Neonatal sepsis

Introduction to neonatal sepsis Septicemia of newborn refers to the pathogenesis of neonatal pathogens invading the neonatal blood circulation through various ways, and growing and breeding, producing toxins and causing systemic infection. The incidence and mortality of the disease are high in the neonatal period. With the deepening of the study of systemic inflammatory response syndrome, the definition of sepsis is also expanding, including the initiation of endogenous infectious agents (such as intestinal flora). Systemic inflammation and infection, neonatal sepsis generally refers to the presence of bacteria in the blood and continuous reproduction, a pathological process that can obtain positive bacterial results through blood culture, with evidence of bacterial-immunological diagnosis, and Diagnosis can also be made without obtaining positive blood culture results. It is still a very important disease in the neonatal period, and its incidence rate is about 110 of live births, and the incidence rate is higher in premature infants. basic knowledge The proportion of illness: 0.001% Susceptible people: seen in newborns Mode of infection: non-infectious Complications: neonatal purulent meningitis pneumonia osteomyelitis

Causes of neonatal sepsis

(1) Causes of the disease

Pathogen

The pathogens in different regions are different. In Europe and the United States, Group A hemolytic streptococcus dominated in the 1940s. Staphylococcus aureus was dominant in the 1950s. Escherichia coli dominated in the 1960s. Group B hemolytic streptococcus (GBS) in the 1970s. It is the most common bacteria, followed by Escherichia coli, Klebsiella, Pseudomonas aeruginosa and Salmonella. In recent years, Staphylococcus epidermidis has become the most common bacterium in American hospitals for acquired infections. More K1 antigens and Staphylococcus aureus are the most common, Klebsiella, Pseudomonas aeruginosa and L bacteria (named after the Lister Institute) infections have often been reported, Staphylococcus epidermidis infections continue to increase, GBS reported but not much .

Route of infection

Neonatal sepsis can occur before birth, at birth and after birth, mainly through the placenta infection; caused by bacterial infection in the birth canal during childbirth; infection is most common after birth, bacteria can invade the skin, mucous membranes, such as the digestive tract, The respiratory tract, the urinary tract, and the umbilicus are the most susceptible parts. The neonatal period has respiratory depression and undergoes resuscitation intervention. The amniotic membrane breaks water for too long (>24h), and the mother has infection or fever during birth.

Self factor

Non-specific and specific immune functions are imperfect, IgM, IgA deficiency, poor ability to limit the disease, bacteria into the body can easily spread the infection and cause sepsis, male infants and low body weight are relatively easy to get infected, with birth weight The decline is accompanied by an increase in morbidity and mortality.

(two) pathogenesis

The main mechanism of inflammatory reaction caused by neonatal sepsis is the result of two factors. One is due to the direct effect of bacterial toxin on various systems of the body, especially the affected organs, mainly the damage of toxins to related organs and cells. On the other hand, inflammatory reactions and multiple organ dysfunction are caused by various proinflammatory factors and cytokines; including tumor necrosis factor (TNF), procalcitin, activated complement, and platelet activating factor (PAF) and a variety of interleukins (IL-1, 6, 8 etc.), in mature neonates, especially in severely infected neonates, inflammatory mediators and cytokines have become the main causative mechanism of SIRS and MODS. On the other hand, the inflammatory response of premature infants, low birth weight infants and immature infants is not perfect, especially immune cell dysfunction associated with inflammatory reactions, including neutrophil chemotaxis, required during agglomeration Some adhesion factors such as selectin dysfunction can also be an important factor in infection spread and poor prognosis.

Neonatal sepsis prevention

1. Do a good job in perinatal care: Regular prenatal examinations for pregnant women should be strictly performed during the delivery process. Premature rupture of membranes, intrauterine asphyxia or long-term labor should be treated prophylactically. Mothers with infection and fever apply a broad spectrum of antibiotics through the placental barrier to minimize the chance of cross-infection in the recovery of asphyxiated neonates.

2. Strengthen monitoring of high-risk children: high-risk newborns who may have sepsis should be closely monitored, pay attention to the neonatal complexion, breast milk, mental status and body temperature changes.

3. Do a good job of skin and mucous membrane care: pay special attention to keep the mouth, skin, mucous membrane and umbilical area clean, avoid infection or injury, do not pick "horse teeth", cut "oral fat pad", do not use rough and dirty cloth towel Scrub the newborn's mouth to avoid damage to the oral mucosa. If there is an infectious lesion, it should be treated promptly, and appropriate antibiotics should be used to prevent infection.

Neonatal sepsis complications Complications neonatal purulent meningitis pneumonia osteomyelitis

1. Suppurative meningitis: neonatal sepsis is most likely complicated by purulent meningitis. Sometimes the nervous system symptoms are not obvious, but this disease has been complicated. Therefore, be vigilant and check cerebrospinal fluid early.

2. Pneumonia or lung abscess: followed by pneumonia or lung abscess, respiratory symptoms.

3. Migratory lesions: such as cellulitis, osteomyelitis, pyelonephritis can also occur.

4. Multiple organs dysfunction syndrome (MODS): The serious result of infection spread is often MODS.

Neonatal sepsis symptoms Common symptoms Septicemia signs Septic irritability Abdominal distension diarrhea Freckle liver splenomegaly Heart rate increased Sanfeng thermal bacterial infection

The clinical manifestations of neonatal sepsis are mainly non-specific symptoms in the early stage, including poor mental health, poor response, weakened crying, and decreased milk loss. The main manifestations of disease progression are:

1. Changes in body temperature: Most full-term children show fever; while premature and immature children mainly show that body temperature does not rise, and a few newborns may have unstable body temperature.

2. Astragalus: The performance of jaundice is too heavy, the delay is delayed or reappears after disappearing, and the cause of jaundice cannot be explained.

3. Hepatosplenomegaly: due to the inflammatory reaction and the involvement of organs.

4. Irritation and changes in muscle tone of the extremities: Some newborns may have excitement-irritation symptoms, and some premature infants may show decreased muscle tone in the extremities.

Examination of neonatal sepsis

[Laboratory Inspection]

Once sepsis is considered, laboratory tests should be performed as much as possible before systemic antibiotics are applied.

Non-specific examination

(1) Peripheral blood: The total number of white blood cells in the blood around the newborn fluctuates greatly, and the total number of white blood cells can be high or low. Therefore, it is only diagnosed when the height of the white blood cells is significantly increased (>20×109/L) and the rod-shaped nuclear cells are 20%. Significance; while the total number of white blood cells decreased (<5 × 109 / L) with rod-shaped nucleated cells is more significant, with nuclear left shift and poisoning particles, anemia and total number of BPC decreased (<50 × 109 / L) also suggest sepsis possibility.

(2) ESR: ESR is accelerated.

(3) Acute phase reactants: including C-reactive protein (CRP) quantitative method > 8 ~ 10g / ml, is helpful for diagnosis, reflecting the presence of inflammatory reactions, haptoglobin, a1-acid glycoprotein increased.

2. Pathogen examination

(1) Blood culture: It is more clinically meaningful to find the same bacteria in blood culture and lesion secretion culture. Bacterial culture should be used as drug sensitivity at the same time to guide treatment. Multi-site blood collection and multiple blood cultures can help improve bacterial culture. Positive rate; application of specific antibiotic neutralization blood culture bottle storage sensitization, can also effectively increase the positive rate.

(2) Smear and other parts of bacterial culture:

1 direct smear to find bacteria: after birth can take umbilical secretions and other direct smear to find bacteria, such as suspected intrauterine infection, within 1h after birth, take the liquid or gastric juice in the external auditory canal for smear to find bacteria, if positive means intrauterine Amniotic fluid is contaminated, but small babies are not necessarily ill.

2 Urine and cerebrospinal fluid bacterial culture: urine can be taken by pubic symphysis puncture method for bacterial culture, and cerebrospinal fluid for bacterial culture. For example, bacterial culture results are consistent with blood culture results, and the diagnosis is the most reliable.

(3) Blood brown yellow smear: After the bacteria are swallowed by neutrophils, they can be detected after smear staining.

3. Other serological diagnosis

(1) Detection of bacteriological specific antibodies: Detecting bacteriological specific antibodies, including monoclonal antibodies against specific bacteria, by convection immunoelectrophoresis and latex agglutination tests.

(2) Early diagnosis indicators: Recently, there have been studies at home and abroad that the increase of intercellular adhesion molecule (cICAM-1), the decrease of fibronectin (Fn), the increase of NO level and serum tumor necrosis factor (TNF) can be used as early Diagnostic indicators.

[Auxiliary inspection]

1. Imaging examination Chest X-ray examination should be performed in children with respiratory symptoms, mainly manifested as pulmonary invasive changes, pleural effusion, intestinal wall cystic gas and abdominal free gas.

2. Skull B-ultrasound and CT examination can help diagnose ventriculitis, brain abscess and other diagnoses.

3. Radionuclide brain scan is valuable for multiple brain abscesses.

4. Magnetic resonance (MRI) is of great value for multi-atrial and multiple small abscesses.

Diagnosis and diagnosis of neonatal sepsis

diagnosis

1. History: All the following risk factors should consider the possibility of bacterial infection: 1 premature rupture of amniotic membrane is greater than 12 ~ 24h; 2 history of fever and chorioamnion in late maternal pregnancy; 3 low Apgar score at birth and a history of rescue; 4 Premature birth, twins.

In-hospital infections are prone to the following conditions: 1 children treated with neonatal care unit (NICU); 2 children with invasive treatment such as tracheal intubation, umbilical vein cannulation; 3 long hospital stay; 4 undergo surgery Children; 5 ward crowded; 6 long-term application of broad-spectrum antibiotics.

2. Clinical manifestations: Newborns often present with non-specific symptoms.

(1) Respiratory distress is the most common, accounting for 90% of septic infants, the severity may be different: such as mild shortness of breath, three sinus breathing, increased need for oxygen, apnea, difficulty breathing, and even Respiratory failure requires artificial ventilation.

(2) Increased heart rate and poor perinatal circulation, bruising.

(3) Low blood pressure.

(4) Acidosis (metabolic), hypoglycemia or hyperglycemia.

(5) Unstable body temperature: 10% to 30% of newborns may have fever and body temperature.

(6) Gastrointestinal symptoms: including vomiting, diarrhea, bloating, anorexia.

(7) Activities are weakened or lethargic, irritability, and embarrassment.

(8) convulsions.

(9) Freckles or blemishes.

(10) Others such as jaundice, hepatosplenomegaly and so on.

3. Laboratory inspection

(1) Peripheral blood white blood cell count and classification The white blood cell count <5×109/L, and the ratio of immature white blood cells and neutrophils>0.2 indicates bacterial infection.

(2) Platelet count platelet count <100×109/L suggests the possibility of neonatal sepsis.

(3) Acute phase protein 1C-reactive protein>15g/ml suggested bacterial infection, 2ESR>15mm/h.

(4) Blood culture examination: blood culture positive can establish the cause of diagnosis, children with suspected infection need to take the surrounding blood before the hospital to take the antibiotics for cultivation, and should strictly follow the aseptic operation to prevent pollution, such as children Antibiotics acting on the cell wall, such as penicillin and cephalosporin, can be cultured in a hypertonic medium for L-type bacteria. When anaerobic infection is suspected, it can be used as an anaerobic culture.

(5) Cultivation of other parts: culture of umbilical, urine, stool or other local infections.

(6) Radiological examination: Chest X-ray examination should be performed in children with respiratory symptoms.

(7) Pathogen antigen detection: such as convection immunoelectrophoresis, latex agglutination test, hemagglutination inhibition test and the like.

Differential diagnosis

1. Intracranial hemorrhage, asphyxia: sepsis has apnea, tremor, convulsions, anterior hernia, indicating that there is a neurological invasion, especially in children within 1 week of birth, should be identified with intracranial hemorrhage, asphyxia, etc. More often, within 1 or 2 days after birth, there is a history of birth injury, and when there is congenital malformation of the nervous system and meningitis, it should also be differentiated from sepsis.

2. Respiratory diseases: early symptoms of sepsis may have difficulty breathing, urgency, cyanosis, etc., should be differentiated from pneumothorax, pneumonia, immature primary respiratory distress syndrome, lung insufficiency, etc., if necessary, chest X-ray film can be taken Assist in diagnosis.

3. Gastrointestinal diseases: bloating, vomiting, frequent or reduced stool frequency, is the manifestation of primary intestinal disease, can also occur in sepsis, should analyze the development of each symptom and causal relationship, the sepsis caused by intestinal bacteria should be Be vigilant.

4. Hematological diseases: hemolytic disease of the newborn, lack of erythrocyte enzymes can also show jaundice, anemia, shortness of breath and difficulty in breathing, but severe hemolytic anemia has no signs of infection, and hyperbilirubinemia caused by sepsis Identification, neonatal hemorrhagic disease must be differentiated from sepsis and blood. The former has no infection, blood transfusion and vitamin K treatment can be cured, idiopathic thrombocytopenic purpura and congenital leukemia should be differentiated from sepsis, can be diagnosed by blood routine examination .

5. Neonatal hepatitis: the first symptom of jaundice, obvious yellow skin infection and systemic infection, mild symptoms of poisoning, so often misdiagnosed, neonatal sepsis has jaundice mechanism in addition to hemolysis caused by bacterial toxins, damage with liver cells, liver Excretion of biliary dysfunction and neonatal liver enzyme system development is imperfect, bilirubin is inhibited in the liver binding process, so some children with elevated blood transaminase and direct bilirubin, clinically misdiagnosed as hepatitis syndrome and delayed treatment.

The child had no history of hepatitis exposure, and all of her mother HBsAg was negative. Laboratory tests showed that the number of white blood cells increased in most children. The symptoms were improved rapidly with antibiotics. At the same time, local infection was an important clue to diagnose sepsis, but there was no obvious infection. The only basis for neonatal sepsis is blood culture. Therefore, when the child has unexplained jaundice, you should think of the possibility of sepsis and early blood collection for bacterial culture. If a blood culture is negative and highly suspected of sepsis, blood or infection should be repeated. Bacterial culture of the exudate of the stove to increase the positive rate.

6. Other infections: Herpes simplex, giant cell inclusion disease, Coxsackie virus infection, etc. can occur in the neonatal period, the symptoms are similar to sepsis, simple sore virus infection, half of which can be herpes-free, only systemic symptoms, Ke The Saatchi virus can cause fever, anorexia, vomiting, paleness, cyanosis, difficulty breathing, hepatomegaly, jaundice, hemorrhage, etc., mainly manifested as myocarditis and meningitis, which occur more than 2 weeks after birth, in addition, toxoplasmosis, globular spores Bacterial disease, disseminated histoplasmosis and other rare diseases, and sometimes should be identified with sepsis.

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