Intensive Care Medicine

Neutrophil and monocyte CD64 indexes, lipopolysaccharide-binding protein, procalcitonin and C- reactive protein in sepsis of critically ill neonates and children

Mojca Groselj-Grenc, Alojz Ihan, Maja Pavcnik-Arnol, Andreja Natasa Kopitar, Tanja Gmeiner-Stopar, Metka Derganc

Correspondence to: Mojca Groselj-Grenc, MD, PhD, Department of Pediatric Surgery and Intensive Care, University Medical Center, Zaloška 7, 1525 Ljubljana, Slovenia e-mail: [email protected]

Inclusion criteria and outcome measures Patients were included if they had met two inclusion criteria: 1. at least two of the four criteria of SIRS [4] and 2. initiation of antibiotic therapy. Outcome measures were: SIRS with bacterial sepsis and SIRS without bacterial sepsis. Potential sepsis caused by viruses was included in SIRS without bacterial sepsis group. Fungal sepsis was included in bacterial sepsis group. Patients were not included if they had received antibiotic therapy for more than 24 hours prior to admission, if they had undergone surgery in the previous week, or if they had a proven viral infection at admission without starting antibiotic therapy.

LBP, PCT and CRP measurements Blood samples for LBP measurements were centrifuged, the serum separated and stored frozen at –80 °C. LBP was measured by chemiluminescent immunometric assay (Immulite®LBP, DPC, Los Angeles, CA, USA). The sensitivity of the assay was 0.2 mg/L. PCT was measured by automated immunoluminometric

® ® assay (LIAISON BRAHMS PCT , DiaSorin, Saluggia, Italy). The sensitivity of the assay was 0.04 μg/L; measurements below 0.04 µg/L were assigned a value of 0.04 µg/L. Turbidimetric determination of CRP was made using an automated analyzer (Boehringer-Mannheim, Mannheim, Germany). The sensitivity of the assay was 3.0 mg/L; measurements below 3.0 mg/L were assigned a value of 3.0 mg/L.

Diagnoses in neonates with SIRS without bacterial sepsis Diagnoses in neonates with SIRS without bacterial sepsis were: 17 cases of respiratory distress (hyaline membrane disease 12, transient tachypnea of the newborn 2, meconium aspiration 2 and pneumothorax 1), 7 cases of low cardiac output syndrome (transposition of great vessels prior to operation 2, double-outlet right ventricle 1, ventricular septal defect 1, trisomy 18 1, gastroschisis more than 1 week after surgery 1, and bladder exstrophy more than 1 week after surgery 1), 4 cases of perinatal hypoxia and 1 case of adrenal insufficiency. In children with SIRS without bacterial sepsis, there were 5 cases of acute respiratory distress (bronchopulmonary dysplasia 4 and spontaneous pneumothorax 1), 5 cases of low cardiac output (tetralogy of Fallot 1, coarctation of the aorta 1, sudden cardiac death and cardiopulmonary resuscitation 1, and short bowel syndrome 2) and 2 cases of status epilepticus.

Comparison of laboratory markers between day 0 and day 1; children and neonates; and Gram- positive and Gram-negative sepsis A significant increase from day 0 to day 1 in the neonates with SIRS and bacterial sepsis was found for CD64in (p <0.01), LBP (p <0.05) and CRP (p <0.01), and in the neonates with SIRS without bacterial sepsis for LBP (p <0.05) and CRP (p <0.01). Levels of CD64im on day 0 (p = 0.0300) and CRP on day 0 (p = 0.0179) were significantly higher in the children than in the neonates with SIRS and bacterial sepsis, and levels of CD64im on day 0 (p = 0.0305), LBP on day 0 (p = 0.0054), and CRP on day 0 and 1 (p = 0.0328 and p = 0.0244, respectively) were significantly higher in the children than in the neonates with SIRS without bacterial sepsis. In contrast, levels of PCT were significantly higher in both neonates with SIRS and bacterial sepsis (p = 0.0046 and p = 0.0152, respectively) and neonates with SIRS without bacterial sepsis (p = 0.0001 and p = 0.0009, respectively) than in the children on day 0 and day 1. We did not find any significant differences for CD64in, LBP, PCT and CRP, between Gram-positive and Gram-negative sepsis (p >0.05 for all comparisons; data not shown). CD64im was significantly higher in Gram-positive sepsis (median: 14.4; IQR: 11.7–16.6) than in Gram-negative sepsis (median: 8.95; IQR: 7.22–12.2) on day 1 (p <0.01).

Comparison of laboratory markers between culture-negative and culture-positive sepsis There were 7 neonates and 1 child with culture-negative sepsis (Table 2). The comparison of CD64in and CD64im between culture-negative and culture-positive sepsis in neonates is shown in Table A. No significant statistical differences were found between culture-negative and culture-positive sepsis. As only one child had culture-negative sepsis, we could not compare the levels in children. Table A. Medians (interquartile range) of neutrophil CD64 index (CD64in) and monocyte CD64 index (CD64im) in culture-negative and culture-positive sepsis in critically ill neonates at the time of suspected sepsis (day 0) and 24 hours later (day 1).

Culture-negative sepsis Culture-positive sepsis p (n = 7) (n = 10) CD64in day 0 2.10 (1.56–3.68) 3.72 (2.50–6.09) >0.10 day 1 2.51 (2.05–4.55) 4.55 (2.76–7.61) >0.10 CD64im day 0 10.1 (5.27–10.9) 9.26 (6.73–11.5) >0.10 day 1 9.38 (7.25–15.2) 11.7 (9.10–15.1) >0.10