Maternal-infant antibiotic resistance genes transference: what do we know?

Abstract

Resistance to antibiotics is becoming a worldwide threat as infections caused by multidrug-resistant pathogenic microorganisms can overcome antibiotic treatments and spread quickly in the population. In the context of early life, newborns are at increased risk as their immune system is still under development, so infections and acquisition of resistance during childhood have short- and long-term consequences for the health. The moment of birth is the first exposure of infants to possible antibiotic-resistant microorganisms that may colonize their gut and other body sites. Different factors including mode of delivery, previous antibiotic exposure of the mother, gestational age and consumption of antibiotics in early-life have been described to modulate the neonate's microbiota, and thus, the resistome. Other factors, such as lactation, also impact the establishment and development of gut microbiota, but little is known about the role of breastmilk in transferring Antibiotic Resistant Genes (ARG). A deeper understanding of vertical transmission of antibiotic resistance from mothers to their offspring is necessary to determine the most effective strategies for reducing antibiotic resistance in the early life. In this review, we aim to present the current perspective on antibiotic resistances in mother-infant dyads, as well as a new insight on the study of the human gut and breastmilk resistome, and current strategies to overcome this public health problem, toward highlighting the gaps of knowledge that still need to be closed.

Keywords: Antibiotic; breastmilk; gut; infant; microbiota; mother; pregnancy; resistome.

Figure 1.

A schematic overview of the human resistome and mobilome. Intrinsic resistance is a property controlled by chromosomes and is related to the general physiology of the microorganism. The acquired resistance is encoded on plasmids and may be classified into four mechanisms: changes in the cell wall that make it less permeable to antibiotics, modifications of enzymes that inactivate antibiotics, changes in the target site of the drug, and efflux pumps that remove antibiotics from the cell. Phenotypic bacterial resistance appears in three categories: persistence, where a subpopulation of bacteria survive even though the majority is inhibited by the antibiotic; formation of biofilms, where bacteria form communities protected by a matrix; and swarming, where cells become hyper-flagellated, allowing them to colonize nutrient-rich environments and become less susceptible to antibiotics. MGE: mobile genetic elements; HGT: horizontal gene transfer; VGT: vertical gene transfer; ARG: antibiotic genetic elements. .

Figure 2.

Factors influencing antibiotic resistance acquisition and vertical transmission.