymphadenitis.

3, occurs in the face, the erythema begins from one side, gradually spread and expand, across the bridge of the nose to the side of the cheek, forming a butterfly shape redness, swelling of the nearby lymph nodes, and then spread to the scalp and the edge of the jaw to make the entire face red and swollen, It is difficult to blink because of obvious swelling of the eyelids. Occurred in the calf often have inguinal lymph nodes.

Bacterial pneumonia

There are many chills, fever, cough, cough, chest pain and other symptoms, fever is common, mostly for persistent high fever, heat type after antibiotic treatment can be atypical, cough, cough, early dry cough, gradually cough, sputum How many different, sputum is more purulent, Staphylococcus aureus pneumonia is more typical than yellow purulent; Streptococcus pneumoniae pneumonia is rust color; Pneumococcal pneumonia is brick red jelly; Pseudomonas aeruginosa pneumonia is pale green Anaerobic infections are often accompanied by odor. After the antibacterial treatment, the typical sputum development is rare. A few have hemoptysis and dyspnea, some have chest pain, and when the pleura is involved, there is acupuncture-like pain. Stimulate the pleura, pain can be radiated to the shoulder or abdomen, the latter is easily misdiagnosed as acute abdomen, systemic symptoms have headache, muscle aches, fatigue, a few nausea, vomiting, bloating, diarrhea and other gastrointestinal symptoms, severe patients can There are nervous system symptoms such as lethargy, disturbance of consciousness, and convulsions.

Bacterial infection check

Pathogen detection

First, the principle of collection and inspection of specimens

1. Different materials: According to the distribution and discharge parts of different pathogenic bacteria in the body, take different specimens. Try to take the material of obvious parts of the lesion.

2, strict aseptic operation, to avoid specimen contamination: sterile materials to prevent contamination of bacteria.

3, proper treatment: specimen collection should be before the use of antibacterial drugs.

4, as soon as possible to send the test: the specimen must be fresh, sent as soon as possible after collection. Most of the bacteria can be refrigerated, fecal specimens should be added with glycerol buffered saline preservation solution.

5, make a good mark, fill the test.

Second, bacterial morphology and structure inspection

1. Microscope amplification

The bacteria are tiny and can't be seen directly by the naked eye. Usually, the lens is observed with an optical microscope lens, and the morphology of the bacteria is observed at a magnification of about 1000 times. The internal ultrastructure of the bacteria must be magnified tens of thousands of times with an electron microscope to observe.

2, dyeing method

(1) The single staining method is dyed with a single dye, and the size, shape and arrangement characteristics of the bacteria can be observed, but the bacteria cannot be identified.

(2) The counterstaining method is dyed with two or more different dyes, and different bacteria can be dyed into different colors. In addition to observing the morphological characteristics of the bacteria, bacteria can be identified, and the most commonly used method is Gram staining.

3. Separation and identification

Is the most reliable way to diagnose bacterial infections

4. Detection of pathogenic antigens

5, other detection methods

6. Auxiliary inspection

Blood: Most of the white blood cells are significantly increased.

Pathogen examination.

Bacterial culture.

Bacterial smear: direct smear examination of pus, cerebrospinal fluid, chest and ascites, sputum, etc., can also detect pathogenic bacteria, has a certain reference value for the rapid diagnosis of sepsis.

It is extremely important to ask about the medical history in detail and to do a detailed physical examination. Anyone with acute hyperthermia, white blood cells and neutrophils increased significantly, but not limited to a certain system infection, or local lesions, catheter and device operation history should consider the possibility of sepsis; blood or bone marrow culture positive For the basis of diagnosis. It should be differentiated from diseases such as typhoid, miliary tuberculosis, connective tissue disease and lymphoma.

Diagnosis and identification of bacterial infection

diagnosis

Clinically, it is characterized by chills, high fever, rash, joint pain and hepatosplenomegaly. Some of them may have septic shock and migratory lesions. An acute systemic infection caused by a pathogenic microorganism invading the blood from a wound or an infected lesion in the body. Clinically, some patients may also have irritability, cold limbs and purpura, rapid pulse rate, rapid breathing, and decreased blood pressure.

Identification

Viral infection: An infectious disease caused by a virus that can be parasitic in the human body and can cause disease. Mainly manifested as fever, headache, general malaise and other symptoms of systemic poisoning and local symptoms caused by inflammatory damage caused by viral hosts and invading tissues and organs.

Fungal infection: The disease caused by fungal infection is called fungal disease. The highest incidence of candidiasis and dermatophytosis is caused by the fungus of the normal flora of the human body. The infection can be distinguished as: surface infection, skin infection, subcutaneous tissue infection, deep Infection and conditional infections.

Clinically, it is characterized by chills, high fever, rash, joint pain and hepatosplenomegaly. Some of them may have septic shock and migratory lesions. An acute systemic infection caused by a pathogenic microorganism invading the blood from a wound or an infected lesion in the body. Clinically, some patients may also have irritability, cold limbs and purpura, rapid pulse rate, rapid breathing, and decreased blood pressure.

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