A pneumococcal vaccination reduces antibiotic-resistant bacteria in children

A pneumococcal vaccination reduces antibiotic-resistant bacteria in children

Children in Guatemala who received a common vaccine to prevent pneumonia were less likely to carry antibiotic-resistant bacteria, according to a new study by researchers at Washington State University.

The team examined whether vaccines against rotavirus (RV) and pneumococcus (PCV13) reduce intestinal colonization by a group of bacteria that includes Escherichia coli and are resistant to critical antibiotics used to treat serious infections. Colonization occurs when the bacteria are present in the body, often in the intestines, without causing disease. However, they can persist and later cause infections or spread to others.

While results from rotavirus vaccination were inconclusive, children under five who received the pneumococcal vaccine had significantly lower colonization rates. These antibiotic-resistant bacteria - known as extended-spectrum cephalosporin-resistant Enterobacterales (ESCrE) - were less common in vaccinated children, largely because they were less likely to visit health care facilities, a factor previously linked to higher rates of antimicrobial-resistant bacteria. The team's results were published in the journal Vaccine.

Most antimicrobial resistance vaccine studies focus on infections and how vaccines prevent disease and reduce antibiotic use, thereby reducing the selection processes of antibiotic-resistant bacteria. We took a different approach by looking at bacterial colonization and found that vaccination reduced antimicrobial resistance through a completely different mechanism: vaccination prevented clinic visits and led to a lower likelihood of colonization with antibiotic-resistant bacteria. We hypothesize that this may be because individuals were exposed to fewer environments where these resistant bacteria are present.”

Dr. Brooke Ramay, lead author of the study and a researcher at the Paul G. Allen School for Global Health at WSU's College of Veterinary Medicine

Antibiotic resistance is one of the most pressing health threats worldwide, causing millions of deaths every year. Resistant infections are harder to treat, often require longer hospital stays and increase the risk of complications and death. Previous studies in Guatemala have shown that children who went to hospitals or clinics for an illness were more than twice as likely to carry antibiotic-resistant bacteria, while antibiotic use itself was not strongly linked to colonization.

The new study was conducted in the western highlands of Guatemala, where researchers analyzed stool samples, vaccination records and health data from 406 children.

Researchers could not conclusively determine the effects of the rotavirus vaccine - which helps prevent rotavirus infections, a leading cause of severe gastroenteritis in infants and young children - mainly because there were few reports of diarrhea, likely due to recall errors. Ramay said the rotavirus vaccine may have similar indirect protective effects by preventing diarrhea and gastrointestinal inflammation, although it is important to collect clinical data on diarrheal events before drawing conclusions.

The researchers also identified several additional factors that influenced colonization. For example, children who reported diarrhea in the previous month were significantly more likely to be carriers of ESCrE. Researchers suspect this is due to inflammation in the gut, which creates conditions that favor the growth of hardy bacteria like E. coli.

On the other hand, consuming yogurt appeared to be protective, suggesting that beneficial bacteria from probiotic foods may help maintain a healthy gut environment and reduce colonization by resistant bacteria.

Environmental exposure also appears to play a role, as children from households using agricultural land were at higher risk of colonization, likely due to contact with soil and water contaminated by faeces from animals or humans. Ramay said her team plans to conduct further studies to better understand how agricultural land use and environmental factors influence colonization with resistant bacteria.

The study was conducted in collaboration with the Universidad del Valle de Guatemala and was supported by the Centers for Disease Control and Prevention and the Wellcome Trust, a nonprofit foundation focused on health research based in London.

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