|Year : 2013 | Volume
| Issue : 3 | Page : 254-257
Role of sepsis screen in the diagnosis of neonatal sepsis
Rabindra N Misra, Savita V Jadhav, Purbasha Ghosh, Nageswari Gandham, Kalpana Angadi, Chanda Vyawahare
Department of Microbiology, Padmashree Dr D Y Patil Medical College, Hospital and Research Centre, Dr D Y Patil Vidyapeeth, Pune, India
|Date of Web Publication||5-Jul-2013|
Savita V Jadhav
Department of Microbiology, Pad. Dr. D.Y. Patil Medical College, Hospital and Research Centre, Pune - 18, Maharashtra
Background: Neonatal sepsis is the single most important cause of neonatal deaths globally. The incidence of neonatal sepsis in India is 30/1000 live births. Though blood culture is the gold standard, but it is not always positive even if clinical features of sepsis are present in the neonate. Materials and Methods: Blood cultures and sepsis screen was carried out on 115 neonates. Out of 115 neonates with clinical features of sepsis, 75 were blood culture positive. Sepsis screen was carried out with total leucocytes count, absolute neutrophils count, ratio of immature neutrophils (band forms) to total neutrophil count, C-reactive protein. The identification of the causative organism was carried out by standard identification tests and antibiotic sensitivity testing as per Clinicaland Laboratory Standards Institute (CLSI) guidelines. Results: In this study, out of 115 cases of clinical neonatal sepsis 75 (65.2%) were culture positive. Among isolates, number of gram negative bacilli were 39 (52%) was more than gram positive cocci 36 (34.8%). However, Staphylococcus aureus 24 (32%) was most predominant. Forty (34.8%) were culture negative out of which 15(13%) neonates were positive for two or more sepsis screen tests. Conclusion: Blood culture and sepsis screen should be carried out in neonates suspected of sepsis; however, an immediate institution of empirical antibiotic therapy should be considered as culture positive and sepsis screen may not be positive in all the clinical sepsis cases to save lives.
Keywords: Blood culture, sepsis screen, methicillin sensitive Staphylococcal aureus, neonatal sepsis
|How to cite this article:|
Misra RN, Jadhav SV, Ghosh P, Gandham N, Angadi K, Vyawahare C. Role of sepsis screen in the diagnosis of neonatal sepsis. Med J DY Patil Univ 2013;6:254-7
|How to cite this URL:|
Misra RN, Jadhav SV, Ghosh P, Gandham N, Angadi K, Vyawahare C. Role of sepsis screen in the diagnosis of neonatal sepsis. Med J DY Patil Univ [serial online] 2013 [cited 2014 Apr 19];6:254-7. Available from: http://www.mjdrdypu.org/text.asp?2013/6/3/254/114649
| Introduction|| |
Neonatal sepsis is the leading cause of neonatal deaths globally. The incidence of neonatal sepsis in India is approximately 30/1000 live births.  However, the diagnosis of neonatal sepsis may not be easy clinically. Many risk factors are associated with neonatal sepsis, and clinical features of neonatal sepsis are often non-specific. Though, blood culture is the gold standard, but it is not always positive even if clinical features of sepsis are present in the neonates. Hence, high index of suspicion is necessary for early diagnosis of sepsis, and when blood culture tests are negative, a battery of sepsis screen tests may help in the diagnosis. The aim of the present study is to find out the relevance of sepsis screen tests in the diagnosis of neonatal sepsis.
| Materials and Methods|| |
A prospective study was carried out from October 2010 to October 2011 in Pad. Dr. D.Y. Patil Medical College and Hospital, a Tertiary Care Hospital in Semi-urban area of Maharashtra. During this period, 115 neonates with the clinical features of sepsis were admitted to this hospital. Blood cultures from neonates were carried out as per standard guide lines before starting empirical antibiotics.  In short 1-2 ml blood was collected aseptically from each clinically suspected new born with the suspected sepsis and inoculated into 10 ml brain heart infusion broth and incubated at 37° C for 24 h. Subcultures were carried out on Blood agar and MacConkey agar and incubated aerobically overnight at 37°C. The identification of organisms were carried out as per standard protocols.  Antibiotic sensitivity tests for the isolates including detection of methicillin resistant Staphylococcus aureus (MRSA) and Metallo β-lactamase among Enterobaceriaceae were carried out as per CLSI guidelines. 
A battery of sepsis screen tests were carried out on the blood samples of all the neonates. These included C-reactive protein ([CRP]>1 mg/dl), total leukocyte count (TLC) for the presence of leukocytosis (>15,000/cumm) or leucopenia (<5000/cumm), absolute neutrophil count for neutropenia <1800/cumm, immature to total neutrophils ratio ([I/TN]>0.2). Presence of two or more abnormal septic screen parameters is suggestive of neonatal sepsis. ,, Cerebrospinal fluid (CSF) study, radiological tests were carried out where indicated depending on the clinical features. The statistical significance of individual sepsis screen test for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using Epi Info software system.
| Results|| |
A total of 115 neonates presented clinically with features of sepsis as shown in [Table 1]. Out of them 75 (65.21%) were blood culture positive and 40 (34.78%) were blood culture negative. Among the sepsis screen tests, CRP was positive in 90.7% of culture positive cases TLC was increased in 93.3% of culture positive cases. Neutropenia was present in 15/75 neonates with blood culture positive and 5/40 neonates with blood culture negative. It had 87.5% specificity and PPV was75%. The sensitivity, specificity, PPV, and NPV of all the tests are shown in [Table 2], [Figure 1].
|Figure 1: Comparisons of sepsis screen parameters between culture positive and negative cases|
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Out of 75 culture positive cases, 39 (52%) were Gram negative bacilli, 36 (48%) were Gram positive cocci and 1 (1.33%) was a fungal isolate (Candida sp.) [Figure 2]. S. aureus was isolated in 24 (32%) blood cultures followed by Klebsiella spp. 12 (16%).
Methicillin sensitive Staphylococcus aureus (MSSA) 14 (19.44%) was the major Gram positive isolate, which showed 100% susceptibility to oxacillin, cefoxitin, and vancomycin, The major Gram negative isolates were Klebsiella spp. (24.11%) including Klebsiella oxytoca. Klebsiella sp. was 97.67% susceptible to imipenem followed by ciprofloxacin (93.02%).
| Discussion|| |
Neonatal infection is one of the major problems in developing countries, including India. It is extremely important to make an early diagnosis of sepsis, because prompt institution of empirical antimicrobial therapy may be life-saving.  In this prospective study, out of 115 cases, 75 were culture positive and 40 were culture negative. The proportion of culture positive septicemia cases were higher among the low birth weight, premature, and preterm neonates as they were more susceptible to infections due to inherent deficiency of both humoral and cellular immunity during the first week of life. 
Clinical features of septicemia were varied and non-specific. We observed that the respiratory distress was the commonest presentation in 74/115 neonates and hypoxic ischemic encephalopathy (HIE) in 15 neonates [Table 1]. CRP was positive in 68/75 culture positive sepsis cases (90.7%) and 25/40 culture negative sepsis cases (62.5%) with specificity of 90.7% and sensitivity of 37.5%. Similar observations were made by Da Silva et al. 
Among the sepsis screen tests 70 (93.3%) neonates with septicemia were having leukocytosis, and 20 cases were found to be leucopenic [Table 2]. Leucopenia was a better predictor of septicemia as compared to leukocytosis as it had higher specificity (87.5% vs. 25%). Since, leucopenia was present in very few sepsis cases, the sensitivity was low (20%) but of great help in the diagnosis of septicemia in culture negative cases (5/40). Severe bacterial sepsis may demonstrate an increase in TLC due to rise in mature and immature neutrophils. This could be possibly due to release of various growth factors and cytokines viz. G-CSF, GM-CSF, IL-3, IL-6, which stimulate bone marrow. Band forms or immature neutrophils may increase due to rapid production. , On the other hand, very severe and fatal bacterial sepsis were often characterized by leucopenia.  I/TN ratio showed relatively high (80%) sensitivity and 65% specificity; however, results may be variable as shown in other studies. , When results of two or more sepsis screen tests were combined, both sensitivity and specificity increased.  The relationship between sepsis screen tests and blood culture positivity is shown in [Figure 1].
Among 40 culture negative suspected neonatal sepsis cases, 15 (37.5%) were positive for two or more sepsis screen tests. Twenty six (65%) blood culture negative babies with features of sepsis were with risk factors such as respiratory distress or HIE and 3 (7.5%) had radiological evidence of pneumonia. Most of the babies had more than one clinical criteria for diagnosis of sepsis. They also showed abnormal TLC (6.9%), abnormal neutrophil count (48.9%), CRP positive (51.4%). Two or more tests positive in 48.2% of culture negative cases as seen by other workers. , In their study, they observed low birth weight (LBW) in 48.7%, preterm 20.5%, birth asphyxia in 29.5%. Hence, culture negativity cannot exclude sepsis totally though culture is the gold standard.
Our percentage positivity of blood culture results were comparable with other workers. , Two sets of blood culture usually improve the chance of isolation. In the present study, S. aureus was the predominant isolate, followed by Klebsiella pneumonia [Figure 2] as was found by other workers. , The acquisition of pathogenic S. aureus from sites such as anterior nasal alae, axilla, perineal area of carriers, e.g., health workers, mother, relatives, and umbilical stump of other babies was possible. K. pneumoniae, a normal flora of the gastrointestinal tract had emerged as a significant nosocomial pathogen in neonatal intensive care unit (NICU) (24.11%). Most of the MSSA, i.e., 14 (19.44%) strains were sensitive to routinely used antibiotics and possibly acquired from the community. However, some MRSA strains, i.e., 10 (11.5%) were possibly acquired from the hospital environment. The Klebsilla spp. was sensitive to many antibiotics including imipenem.
| Conclusion|| |
In the view of changing spectrum of etiology and growing multidrug resistant neonatal sepsis pose a serious problem globally. Management of neonatal sepsis can be carried out by proper antenatal care, proper hand washing, and clean birth environment, clean cord care, and strict asepsis in nursery. The prompt institution of empirical antibiotic therapy and supportive care will save many cases of neonatal sepsis. Sepsis screen together with blood culture helps in diagnosis of neonatal sepsis.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]