The following is the summary of “Neonatal intestinal resistome and factors that influence it—a systematic review” published in the December 2022 issue of clinical microbiology and infections by Leo, et al.

Antibiotic-resistant genes can be stored in the gut microbiota (ARGs). When compared to the mature microbiome, the one present in newborns is more easily disrupted by environmental stimuli. Here, researchers carefully outline research on neonatal intestinal resistome. First, investigators looked through the MEDLINE and Embase databases for relevant information. Molecular diagnostic investigations were included for ARGs in neonatal feces or rectal swabs. Information was collected by 2 authors and summarized in tables. yielded up a total of 2,701 studies, of which 23 were included (22 cohorts). Recent research has demonstrated that even in the absence of direct antibiotic treatment, the newborn gut harbors a rich population of ARGs. Aminoglycoside, -lactam, macrolide, tetracycline, and multidrug resistance (MDR) are the resistance most typically associated with ARGs. 

There is data suggesting that ARGs can be passed on from mothers to their newborns. However, contrary to maternal reports, research suggests that newborns have a greater abundance of ARGs. The high concentration of Gammaproteobacteria in newborn feces may be a contributing factor. Use of antibiotics during labor and delivery, as well as in neonates, has been linked to an increase in ARG production. In studies, the usage of breast milk or probiotics in infants has been linked to a reduced number of ARGs. Prenatal antibiotics, regardless of how they are delivered or the gender of the mother, have been shown to have minimal impact. 

This, however, maybe because impact modifiers are hard to account for, and studies were underpowered. Neonatal intestine appears to have decreased colonization resistance, which may facilitate the establishment of antibiotic-resistant populations. The abundance of ARGs in neonates can be modified, for instance, by the use of pre- and probiotics and bacteriophages; future research will aid in the development of evidence-based therapies.