Serial measurement of PCT levels on a daily basis seems to be helpful for early prediction of severe bacterial infections, monitoring febrile episodes regarding response to antibiotic therapy, and early detection of complications in the infectious process.

A prospective study was undertaken to assess the usefulness of leukocyte count, serum C-reactive protein (CRP), procalcitonin (PCT), and the activities of total adenosine deaminase (tADA) and its isoenzymes ADA1 and ADA2, in the aetiological diagnosis of pneumonia in children. The study included three groups. Group A consisted of 23 children with bacterial pneumonia, group B of 50 children with viral and mycoplasmal pneumonia and group C of 46 healthy children. On the first day of admission in the clinic, blood samples were collected before the start of antimicrobial treatment, for culture, serological tests, leukocyte count and for the determination of CRP and PCT levels as well as tADA activity and its isoenzymes ADA1 and ADA2. According to our results, the mean leukocyte count and the mean concentrations of PCT and CRP were significantly higher in the children of group A than those in groups B and C. The admission serum PCT concentration has a higher sensitivity, specificity and positive predictive value for bacterial pneumonia than either CRP or the leukocyte count. The mean serum tADA, ADA1 and ADA2 activity in children of group A was not significantly different from those in group C, while the difference between groups B and C was statistically significant. In conclusion, we found that CRP is a good marker for screening various infectious diseases, but it cannot be used to distinguish between bacterial and viral infections. Serum PCT measurement might be a useful tool for the physician for the aetiological diagnosis of pneumonia in children. Measurements of serum tADA and ADA2 activity may provide useful additional diagnostic information on the aetiology of pneumonia so that appropriate antibiotic therapy can be given promptly. Further studies with larger patients groups are required to confirm our results.

Neutropenia as a state of immunosuppression is probably the major problem in patients suffering from acute lymphoblastic leukaemia undergoing intensive chemotherapy. Fever is frequent in neutropenic patients and often related to infection. Clinically, the presence of infection in patients with neutropenia may be difficult to establish, because there are usually few signs of infection. The aim of this work was to study sensitive markers for early diagnosis of microbial infection in neutropenic children undergoing intensive chemotherapy as a treatment for acute lymphoblastic leukaemia. The study included three groups (A, B and C) of children with acute lymphoblastic leukaemia and neutropenia. Group A consisted of 29 children with febrile neutropenia and microbial infection, aged 1-14 years (5.8+/-2.9), 11 boys and 18 girls; Group B of 38 children with febrile neutropenia without microbial infection, aged 2-14 years (6.8+/-3.1), 14 boys and 24 girls; and Group C of 53 children with neutropenia without fever and without infection, aged 1-14 years (5.9+/-2.1), 21 boys and 32 girls. Blood samples were collected upon admission and before the start of any antimicrobial treatment. The samples were used for blood culture, serological tests, leukocyte count and analysis of levels of C-reactive protein, procalcitonin, total adenosine deaminase (ADA) activity and its isoenzymes, ADA-1 and ADA-2. According to our results the procalcitonin levels and total ADA activity discriminated best between neutropenic febrile (Groups A and B) and neutropenic afebrile episodes (Group C). In conclusion, this study suggests procalcitonin and total ADA activity as two easily measurable and cost effective markers for the assessment of immune response in febrile neutropenic patients with acute lymphoblastic leukaemia.