Antibiotic treatment for newborns with congenital syphilis

Congenital syphilis continues to be a substantial public health problem in many parts of the world. Since the first use of penicillin for the treatment of syphilis in 1943, which was a notable early success, it has remained the preferred and standard treatment including for congenital syphilis. However, the treatment of congenital syphilis is largely based on clinical experience and there is extremely limited evidence on the optimal dose or duration of administration of penicillin or the use of other antibiotics.

To assess the effectiveness and safety of antibiotic treatment for newborns with confirmed, highly probable and possible congenital syphilis.

We searched the Cochrane STI Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, WHO ICTRP, ClinicalTrials.gov and Web of Science to 23 May 2018. We also handsearched conference proceedings, contacted trial authors and reviewed the reference lists of retrieved studies.

Randomised controlled trials (RCTs) comparing antibiotic treatment (any concentration, frequency, duration and route) with no intervention or any other antibiotic treatment for neonates with confirmed, highly probable or possible congenital syphilis.

All review authors independently assessed trials for inclusion, extracted data and assessed the risk of bias in the included studies. We resolved any disagreements through consensus. We assessed the quality of the evidence using the GRADE approach.

Two RCTs (191 participants) met our inclusion criteria and none of these trials was funded by the industry. One trial (22 participants) compared benzathine penicillin with no intervention for infants with possible congenital syphilis. Low-quality evidence suggested that benzathine penicillin administration may not have decreased the rate of neonatal death due to any cause (risk ratio (RR) 0.83, 95% confidence interval (CI) 0.06 to 11.70), and showed a possible reduction into the proportion of neonates with clinical manifestations of congenital syphilis (RR 0.12, 95% CI 0.01 to 2.09). Penicillin administration increased the serological cure at the third month (RR 2.13, 95% CI 1.06 to 4.27). These results should be taken with caution, because the trial was stopped early because there were four cases with clinical congenital syphilis in the no treatment group and none in the treatment group. Interim analysis suggested this difference was significant. This study did not report neonatal death due to congenital syphilis or the frequency of serious or minor adverse events after therapy. We downgraded the quality of evidence because of imprecision and risk of bias.One trial (169 participants) compared benzathine penicillin versus procaine benzylpenicillin. High- and moderate-quality evidence suggested that there were probably no differences between benzathine penicillin and procaine benzylpenicillin for the outcomes: absence of clinical manifestations of congenital syphilis (RR 1.00, 95% CI 0.97 to 1.03) and serological cure (RR 1.00, 95% CI 0.97 to 1.03). There were no cases of neonatal death due congenital syphilis; all 152 babies who followed up survived. This study did not report on the frequency of serious or minor adverse events after therapy. We downgraded the quality of evidence because of serious risk of bias.

At present, the evidence on the effectiveness and safety of antibiotic treatment for newborns with confirmed, highly probable or possible congenital syphilis is sparse, implying that we are uncertain about the estimated effect. One trial compared benzathine penicillin with no intervention for infants with possible congenital syphilis. Low-quality evidence suggested penicillin administration possibly reduce the proportion of neonates with clinical manifestations of congenital syphilis, penicillin administration increased the serological cure at the third month. These findings support the clinical use of penicillin in neonates with confirmed, highly probable or possible congenital syphilis. High- and moderate-quality evidence suggests that there are probably no differences between benzathine penicillin and procaine benzylpenicillin administration for the outcomes of absence of clinical manifestations of syphilis or serological cure.