By Dr Krishna Sahoo
What is E. coli?
E. coli is a gram-negative bacterium that belongs to the intestinal microflora of livestock, including poultry. These bacteria are capable of surviving long periods outside the host and are present in almost all bird environments, particularly the litter and house dust. Opportunistic infections may occur under certain conditions (stress, weakened immune system, accompanying diseases and infections), however, pathogenic bacteria may also enter the body from the external environment. Poultry feed & water is often contaminated with coliforms and are the most common route of infection with new serotypes. Outbreaks often occur in broilers, layers & breeders causing enteritis, affecting the fallopian tube causing inflammation and colisepticemia are the most common cause of birds’ mortality.
Economic losses and estimates
The economic losses due to pathogenic E. coli infection can be both: direct and indirect. Weight loss, decreased egg production, increasing mortality and secondary infections affect the livestock production systems. Moreover, disinfection, cleansing, disposal, and excessive use of antibiotics can lead to additional expenses for poultry farmers. The indirect effects comprise the influence on the domestic economy, including interference with major industries, increase in antibiotic resistance, and impact on other sectors.
Susceptibility in poultry farms
Not all age of birds is equally susceptible to the bacterium. When chickens are 18 to 30 weeks old, egg production is at its peak. They are still developing, and their bodies are under a lot of stress, making them more prone to various infections. Laying hens that are more than one year old are also quite vulnerable. They breathe in the Avian Pathogenic Escherichia coli-laden dust that is quite prevalent in dried out faeces, which tend to accumulate in the layer house in most Indian poultry farms due to poor farm management practices. Pullets are susceptible when their bodies begin to produce hormones that are necessary for egg production. It is a stressful time and their immune systems are not functioning at full capacity, making them an easy target for the colonization of pathogenic bacteria such as E. coli. In broilers when reared in deep litter system the prevalence of E. coli infection increases due to more exposure to contaminated litter.
Control measures
Biosecurity measures play a key role in controlling the spread of E. coli. Keeping the bacteria out of the flock is not practical or possible since intestinal colonization is common in warm-blooded animals. Fortunately, external infections can be limited through feed, water, and environmental sanitation, as well as good air quality. Pelleted feed has a lower percentage of E. coli bacteria compared to mash feed. Rodent faeces are a ubiquitous source of E. coli. Furthermore, contaminated water supply can also contain high numbers of bacteria. One of the possible way to curb the spread of pathogenic microorganisms is to chlorinate the drinking water and use closed watering systems.
Maintaining litter and air quality can greatly reduce the risk of colibacillosis infection. The damage caused to the respiratory mucosa of the flock has a direct correlation to the degree of ammonia exposure. Dust also increases the risk of an infection. The combination of ammonia and dust results in the inhalation of bacteria in high numbers, making it difficult for birds to clear them from their respiratory tract.
Treatment
Although E. coli infection is commonly treated with antibiotics, a survey of commercial poultry producers found that chickens raised for eggs and meat have high levels of antibiotic-resistant bacteria. The survey found that more than half of the E. coli isolates were resistant to multiple drugs and nearly 60% of them contained broad-spectrum beta lactamase, an enzyme that provides resistance to beta-lactam antibiotics. Broiler farms are twice as likely to be exposed to antibiotic-resistant bacterial strains compared to layer farms due to the high level of antibiotic usage. Independent farms are more likely to develop antibiotic-resistant E. coli than contracted farms, that are mostly owned by large producers and have to follow strict production protocols, including better veterinary care and hygiene methods. On the other hand, independent farms misuse antimicrobials.
| Nalidixic acid | 86 percent |
| Tetracycline | 47 percent |
| Ampicillin | 43 percent |
| Cotrimoxazole | 42 percent |
| Ciprofloxacin | 39 percent |
The problem will only get worse. An increase in income and an increase in demand for poultry products would cause an exponential increase in the use of antibiotics in food production. Poultry producers must take rigorous action and implement government regulations to control the massive use of antibiotics on poultry farms in India. The transition to a more sustainable way of production should also be promoted by setting up funds to subsidize biosecurity measures at farm level. Poultry farmers should switch to feed additives containing bacteriophages. Since they target specific pathogenic bacteria without affecting the host, they are the most valuable tool in the arsenal of poultry producers in the fight against multi-drug resistant bacteria. Bacteriophages are being adopted successfully by poultry producers around the world, recently introduced to the market in India by Proteon Pharmaceuticals and it is time to mainstream this solution.
The author is Global Product Manager, Proteon Pharmaceuticals, a subsidiary of Proteon Pharmaceuticals SA Poland. Proteon Pharmaceuticals focuses on precision biology for microbiome protection to improve animal and human health, increasing environmental sustainability and eliminating the unnecessary use of antibio.tics