Diagnosis (a) Susceptibility factors: 1. Mother’s medical history: history of infection during pregnancy and delivery (such as urinary tract infection, chorioamnionitis, etc.), colonization of the mother’s birth canal with specific bacteria, such as group B hemolytic streptococcus (GBS), gonococcus, etc. 2. Obstetric factors: premature rupture of membranes, prolonged labor, cloudy or smelly amniotic fluid, unclean delivery environment or poor disinfection during delivery, prenatal and intrapartum invasive examinations, etc. 3. Fetal or neonatal factors: multiple fetuses, intrauterine distress, prematurity, infants younger than gestational age, long-term intubation, tracheal intubation, surgical interventions, malpractices on newborns such as picking “horse teeth”, squeezing breasts, squeezing carbuncles, etc., skin infections in newborns such as impetigo, diaper dermatitis, umbilical and pulmonary infections are also common causes. Common causes (B) Pathogenic bacteria: Staphylococcus and Escherichia coli predominate in China, coagulase-negative staphylococcus (CNS) is mainly seen in premature infants, especially those with long-term arteriovenous placement; Staphylococcus aureus is mainly seen in septic skin infections; prenatal or perinatal infections with Escherichia coli as the main gram-negative (G-) bacteria are more common. G- bacteria such as Pseudomonas aeruginosa, Klebsiella pneumoniae and Serratia marcescens are more common in mechanically ventilated children with tracheal intubation. (C) Clinical manifestations: 1. Systemic manifestations: 1) Temperature change: fever or hypothermia may be present. (2) Less food, less crying, less movement, poor facial color, cold extremities, no weight gain or slow growth. (3) Jaundice: Sometimes it is the only manifestation of sepsis, and in severe cases it may develop into bilirubin encephalopathy. (4) Shock manifestations: cold extremities with florid spots, weakened femoral artery pulsation, prolonged capillary filling time, reduced blood pressure, diffuse intravascular coagulation (DIC) in severe cases. 2. Systemic manifestations: 1) Skin and mucous membranes: sclerosis, subcutaneous gangrene, impetigo, periumbilical or other areas of cellulitis, nail bed infection, skin burns, petechiae, petechiae, oral mucosa with picking injury. (2) Digestive system: anorexia, abdominal distension, vomiting, diarrhea, and in severe cases, toxic intestinal paralysis or necrotizing small intestine colitis (NEC), and in later stages, hepatosplenomegaly. (3) Respiratory system: shortness of breath, cyanosis, irregular breathing or apnea. (4) Central nervous system: easily combined with septic meningitis. Manifestations include drowsiness, agitation, convulsions, increased fontanelle tone and extremity muscle tone, etc. (5) Cardiovascular system: infective endocarditis, infective shock. Hematologic system: may be combined with thrombocytopenia and bleeding tendency. (7) Urinary system infection. Others: septic inflammation of bone and joint, osteomyelitis and deep abscesses, etc. (D) Laboratory tests: 1) Bacteriological examination: 1) Bacterial culture: try to do blood culture under strict disinfection before the application of antibiotics, suspected of intestinal origin infection should be done at the same time for anaerobic bacteria culture, there is a longer period of time with penicillin and cephalosporin antibiotics should do L-type bacterial culture. If prenatal infection is suspected, take gastric fluid and external ear secretions for culture within 1h after birth, or smear Gram stain to find polymorphonuclear cells and intracellular bacteria. If necessary, clean urine culture should be obtained. Cerebrospinal fluid, infected umbilical, plasma cavity fluid and all removed catheter heads should be sent for culture. (2) Pathogenic bacteria antigen and DNA detection: use known antibodies to measure unknown antigens in body fluids, for GBS and E. coli K1 antigen can be used convective immunoelectrophoresis, latex agglutination test and enzyme chain immunosorbent assay (ELISA) and other methods, for those who have used antibiotics more diagnostic value; using the 16SrRNA gene polymerase chain reaction (PCR) typing, DNA probes, etc. Molecular biology techniques to assist in early diagnosis. 2, non-specific tests: 1) white blood cell (WBC) count: blood collected after 12h of birth is more reliable. wbc decrease (<5×109>25×109/L; >3d WBC>20×109/L). (2) leukocyte classification: rod-shaped nuclear cells / neutrophils (immature/totalneutrophils, I/T) ≥ 0, 16. (3) C-reactive protein (CRP): more commonly carried out in the acute phase of the protein and more sensitive items, inflammation can be increased after 6-8h, ≥ 8μg/ml (peripheral blood method). Serum pre-calcitonin (PCT) or interleukin 6 (IL 6) can be measured in units where available. (4) platelets ≤ 100 × 109 / L. (5) microhemoglobin ≥ 15mm / 1h. (E) diagnostic criteria 1, determine the diagnosis: with clinical manifestations and in line with any of the following 1) blood culture or sterile body cavity culture of pathogenic bacteria; (2) if the blood culture specimen culture of conditional pathogenic bacteria, it must be with another (part) of the blood, or sterile body cavity, or catheter tip culture of the same bacteria. 2, clinical diagnosis: with clinical manifestations and have any of the following 1) non-specific examination ≥ 2. (2) Positive blood specimen pathogenic bacterial antigen or DNA test. Second, treatment (a) antibacterial drug application 1, the general principles: 1) clinical diagnosis of sepsis, in the use of antibiotics before the collection of various specimens, without waiting for the results of bacteriological examination, that is, antibiotics should be used in a timely manner. (2) according to the pathogenic bacteria may be the source of the initial judgment of the pathogenic species, the pathogenic bacteria are not clear before you can choose both for gram-positive (G+) bacteria and gram-negative (G-) bacteria antibiotics, can first use two antibiotics, but should grasp different areas, different periods have different advantages pathogenic bacteria and resistance spectrum, empirical selection of antibiotics. (3) once the drug sensitivity results, should be adjusted accordingly, try to choose a targeted antibiotics; such as clinical efficacy, although the drug sensitivity results are not sensitive, but also temporarily do not change the drug. (4) generally use intravenous injection, the course of treatment 10 ~ 14d. combined with GBS and G- bacteria caused by septic meningitis (referred to as chemobrain), the course of treatment 14 ~ 21d. 2, mainly for G + bacteria antibiotics: 1) penicillin and penicillin class: such as streptococcal (including GBS, Streptococcus pneumoniae, group D streptococcus such as Streptococcus faecalis, etc.) infection, the first choice of penicillin G. Staphylococcus spp. including For Staphylococcus spp. including Staphylococcus aureus and CNS, penicillin is generally resistant, so enzyme-resistant penicillin such as benzocillin and cloxacillin (o-chloroprim) should be used. (2) The first and second generation cephalosporins: cefazolin is the better variety of the first generation cephalosporins, mainly for G+ bacteria, and partly for G- bacteria, but it is not easy to enter the cerebrospinal fluid; cefradine is good for G+ and G-cocci, but weak for G- bacilli. Cefuroxime is commonly used in the second generation, which is slightly weaker to G+ bacteria than the first generation, but more stable to G- and β-lactamase, so it is more effective to G- bacteria. (3) Vancomycin: as the second-line anti-G+ antibiotics, mainly against methicillin-resistant staphylococcus (MRS). 3, mainly for G-bacteria antibiotics: (1) the third generation cephalosporins: the advantage of the lowest inhibitory concentration of enterobacteria, very easy to enter the cerebrospinal fluid, commonly used in G-bacteria caused by sepsis and chemobrain, but should not be empirical single use of this class of antibiotics, because of the weak role of Staphylococcus aureus, Listeria monocytogenes, enterococci completely resistant. Commonly used: cefotaxime, cefoperazone (not easy to enter the cerebrospinal fluid), ceftazidime (commonly used in Pseudomonas aeruginosa septicemia complicating the chemoencephalitis), ceftriaxone (can be the first choice of antibiotics for chemoencephalitis, but caution when neonatal jaundice). (2) piperacillin: sensitive to G-bacteria and GBS, easy to enter the cerebrospinal fluid. (3) Ampicillin: Although it is a broad-spectrum penicillin, the resistance rate to Escherichia coli is too high, so it is recommended to use other antibiotics for this bacteria. (4) Aminoglycosides: mainly for G-bacteria, the sterilization effect of staphylococci is also good, but into the cerebrospinal fluid is poor. Amikacin is prone to ototoxicity and nephrotoxicity in neonates, so it can be used with caution and not as the first choice if there is a basis for drug sensitivity testing and conditions to monitor its blood concentration, and pay attention to clinical monitoring. Nethimycin has less otorhinolysis and nephrotoxicity. (5) Aminotrans: monocyclic β-lactam antibiotics, strong effect on G-bacteria, β-lactamase stability, less adverse reactions. 5) Other broad-spectrum antibiotics 1) Imipenem + cistatin: a new type of β-lactam antibiotics (carbapenems), the majority of G+ and G- aerobic and anaerobic bacteria have a strong bactericidal effect on the production of ultra-broad-spectrum β-lactamase bacteria have strong antibacterial activity, often as the second and third line of antibiotics. However, it is not easy to pass the blood-brain barrier and has the side effect of causing convulsions, so it is not recommended for septic meningitis. (2) Panipenem + betametholone: Another new carbapenem antibiotic with the same antibacterial spectrum as imipenem + cistatin. (3) Ciprofloxacin: as a third generation quinolone drug, the effect on G-bacteria exceeds that of third generation cephalosporins and aminoglycoside antibiotics, and has antibacterial activity against MRS, mycoplasma and anaerobic bacteria, and is the first choice as a similar drug. When other drugs are ineffective and have the basis of drug sensitivity, this drug can be used. (4) Cefepime: It is the fourth generation cephalosporin with wide antibacterial spectrum, sensitive to G+ and G-, stable to β-lactamase, and not easy to have drug resistance mutation, but not sensitive to MRS. (B) remove the infection foci umbilicus local disinfection with 3% hydrogen peroxide, 2% iodine and 75% alcohol, 2-3 times a day, skin infection foci can be coated with antibacterial ointment. The oral mucosa can also be washed with 3% hydrogen peroxide or 0.1% to 0.3% Raffles’ solution twice a day. (C) Maintain the stability of the internal and external environment of the body, such as attention to warmth, oxygen supply, correction of acid-base imbalance, maintenance of nutrition, electrolyte balance and blood circulation stability, etc. (D) Increase immune function and other therapies for premature infants and severe infections can be used to inject immunoglobulin (IVIG) 200-600mg/kg once a day for 3-5 days. Severe infections can also be treated with blood exchange therapy.