Neonatal pneumonia is a common disease in the neonatal period, characterized by diffuse lung lesions and atypical clinical manifestations, requiring early diagnosis and proper management.

bubble_chart Etiology

Neonatal pneumonia can be categorized into prenatal infections (including intrauterine and intrapartum) and postnatal infections. These infections often originate from the pregnant woman, transmitted to the fetus through the placenta, or caused by premature rupture of the amniotic membrane, prolonged labor, or ascending infections from microorganisms in the vagina.

bubble_chart Pathogen

Pathogens causing prenatal infections: viruses such as cytomegalovirus and rubella virus are more common; bacteria such as group B hemolytic streptococcus and enterobacteria are more common, and chlamydia and toxoplasma are also common pathogens. Pathogens causing postnatal infections include Staphylococcus aureus, large intestine bacillus, syncytial virus, and influenza virus, among others. Other pathogens such as Proteus, Enterococcus, and Diplococcus pneumoniae can also cause pneumonia. Hospital-acquired pneumonia is more commonly caused by drug-resistant Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella, Pseudomonas aeruginosa, and respiratory viruses.

bubble_chart Pathological Changes

Gross anatomy of prenatal pneumonia shows no substantial lesions on the appearance of the lungs and pleura. Only extremely widespread inflammatory changes within the alveoli can be observed on tissue sections, and sometimes amniotic fluid residues such as keratinized epithelial cells can also be seen. Pulmonary lesions occurring on the first day after birth may resemble hyaline membrane disease. Bacterial pneumonia acquired after birth is similar to pediatric bronchopneumonia, while viral pneumonia presents with interstitial changes.

Pneumonia caused by prenatal infection usually occurs within 3 to 7 days after birth. The symptoms are often atypical, and the smaller the gestational age, the more atypical the symptoms. About half of the cases have normal body temperature, while the rest have unstable body temperature. Severe cases or premature infants often have no rise in body temperature. Symptoms are mostly non-specific, such as refusal to eat, drowsiness or irritability, poor complexion, failure to gain weight, and often no cough. Soon, symptoms like rapid breathing, nasal flaring, moaning, retraction of soft tissues during inhalation, and increased heart rate may appear. Premature infants are prone to apnea. Lung signs may include increased or decreased breath sounds, accompanied by dry or wet rales, but may also be completely negative.

Although chlamydial infection occurs prenatally, the onset of pneumonia occurs 3 to 12 weeks after birth. Some infants may have had chlamydial conjunctivitis 5 to 14 days after birth (see conjunctivitis), and the pathogen can gradually spread downward from the nasolacrimal duct, but some infants without conjunctivitis can also develop pneumonia. Chlamydial pneumonia has a slow onset, starting with stuffy nose and cough, gradually increasing respiratory rate, usually no fever, and wet rales in the lungs. If the lesion involves the bronchioles, wheezing may occur. The entire course can last for several weeks. The white blood cell count may be normal, sometimes with an increase in eosinophils.

Pneumonia that occurs after birth has a later onset and more typical symptoms, including stuffy nose, cough, rapid breathing. Full-term infants often have fever, but may also have normal body temperature, while premature infants may have no rise in body temperature. Coarse or fine wet rales can be heard in the lungs. When complicated by empyema or pyopneumothorax, breath sounds are reduced, and percussion may show dullness or increased resonance. Pneumonia caused by different pathogens has some specific characteristics.

Diagnosis based on the following points {|###|}1. History and signs: If the pregnant woman has had infectious diseases before delivery or the fetus has experienced intrauterine distress, the newborn should be alert to the possibility of prenatal infectious pneumonia. The diagnosis of postnatal pneumonia relies on the symptoms and signs of the child. Although the diagnosis is relatively easy, attention should be paid to the progression of the disease and complications. {|###|}2. Chest X-ray: Viral pneumonia is mainly characterized by interstitial changes, while bacterial pneumonia is mainly bronchopneumonia, sometimes resembling hyaline membrane disease. Chlamydial pneumonia is more characterized by interstitial pneumonia with focal infiltration. In neonatal pneumonia, lung qi swelling is more obvious, sometimes causing mediastinal hernia. The incidence of local atelectasis is also higher than in other age groups. {|###|}3. Etiological diagnosis: The etiological diagnosis of pneumonia is not very easy. For bacterial pneumonia, tracheal aspirates or nasopharyngeal swabs can be taken for culture, and blood culture can be performed simultaneously. For viral pneumonia and chlamydial pneumonia, rapid diagnostic methods such as ELISA or PCR can be used (refer to the overview of neonatal infections).

bubble_chart Treatment Measures

For those with low body temperature, pay attention to keeping warm. The amount of milk fed at one time should not be too much to avoid cough, vomiting, and dampness transformation in the respiratory tract. For bacterial pneumonia, choose antibiotics based on drug sensitivity tests. For respiratory infections caused by syncytial virus, Ribavirin can be used for aerosol inhalation, 15mg/kgd wv twice, along with 0.5% solution for nasal drops. For chlamydial pneumonia, erythromycin can be taken orally or intravenously at 50mg/kg.d, divided into 2-3 times, for 2-3 weeks. Some also use chloramphenicol orally, 25mg/kg.d for premature infants and 50mg/kg.d for full-term infants, divided into 2-3 times. If the parents of the child have chlamydial infection, treatment and prevention should be seen as neonatal conjunctivitis.

bubble_chart Differentiation

It is necessary to differentiate from the following diseases, especially for prenatal infectious pneumonia, which is particularly important.

1. Hyaline membrane disease: Due to the lack of pulmonary surfactant, respiratory distress occurs within 12 hours after birth and gradually worsens. The progression of the disease is slightly slower than that of prenatal pneumonia. However, these two diseases are often difficult to differentiate clinically, radiographically, and pathologically. Therefore, hyaline membrane disease may also be treated as prenatal infectious pneumonia (especially group B streptococcal pneumonia), using a higher dose of penicillin.

2. Hypoxic-ischemic encephalopathy: In full-term infants, this condition is mostly caused by asphyxia, while in premature infants, there may not necessarily be a history of hypoxia. The onset of the disease is characterized by irregular breathing, increased or decreased muscle tone, and sometimes seizures. However, prenatal pneumonia has a slightly later onset and fewer neurological symptoms.

3. Congenital heart disease: Generally, it should be differentiated from complex congenital heart disease or cyanotic congenital heart disease that appears shortly after birth. Congenital heart disease presents with increased respiratory rate or cyanosis within a few days after birth, and a heart murmur may sometimes be heard, but there are no rales in the lungs. Chest X-rays can help differentiate.

4. Diaphragmatic hernia: Abdominal organs enter the thoracic cavity through the hernia orifice, compressing the heart and lungs, leading to pulmonary hypoplasia and causing shortness of breath. Chest X-rays can assist in differentiation.

5. Pneumonia caused by cytomegalovirus: The onset is slow, with symptoms including fever, dry cough, and shortness of breath. Chest X-rays show typical interstitial pneumonia, which is similar to chlamydial pneumonia. However, children with cytomegalic inclusion disease have significant hepatosplenomegaly and sometimes jaundice.