Diagnostic Utility of Procalcitonin and Neutrophil-Lymphocyte Ratio in Bacterial Septicaemia - A Retrospective Case Control Study from a Tertiary Care Institute

Author(s): Mamatha T. Shenoy1 , Hariharan Alexander2 , Jeyakumar Manavalan3 , K. Suganthy4 , Pradipta Kumar Mohanty5

BACKGROUND Sepsis is a frequently encountered critical care problem wherein great emphasis is laid on early and accurate diagnosis of the infective organism. Blood culture though precise, is time consuming. Empiric antibiotic therapy leads to development of antibiotic resistance amongst organisms. Thus, there is a need for a biomarker that is cost effective, simple and rapid to perform. Procalcitonin elevates in response to chemical mediators produced due to bacteraemia within 2 - 4 hours and serves as an early marker. Neutrophil-Lymphocyte Ratio is available universally and is highly cost-effective. We wanted to assess the utility of Procalcitonin (PCT) and Neutrophil-Lymphocyte Ratio (NLR) in detecting the bloodstream infections and determine their usefulness in establishing the nature of infective organisms. METHODS A retrospective case control study was undertaken from January 2018 to December 2018 in a tertiary care teaching hospital in Madurai, Tamil Nadu. Patients tested for serum PCT, complete blood count and blood culture simultaneously prior to antibiotic therapy were included in the study (n = 288). The study cohort was classified into two groups. Group I, controls (n = 155) and group II, cases (n = 133). Out of 133 patients, 73 % (98) were infected by Gramnegative bacteria and 27 % (35) by Gram-positive bacteria. Data was analysed using SPSS V.16 software (SPSS Inc., Chicago, IL, USA). Students unpaired t test and Mann-Whitney U test were used for intergroup comparisons of continuous variables. p < 0.05 was considered to be statistically significant. Cut off for detecting bacteriemia and gram negative bacteriemia was created using Receiver Operating Characteristic (ROC) curve. RESULTS The area under ROC of PCT to detect gram negative bacteraemia was 0.752 (95 % CI = 0.692 – 0.812). CONCLUSIONS Escherichia coli was the most frequent cause of sepsis. Higher levels of PCT and NLR were associated with gram negative organisms. PCT levels can help in determining the cause of infection. NLR and PCT are able to establish the presence of bacteraemia in a short span of time, thus alleviating the over dependence on blood culture reporting. Such earlier decision-making tools help in reducing empirical antibiotic usage and thereby lessen the burden of bacterial resistance to antibiotics.