|Year : 2016 | Volume
| Issue : 2 | Page : 252-258
Serum leptin level as a marker of neonatal sepsis
Ghada M El-Mashad, Hanan M El-Sayed, Osama H Salem
Department of Pediatrics, Faculty of Medicine, Menoufia University Nefia, Tanta, Gharbia, Egypt
|Date of Submission||17-Aug-2014|
|Date of Acceptance||24-Sep-2014|
|Date of Web Publication||18-Oct-2016|
Osama H Salem
Nefia, Tanta, Gharbia, 31511
Source of Support: None, Conflict of Interest: None
For evaluation of serum leptin level in neonates with sepsis to aid early and accurate diagnosis and treatment.
Leptin is a polypeptide hormone that is mainly, but not exclusively, produced in adipose tissue and plays an important role in the innate immune defense. This study was designed to evaluate the level of serum leptin in cases of neonatal sepsis.
Materials and methods:
This study was carried out on 50 neonates divided into a case group (30 neonates with sepsis) and a control group (20 healthy neonates). All patients in the study were subjected to adequate assessment of history, full clinical examination, complete blood cell, C-reactive protein with titer, blood culture, and serum leptin assay by ELISA at the time of diagnosis and after recovery from sepsis.
The study showed that neonates who developed sepsis had significantly higher serum leptin levels than those of the control group and leptin levels were significantly higher in patients before antimicrobial therapy than after antimicrobial therapy.
Also, there were no significant correlations between serum leptin and complete blood cell parameters or C-reactive protein, but there was a significant positive correlation with the sepsis score.
A significantly higher level of serum leptin was found in patients with positive blood cultures compared with those with negative blood cultures, but there was no difference in the serum leptin level between survivors and nonsurvivors.
The study showed that the best cut off value for serum leptin in the detection of sepsis was 2.75 ng/ml with a sensitivity of 75% and a specificity of 70%.
Serum leptin plays a role in neonatal sepsis.
Keywords: leptin in sepsis, leptin marker, neonatal sepsis, neonatal septicemia, sepsis markers
|How to cite this article:|
El-Mashad GM, El-Sayed HM, Salem OH. Serum leptin level as a marker of neonatal sepsis. Menoufia Med J 2016;29:252-8
| Introduction|| |
Despite improved neonatal care over the past decades, infections remain common and sometimes life-threatening in neonates admitted to the neonatal intensive care units (NICU).
For many years, a search has been ongoing to find predictors for neonatal sepsis that identify effectively patients who are at risk of infection.
Leptin is an important immunoregulatory hormone as it enhances a number of immune responses, including macrophage effector functions .
The leptin level increases in response to infection and inflammatory stimuli .
The aim of this study was to evaluate serum leptin level in neonates with sepsis to aid early and accurate diagnosis and to provide an effective treatment.
| Materials and Methods|| |
This study was carried out on 50 neonates delivered in the Obstetrics and Gynecology Department, El Menshawy Hospital, and followed up at the neonatal intensive care unit in the same hospital. The study was carried out from April 2013 to December 2013.
The neonates were divided into two groups.
Group 1 was the case group, which included 30 neonates diagnosed with neonatal sepsis on the basis of clinical and laboratory data.
Group 2 was the control group, which included 20 apparently healthy neonates with no clinical signs or laboratory evidence of sepsis.
This study was carried out on full-term neonates and preterm neonates.
- Severe congenital anomalies.
- Chromosomal abnormalities.
- Intrauterine growth retardation.
- Perinatal asphyxia.
- Infant of a diabetic mother.
For all neonates, the following were performed:
- Assessment of history (to detect risk factors for sepsis).
- Obstetric history (death of a previous sibling, previous admission to NICU, etc.).
- Prenatal history [diabetes mellitus, maternal fever >38°C, maternal antibiotics, maternal urinary tract infection (UTI), etc.].
- Natal history [premature rupture of membrane (PROM), maternal fever, prolonged second stage of labor, etc.].
- Postnatal history (low Apgar score at 1 and 5 min, aggressive resuscitation, respiratory distress, cyanosis, fever, jaundice, etc.).
- Current history, which includes most common symptoms of sepsis.
- Thorough clinical examination:
- Assessment of gestational age using the new Ballard score.
- Birth weight measurement.
- Detection of clinical signs of sepsis:
- Temperature instability (<37 or >38.5°C).
- Respiratory dysfunction (apnea, intercostal retraction, increased oxygen requirement, signs of respiratory distress).
- Circulatory dysfunction (poor peripheral circulation, hypotension, tachycardia, shock, prolonged capillary refill).
- GIT dysfunction (abdominal distension, bloody stool, feeding intolerance, hepatomegaly, jaundice).
- Neurological dysfunction (irritability, hypotonia, lethargy).
- Hypoglycemia or hyperglycemia.
- Petechiae, bleeding (with thrombocytopenia), or DIC.
- Laboratory investigations at diagnosis of sepsis including:
- Complete blood cell count with differential leukocytic count.
- C-reactive protein (CRP) quantitative assay.
- Blood culture.
- Serum leptin level was assessed by an enzyme-linked immunosorbent assay (ELISA) using a commercially available kit. This was repeated after successful antibiotic treatment indicated by CRP less than or equal to 6.
- Statistical presentation and analysis of the present study were carried out using the mean, SD, and χ2-test.
Neonates were followed up in the NICU for clinical symptoms and signs of sepsis, and laboratory evidence of sepsis.
An informed consent was obtained from the parents before their enrollment in the study. The study was approved by the Ethical Committee of Faculty of Medicine, Menoufia University.
Principle of the leptin test
The DRG Leptin (Sandwich) ELISA (EIA-2395) RUO in the USA is a solid-phase ELISA based on the sandwich principle. The microtiter wells are coated with a monoclonal antibody directed toward a unique antigenic site on a leptin molecule. An aliquot of sample containing endogenous leptin is incubated in the coated well with a specific biotinylated monoclonal antileptin antibody. A sandwich complex is formed. After incubation, the unbound material is washed off and a streptavidin peroxidase enzyme complex is added for detection of the bound leptin. On addition of the substrate solution, the intensity of color developed is proportional to the concentration of leptin in the sample.
| Results|| |
This study showed that there was no significant difference between the case and the control group in the mean gestational age, sex, and mode of delivery. Birth weight and Apgar scores at 1 and 5 min. were highly significantly lower in the case group compared with the control group.
It was also found that in the case group, there was a highly significant increase in the occurrence of PROM more than 18 h, need for resuscitation, and maternal UTI, whereas there was no significant difference between both groups in the incidence of chorioamnionitis or mortality rate.
It was also observed that 56.7% of cases needed mechanical ventilation, 90% developed respiratory distress, 23.3% developed pallor, 16.7% developed bleeding, 26.7% developed jaundice, 46.7% developed hypotonia, 63.3% of cases had poor reflexes, 100% developed feeding intolerance, 83.3% had poor perfusion, 66.7% were lethargic, 56.7% developed hypotension, and 83.3% had temperature instability ([Figure 1]).
In addition, there was a highly significant decrease in hemoglobin (Hb) and platelet count in the case group before treatment compared with the control group. Also, there was a highly significant increase in total leukocytic count (TLC), mature polymorphonuclear leukocytes (PMN) count, immature PMN count, immature to total neutrophil (I/T) ratio, CRP, and serum leptin level (before and after treatment) in the case group ([Table 1]).
|Table 3: Comparison between survivors and nonsurvivors in the case group|
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Moreover, 23.3% had negative blood cultures and 76.6% of the case group (23 patients) had positive blood cultures; 36.7% of these were positive for Klebsiella spp., 16.7% were positive for Staphylococcus aureus, 13.3% were positive for Escherichia More Details coli, 6.7% were positive for b-hemolytic streptococci, and 3.3% were positive for Candida albicans ([Figure 2]).
|Figure 4: Comparison between serum leptin level in patients with positive and negative blood cultures in the case group.|
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There was also a highly significant decrease in serum leptin in the case group after successful management of neonatal sepsis ([Figure 3]).
|Figure 3: Comparison between serum leptin level before and after treatment in the case group.|
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This study showed that serum leptin showed a significant positive correlation with the sepsis score (the higher the sepsis score, the higher the serum leptin level), whereas there were no significant correlations with the other parameters measured in the case group ([Table 2]).
|Table 2: Correlation between serum leptin and other parameters measured in the case group|
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Serum leptin was significantly higher in patients with a positive blood culture compared with those with a negative blood culture ([Figure 4]).
There was no significant difference between survivors and nonsurvivors in the case group in the parameters presented in [Table 3].
|Table 1: Comparison between the case group (before treatment) and the control group of laboratory data for neonatal sepsis|
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Finally, it was found that serum leptin level was reliable in the detection of sepsis (P<0.01). The cutoff value was 2.856 ng/ml with 76.1% sensitivity and 71.4% specificity ([Figure 5]).
|Figure 1: Percentages of clinical manifestations of neonatal sepsis in the case group.|
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| Discussion|| |
In the current study, it was found that lower birth weight was associated significantly with increased frequency of sepsis. This was also observed in several other studies ,,,.
In the current study, it was found that Apgar scores at 1 and 5 min were highly significantly lower in the case group than in the control group. This was in agreement with a study that observed that a 5-min Apgar score of less than 7 carries a significantly higher risk of sepsis than infants with higher scores and that an Apgar score less than 5 at 1 min may be because of sepsis, especially with the presence of risk factors for infection .
Furthermore, low Apgar scores usually necessitate more prolonged and aggressive resuscitation, which is a known risk factor for sepsis .
In the current study, it was found that the mode of delivery was not associated significantly with increased frequency of sepsis. This is in agreement with other studies ,.
However, this is not in agreement with a study that observed that babies born by vaginal delivery were more likely to have EOS than those delivered by cesarean section. This may be related to good sterilization and intrapartum chemoprophylaxis, which markedly decreased the risk of sepsis in neonates delivered by cesarean section .
In the current study, it was found that PROM more than 18 h, need for resuscitation, and maternal UTI were significant risk factors for neonatal sepsis, whereas chorioamnionitis was not on comparing the case and the control groups.
These results are in agreement with the studies of Kaufman and colleagues ,, and not in agreement with the studies of López Sastre and colleagues ,, who found that chorioamnionitis was also a significant risk factor for neonatal sepsis.
In the present study, clinical evaluation of neonates with sepsis showed that feeding intolerance (100%), respiratory distress (90%), temperature instability (84%), lethargy (66.7%), poor perfusion (83%), hypotension (56.7%), poor reflexes (64%), and jaundice (27%) were the most common clinical presentations. This is in agreement with a study that described them as the major clinical presentations of sepsis .
In this study, it was found that there was a significant difference in hematological parameters (Hb level, TLC, platelet count, I/T ratio, mature PMN, and immature PMN) between the case and the control group. These results were in agreement with those of some studies ,,.
In the current study, there was a significant difference in the CRP level between the case and the control group. This is in agreement with the results some studies ,,.
In the current study, blood cultures were positive in 23 (76.7%) cases. The sensitivity of blood cultures in neonatal sepsis is low and depends on the number and timing of cultures taken, blood volume, culture medium, technique, temperature and organism density .
Similar results have been found in the Betty and Inderpreet study , which found that culture-proven sepsis occurred in 41.6% of cases with sepsis.
In the study by Procianoy and Silveira , it was found that blood cultures were positive in only 18 of a total of 85 cases (21%).
In addition, a study reported that the actual burden of EOS as indicated by culture-proven cases is underestimated because blood cultures can be falsely negative in at least 50% of infants .
Furthermore, another study  reported that the administration of peripartum maternal antibiotic treatment makes the diagnostic value of neonatal blood cultures uncertain.
In the present study, Klebsiella pneumoniae was the most common organism isolated in the positive blood cultures, followed by S. aureus and E. coli (36.7, 16.7, and 13.3%, respectively), and the least common organisms were C. albicans and β-hemolytic streptococci (6.7 and 3.3%, respectively).
This is in agreement with the study of Dzwonek et al. , in which nearly half of the positive blood cultures grew K. pneumoniae.
However, in the study of de Benedetti et al. , the isolated pathogens included K. pneumoniae (47.5%), Pseudomonas aeruginosa (20%), E. coli (10%), C. albicans (10), S. aureus (7.5%), and Enterococcus spp. (5%).
This variation may be because of differences in the environment, the microbial etiology of sepsis, and supportive care practice in the centers .
In the current study, it was found that leptin levels were highly significantly higher in the patient group than the control group. Also, it was found that leptin levels decreased significantly in the patient group after antimicrobial therapy.
This is in agreement with the study of Orbak et al. , which found that serum leptin levels in newborns with septicemia were significantly higher than those of the control group and that leptin levels were significantly higher in patients before antimicrobial therapy than after antimicrobial therapy. Similar results have been found by a study by Saleh et al.  that included 14 full-term infants with clinical or proven septicemia and 14 full-term healthy infants in a control group. They showed a highly significant increase in serum leptin levels on comparing the studied cases before and after treatment separately and with the control group.
This is also in agreement with the studies of Bornstein and colleagues ,, who found that leptin levels were significantly higher in adult septicemic patients.
This is not in agreement with the Koç et al.'s study , which found that there was no significant difference in serum leptin levels between septic and control infants; there was also no difference in serum leptin levels in septic neonates before and after therapy.
In the current study, it was also found that there was no correlation between serum leptin levels and birth weight.
These results are not in agreement with the studies of Christou et al. ,,,, who found that birth weight was related strongly to leptin levels in cord blood.
In the current study, it was also found that there was no correlation between serum leptin levels and gestational age.
These results are not in agreement with the Tarquini et al.'s study , which found that gestational age was related strongly to leptin levels in cord blood.
In the current study, it was found that there were no correlations between serum leptin levels and all other hematological parameters (Hb level, TLC, platelets count, ANC, I/T ratio, and I/M ratio).
This is in agreement with other studies , that found that there were no correlations between serum leptin levels and Hb level, TLC, platelets count, ANC, and I/M ratio and not in agreement with the Somech et al.'s study , which found that there were positive correlations between serum leptin and both TLC and ANC. Also, the Orbak et al.'s study  differed in that there was a positive correlation between serum leptin levels and the IT ratio.
In the current study, it was found that there was no correlation between serum leptin levels and CRP.
This is not in agreement with the results of the studies of Orbak and colleagues ,,, who found that there was a positive correlation between serum leptin levels and CRP.
In the current study, it was also found that there was a positive correlation between leptin level and the sepsis score, which increased with increasing severity of sepsis.
This is not in agreement with the results of the Carlson et al.'s study , which showed that the severity of sepsis had no significant influence on serum leptin concentration. Also, the Quirós et al.'s study  found that increases in leptin levels were not associated with the severity of sepsis score.
Our study showed that serum leptin level was significantly higher in patients with a positive blood culture compared with those with a negative blood culture.
These results were not in agreement with the Díez et al.'s study , which found that patients with positive blood cultures showed lower serum leptin levels in septic adults.
In the current study, it was found that there was no significant difference in leptin levels between survivors and nonsurvivors in the case group.
These results were not in agreement with the Torpy et al.'s study , which found that leptin levels were lower in the non-survivors than in the survivors. Also, the Arnalich et al.'s study  showed that survivors of severe sepsis and septic shock had leptin concentrations that were 1.3-fold and 1.6-fold greater than those of non-survivors in each group.
Also, our results were not in agreement with the Quirós et al.'s study  study, which found that the increase in the leptin level was higher among nonsurvivor patients than in survivors.
Our study showed that the best cut-off value of serum leptin for the detection of sepsis is 2.856 ng/ml with a 76.1% sensitivity and a 71.4% specificity.
| Conclusion|| |
From the results of the study, we conclude that serum leptin level increases significantly in neonates with sepsis and decreases significantly after antimicrobial therapy.
This suggests that leptin is not only an adipostatic hormone but also a stress-related hormone.
Also, it seems that serum leptin plays a role in neonatal sepsis.
Conflicts of interest
There are no conflicts of interest.
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[Figure 5], [Figure 4], [Figure 3], [Figure 2], [Figure 1]
[Table 3], [Table 2], [Table 1]