Predictors of gentamicin therapy failure in neonates with sepsis.

Sepsis is a common disease with high morbidity and mortality among newborns in intensive care units world-wide. Gram-negative bacillary bacteria are the major source of infection in neonates. Gentamicin is the most widely used aminoglycoside antibiotic in empiric therapy against early-onset sepsis. However, therapy failure may result due to various factors. The purpose of this study was to identify predictors of gentamicin therapy failure in neonates with sepsis. This was a prospective cross-sectional study at the Neonatal Intensive Care Unit at Windhoek Central Hospital over a period of 5 months in 2019. Neonates received intravenous gentamicin 5 mg/kg/24 h in combination with either benzylpenicillin 100 000 IU/kg/12 h or ampicillin 50 mg/kg/8 h. Logistic regression modeling was performed to determine the predictors of treatment outcomes. 36% of the 50 neonates were classified as having gentamicin treatment failure. Increasing treatment duration by 1 day resulted in odds of treatment failure increasing from 1.0 to 2.41. Similarly, one unit increase in CRP increases odds of gentamicin treatment failure by 49%. The 1 kg increase in birthweight reduces the log odds of treatment failure by 6.848, resulting in 99.9% decrease in the odds of treatment failure. One unit increase in WBC reduces odds of gentamicin treatment failure by 27%. Estimates of significant predictors of treatment failure were precise, yielding odds ratios that were within 95% confidence interval. This study identified the following as predictors of gentamicin therapy failure in neonates: prolonged duration of treatment, elevated C-reactive protein, low birthweight, and low white blood cell count.

Plasma concentration and eGFR in preterm and term neonates receiving gentamicin or successive amikacin therapy.

BACKGROUND: Gentamicin and amikacin are aminoglycoside antibiotics which are renally excreted and known to be nephrotoxic. Estimate of glomerular filtration rate (eGFR) per body surface area is lower in neonates than in adults and exposure to these drugs could lead to more suppression in kidney function. The aim of this study was to determine maximum and minimum plasma concentrations (Cmax and Cmin), time to reach Cmin levels of gentamicin and amikacin, and to assess eGFR in preterm and term neonates. METHODS: Two groups of patients were recruited, 44 neonates receiving gentamicin (5 mg/kg/24 h) and 35 neonates receiving amikacin (15 mg/kg/24 h) by slow intravenous injection. Patients on amikacin had been on gentamicin before being switched to amikacin. Two blood samples were drawn for the determination of the maximum and minimum plasma concentration. Primary outcomes were determination of Cmax, Cmin, and the time it took to clear the aminoglycoside to a plasma concentration below the toxicity threshold (gentamicin: < 1 mcg/mL; amikacin: < 5 mcg/mL. RESULTS: Therapeutic range for Cmax of gentamicin (15-25 mcg/mL) or amikacin (30-40 mcg/mL) was achieved in only 27.3 and 2.9% of neonates, respectively. Percentage of neonates reaching plasma concentrations below the toxicity threshold within the 24-hour dosing interval was 72.7% for gentamicin and 97.1% for amikacin. Positive correlation between gentamicin clearance and postnatal age borderline statistical significance (p = 0.007), while the correlation between amikacin clearance and postnatal age was poor and not statistically significant (r2 = - 0.30, p = 0.971). CONCLUSION: Although eGFR decreased significantly as a function of postnatal age in neonates receiving amikacin, the majority (91.4%) of these neonates were able to clear the drug to < 5 mcg/mL within a 24-hour dosing interval.