Gut health and antibiotic resistance in poultry

By Tanushyam Ghosh

Gut health relies on the balance between the host, the intestinal microbiome, the intestinal environment, and the diet. It can be affected by everything from feed and water hygiene to bird and farm management practices. In birds with a healthy gut, the feed gets thoroughly digested and the nutrient components are completely absorbed. Any disruption can cause incomplete digestion and nutrient absorption, leading to gut imbalance and malabsorption. Suboptimal digestion and nutrient absorption increase the availability of nutrients for pathogenic bacteria, causing an infection.

The good bacteria in the intestine form a protective barrier, preventing the growth of pathogenic bacteria like campylobacter, salmonella and clostridium perfringens. The friendly bacteria dominate the receptor on gut cells, making it difficult for the pathogenic bacteria to attach themselves. When this balance is disturbed due to the feed mismanagement, poor hygiene practices, and suboptimal breeding environments, it leads to the proliferation of pathogenic bacteria, which can spread easily and cause significant economic losses, apart from posing a major health concern. To combat pathogenic invasions, promote faster growth and improve conversion rates, poultry producers tend to add antibiotics to the feed. These are intended to keep the harmful bacteria in check and promote healthy growth. However, rampant and indiscriminate use of antibiotics in poultry farms across the country has led to the rapid proliferation of multidrug resistant bacteria, which not only cause infections that are difficult to treat but also transfer their resistance across a wide range of bacterial species.

Figure 1 – The mechanism of antibiotic resistance

Problem of antimicrobial resistance

As poultry production continues to increase, animals are becoming more resistant to antimicrobial drugs. Analysis of epidemiological studies focusing on the most common pathogenic bacteria found that the antimicrobial drugs that are most commonly used to help livestock gain weight, like tetracyclines, sulfonamides, and penicillins, are also the ones with the highest resistance rates. Over the course of the last decade, the number of drugs to which pathogenic bacteria have become resistant has tripled. The largest hotspots of antimicrobial resistance in animals are in fact in Asia, which is home to 54 percent of the chickens in the world. Last year, the Indian government banned the use of colistin, which is widely used as a growth promoting agent, on animal farms.

As early as 2015, scientists discovered a colistin-resistant gene that can pass between bacteria and confer drug resistance on bugs that have not been exposed to the drug. It is believed that the gene originated in Chinese livestock and has since been found across five continents. To what extent the ban will be enforced at the state level remains to be seen. In any case, it is high time that the government takes strict legislative action to control the rampant use of antibiotics to curb the problem of increasing antimicrobial resistance that is fast becoming one of the major points of concern in poultry farms across the country. The government should also support the transition to sustainable poultry production by setting up funds to subsidize farm-level biosafety improvements. Meanwhile, poultry farmers should consider using natural and synthetic antibiotic alternatives to help maintain the gut health of livestock.

(The author is a regional sales manager – Proteon Pharmaceuticals. Views expressed are personal.)