Abstract.Objective: To study the diagnostic value of serum procalcitonin (PCT) for bacterial infection. Methods: 189 cases of children based on medical history, clinical situation, and laboratory test results to make the diagnosis, were divided into normal control group (40 cases), bacterial infection group (51 cases), viral infection group (49 cases) and autoimmune system diseases (49 cases). In the selected patients at admission, 48h, 1 week, Serum procalcitonin, C-reactive protein (CRP) levels, white blood cell count and other appropriate laboratory tests. Conclusion: The white blood cell count (WBC), CRP in bacterial infection, autoimmune disease group had significantly increased, PCT only in the bacterial infection was significantly higher; PCT may be a more sensitive marker than WBC and CRP.
Key words： Bacterial Infection; Procalcitonin; Pediatrics
1.Introduction
Pediatric infectious diseases are seen the most commonly in clinic; the failed early diagnoses on the abuse of antibiotics or the severe bacterial infection are two problematic issues in clinical work.
Pathogenic detection is a gold index for the diagnosis of infectious diseases, but the bacterial culture and viral isolation take a long time and simultaneously the positive rate is low.
Therefore, it is of great clinical significance to seek a fast and reliable laboratory method for carrying out the differential diagnosis on the bacterial infections, viral infections and autoimmune diseases to prevent the abuse of antibiotics.
2.Data and Methods
2.1.General data
189 cases of children that were in our hospital from October 2005 to December 2007 were selected in this study.
Among them, 91 cases were male, and the other 91 cases were female; 76 cases were between 3 months and 1 year old, 56 cases were between 1 year old and 3 years old, 31 cases were between 3 years old and 10 years old and 35 cases were above ten years old.
40 cases were in the normal control group and had no infection history as well as no systemic infection and local infection expression through the physical examination; the laboratory test on all indexes showed no existence of infection in these 40 cases; excluding the autoimmune diseases, 13 cases out of the 40 cases were attacked by the epilepsy, 9 cases were attacked by the myasthenia gravis, 9 cases were attacked by cerebral palsy, 7 cases were attacked by congenital heart disease and 2 cases were attacked by progressive muscular dystrophy.
51 cases were in the bacterial infection group. Among them, 30 cases were attacked by bacterial pneumonia; 9 cases were attacked by purulent meningitis; 3 cases were attacked by bacillary dysentery; 4 cases were attacked by urinary tract infection; 2 cases were attacked by staphylococcal scalded skin syndrome; 2 cases were attacked by leukemia complicated with lung infection; 1 case was attacked by leukemia complicated with lung infection as well as infectious shock.
49 cases were in the viral infection group. Among them, 17 cases were attacked by viral encephalitis; 6 cases were attacked by infectious mononucleosis; 11 cases were attacked by autumn diarrhea; 4 cases were attacked by cytomegalic inclusion; 11 cases were attacked by capillary bronchitis.
49 cases were also in the autoimmune disease group. Among them, 8 cases were attacked by rheumatic fever; 18 cases were attacked by Kawasaki disease; 5 cases were attacked by systemic lupus erythematosus; 18 cases were attacked by anaphylactic purpura.
2.2.Methods
The selected cases received a test on PCT, WBC and CRP respectively on admission, after 48h and after 1 week.
Part of the cases received a chest X-ray and the tests on urine culture, sputum culture, blood culture, stool culture, pus smear and viral virus antibodies according to the actual conditions.
2.3.Statistical method
SPSS 13.0 software is used for the statistical analysis: the data is expressed with +S, the row×column table is for the data X2 test, the one-way ANOVA is used for the comparison between groups, the SNIC-q test is used for the multiple comparison, and P 0.05).
3.2.Test results after 48h
The test results after 48h are the same to that on admission. For this reason, there is no table for the test results after 48h
3.3.Test results after 1 week
Table 3: PCT test results of all groups after 1 week
Through the comparison among the four groups in PCT (after 1 week of the treatment), it is found that the serum PCT level of the bacterial infection group is higher than that of the normal control group, the viral infection group and the autoimmune disease group (P 0.05).
4.Discussion
PCT, which was found in 1992, is the precursor of human procalcitonin, and contains the protein with 116 amino acids that are secreted by the endocrine cells of lung and small intestine; its molecular weight is 13kD); it is composed of N-terminal, procalcitonin and C-terminal, but will never be degraded to procalcitonin, and is not affected by the hormone level in vivo; its half-life period in vivo is 25～30h.
PCT level is extremely low in the serum of healthy people and almost can’t be detected.
However, when there is a bacterial inflammation or infection, PCT level is obviously rising (PCT>0.5ng/ml).
Therefore, according to clinical conditions, antibiotics are used. When there is serum PCT> 10ng/ml, PCT can be mainly seen in the patients with severe bacterial infection such as sepsis, and hence it is necessary to give consideration to using the high-grade antibiotics and also a combination therapy. When there is serum PCT＜0.5ng/ ml, PCT can be mainly seen in viral infections or autoimmune diseases, and hence the application of antibiotics are not taken into account in general.
In this study, it is found that the CRP and WBC counts did not increase in the normal control group and the viral infection group, but increased in the autoimmune disease group and the bacterial infection group, and the difference was of no obvious significance.
However, the PCT in the autoimmune disease group and the bacterial infection group had a significant difference (P