Flies And Birds Carry Antibiotic Resistance Genes

Flies and birds carry antibiotic resistance genes

Researchers at Cardiff University found that the bacteria that caused disease in 1% of patients in Chinese hospitals had already developed resistance to the "last resort antibiotic" colistin, even if it was not used in therapy.

The first systematic study of bacterial resistance to "antibiotics of last resort" took place in hospitals and farms in China. It turned out that the problem is much more serious than previously thought - firstly, the resistance of microorganisms to antibiotics was much stronger than experts expected, and secondly, the genes of this resistance are carried by flies. "Antibiotics of last resort", among which the group of carbapenems can be distinguished, are used in cases where no others help. If carbapenems do not work, colistin is considered one of the few remaining options. Previously, it was believed that there are no bacteria resistant to it, but in 2015, microorganisms with this property were found in China. Antibiotic resistance genes can be passed between different types of bacteria.

Read more: Bacteria developed resistance to antibiotics long before they appeared

Scientists from McMaster University and The University of Akron during excavations in one of the longest caves in the world - Lechuguilla in the United States - discovered a new bacterium, unique in its properties. For 4 million years, the bacteria called Paenibacillus have been isolated from the outside world, but analysis has shown that they are resistant to 18 of the antibiotics currently developed, and among this number there are even "antibiotics of last resort", which are used only in extreme cases. This means that evolution developed defense mechanisms in these bacteria long before the potential danger appeared in the form of the first antibiotics.

Colistin is not used in China to treat humans. It is given to animals (mainly pigs and chickens) as a dietary supplement to stimulate their growth - about 8 thousand tons annually throughout the country. It is planned to end this practice in April and start using colistin as a human antibiotic - but it may be too late for that. Researchers at Cardiff University found that the bacteria that caused disease in 1% of patients in Chinese hospitals had already developed resistance to colistin, even when it was not used in therapy.

Other scientific work has shown that about a third of poultry and animal meat samples are contaminated with microorganisms resistant to carbapenems. In a quarter of the samples from this number, the bacteria were also resistant to colistin. Moreover, the genes for resistance, as it turned out, "have wings." They have been found in dog faeces in poultry farms, as well as in flies from these farms. Cardiff University researcher Tim Walsh explained that in the summer flies carry these genes everywhere. Later, the genes were also found in poultry droppings, which means that resistance to "antibiotics of last resort" can "move" into neighboring plans.

When specialists sequenced the bacterial genome, they found that almost all samples of chicken meat contained microorganisms with the mrc-1 colistin resistance gene, but only half of them actively promoted the antibiotic, in the rest of the bacteria this gene was in "dormant mode". Thus, in the past - in standard tests - the danger was significantly underestimated.

Source: Flies are spreading antibiotic resistance from farms to people

It is now the year of the chicken in China - in more ways than we knew. The first systematic study of bacterial resistance to last-resort antibiotics on farms and hospitals in China has revealed far more resistance than standard tests had previously suggested, especially on chicken farms and meat. Worse, the study reveals for the first time that the genes that give bacteria their resistance are being spread by flies. Antibiotics of last resort constitute our final weapons against bacterial infections that have resisted all other drugs. Carbapenems are often used as such drugs, but bacteria with genes for resisting carbapenems are spreading.

New Scientist