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23 MAY 2019
Muhammad Zahir Hassan Nabil
Spread of antibiotic-resistant bacteria in the environment due to antibiotic overuse has long been a public health concern, now presence of these bugs inside healthy children’s guts or ready foods may pose a greater threat to public health.
Drug-resistant bacteria inside the gut and in foods can cause serious illness. Photo: Shehzad Noorani / icddr,b
Presence of useful bacteria, not virulent ones, in human guts is part of a healthy, functioning bodily system.
However, a new icddr,b study on children from rural Bangladesh has recently shown that over 80 percent of these children had multi-drug resistance Escherichia coli (E. coli) bacteria in their gut microbial community, as their stool samples would indicate.
E. coli under microscope, 40x magnified. Photo:Â Minyoung Choi. CC BY-SA 2.0
E. coli, a diverse group of bacteria found across the environment e.g. in food, and in the intestines of people and animals, are mostly innocuous. Nevertheless, some E. coli are virulent enough to cause serious gut illnesses. Antibiotic-resistant virulent E. coli can cause diseases and would not be tamed by antibiotics they are resistant to.
“The E. coli we found demonstrated resistance to third generation cephalosporins (3GC) – an antibiotic known for its overuse widely across the developing countries,” says Dr Mohammad Aminul Islam, icddr,b adjunct scientist leading the study, also an assistant professor at Washington State University.
Published in Frontiers in Microbiology, the study found that over 25 percent of the bacteria in the guts of these children were pathogenic or disease-causing.
Bacteria show resistance to antibiotics. Detection and confirmation of Extended Spectrum Beta Lactamase production. Photo: Nathan Reading. CC BY-NC-ND 2.0
The study was conducted with collaborators from Oregon State University, Centers for Disease Control and Prevention (CDC), Rollins School of Public Health at Emory University, Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Swiss Tropical and Public Health Institute, and University of Basel, Switzerland.
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“Harmful pathogens have become part of the bodily system of these children, cautions Dr Islam.
It means that they could fall ill anytime but antibiotics that these superbugs are resistance to will not work.”
Besides, these children are shedding these bacteria through their feces and contaminating the surrounding environment.
 Our gut is a colony of many beneficial bacteria. Photo: ibmphoto24. CC BY-NC-ND 2.0
“It was surprising to see that the presence of these virulent pathogens were not associated with antibiotic use in those children or their mothers. We need to investigate further to ascertain whether they have acquired these pathogens from the environment,” he adds.
Similar research led by Dr Aminul Islam looks at another innocuous bacteria Staphylococcus aureus (S. aureus) or simply ‘Staph,’ commonly found on people’s skins. Staphs, when resistant to antibiotics, can too become virulent.
When resistant to the antibiotic methicillin, it is called methicillin-resistant staph (MRSA) which can cause serious infections and can claim lives.
Dr Islam investigated presence of S. aureus in food samples including ready-to-eat foods and processed raw meat and fish samples from retail vendors in Dhaka city.
Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteria under electron microscope. Photo: NIAID. CC BY 2.0
This research found that over 20 percent of the samples were positive for presence of S. aureus, and 6% were positive for MRSA according to findings published in Frontiers in Microbiology from a study in collaboration with scientists from BCSIR, Jahangirnagar University, Utrecht University and Wageningen Bioveterinary Research, Netherlands.
“It was awkward to find MRSA in foods because they are not meant to be found in food,” he exclaims.
It is clear from these findings that some foods are quite contaminated. Dr Islam says further investigation is needed to understand how these pathogens are finding their ways to unlikely places like ready-to-eat (RTE) foods.
Drug-resistant bacteria in ready-to-eat foods can cause infection through any internal bodily scars. Photo: cyclonebill. CC BY-SA 2.0
At least 37 percent of these bacteria were resistant to at least three antibiotics, with 74 percent resistant to erythromycin, 49 percent to ciprofloxacin and around 30 percent to oxacillin and cefoxitin.
More to this finding, around 71 percent of all S. aureus and in 44 percent of MRSA contained virulent genes indicating they these are able to cause serious infections.
“The presence of toxigenic MRSA in food poses a clear threat to street food consumers since these pathogens can cause infections if they enter into the bloodstreams of the patients through any scars present inside their mouth or elsewhere,” explains Dr Islam.
The study recommends immediate systematic surveillance of MRSA, and a focused educational and awareness campaign along the entire food production and supply chain, especially targeting the sectors involved with RTE foods.
