How Do I Recognize Strep Throat in Babies?

The disease caused by group B streptococci (GBS) infection in the neonatal period is neonatal B streptococci infection. Streptococcus B is closely related to perinatal infection and has been proved to be an important pathogen of neonatal sepsis and meningitis in the 1970s. Among 105 cases of children with pneumonia, sepsis, and meningitis in the neonatal ward of Beijing Children's Hospital, GBS infection was identified in 27 cases, accounting for 25.9%.

Streptococcal B infection in newborns

Overview of B streptococcal infections in newborns

Epidemiology of B streptococcal infection in newborns

GBS resides in the mucous membranes of the mother's urinary tract and gastrointestinal tract. The carrier rate of pregnant women ranges from 4% to 40%, and the number of newborn babies born to mothers with more carriers is also more, with 40% to 70%. 8% were carriers. The factors that affect the mother's carrier include: poor economic conditions, young age, sexual behavior, etc. In addition, the choice of culture medium (broth is better than agar), the number and location of materials (cervix, vagina, urine, rectum, etc.), and newborn materials The location (the external ear canal is superior to the nostril, umbilicus, anorectum, pharynx, etc.) at birth also affects the detection rate. According to reports, mothers can be chronic (36%), temporary (20%), intermittent (15%), undecided (29%). GBS can become negative during the second trimester until delivery; or it can change from negative to positive. Asymptomatic health search is often carried by pregnant women, and late abortion, premature delivery, stillbirth, low birth weight infants, premature rupture of amniotic membrane, endometritis, chorioamnionitis, etc., GBS is also an important pathogen of puerperal infection. The above factors Can affect neonatal carrier.

Neonatal infections are mostly vertical transmission from mother to infant. For example, premature rupture of amniotic membrane can cause ascending infection, or contact with bacteria in the birth canal, and fetuses with intact amniotic membrane inhaled amniotic fluid contaminated by amniitis can also cause disease. A small number of neonatal infections are searched for horizontally spread health, but late-onset GBS infections are rarely endemic in infants.

Early-onset infections (7 days, with an average onset of 20 hours after birth) depend on the type of maternal carrier and complication of pregnancy. It is reported that the incidence of live births is 0.7 to 3.7 , and that of neonates with carrier mothers with bacteremia 0.5 2.0 , 50% of people with intrauterine infection have symptoms at birth. The incidence of <1500g is 2 2.6 , and the rate of 2500g is 0.8 1.8 . Full-term infants account for 50% of early infections. Late-onset infections (> 7 days, with an average onset of 24 days), the incidence of live births is 0.5 to 1.8 , and those without obstetric risk factors, the latest onset can be within 3 months.

Causes of B streptococcal infection in newborns

Streptococcus is divided into three types: (incomplete hemolysis), (complete hemolysis), and (health search insoluble) according to hemolysis. Lance-field divides B hemolytic streptococci into 18 groups based on different antigen structures, of which group A (GAS) causes pharyngitis, scarlet fever, skin infections, and is related to rheumatic fever and nephritis; GBS is related to pregnancy, maternal and newborn Infants are related. GBS is divided into at least 6 serotypes according to the type-specific capsular polysaccharide antigen (substance S): a, b, c, , , and . Those who cannot be typed have nothing to do with neonatal disease. Early-onset neonatal infections can be caused by any serotype, and 90% of late-onset infections are caused by type III.

Pathogenesis of Streptococcus B infection in newborns

Early-onset infections are due to immature defense mechanism of low birth weight infants, mothers carry more bacteria, GBS causes local amnionitis, and amniotic membrane ruptures there to induce premature birth. The incidence of premature rupture of amnion <19h is 0.7 , and 30h is 18.3 . Fetuses with intact amniotic membrane can also be infected. Amniotic fluid contains lower levels of type-specific GBS antibodies, complement, phagocytic cells, and other non-specific defense components. It is a good GBS medium. Inhalation of infected amniotic fluid by the fetus can cause the fetus. And later neonatal pneumonia, bacteremia, and septic shock.

Serum GBS specific capsular polysaccharide antibody IgG levels> 2 g / ml can enhance leukocyte conditioning and phagocytosis, and can kill GBS healthy search. Immature children lack type-specific antibodies from the mother, and are prone to GBS infection. Once they occur, they can further affect the defects of opsonization and phagocytosis that immature children already have.

Early-onset GBS infection is characterized by bacteremia, pneumonia, and pulmonary hypertension. In the later stages of sepsis, peripheral blood neutropenia, pulmonary granulocyte infiltration, increased vascular permeability, myocardial dysfunction, decreased blood pressure, and center Elevated venous pressure and DIC.

The onset of late-onset GBS infection is related to the early carrier of the child. When respiratory infection occurs, the health search of the mucosal barrier is disrupted, GBS multiplies, produces a large number of GBS type III capsular polysaccharide antigens, or decreases in maternal autoantibodies. The onset of GBS osteomyelitis is due to early-onset GBS bacteremia. Although asymptomatic, bacteria can be inoculated into the injured bone (humerus) and then cause localized osteomyelitis. Children may have no systemic symptoms. Because the child has produced a small amount of antibody, the type III specific IgG antibody in the blood increases, which can limit the infection to the metaphysis.

Clinical manifestations of B streptococcal infection in newborns

1. Early onset Early onset can occur at birth, especially in premature babies, and it occurs 6 to 12 hours after birth, and it is late to 24 hours in term infants. Mild infection is asymptomatic bacteremia, pneumonia is difficult to distinguish from hyaline membrane disease, and severe disease is characterized by severe perinatal asphyxia (with pneumonia, coma, shock), septic shock, or continuous fetal circulation. Respiratory symptoms clearly include bruising, apnea, shortness of breath, nasal fan, and three concave signs. Chest radiographs have reticular grain shadows (50%), pulmonary infiltrates (30%), and rare pleural exudation, pulmonary edema, large heart, and Increased lung blood.

Septicemia has no localized lesions, accounting for 30% to 40%, meningitis accounts for 30% (mostly type III), pneumonia accounts for 30% to 40%, and bacteremia is present in all three manifestations. Patients with meningeal involvement may have convulsions, drowsiness, coma, milk rejection, lordosis, etc., but cannot be diagnosed on a clinical basis. Anyone suspected of having early-onset or late-onset neonatal sepsis should be lumbar punctured.

2. Late-onset infections manifested as meningitis accounted for 60%, mainly of type III, which could not be distinguished from meningitis of other pathogens. Others may have localized lesions such as osteomyelitis and urinary tract infections.

There were 27 cases of GBS infection in the neonatal ward, including 18 cases of early onset and 9 cases of late onset. The average age of onset in early onset was 2.6 days, 12 cases of pneumonia, 5 cases of sepsis, and 1 case of meningitis. There were 6 cases of obstetric complications (premature rupture of water, aspiration of amniotic fluid, delayed labor, etc.), and 4 cases of premature infants. Among the 9 cases of late onset, the average age of onset was 12.6 days, 5 cases of sepsis, 3 cases of pneumonia, and 1 case of meningitis. There were no obstetric complications and 1 case of premature infants. GBS pneumonia is heavier than other infectious pneumonias in apnea, bruising, moaning, three concave signs, and poor response; sepsis is larger in E. coli enterovirus K1 infection, which is heavier than other pathogens.

Complications of Streptococcus B in Neonates

Early-onset apnea, persistent fetal circulation, pleurisy, pulmonary edema, meningitis, and ventricular meningitis are seen. Late onset may be complicated by osteomyelitis and urinary tract infections.

Diagnosis of B streptococcal infection in newborns

According to the history and clinical characteristics, combined with laboratory tests to confirm the diagnosis.

Differential diagnosis of B streptococcal infection in newborns

Differential diagnosis of early onset includes: hyaline membrane disease, amniotic fluid aspiration syndrome, persistent fetal circulation, sepsis (Escherichia coli, herpes simplex infection), metabolic diseases (hypoglycemia, hyperammonemia), anatomy Bruising and sepsis-like manifestations due to abnormalities (congenital heart disease, diaphragmatic hernia) or other causes.

In some cases, GBS infection is difficult to distinguish from hyaline membrane disease, such as low Apgar scores, shock and apnea on the first day after birth, premature hydration, large heart, pleural effusion, and rapid deterioration of the disease. Continuous fetal circulation can occur if GBS infection in term infants is accompanied by hypoxia, hypotension, granulocytopenia, and apnea.

Newborn B streptococcal infection test

Newborn B Streptococcus infection laboratory test

Confirmation of diagnosis depends on positive bacterial culture (from blood, cerebrospinal fluid, urine, local lesions), while positive skin and mucous membranes only indicate bacteria.

In recent years, the diagnosis of bacterial antigens has progressed rapidly. Antigen detection methods can be used whether or not antibiotics have been used. Commonly used are latex agglutination, synergistic agglutination, convection immunoelectrophoresis and enzyme-linked immunosorbent assays, etc. It has better sex, and it is better for antigen-detecting bacteria culture for specimens with less GBS content.

An increase in specific GBS antibodies may indicate recent GBS infection. Anti-streptolysin O (ASO) and anti-DNAse B (DNAse B) are only helpful for the diagnosis of GAS, but not for GBS.

Other auxiliary tests for streptococcal infection in newborns

X-ray examination should be done routinely to understand the heart and lung conditions, EEG, ECG examination, brain CT examination and B-ultrasound examination if necessary.