Prof. Aziza Mahrous
Professor of Veterinary Medicine, Cairo
Poultry is one of the most important sources of protein and is the fastest growing source compared to other sources, as poultry is ready for human consumption in less than six weeks. Development in this industry depends on genetic testing, improving feeding and healthcare methods, and also the use of antibiotics in treating various diseases, whether in production farms . It is worth noting that sometimes antibiotics are used in healthy birds in water or feed in small doses lower than the therapeutic dose for the purpose of stimulating growth, increasing weight, and improving the conversion rate (which is scientifically incorrect). It has been observed that, based on this, the therapeutic doses of many antibiotics have increased tenfold to twentyfold over the past ten years. The use of antibiotics has led to significant productivity gains in the poultry industry, but:
1 – When antibiotics are used in poultry, they affect the microbes that are sensitive to them
and leave the insensitive (resistant) microbes to multiply until they reach a million
fold within a day and become dominant in the birds' bodies.
2 – The resistance trait is then transferred to other microbes through the transfer of resistant plasmids
(Plasmid-mediated) or the emergence of resistant mutations (Gould, 2008).
The World Health Organization has defined resistant bacteria as bacteria that
can survive in the presence of antibiotics at concentrations that inhibit other bacteria
(Catry et.al., 2003).
B – Handling and trading poultry meat contaminated with resistant microbes.
Once these resistant microbes enter the human body, especially the intestines, they multiply inside it, and then the genetic component responsible for resistance to antibiotics is transferred to the rest of the bacteria in the intestines, which also become resistant. As a result, antibiotics lose their ability to treat these microbes and the diseases they cause, such as:
1 – The use of fluoroquinolone antibiotics in poultry leads to the emergence of resistant strains
of Campylobacter in poultry, which are associated with the emergence of numerous cases of diseases
caused by Campylobacter in humans (Randall et. al., 2003), such as stomach
and duodenal ulcers and some stomach and duodenal cancers.
2 – The use of avilamycin as a growth promoter leads to the emergence of avilamycin-resistant strains
such as Enterococcus falcium in poultry farms (Aarestrap et. al., 2000).
3 – The use of vancomycin in poultry feed leads to the transfer of the gene responsible for
vancomycin resistance to turkeys and then from turkeys to humans (Stobbering et al., 1999).
It is important that what happens in the spread of antibiotic resistance in humans applies to what happens in animals and birds, as this facilitates the monitoring of the transfer of resistant bacteria or the gene responsible for resistance from birds and animals to humans and vice versa.
The European Union, the United States, and Australia have discovered dangerous types of antibiotic-resistant bacteria in various production areas, especially in Africa and Asia, where there is insufficient information on bacterial resistance to antibiotics.
• How does antibiotic resistance develop in bacteria?
Antibiotic-resistant bacteria develop in humans and animals in the same scientific ways, which are as follows:
1 – The bacteria may have a natural resistance to antibiotics due to the presence of an enzyme that inhibits the activity of the antibiotic, such as the enzyme penicillinase in Staphylococcus bacteria, which breaks down the chemical structure of penicillin.
2 – The second type of resistance depends on the ability of bacteria to grow and survive in the presence of antibiotics and depends on the presence of a gene responsible for the bacteria's resistance to antibiotics. This gene arises as a result of the bacteria being exposed to a concentration lower than the minimum inhibitory concentration (MIC). The danger of this type of resistant bacteria is:
First: It does not respond to treatment with certain types of antibiotics to which it has developed resistance.
Second: It becomes a permanent source of the gene responsible for resistance, which continues to be transferred to other bacteria.
This depends on the R-factor Plasmid-mediated resistance. This plasmid may contain 20–500 genes that confer resistance to a large number of bacterial species in multiple locations within ecosystems and are transmitted by various means (Benzanson et al., 2008).
Are antibiotic-resistant bacteria spreading in poultry?
Yes... As the use of antibiotics in poultry has become more widespread, this increases the risk of antibiotic-resistant bacteria being transmitted to humans. This is evident in the high levels of resistance found in a number of microbes, such as:
(Escherichia coli, Staphylococcus spp., Entercoccus spp. Etc………) to many of the most commonly used antibiotics Table (1)
Bacterial resistance to antibiotics can be overcome by:
1 – Conducting continuous screening and surveillance of antibiotic-resistant bacteria in farms and in
humans .
2 – Optimal use of antibiotics .
3 – Following proper hygiene practices when handling meat .
4 – Using antibiotic alternatives, especially in poultry.
