NEW DELHI: Misuse of antibiotics in poultry farms is leading to a proliferation of multi-drug resistant bacteria. To make matters worse, these bacteria are now spreading in the environment because of unsafe disposal of poultry litter and waste in agricultural fields and this has a potential to infect human beings, says a new study released Thursday.
The study – titled ‘Antibiotic Resistance in Poultry Environment’ – conducted by the Centre for Science and Environment (CSE) pollution monitoring laboratory, collected samples of litter and soil from in and around 12 randomly selected poultry farms.
These were located in four key poultry-producing states in north India – Uttar Pradesh, Haryana, Rajasthan and Punjab. A total of 217 isolates of three types of bacteria – E. coli, Klebsiella pneumoniae and Staphylococcus lentus – were extracted and tested for resistance against 16 antibiotics. Ten of these antibiotics have been declared Critically Important (CI) for humans by the World Health Organization (WHO).
The poultry farms identified by CSE for this study are spread out across 12 different clusters in nine districts. CSE researchers found that antibiotics were being used in these poultry farms, and that the litter was used as manure in neighbouring agricultural lands. As a control, the study also collected 12 soil samples at a distance of 10 to 20 kilometres from the respective farms, where the litter was not being used as manure.
Releasing the findings, Chandra Bhushan, deputy director general, CSE, said: “Antibiotic misuse is common in the poultry sector. What makes the situation worse is the fact that the sector is also plagued with poor waste management.”
If any bacteria are resistant to antibiotics of at least three classes, they are considered as multi-drug resistant. The study found that 100 percent of the E. coli, 92 percent of Klebsiella pneumoniae and 78 percent of Staphylococcus lentus isolated from the poultry environment were multi-drug resistant.
About 40 percent of E. coli and 30 percent of Klebsiella pneumoniae isolates were resistant to at least 10 out of 13 antibiotics against which these bacteria were tested for resistance. Also, both E. coli and Klebsiella pneumoniae had very high resistance to antibiotics of critical importance to humans such as penicillins, fluoroquinolones, third and fourth generation cephalosporins and carbapenems, which is a last resort antibiotic used in hospitals.
“In humans, E. coli and Klebsiella pneumoniae cause infections which are becoming difficult to treat due to high resistance. Disturbingly, we found very high resistance in E. coli and Klebsiella pneumoniae isolates from the poultry environment. In some of the isolates, all antibiotics that we tested were ineffective. If these bacteria infect a human, then hardly any medicine will work as cure,” said Bhushan.
The study found strong similarity in the resistance pattern of E. coli from the litter and from agricultural soil in the surrounding areas where the litter was used as manure. This similarity was statistically established by the study.
“This indicates that the multi-drug resistant E. coli being created in the poultry farms is entering the environment through litter. From the agricultural fields, these bacteria can go anywhere – into groundwater and food – and can infect agricultural workers and animals, thereby becoming a public health threat,” says Amit Khurana, senior programme manager, food safety and toxins team, CSE.