How to tackle antibiotic-resistant bacteria?

Better dosage and systematic screening in hospital. These are the recommendations of a conference on antibiotic-resistant bacteria held at the University of Montreal (UdeM) in mid-April. Update on successes and concerns in the field of bioresistance.

“The figures for victims of antibiotic resistance are truly impressive,” says Yves Longtin, head of the infection prevention and control unit at the Jewish General Hospital. “In 2022, in the Lancet, an estimate put the number of deaths worldwide at 1.3 million each year. In comparison, HIV kills 700,000 and malaria 600,000.”

Great progress has been made for HIV and malaria, notes the D^r Longtin. “Twenty years ago, they each caused 1 million deaths. We realize that such major efforts must be made to deal with microbes that are multi-resistant to antibiotics. »

At the conference, which took place in mid-April at the Faculty of Pharmacy of the University of Montreal, Dr.^r Longtin presented the latest advances in screening for antibiotic resistance with diagnostic tests.

CPE often results in a UTI having to be treated intravenously rather than with oral antibiotics (pills). This type of antibiotic resistance has become twice as common in Canada over the past 10 years, but remains much less important than MRSA and VRE. In some European countries, such as Greece and Italy, CPEs are a “huge” problem in hospitals, says D^r Longtin. And in India, even outpatient treatment of UTIs is compromised by CPE.

EPCs produce enzymes called carbapenemases, which render several antibiotics, including carbapenems, ineffective.

Travel

Routine screening does not mean that all patients in hospitals are tested. “In Montreal, for MRSA, for example, hospitals test all patients,” says Dr.^r Longtin. But in certain regions where antibiotic resistance is rarer, we can only test certain patients, for example those who have recently traveled abroad or been hospitalized, or come from a CHSLD. »

The Jewish General Hospital began systematically screening for CPE before the pandemic, and more and more Quebec hospitals are following this approach, says Dr.^r Longtin.

This screening for antibiotic resistance is done in the laboratory, after taking nasal or anal samples with swabs. Results are ready in one or two days.

Isolating patients carrying antibiotic-resistant bacteria but who do not show symptoms helps prevent the spread of this bacteria to other patients.

Wouldn’t it be better to have faster tests to isolate asymptomatic patients upon arrival at the hospital? “We currently have good results with this approach. We could use bedside PCR tests to get a result in one or two hours, but it costs much more, $30 to $40 instead of $7 to $10 per test. When you do hundreds of thousands of tests per year, that counts. »

Can’t we have rapid tests like those distributed by pharmacies for COVID-19? “Rapid test for COVID-19 detects a single protein, says D^r Longtin. For antibiotic resistance, six to ten targets should be detected. It can’t be done easily. »

The D^r Longtin previously worked on Clostridium difficile, demonstrating in 2016 that it was possible to halve infections of this bacteria by isolating its asymptomatic carriers upon their arrival at the hospital. “But ultimately, we managed to reduce the problem of VS. difficult with preventive measures, then we do not do systematic screening. » The annual number of cases has fallen from more than 3,500 to less than 2,500 over the past 10 years in Quebec.

Dosage

Another approach is to dose antibiotics for each patient. “It’s very widespread in Europe,” explains another speaker, Amélie Marsot, from the faculty of pharmacy at the University of Montreal. “The goal is to have a dosage high enough to be sure that an infection is defeated. »

Antibiotic resistance occurs, among other things, when a treatment is not strong enough or long enough to kill all the microbes responsible for an infection. Those that remain are genetically more likely to be resistant to the antibiotic used, and this antibiotic-resistant genetics becomes more common within this population of microbes.

Another aspect of dosing is to suggest antibiotics where antibiotic resistance is potentially less of an issue, says Dr.^D Marsot.

A broad-spectrum antibiotic is effective against several microbes. This category of antibiotics generates more antibiotic resistance because they can affect the genetics of more microbes.