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Clinico-bacteriological Profile of Neonates Born with Risk Factors of Septicemia |
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Priyamvada Roy, Ashwani Kumar, MMA Faridi, Iqbal R Kaur, Bineeta Kashyap 1. Senior Resident, Maulana Azad Medical College. 2. Professor, Department of Microbiology, U.C.M.S and G.T.B hospital. 3. Professor and Head, Department of Pediatrics, U.C.M.S and G.T.B hospital. 4. Professor and Head, Department of Microbiology, U.C.M.S and G.T.B hospital. 5. Assistant Professor, Department of Microbiology, U.C.M.S and G.T.B hospital. |
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Correspondence Address : Dr. Priyamvada Roy, Care of Group Captain DD Roy, Flat Number C-115, Jalvayu Vihar (Near AWHO), Plot Number 8, Pocket P-4, Builder’s Area, Greater Noida-201310, Uttar Pradesh, India. Phone: 9953820283 Email: priyamvadaroy@yahoo.in |
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| ABSTRACT |  | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
: Background: Septicemia is the single most important cause of neonatal morbidity and mortality in the world, accounting for over half of the cases. Aim: This study was conducted to establish the clinical and bacteriological profile in newborns with risk factors of septicemia. Subjects and Methods: One hundred and fifty consecutive neonates delivered with risk factors of septicemia were recruited after obtaining informed consent. Blood culture was done using BACTEC PEDS PLUS/F CULTURE vials as a part of sepsis screen used to diagnose septicemia. In addition acute phase reactants like total leucocyte count and C-reactive protein measurements were also documented. Statistical analysis: Correlation of all risk factors with laboratory findings was obtained by using Pearson chi-square test and Fisher’s exact test. p-value of less than 0.05 was considered as significant. Results: Blood culture positivity was found in 28% neonates born with risk factors of septicemia out of which 57.1% were gram-positive and 42.9% were gram-negative isolates respectively. Staphylococcus aureus being the most common among the gram-positive bacteria, was isolated in 19 (45.2%) of cases. Among the gram-negative bacteria, Acinetobacter baumannii was the most common being present in 13 (30.9%) of cases. Among all the risk factors studied, fever in the mother was significantly correlating with positive sepsis screen. Conclusion: Blood culture positivity increases with increase in number of risk factors in neonatal septicemia. Hence screening tests for septicemia must be done routinely in such cases. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Keywords : Neonate, Risk factors, Septicemia, C-reactive protein, Fever in mothers | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| INTRODUCTION |
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Neonates hospitalized with septicemia in the Neonatal Intensive Care Unit (N.I.C.U.) is a global problem and a significant contributor to morbidity and death. World Health Organization (WHO) estimates about 3.3 million neonatal deaths a year, majority of them occurring in developing countries (1). Septicemia has been found to occur in 2.3% of intramural live births (2). A high index of suspicion is important in the management of neonatal septicemia because the diagnosis is hampered by vague, nonspecific or nonexistent clinical manifestation. However, it is imperative that treatment is instituted early in these cases because of the high mortality associated with neonatal septicaemia (2). Early empiric antibiotic treatment of neonates suspected of having septicemia is the standard practice. Nonetheless, the problem of unnecessary exposure to antibiotics in this vulnerable population remains, creating an environment for emerging bacterial resistance and the potential for poor outcomes (3). Also definitive culture results takes at least 48-72 hours resulting in treatment delays. Hence, a battery of tests called sepsis screen which includes acute phase reactants, X-ray chest, urine examination and blood culture, is used to diagnose septicemia early and initiate a presumptive treatment. Acute phase reactants include CRP, IL-6, micro-ESR, total leucocyte count and absolute neutrophil count. If any two of the tests in sepsis screen are positive, it is taken to be positive as per A.I.I.M.S. N.I.C.U. protocol 2008 (4). Isolation of bacteria from a central body fluid (usually blood) is the standard and the most specific method to diagnose neonatal septicemia (4). Despite the fact that a majority of the cytokine markers have high negative predictive values these have not been adopted for general medical use (5), mainly because of their relatively high cost and lack of validated studies. There is insufficient data available to correlate the risk factors of neonatal septicemia with the clinical and bacteriological profile of these neonates. Through this study, an attempt was made to establish the clinical and bacteriological profile of newborns with risk factors of neonatal septicemia. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material and Methods |
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This prospective observational study was conducted in the Department of Microbiology and Pediatrics (N.I.C.U level III) of a 1500-bedded government hospital in Delhi, India for 18 months. Ethical approval certificatefor the study was obtained from the institutional ethical committee. Inclusion criteria All consecutive neonates delivered in the hospital with at least one of the following risk factors of sepsis mentioned below (4) were recruited after obtaining informed consent from the parents. Preterm premature rupture of membranes1. Amnionitis2. Meconium stained liquor3. Low birth weight (<2.5 kg)4. Preterm (<37 weeks)5. ≥6. 3 per vaginal examinations during labour Active resuscitation required in labour room7. Dai handling8. Fever in the mother during labour (temperature of 9. 38ºC or more) Urinary tract infection in the mother10 Exclusion criteria Babies born to mothers who had received antenatal antibiotic therapy within 48 hours prior to the delivery or had major congenital anomaly. Methodology Hundred and fifty consecutive neonates born with risk factors of septicemia were studied. Of them 90 were males and 40 were females. After recruitment 1.5-2 ml venous blood sample was collected within six hours of birth using aseptic technique, 0.5-1 ml of which was directly transferred into the BACTEC PEDS PLUS/F Culture Vials (Becton Dickinson Biosciences). The remaining portion was used for estimation of C-reactive protein (CRP) and total leukocyte count (TLC). All the samples were transported at room temperature as soon as possible to Microbiology laboratory for further processing. The inoculated BACTEC vials were placed in BACTEC 9120 system. A positive result was indicated by an audible alarm and yellow illumination of the positive indicator lamp at the site of positive vial. On the computer instrument status display the station number was showed by flashing green in case of a positive vial. The bottles were incubated for five days before being reported as negative. A Gram stain and a subculture on blood agar and MacConkey agar were performed from each presumptive positive vial. After incubation at 37ºC the bacterial isolates were identified by gram staining, colony characteristics and a battery of biochemical tests, following a standard protocol (6). Leucocyte count Total leucocyte count (TLC) was done by automated analyser-Coulter L H 500. 5000-25000 leucocytes/μl was taken as normal. C-reactive protein (CRP) CRP latex slide test (SmarTest Diagnostics) was used forthe semi-quantitative measurement of C-reactive protein in human serum. The threshold value was taken as 0.8 mg/dl. Statistical analysis Correlation of all risk factors with laboratory findings was obtained by using Pearson chi-square test and Fisher’s exact test. p-value of less than 0.05 is considered as significant. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results |
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[Table/Fig-1] shows the number of each bacterial species isolated from the blood samples. Staphylococcus aureus being the commonest was isolated in 19 of the cases. Among the gram-negative bacteria Acinetobacter baumannii was the most common being present in 13 of the cases. The frequency of risk factors among newborns recruited for study along with blood culture positivity is shown in [Table/Fig-2]. Low birth weight was the most evident risk factor present among the neonates (87%). Staphylococcus aureus was the commonest isolate recovered from the septicemic neonates (45.2%) followed by Acinetobacter baumannii (31%), Enterococcus sp. (7.1%), Klebsiella pneumoniae (7.1%), Staphylococcus epidermidis (4.8%), Citrobacter koseri (2.4%) and Pseudomonas aeruginosa (2.4%). Staphylococcus aureus was the most common isolate in neonates born with maternal fever during labour. Only Acinetobacter baumannii could be isolated in neonates with history of dai handling and amnionitis. Staphylococcus aureus was the only isolate in neonates born to mothers with preterm premature rupture of membranes. It was also the commonest isolate in neonates born with meconium-stained liquor, preterm and low birth weight neonates. Acinetobacter baumannii was isolated in neonates in whom active resuscitation was done. The blood culture positivity related to the number of risk factors present is shown in [Table/Fig-3]. Maximum numbers of neonates were born with two 79 (52.7%) risk factors followed by three (29.3%) and one (18%) risk factors. The blood culture positivity increased with rising number of risk factors. It was 45.5%, 26.6% and 3.7% with ≥ 3, 2 and 1 risk factors respectively. The CRP and TLC values among the blood culture positive and negative samples are compared in [Table/Fig-4]. Of 42 positive blood cultures, 15 (35.7%) had CRP more than 0.8 mg/dl, whereas amongst the 108 blood culture negative neonates 20 (18.5%) had CRP more than 0.8 mg/dl. Significant association was present between CRP and blood culture result as shown by the p-value. Abnormal leucocyte counts were seen in 2 (4.8%) of 42 positive blood cultures, whereas in all the blood culture negative neonates, leucocyte count was normal. Insignificant association was found between leucocyte count and blood culture results as shown by the p-value. Out of the 42 culture positive neonates, 25 (59.5%) died within seven days, of whom 16(64%) were males and 9 (36%) were females. There was no mortality amongst the culture negative neonates. Mean birth weight of the neonates who died was 1.624±0.568SD kg, and their mean gestational age was 30.12± 0.544 weeks. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Discussion |
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The bacterial species responsible for sepsis vary by geographical location. In [Table/Fig-5] recent studies on causes of neonatal septicemia have been elaborated along with their findings. In the United States Group B Streptococcus is the leading cause of neonatal septicemia (7). However according to the recent (2002-2003) national neonatal perinatal database in India Klebsiella sp. is the commonest bacteria causing neonatal septicemia, followed by Staphylococcus aureus (2). In the present study Staphylococcus aureus, being present in 19(45.2%) of the positive cases, was the most commonisolate. The difference probably reflects variations in population characteristics and in predisposing factors. In our study Gram-positive bacteria were isolated in 24(57.1%) of neonates whereas gram negative bacteria were isolated in 18(42.9%) of neonates. In a study done by Khanal et al., (8) blood samples from 1567 neonates with suspected septicaemia were cultured. Gram-positive bacteria (74%) were more common than gram-negative bacteria (26%), Staphylococcus aureus (60%) being the most common bacterial isolate. The results in this study were comparable to our study as in our study too gram-positive bacteria were more commonly responsible for neonatal septicemia than gram-negative bacteria, with Staphylococcus aureus as the most common bacterial isolate. Our findings are corraborated by two more studies on neonatal septicemia conducted by Muhammad et al., (9) and Agnihotri et al., (10) respectively. In both studies Staphylococcus aureus was the commonest isolate being present in 27% cases in the former and 35% in the latter. Among the gram-negative bacteria obtained in this study, Acinetobacter baumannii was the commonest isolate. Acinetobacter species are gaining importance as a potential pathogen in neonatal septicaemia because of frequent isolation in the recent years (11). In this study Acinetobacter baumannii was isolated in 30.9% of the total septicaemia cases, which is in tune with the incidence of Acinetobacter sepsis reported from India (6.5 to 31.5%) (11). Acinetobacter septicaemia is common in babies with intravenous catheterization and artificial ventilation [11,12]. The most important neonatal factor predisposing to infection is prematurity and/or low birth weight [11,13], since they often require prolonged intravenous access, endotracheal intubation or other invasive procedures that provide a portal of entry for infection. In this study, Acinetobacter baumannii was isolated from majority of the premature and low-birth weight neonates suffering from gram-negative septicemia [Table/Fig-2]. Acinetobacter baumannii was also the only isolate obtained from neonates that had undergone active resuscitation [Table/Fig-2]. A recent study from Pakistan has reported that prematurity and LBW are associated with increasing risk of Acinetobacter infection in neonates (14). Also, use of both central venous catheter and mechanical ventilation were identified as significant risk factors for neonatal Acinetobacter baumanii septicaemia in a Brazilian study (15). Blood culture positivity in our study was related to the number of risk factors present. In the presence of a single risk factor, blood culture positivity was present in 3.7% cases. In the presence of two risk factors, blood culture positivity increased by more than seven times to 26.6%, while in the presence of ≥3 risk factors, blood culture positivity increased by more than 12 times to 45.5%. It may be concluded that as the number of risk factors increase, risk of septicaemia in the neonate also increases. Hence, screening tests for septicaemia must be done routinely in such cases. In the present study, among all the maternal and neonatal risk factors, only maternal fever during labour had a statistically significant association with septicemia (p-value 0.000) [Table/Fig-2]. Maternal fever during labour is defined as a temperature of 38ºC or more. Maternal temperature elevation during labour can be a nonspecific indicator of maternal and/or fetal infection. Much of the fever during labour might not be so much a result of infection, but rather a consequence of the use of epidural analgesia. However, some evidence suggests that epidural analgesia is associated with fever during delivery only in the presence of placental inflammation (21). Similar findings were also present in a study done by Nili et al., (22) where sepsis was present in all (100%) cases with fever in the mother during labour as the risk factor which was a significant finding (p-value= 0.000),and in a retrospective cohort analysis done in the United States for the period 1995-1997 (21), wherein strong association (p-value<0.05) was found between intrapartum fever and neonatal sepsis and mortality. In this study significant association was found between CRP and positive blood culture results (p-value 0.025 [Table/Fig-3]. Similar results were obtained in a study by Caldas et al., (23) where elevated CRP levels were associated with culture-positive cases (p-value<0.05). This indicates the importance of CRP as a significant marker of septicaemia. No significant association was found between leucocyte counts and neonatal septicaemia in this study. Similar result was obtained in a study done in Philippines by Mayuga et al., (24). In a study by Ottolini MC et al., (25) it was found that total leukocyte counts are of limited value in the diagnosis of septicemia in newborns. Total leukocyte counts are particularly unreliable indicator of infection during the first several hours of early-onset (within 48h of birth) sepsis because these are normal at the time of initialevaluation in more than one third of infants with proven bacteremia. Conversely, among neonates evaluated for suspected sepsis, far less than half of neonates with reduced (<5000 cells/mm3) or elevated (>20,000 cells/mm3) cell counts are ultimately identified to be infected (25). Gram-negative (GN) bacteria have often been implicated in the pathogenesis of severe sepsis and septic shock, although the exact mechanism is uncertain (26).There is evidence to support two different theories on how GN bacteria induce harmful systemic responses. The intravascular stimulus hypothesis states that bacteria invade through a normal or damaged epithelium and enter the bloodstream, inducing systemic inflammatory responses (for example, increased vascular permeability, leukocyte–endothelial adhesion, and activation of complement and clotting pathways)resulting in multiorgan failure. A second theory suggests that the multiorgan dysfunction and shock result from neuroendocrine dysregulation and mediators released into the bloodstream from the infected tissues; circulating bacteria or endotoxin are not needed as direct stimuli for intravascular inflammation (27). In the present study gram-negative bacteria, being present in 60% of the non-survivors outnumbered the gram-positive bacteria that were present in 40% of the non-survivors, Similar result was seen in the study by Trotman et al., (28) study where gram-negative bacteria were present in 67% of the non-survivors and gram-positive bacteria were present in 33% of the non-survivors. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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