What is Antimicrobial and Antibiotic Resistance?

There are two types of antimicrobial resistance:

• Intrinsic resistance is the ability of a microorganism to resist the action of a specific class of antimicrobials due to certain intrinsic genetic and cellular characteristics.
• Acquired resistance, which a microorganism develops by accumulating mutations in its DNA or acquiring genetic material from other already resistant microorganisms, making it resistant to an increasingly large number of antimicrobial classes.

Antibiotic Resistance

Acquired resistance is currently the most insidious type of antibiotic resistance, which refers to drugs targeting infections caused by bacteria, and it is also the best-known form of resistance.

The WHO estimates that in 2019, antibiotic resistance was the direct cause of more than 1 million deaths worldwide. It is the result of the improper and uncontrolled use of antibiotics, for example, to treat infections caused by viruses, against which antibiotics are not effective.

Another significant cause is the transmission of resistant bacteria, both in hospital settings and within communities.

“The issue does not concern human health alone but also the entire ecosystem in which we live, including plants and animals.

Antibiotics used to treat infections in animals, for instance, require a medical prescription. However, some of these substances are not classified as antibiotics but as supplements, which do not require a prescription. These can be used in intensive farming, for example, poultry farming.

Some of these supplements, however, are analogs of antibiotics, resembling them in function or structure. Their uncontrolled use can, in turn, lead to the development of antibiotic resistance in humans,” explains Dr. Cirillo.

In addition to improper use in healthcare and veterinary fields, there is also the issue of partially active antibiotics being released into wastewater from industrial production plants, often located in countries outside the European Union where production costs are lower and regulations are less stringent.

Another problem is the use of antibiotics in animal farming, which can reach humans through their diet and affect the microbiota—the community of bacteria inhabiting the intestines and other body systems, now considered crucial for overall health.

Antibiotic resistance is also linked to the widespread prescription of broad-spectrum antibiotics, which do not target the specific type of bacteria causing the infection but affect a wider range, increasing the likelihood of selecting bacteria that are more resistant to antibiotic action.

“It is essential to develop new antibiotics that target the specific class of bacteria responsible for the infection. To achieve this, it is crucial to integrate molecular diagnostic tests for resistance with the development and use of new drugs.

These tests would help identify which mutations are present in specific DNA regions and how they enable bacteria to survive the action of the drug.

Understanding in detail the genetic traits that make a bacterium resistant to one antibiotic rather than another would guide the prescription of highly specific treatments for the ongoing infection, thereby reducing the risk of spreading drug resistance,” explains the doctor.

One of her research lines focuses on the use of molecular genomics technologies for diagnosing antibiotic resistance. For years, the team led by Cirillo has collaborated with the European Centre for Disease Prevention and Control and the WHO to monitor antimicrobial resistance in Europe and implement molecular diagnosis on a global scale.

Antimicrobial resistance develops faster than industries can produce new drugs, which typically take about 10 years to reach the market. Therefore, it is essential to act promptly through prevention and education for patients, healthcare professionals, pharmacists, and policymakers.

“The first life-saving practice is handwashing. It may seem trivial, but washing hands properly is the primary habit to adopt to prevent the transmission of pathogens and, consequently, diseases,” says Dr. Cirillo.

Doctors and healthcare professionals should also:

• explain to patients when, how, and for how long to take an antibiotic;
• avoid, as much as possible, prescribing broad-spectrum antibiotics.

Patients, for their part, should:

• strictly adhere to the prescribed antibiotic regimen, starting and ending treatment on the days specified by their doctor;
• get vaccinated whenever possible, especially against viral diseases like influenza, which predispose to bacterial superinfections, and against bacterial pathogens that cause severe diseases such as pneumonia and meningitis in vulnerable individuals.

“It is also crucial to follow shared international guidelines that strictly regulate antibiotic use.

Finally, to minimize the risk of resistance emerging against the latest-generation antibiotics, these drugs must be protected from indiscriminate use and prescribed by infectious disease specialists only when necessary. Infectious disease specialists, using diagnostic tools for resistance, should guide the prescription of an appropriate antibiotic to combat the infection,” concludes Dr. Cirillo.