Role of sepsis screening in early diagnosis of neonatal sepsis

Correspondence: Dr. Ashish Lakhey, MD Department of Pathology Kist Medical College & Teaching Hospital, Lalitpur, Nepal E-mail: aashishlakhey@hotmail.com/lakheyashish@gmail. Background: Neonatal sepsis, a clinical syndrome of bacteremia with systemic signs and symptoms of infection in the first 4 weeks of life is a major cause of morbidity and mortality in newborn inborn. Early diagnosis is critical, as sepsis can progress more rapidly in neonates than in adults. An attempt was made to establish correlation between early neonatal sepsis screening & blood culture in neonates presenting with features of sepsis. The aim of this study is to assess the usefulness of sepsis screen in early diagnosis of neonatal septicemia.


INTRODUCTION
Neonatal sepsis (NS) is a clinical syndrome characterized by systemic signs of circulatory compromise caused by invasion of the blood stream by bacteria in the first four more common in developing countries when compared with developed countries. 2Neonatal sepsis may be classified according to the time of onset of the disease: early onset sepsis (EOS) and late onset sepsis (LOS). 8The distinction has clinical relevance, as EOS disease is mainly due to bacteria acquired before and during delivery, and LOS disease to bacteria acquired after delivery (nosocomial or community sources). 9Early onset sepsis usually presents within the first 72 hours of life and Late onset sepsis usually presents after 72 hours of age. 10 Infections are more common in low birth weight and preterm babies. 11In neonates the illness can progress more rapidly than in adults; therefore early diagnosis is of utmost importance. 11Clinical features of sepsis are nonspecific in neonates and a high index of suspicion is required for the timely diagnosis of sepsis.
Positive blood culture is a gold standard for diagnosis, but it is time consuming (requires 72 hours, atleast 24 hours in case of BacT-ALERT®) and demands a well-equipped laboratory. 12Many investigators have evaluated various inflammatory markers such as interleukin-6, interleukin-8 and plasma elastase.4][15] A good diagnostic test should have high sensitivity and specificity and should be cost effective with early availability of results. 13Even though a positive blood culture is gold standard for diagnosis of neonatal sepsis the technique is time consuming, demands a proper laboratory setup and is positive in only 40% cases. 16rly treatment with antibiotics is possible with the help of certain indirect markers such as neutropenia (<1800 cells/ mm 3 ), leucopenia (<5000 cells/mm 3 ), band cells, micro ESR and C-reactive protein (CRP).All these investigations are collectively known as sepsis screen and aids in early diagnosis of neonatal sepsis in absence of negative blood cultures.They together can be used as sepsis screen.Presence of two or more abnormal parameters in case of strong clinical suspicion is considered as positive sepsis screen.The results can be obtained much earlier than blood culture and early medical intervention can be issued.This can be helpful to reduce neonatal mortality and morbidity. 17e purpose of this study was to evaluate the early indicators of sepsis screen and their statistical correlation with blood culture (considered as gold standard) in neonatal septicemia.All these will help in early diagnosis of neonatal septicemia and its speedy management and ultimately lead to timely intervention thus leading to reduced mortality and morbidity amongst neonates afflicted with neonatal sepsis. 18

MATERIAL AND METHODS
This was a descriptive prospective study carried out in Kist Medical College, Imadol, Kathmandu, Nepal.For ethical issues confidentiality of patient's information was considered and ethical clearance was duly taken from institutional ethics committee and progress of study was duly intimated to the ethics committee time to time.All the neonates admitted to the baby nursery between October 2015 to October 2016, with signs and symptoms of sepsis or presence of predisposing factors for development of sepsis, were included in this study.

Inclusion criteria
Neonates were enrolled on the basis of signs and symptoms of clinical sepsis (as per NNF criteria) 18 after through clinical examination and proper history taking.

Exclusion criteria
Neonates who received antibiotics before Admission, Neonates who died before work up was complete, Neonates who underwent surgery, Congenital anomalies e.g.tracheoesophageal fistula, lobar agenesis, malrotation of the gut, complex heart diseases, neural tube defects etc. Inborn errors of metabolism Each patient was studied in a methodical manner using a

Statistical analysis and Ethical Clearance
It was done as per standard statistical tools.A 'p' value less than 0.01 was considered to be statistically significant.Some help was taken from statistical package for social sciences (SPSS, Version 21) software.

RESULTS
Out of 150 suspected neonatal sepsis patients, 56 % (84) were males and 44% (66) were females.Thus male babies were more affected by suspected neonatal sepsis than female babies.Among the patients with suspected neonatal sepsis, the most common presenting clinical feature was respiratory distress followed by fever and feeding problems.
( to identify the pathogen and determine its antibiotic susceptibility pattern, but for better survival and outcome, simple and rapid diagnostics tests are required as adjuncts to the blood culture for early and effective initiation of treatment to the septicemia in neonates. In this study, Coagulase positive Staphylococcus(41%), Coagulase negative staphylococcus (CONS) (29%), Citrobacter (12%), Acinitobacter (6%), Escherichia coli (6%), Enterobacter(6%) were the common organisms associated with sepsis.
In a similar study done in India most prevalent organisms were coagulase negative staphylococcus(CONS) followed by Coagulase positive staphylococcus, streptococcus fecalis, alpha-hemolytic Streptococcus, klebsiella, proteus, E.coli and Candida albicans. 19The causative organisms in neonatal sepsis vary from place to place and the frequency of the causative organisms is different in different hospitals and even in the same hospital at different time.
The other published data in Nepal on the subject shows E.coli as the most common isolate. 20,21The study carried out in western Nepal showed Staphylococcus aureus to be the most common isolate. 22E.coli was the leading cause in many studies done in Nepal. 20,21E. coli was the second most common isolate as reported from Uganda. 23taphylococcus aureus was the third most common isolate as in India. 24Klebsiella pneumoniae was found to be the fourth most common isolate but the other report in Nepal and India showed Klebsiella pneumoniaeas the second most common cause 14 and in West Indies showed as the most common cause. 25Pseudomonas spp.was isolated from one case in this study but the reports from Iran and India showed Pseudomonas spp. to be the most common cause of neonatal sepsis.
The causative organisms of neonatal sepsis vary with time and place.There is increasing trend of antibiotic resistance to the commonly used and available drugs.Continuous surveillance is needed to monitor changing epidemiology of pathogens and antibiotic susceptibility pattern.
The major presenting clinical features were respiratory distress, fever followed by feeding problems which was in concordance with the study done by Basu R 26 Neonatal Sepsis screen was considered positive if any two criteria of the following were present. 18Absolute Neutrophil Count of ≤1800/cumm • CRP ≥1 mg/dL.
• I/T ratio ≥0.2 • Micro-ESR ≥15mm at the end of 1st hour The ratio of culture positive neonatal septicemia cases was higher among males than the females in the present study, showing a ratio of 1.22.The male preponderance in neonatal septicemia may be linked to the X-linked immuneregulatory gene factor resulting in the host's susceptibility to infections in males. 13There is male preponderance, which is due to the prevalent custom of taking male babies Ilias LM et al. preferentially to healthcare institutions and also because female babies are immunologically more competent. 27ximum culture positive cases were seen in neonates of age ≤72 hours (i.e.77%) as compared to neonates aged more than 72 hours (i.e 23%).This was comparable with other studies, which is shown in table 5.The higher proportion of early onset sepsis cases may be due to the immature immunological responses of the neonates in the first week of life, making them more susceptible to infections in this period.
In present study, the percentage of culture positive cases in low birth weight neonates was 70%.According to Barbara Stoll et al. 32 the rate of infection is inversely proportional to the birth weight, and low IgG levels due to impaired cellular immunity in the very low birth weight neonates contributes to the increased susceptibility to infections in these neonates. 32In present study, sepsis was not common in preterms.Similar finding was seen in the study done by Mondal et al. 33 However, the sepsis was more common in preterm neonates than in term babies in other studies.Preterm babies are more susceptible to infections due to inherent deficiencies of both humoral and cellular defense mechanisms.According to Barbara J. Stoll et al 32 the incidence of septicemia increased with the decreased gestational age of the neonates. 32(Table 6) Cut off value of absolute neutrophil count≤1800/μl was taken as diagnostic criterion for sepsis screen.Absolute neutrophil count in the sepsis screen showed low sensitivity (42.9%) and high specificity (99.0%).The positive predictive value was 97.5% and negative predictive value was 65.6% Absolute neutrophil count showed highest specificity and positive predictive value among all the other parameters of sepsis screen.(Table 7) C-reactive protein ≥1mg/dl was considered as positive result for sepsis screen.Predictive accuracy of CRP of this study is compared with other studies (Table 8).
In present study, CRP had a high sensitivity of 77.8%, specificity (66.7%), positive predictive value (68.2%) and negative predictive value (76.5%)CRP proved to be the most efficient of all the markers of sepsis.The principal ligand to CRP is phosphocholine, which is found in lipopolysaccharide, bacterial cell walls, as well as in most biological membranes. 35CRP is part of the acute-phase response which aims to neutralize the inflammatory agent and to promote the healing of the injured tissue. 36ring the acute-phase-response, CRP's hepatic synthesis rate increases within hours and can reach 1,000-fold levels. 35Despite the ongoing rise (and fall) of new infection markers, its wide availability and its simple, fast, and costeffective determination make it one of the preferred indices in many neonatal intensive care units (NICUs). 37 present study, immature to total neutrophils ratio≥0.2 was diagnostic criterion for sepsis screen.Sensitivity, specificity, positive predictive value and negative predictive value was acceptable with a p-value of <0.001.This was comparable to other studies.(Table 9) Two or more abnormal parameters had a high accuracy in predicting neonatal sepsis.The results in the present study were in accordance with Gerdes et al 37 Jadhav et al 15 and Bhale et al 31 The sensitivity of two or more abnormal parameters was 90.3%, specificity was 75.6%, positive predictive value was 77.0% and negative predictive value was 89.0% as shown in table 11.The sepsis screen should be considered as a positive septic screen, If two parameters are abnormal and antibiotic therapy can be started.If there is strong clinical suspicion and sepsis screen is negative, in 12 hours the screen can be repeated.If the screen is negative even after that, then sepsis may not be present.

CONCLUSION
CRP had highest sensitivity, specificity, positive predictive value and proved to be a sensitive and responsive indicator of neonatal sepsis.The presence of two or more abnormal parameters has more sensitivity than any single abnormal parameter.The combination of tests also yielded statistically significant correlation with blood culture status than individual test.The parameters used in this study are simple, quick and cost effective.
Amongst early onset sepsis the predominant clinical features were respiratory distress (manifested by tachypnoea and grunting) followed by fever and poor feeding.The results obtained from sepsis screen cannot establish or rule out neonatal sepsis completely.The gold standard remains blood culture.False positive cases may receive unwanted antibiotic therapy.

Table 3 : Sepsis screening parameters in relation to blood culture Bloodculture positive
i. Sepsis screen (according to NNF criteria) a.Total leukocyte count b.I/T ratio (band cell ratio) c.Absolute neutrophil count d. m-ESR e. C reactive protein ii.Blood culture

Table 1
As illustrated in table 3 significant number (n=65; 90.3%) of culture positive cases were positive for two or more septic screen parameters.On contrary, only 7 of septic screen negative cases were culture positive.Blood culture negative suspicious sepsis cases, which were positive for septic screen parameters were total 33 in number.45 cases were both culture and septic screen negative but had strong clinical suspicion for sepsis.Lakhey A et al.DOI : 10.3126/jpn.v7i1.16944