Early-life acquisition of antimicrobial resistance in newborn children from low- and middle-income countries

Every year, almost 7 million potentially serious bacterial infections are estimated to occur in newborns, resulting in more than 550,000 annual neonatal deaths. Most of these infections and deaths happen in low and middle income countries (LMICs), where often scarce resources can limit the capacity to diagnose and treat sepsis. These problems are further complicated by the global rise of antimicrobial resistance (AMR). AMR is already estimated to account for approximately 5 million deaths a year worldwide, and predicted to cause 10 million deaths a year by 2050.

In a new study, Dr. Maria Carvalho, Dr. Kirsty Sands from the Department of Biology, Oxford, and a network of international colleagues decided to look at the presence of antibiotic resistance genes (ARGs) in the gut of mothers and their babies from 7 LMICs in Africa and South Asia. They found that a large number of samples carried genes linked to antibiotic resistance, suggesting that AMR is far more widespread in these settings than previously anticipated. 

The samples collected from mothers and neonates were also used to identify the bacteria resistant to antibiotics. Whole genome sequencing revealed that, while these bacteria are quite diverse across different locations, there are clear clusters associated with specific countries and hospitals. The genomic analyses showed that some E. coli infections were indistinguishable between mothers and newborns, suggesting that mother-to-child transmission may occur during or after labour. 

Finally, the researchers identified risk factors associated with the carriage of ARGs, looking at features associated with water, sanitation, and hygiene (WASH) and prior infections. The team found that frequent handwashing by mothers reduced the risk of carrying resistance genes, whereas this risk was increased if mothers had reported an infection or taken antibiotics in the 3 months prior to being enrolled in the study. The carriage of such ARGs by mothers was also associated with an increased risk of adverse birth outcomes and neonatal sepsis. 

These findings demonstrate the high prevalence of antibiotic resistance in the microbiota of mothers and their neonates in LMICs, including within hours after birth. Furthermore, the study highlights that better understanding the routes of  ARG transmission, including mother-to-child and within the clinical environment, is essential to prevent neonatal sepsis. Finally, the results reinforce the importance of access to safe water, sanitation, and good hygiene to reduce AMR and lower neonatal sepsis and mortality rates in LMICs. 

Professor Tim Walsh, who supervised the study, stressed the novelty of the findings:

“Clearly, this research poses many questions about transmission and also about how the acquisition of these drug-resistant strains might impact on the growth of the baby – questions we are currently working to address within the IOI and with our collaborators.” 

Dr. Kirsty Sands, who co-led the study, highlighted how the study starts to elucidate the factors governing the spread of AMR:

“We need to continue our research to fully understand these transmission dynamics, which could help to guide better infection prevention and control measures.”  

To read more about this research, published in Nature Microbiology, visit: https://www.nature.com/articles/s41564-022-01184-y