Babies are especially susceptible to illness during the winter and spring months when temperatures are changing. As I’m sure most parents know, a sick baby needs to determine whether it is a viral or bacterial infection? The difference between the two determines the key to treatment, and that is the use of antibiotics. How to make a simple judgment? I’m here to teach you three tricks.
First, look at the white blood cell count (WBC) and classification
An elevated total white blood cell count (WBC), which exceeds the normal reference value, may be a bacterial infection; in more serious bacterial infections, it may increase exponentially. However, an abnormally high total white blood cell count cannot be explained by a bacterial infection and requires a visit to a hematologist.
The classification mainly depends on the lymphocyte ratio (LY%) and the neutrophil percentage (GR%). An elevated lymphatic ratio indicates a viral infection; an elevated neutrophil percentage is a bacterial infection.
Strenuous exercise, painful stimulation, crying and vomiting can cause a temporary increase in total leukocyte count and neutrophil percentage. Parents are reminded that the results of a blood test 24 hours after a fever are more informative. In addition, many parents may not know that the ratio of lymphocytes and neutrophils is different for children of different ages. Here is a table for your reference.
Age
Neutrophil ratio (%)
Lymphocyte ratio (%)
Newborn baby at birth
65 or so
Around 35
4-6 days after birth
Around 50
Around 50
Infancy and early childhood
around 35
Around 65
4-6 years
Around 50
Around 50
After 6 years old
60-70
30-40
Adults
Ditto
Ditto
Second trick Reference ultrasensitive C-reactive protein (ultrasensitive CRP)
C-reactive protein is a non-specific marker of the acute phase of systemic inflammatory response synthesized by the liver. Ultrasensitive C-reactive protein is an ultrasensitive assay technology adopted by clinical laboratories to accurately detect low levels of C-reactive protein, which improves the sensitivity and accuracy of the test and is a sensitive indicator to distinguish low-level inflammatory status. A high ultrasensitive CRP value represents a bacterial infection. A low, may be a viral infection.
However, total leukocyte count, neutrophil ratio and ultrasensitive CRP are also increased in immune and allergic diseases, etc. and need to be identified by an experienced physician.
Third tip: Reference calcitoninogen (pre-calcitonin, PCT)
Calcitoninogen (PCT) is an item that came out in recent years and was not available in the early days. PCT is a protein that is elevated in plasma levels when severe bacterial, fungal and parasitic infections as well as sepsis and multiple organ failure are present. PCT is not generally elevated in autoimmune, allergic and viral infections. Bacterial endotoxins play a crucial role in the induction process. PCT helps to make a definitive diagnosis of systemic infections caused by bacteria and fungi, and the diagnostic value of PCT for systemic severe bacterial infections has been significantly better than that of ultrasensitive CRP.
Factors affecting PCT levels include the size and type of the infected organ, the type of bacteria, the degree of inflammation and the status of the immune response. although PCT reflects the active level of systemic inflammatory response, limited bacterial infections, minor infections and chronic inflammation do not lead to its elevation.
In summary, is the baby’s fever a bacterial or viral infection? Deciding whether to use antibiotics requires a combination of total white blood cell count and classification, ultrasensitive CRP and PCT results, and clinical presentation.