Thrombocytopenia that starts after the first 72 hours since birth is often the result of underlying sepsis or necrotizing enterocolitis (NEC) .  In the case of infection, PCR tests may be useful for rapid pathogen identification and detection of antibiotic resistance genes. Possible pathogens include viruses (. Cytomegalovirus (CMV) ,  rubella virus ,  HIV  ), bacteria (. Staphylococcus sp. ,  Enterococcus sp. ,  Streptococcus agalactiae (GBS),  Listeria monocytogenes ,  Escherichia coli ,   Haemophilus influenzae ,  Klebsiella pneumoniae ,  Pseudomonas aeruginosa ,   Yersinia enterocolitica  ), fungi (. Candida sp.  ), and Toxoplasma gondii .  The severity of thrombocytopenia may be correlated with pathogen type; some research indicates that the most severe cases are related to fungal or gram-negative bacterial infection.  The pathogen may be transmitted during  or before birth, by breast feeding ,    or during transfusion.  Interleukin-11 is being investigated as a drug for managing thrombocytopenia, especially in cases of sepsis or necrotizing enterocolitis (NEC) . 
Several brands of IVIG have been approved by the Food and Drug Adminsitration (FDA) (see table in Appendix). There is a lack of reliable evidence that any one brand of IVIG is more effective than other brands. However, immune globulin products may differ from each other in ways that may be important in a particular patient. Different manufacturers then use various combinations of precipitation and/or chromatography steps to obtain a final preparation that consists of greater than 95 % IgG in all currently available products. The various manufacturers also use different final purification steps and stabilizers to obtain their final products, which may then vary in storage requirement and shelf life. In several currently available products, stabilizers include sugars, such as sucrose, glucose, or maltose. Other products contain amino acids such as glycine and proline. The sodium content of different products also varies.
The most common side effects with Revolade in adults with chronic ITP and hepatitis C (seen in more than 1 patient in 10) are headache, anaemia (low red blood cell counts), decreased appetite, insomnia (difficulty sleeping), cough, nausea (feeling sick), diarrhoea, pruritus (itching), alopecia (hair loss), myalgia (muscle pain), pyrexia (fever), fatigue (tiredness), influenza (flu)-like illness, asthenia (weakness), chills and peripheral oedema (swelling, especially of the ankles and feet). In addition, in children with ITP the most common side effects also included colds, nasopharyngitis (inflammation of the nose and throat), rhinitis (inflammation of the lining of the nose), pain in the belly or in the mouth and throat, toothache, rash, runny nose and abnormal blood levels of certain liver enzymes (AST).