Perinatal vertical transmission of antibiotic-resistant bacteria: a systematic review and proposed research strategy

Antibiotic-resistant bacteria contribute to both early- and late-onset sepsis and outbreaks in neonatal intensive care units (NICUs). The extent to which vertical transmission of these resistant bacteria contributes to colonisation or infection of vulnerable infants in NICUs is unclear. Risk factors for vertical transmission of antibiotic-resistant bacteria are not well described.

To identify studies describing vertical transmission of antibiotic-resistant bacteria, risk factors for transmission and the impact of colonisation on neonatal outcomes.

EMBASE, CINAHL, Cochrane, PubMed, and MEDLINE databases were searched using selected terminology. Titles and abstracts were screened by two reviewers. Selected papers were reviewed in full by two individuals to ascertain whether they fulfilled the inclusion criteria.

Any original article investigating perinatal vertical transmission of antibiotic-resistant bacteria between a mother and neonate was included.

Data were extracted on study design, organism, antibiotic resistance, and means of ascertaining vertical transmission.

Five papers out of 4839 titles fulfilled the inclusion criteria. Four studies were predominantly observational and one was a case report. Each demonstrated perinatal transmission. No study reported risk factors for the transmission of resistant bacteria or the impact of colonisation on neonatal outcomes.

There is an absence of research into the perinatal transmission of resistant organisms despite the potential implications of such a situation. We outline objectives that need to be addressed in future research and describe a study design to ascertain the prevalence and risk factors for vertical transmission.