Neonatal Sepsis: Insight into Incidence, Classification, Risk Factors, Causative Organisms, Pathophysiology, Prognosis, Clinical Manifestations, Complications, Systemic Examination, and Treatment

Background: Neonatal sepsis is a clinical syndrome of bacteremia with systemic signs and is the most important cause of neonatal death in developing country. Mortality increase with delay in diagnosis and initiation of antibiotics. So, improvements in diagnosis and management of sepsis can significantly decrease the sepsis complications and improve its outcome. Objectives: The current review aims to high light on the incidence of neonatal sepsis, classification, risk factors, causative organisms, pathophysiology, prognosis, clinical manifestations, complications, systemic examination, and treatment. The incidence of neonatal sepsis varies among the different geographic areas, the highest being registered in Africa and Asia and the lowest in the U.S.A and Australia. The sepsis has been classified as early-onset sepsis (EOS) and the late-onset sepsis. Late-onset infections onset after 1 month of life, which occurs particularly in VLBW preterm infants or term infants requiring prolonged neonatal intensive care for other chronic problems. Neonatal sepsis includes maternal risk factors and neonatal risk factors. Septic or traumatic risk factors delivery, maternal poverty, pre-eclampsia, cardiac disease and diabetes mellitus are significant risk factors. Prolonged rupture of fetal membranes before the onset of labour, chorio-amnionitis, and maternal genitourinary tract infections have been significantly associated with a wide range of adverse perinatal and maternal outcomes, including miscarriage, stillbirth, preterm birth, fetal growth restriction, neonatal and puerperal sepsis, neonatal encephalopathy and neonatal and maternal mortality. Improvement in the socio-economic status of the population and availability of affordable antenatal care would reduce the incidence of neonatal septicemia. Amniocentesis, cervical cerclage, transcervical chorionic villus sampling, or percutaneous blood sampling, can permit entry of skin or vaginal organisms, causing amnionitis and secondary fetal infection. Infection of skin abrasions after use of obstetric forceps increases the risk of infection in neonates. Infant birth weight is inversely related to risk of early- onset sepsis. Prematurity and low birth weights are the most important neonatal factors predisposing to infection. Endotracheal intubation, insertion of an umbilical vessel catheter, or both, is associated with an increased risk of bacterial infection. Prolonged intravascular access and mechanical ventilation, the use of intravenous intralipids, and the duration of total parenteral nutrition are among the proposed risk factors associated with NICU-acquired coagulase- negative staphylococcus infections. Males have an approximately two-fold higher incidence of sepsis than females. Systemic antibiotics potentiate the overgrowth of certain organisms as Staphylococcus epidermidis. Corticosteroid treatment increases the risk of invasive candidiasis among premature infants. Hospital Acquired Infections are one of the leading causes of mortality and morbidity in (NICU). Group B Streptococcus (GBS) and E. coli as the dominant early onset sepsis (EOS) pathogens and coagulase- negative staphylococci (CONS) as the dominant late onset sepsis (LOS) pathogen followed by GBS and Staph aureus. In developing countries, Gram negative organisms are more common and are mainly represented by Klebsiella, E.coli and Pseudomonas of the Gram positive organisms, Staph aureus, CONS, Streptococcus pneumoniae, and Streptococcus pyogenes are most commonly isolated. Agents that commonly cause nosocomial infection are coagulase-negative staphylococci, gram-negative bacilli, Enterococci, and S. aureus. Causative organisms are bacterial, fungal, viral, and protozoal organism's infections. Mode of infection is prenatal, natal, and postnatal infections. Soon after birth, the newborns are exposed to the "hostile world" of bacteria, viruses, fungi and parasites, so they must immediately defend themselves. Necotizing enterocolitis, Neonatal thrombocytopenia, endophthalmitis, abdominal aortic-iliac thrombosis, fatal complete atrioventricular block, and wide range of signs and symptoms that may be observed in neonates with septicemia frequently suggest a number of alternative diagnoses. Identification of infection may be made by isolating the etiologic agent from a sterile body fluid (blood, CSF, and urine), or by demonstrating endotoxin or bacterial antigen in a body fluid. Investigations are including isolation of the microorganism, blood culture, urine culture, tracheal aspirate culture, isolation of organisms from CSF, complete blood cell count, cerebrospinal fluid analysis, C-Reactive protein, and tissue release of procalcitonin. Purpose of supportive care is to normalize the temperature, stabilize the cardiopulmonary status, correct hypoglycemia, and prevent bleeding tendency. Treatment of sepsis includes antibiotics, antiviral, antifungal, intravenous immunoglobulin, granulocyte transfusion, .