FEATURE AFRICA HEALTH 039
preterm infants, are particularly prone to sepsis as almost all aspects of the immune system are immature and have impaired function.
S
Late onset sepsis LOS presents after a postnatal age of 72 hours and is most often caused by organisms in the hospital environment; gram-positive pathogens such as Coagulase negative staphylococci, Staphylococcus aureus and gram- negatives including Klebsiella sp, Enterobacter sp and Acinetobacter species. Although bacteria usually cause neonatal sepsis, fungi and viruses can cause a sepsis-like syndrome. Risk factors include preterm birth, prolonged use of indwelling intravenous catheters, use of nasal continuous positive airways pressure, H2 receptor antagonist therapy and gastrointestinal conditions. In developing countries, inadequate health resources and resultant overcrowding increase the risk of LOS. Prolonged use of broad-spectrum antibiotics promotes the development of multiresistant organisms and increases the risk of death. The incidence of LOS varies from 5/1000 patient-days in developed countries to > 20/1000 patient days in developing countries.
epsis is an important problem in neonates, which presents challenges in diagnosis, management and prevention. It prolongs hospital stay, increases the cost of hospitalisation and is an important cause of neonatal death. Newborns, especially
surrogate markers of infeCtion Many surrogate markers of infection have been evaluated as a way to confirm the diagnosis on presentation, including interleukins 6 and 8, tumour necrosis factor, procalcitonin, serum amyloid alpha, neutrophil CD64 and CRP. These markers all increase in the inflammatory response and are not specific to sepsis, there are often different normal values at different postnatal ages and assays are expensive. They are best used in combination and can rule out sepsis if the levels do not increase. CRP is a cheap useful surrogate marker of sepsis which increases
later in the sepsis response. A negative CPR 24 hours after presentation is a good negative predictor of sepsis. Antibiotics can be discontinued at this point if the baby is clinically improving and the CRP is negative. CRP, however, is a poor positive predictor of sepsis – a raised CRP should not be treated with prolonged antibiotics in isolation – the patient and other results must be taken into consideration.
management
Babies with suspected sepsis are treated with empiric broad- spectrum antibiotics until sepsis is ruled out. Start liberally, but stop antibiotics aggressively. Protocols for empiric antibiotics are guided by antimicrobial sensitivity patterns of organisms isolated in each unit. Empiric antibiotic therapy is adjusted according to the sensitivity of any
“newborns, especially preterm infants, are particularly prone to sepsis as almost all aspects of the immune system are immature and have impaired function”
CLiniCaL presentation Neonatal sepsis is difficult to confirm on presentation. Signs are vague and may include lethargy, poor feeding, temperature instability, abnormal blood glucose levels, apnoea and seizures. In some cases there is progression to shock with hypotension, oliguria and poor peripheral circulation. Differential diagnosis includes perinatal asphyxia, congenital cardiac lesions, inherited metabolic disorders, hypoglycaemia, hypo- or hyper thermia and respiratory distress syndrome.
investigations There is no rapid, reliable test to confirm sepsis on presentation. Evaluation for suspected neonatal includes a history of risk factors and a full clinical assessment. Laboratory investigations include a full blood count with differential white cell count and platelets, C reactive protein (CRP) and blood cultures. A chest x-ray is indicated if there are signs of respiratory distress. Urine culture is only sent if an underlying renal abnormality is suspected or if the urine dipstick shows leucocytes or nitrates. The inclusion of lumbar puncture (LP) in a routine sepsis evaluation is controversial as there are technical difficulties and neonatal meningitis is uncommon. However, it is possible that meningitis will be missed and inadequately treated if LP is omitted. LP is recommended if neurological signs are present, if the blood culture is positive and in otherwise unexplained hyper thermia. Culture of an organism from a sterile site is considered as the gold standard to confirm sepsis. Only 80% of blood cultures are positive in post-mortem confirmed neonatal sepsis and the yield of other sterile fluids, such as cerebrospinal fluid may be even lower. Most significant pathogens will be cultured within 48 hours. The standard approach to treating a baby with suspected sepsis is to start empiric antibiotic therapy, which is continued until sepsis is ruled out.
organisms isolated in the patient’s cultures. Consultation between the clinician and microbiologist facilitates this process. Indiscriminant and prolonged use of broad-spectrum antibiotics increases the prevalence of multiresistant organisms. In premature infants, this practice increases the risk of necrotising enterocolitis (NEC) and death. The practice of antibiotic stewardship, where the choice and duration of therapy is overseen by a joint clinical and microbiology hospital committee, is encouraged to prevent development of antimicrobial resistance.
prevention A significant proportion of LOS can be prevented by infection control measures. Hand washing is a vital part of this practice. Continuing staff education are essential to achieve acceptable levels of compliance. Babies with proven sepsis must be isolated. Breastmilk has many anti-infective properties and promotion of breastfeeding prevents LOS and NEC.
ConCLusion Neonatal sepsis remains an important health issue. Diagnosis is difficult, but empiric antibiotic therapy must be carefully managed. Simple interventions like hand washing and breastfeeding significantly decrease LOS.
Learn more
Professor Ballot is moderating a session on ‘Infections in the ICU’ at the Pan-African Paediatrics Conference during the Africa Health Exhibition and Congress that is taking place on 9-11th
May 2012 in Johannesburg, South Africa. To find out
more about this event, or to book your place as a delegate at the conference, please visit
www.africahealthexhibtion.com.
www.lifesciencesmagazines.com
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