Abstract: We included three trials (271 infants) in this review. Two of the three included studies had an overall low risk of bias and the remaining study had high risk of selection and performance biases. The use of an antibiotic lock decreased the incidence of confirmed catheter-related infection (typical RR 0.15, 95% CI 0.06 to 0.40; 3 studies, 271 infants) (high-quality evidence). The typical absolute risk reduction (ARR) was 18.5% and the number needed to treat for an additional beneficial outcome (NNTB) was 5. The effect of use of an antibiotic lock on suspected catheter infection was imprecise (typical RR 0.65, 95% CI 0.22 to 1.92) (moderate quality evidence). Confirmed and suspect infection rates combined were lower in the antibiotic lock group (absolute rates, RR 0.25, 95% CI 0.12 to 0.49; rate per 1000 catheter days, RR 0.17, 95% CI 0.07 to 0.40). The ARR was 20.5% and the NNTB was 5. None of the studies report resistance to the antibiotic used during the lock treatment. There was no significant difference in the detectable serum levels of antibiotic. When the data from two studies were pooled, there were significantly fewer episodes of hypoglycaemia in the treatment arm (typical RR 0.51, 95% CI 0.28 to 0.92). There was no statistically significant difference for mortality due to sepsis between the control and intervention group. Based on a small number of trials and neonates, antibiotic lock solution appeared to be effective in preventing CRBSI in the neonatal population. However, as each included study used a different antibiotics and antibiotic resistance could not be reliably assessed, the evidence to-date is insufficient to determine the effects of antibiotic lock on infections in neonates.

Plain-language summary: We included three studies enrolling 271 infants in this review. These studies showed that infants who's tubes contained an antibiotic solution were less likely to develop an infection. One side effect of this treatment could be the development of 'super' bugs. Super bugs cause a type of infection that some antibiotics may not be able to fight. Our included studies did not show any evidence that antibiotic lock was more or less likely to produce super bugs compared with no antibiotic lock, but to show this convincingly the studies would need to be much larger. The rates of death from an infection caused by the tubes were not reduced by the antibiotic lock. Relatively few infants were enrolled in the three included studies. Two of the three included studies had overall low risk of bias, and the remaining study had high risk of bias from two sources: i). Selection bias, namely, the manner in which group allocation took place (based on the room infants were nursed in) posed a major concern as to whether the allocation was truly random, and ii). Performance bias, namely, non-blinding of the people who were involved in the care of the infants might have contributed to differential care and/or expectations which might have affected the results. Based on a small number of trials and infants, antibiotic lock solution appears to be effective in preventing catheter-related blood infections in infants. However, as each included study used a different antibiotic and antibiotic resistance could not be reliably assessed, the evidence to-date is insufficient to determine the effects of antibiotic lock on infections in infants.