Neonatal sepsis - Role of certain immunohematologic tests in rapid diagnosis

Abstract

Background and Objective : Many neonates with sepsis die worldwide due to lack of early diagnosis and prompt treatment. This study was carried out to analyze various immunological and hematological parameters singly and in combination to formulate a guideline for the rapid diagnosis of neonatal sepsis. Materials and Methods : In a prospective study, 62 patients having clinical suspicion of neonatal sepsis were evaluated with a battery of investigations. Neonates admitted for other causes and without clinical suspicion of sepsis were selected as controls ( n = 40). The tests included blood culture, hemoglobin (Hb) level, total and differential blood count, absolute neutrophil count (ANC), immature to total neutrophil count (I/T ratio), micro-erythrocyte sedimentation rate (m-ESR), C-reactive protein (CRP), platelet count, serum immunoglobulin M (IgM), and plasma fibrinogen level. Patients were divided into proven cases (positive blood culture) and probable cases (blood culture negative). Results : Positive blood culture was seen in 38 cases (61.3%). Raised m-ESR (>8 mm in 1 st h) was seen in 63.2% of proven and 66.7% of probable cases. An I/T ratio of ≥0.2 was seen in 63.2% and 58.3% of proven and probable cases. Morphological changes were detected in 68.4% of proved and 91.7% of probable cases. Positive CRP test (≥6 mg/L) was found in 84.2% of proven and 100% of probable cases. Raised serum IgM, leukopenia, and neutropenia were seen in minority of patients (11-37%). Raised fibrinogen (>400 mg/L) was seen in the patients as well as in controls. Conclusions : Four useful tests were m-ESR, I/T ratio, morphological changes in neutrophils, and CRP; and were statistically significant ( P < 0.05). Most sensitive test was CRP (84%) and m-ESR was most specific test (94%). Combination of three or more of these four tests were highly specific (95-100%).