Antibiotics in neonatal infections - A review

The bacteria most commonly responsible for early-onset (materno-fetal) infe ctions in neonates are group B streptococci, enterococci, Enterobacteriacea e and Listeria monocytogenes. Coagulase-negative staphylococci, particularl y Staphylococcus epidermidis, are the main pathogens in late-onset (nosocom ial) infections, especially in high-risk patients such as those with very l ow birthweight. umbilical or central venous catheters or undergoing prolong ed ventilation. The primary objective of the paediatrician is to identity a ll potential cases of bacterial disease quickly and begin antibacterial tre atment immediately after the appropriate cultures have been obtained. Combination therapy is recommended far initial empirical treatment in the n eonate. In early-onset infections, on effective first-line empirical therap y is ampicillin plus an aminoglycoside (duration of treatment 10 days). An alternative is ampicillin plus a third-generation cephalosporin such as cef otaxime, a combination particularly useful in neonatal meningitis (mean dur ation of treatment 14 to 21 days), in patients at risk of nephrotoxicity an d/or when therapeutic monitoring of aminoglycosides is not possible. Anothe r potential substitute for the aminoglycosicie is aztreonam. Triple combina tion therapy such as amoxicillin plus cefotaxime and an aminoglycoside) cou ld also he used for the first 2 to 3 days of life. followed by dual therapy after the microbiological results. In late-onset infections the combinatio n oxacillin plus an aminoglycoside is widely recommended. However, vancomyc in plus ceftazidime (+/- an aminoglycoside for the first 2 to 3 days may be a better choice. Teicoplanin may be a substitute for vancomycin. However, the initial approach should always be modified by knowledge of the local ba cterial epidemiology. After the microbiological results, treatment should be switched to narrower spectrum agents ifa specific organism has been identified, and should be d iscontinued if cultures are negative and the neonate is in good clinical co ndition. Penicillins and third-generation cephalosporins are generally well tolerate d in neonates. There is controversy regarding whether therapeutic drug moni toring of aminoglycosides will decrease toxicity (particularly renal damage ) in neonates, and on the efficacy and safety of a single daily dose versus multiple daily doses of these drugs. Toxic effects caused by vancomycin ar e uncommon, but debate still exists over the need for therapeutic drug moni toring of this agent. When antibacterials are used in neonates, accurate determination of dosage is required, particularly for compounds with a low therapeutic index and in patients with renal failure. Very low birthweight infants are also particu larly prone to antibacterial-induced toxicity.