Since the 1940s, the introduction of antibiotics revolutionized the treatment of infectious diseases, saving countless lives from what are now deemed minor bacterial infections. However, over six decades of both clinical overuse and extensive agricultural application, not just for disease prevention but also to boost meat production, has resulted in the rise of antibiotic-resistant bacteria.
This alarming trend is now seen as a major public health and food safety issue worldwide. While the EU has taken measures against antibiotic resistance, many countries lag behind. The pressing concern is the dwindling effectiveness of existing antibiotics, with a limited number of new alternatives on the horizon.
The World Health Organisation labels antibiotic resistance a “global threat,” attributing over 25,000 annual deaths in the EU to infections by resistant bacteria.
The Development and Spread of Resistance
Antibiotic resistance poses significant threats to public health and food safety, primarily attributed to the prevalent use of antimicrobial drugs in agriculture. In countries like the USA, over half of all antibiotics manufactured are intended for agricultural use.
These drugs serve not only therapeutic purposes, treating infections in livestock, but are also used sub-therapeutically as preventive measures and growth promoters. The practice of incorporating antibiotics as growth stimulants started over 60 years ago in the USA when poultry given tetracycline by-products showed faster weight gain, possibly due to gut microflora suppression allowing enhanced nutrient uptake.
The usage of antibiotics for growth surged fifty-fold between 1951 and 1978 in the USA, outpacing the tenfold increase for therapeutic purposes. Concurrently, reports showed escalating bacterial resistance to antibiotics. For instance, a UK report indicated a swift surge in tetracycline resistance in poultry from 3.5% to 63.2% within four years post its 1957 introduction. The speed of such resistance can be attributed to the inherent nature of bacterial populations.
While DNA mutations offer certain bacteria a competitive edge, resistance often originates from genes on mobile DNA fragments, enabling horizontal gene transmission even between different species. This mechanism permits swift spread of multi-resistance in bacterial communities, especially when exposed to antibiotics, thereby selecting and promoting antibiotic-resistant strains.
Concerns for the Food Industry
The World Health Organization (WHO) emphasizes the pivotal role of the food supply chain in spreading antibiotic-resistant bacteria from animals to humans. Potential transmission vehicles include raw meats, eggs, unpasteurized dairy products, farmed fish, and even fresh produce contaminated through agricultural waste.
The intricacy of global food and feed supply chains facilitates the swift propagation of these antibiotic-resistant strains globally. This issue is particularly concerning for the food industry when antibiotic resistance develops in zoonotic bacterial pathogens—those transmittable from animals to humans.
Notably, agents of foodborne diseases such as Salmonella, Campylobacter, and verocytotoxigenic E. coli have, over the past three decades, displayed resistance to multiple antibiotics, leading to significant food poisoning outbreaks. A striking example is the Salmonella Typhimurium DT104 strain, resistant to five antibiotic types, which originated in the UK in the 1980s and became globally widespread in the 1990s.
Other foodborne pathogens of concern include Campylobacter strains resistant to the fluoroquinolone drug, ciprofloxacin, essential for treating human infections. The resistance emergence is linked to the use of another fluoroquinolone, enrofloxacin, in animals, affecting both Campylobacter and Salmonella.
The E. coli O104:H4 strain, responsible for a major outbreak in Germany in 2011, showcased resistance to multiple antibiotics and had an ESBL (extended-spectrum beta-lactamase) production gene, rendering such infections challenging to treat. MRSA, a widely recognized antibiotic-resistant bacteria, has also sporadically appeared in livestock and animal-based food products.
The WHO underscores the grave repercussions of antibiotic resistance in bacterial strains, correlating them with prolonged illnesses, increased hospitalization durations, and heightened mortality risks.
A recent report by the European Food Safety Authority and the European Centre for Disease Control highlights the prevalent antibiotic resistance in bacteria like Salmonella, Campylobacter, and E. coli derived from animal and food samples, emphasizing the alarming resistance rates in poultry, especially to ciprofloxacin.
Current Strategies
The problem of antibiotic resistance, initially highlighted by the UK government’s Swann Report in 1969, has not been swiftly addressed by governments worldwide. Although the report suggested prohibiting the use of antibiotics for growth promotion in animals, it was mostly disregarded.
It wasn’t until 1986 that Sweden banned the practice, setting off a domino effect with other nations, including Denmark, following suit. By 2006, the EU withdrew all antibiotic growth promoters. However, the unchecked use of antibiotics, especially in some Eastern European countries, remains a concern as they may be readily accessible without prescriptions and potentially exploited by farmers.
On the global scale, the EU’s proactive measures have not been universally adopted. The WHO has advocated for the phasing out or banning of antibiotic growth promoters, yet countries like the USA, a significant meat producer, have been slow to enforce such bans due to strong industry lobbies and economic concerns.
The US Food and Drug Administration (FDA) has shown interest in phasing out growth promoters but has faced legal challenges that have delayed concrete actions. Nonetheless, studies, particularly in Denmark, demonstrate the benefits of such bans. Findings indicate a notable decrease in antibiotic resistance and a substantial drop in antibiotic usage in animal farming without hampering the sector’s economics.
Similarly, Sweden and Norway have reported positive outcomes, especially in fish farming. The EU, however, hasn’t observed a marked decrease in antibiotic-resistant bacteria since 2006, suggesting that resistance genes in bacteria may persist, and a longer observation period may be needed to assess the full impact.
Reducing Antibiotic Use
Policy measures have been introduced to address the rising concern of antibiotic resistance in bacteria within the food chain. Among these is the elimination of antibiotic growth promoters in food animals.
The World Health Organization (WHO) further recommends that antibiotics be administered to animals only upon prescription by a veterinarian, emphasizing that critical drugs, such as fluoroquinolones, should be used judiciously. Enhancing animal health through better biosecurity, vaccination, and on-farm hygiene can decrease the dependency on therapeutic antibiotics.
The potential economic incentives promoting inappropriate antibiotic prescriptions should be curtailed. Effective surveillance is imperative to gauge antibiotic usage in animals and monitor resistance in foodborne bacteria, with the European Food Safety Authority’s (EFSA) report shedding light on varied surveillance efficacy across countries.
The growing bacterial resistance jeopardizes the efficacy of antibiotics in treating infections, underscoring the need for judicious use in food animals. Despite evidence suggesting its feasibility without compromising the industry’s viability, rapid solutions seem distant, as reflected by the 43 years since the Swann report’s release.