Can you imagine a world where even the strongest antibiotics fail to beat back an infection that’s threatening your life?

Unfortunately, you don’t have to — because it’s already happening, according to the World Health Organization.

Resistant strains of bacteria, fungi, parasites and viruses occur naturally when microorganisms replicate themselves erroneously or when resistant traits are exchanged between them, according to the WHO, but the use or misuse of antimicrobial drugs, like antibiotics, accelerates that process.

“There are already rare cases of infections to which no known antibiotics are effective,” said Dr. Paul Carlan of Valley Medical Group in Greenfield, “In time, it’ll become more common.”

In our daily lives, antibiotics are among the most recognizable antimicrobial agents, used to treat infections since the early 20th century.

But their overuse, in both medicine and food production, has seen dangerous infections begin to withstand them such as Methicillin-Resistant Staphylococcus aureus, or MRSA, which is impervious to penicillin, amoxicillin, oxacillin, methicillin, and other antibiotics, according to health professionals.

“Antibiotic resistance,” said Carlan, “is the notion that exposing bacteria in our bodies to antibiotics will kill most of them, but the strongest and most resistant will survive.”

Those become dominant, he said, and as they reproduce, the antibiotics don’t work on them at all anymore. They’re known as “superbugs.”

The first case of MRSA in the United States was seen in 1968, but since 2002, it’s evolved even more resistances, according to the National Institute of Allergy and Infectious Diseases.

Carlan said antibiotics, in particular, don’t have any benefit at all when the infection is caused by a virus.

“Antibiotics are appropriate when an infection likely caused by bacteria is present,” he said. “The great majority of upper respiratory infections are caused by viruses, so infections such as sore throats, rhinitis, bronchitis and the common cold don’t benefit from antibiotics.”

Carlan said the belief that antibiotics will make a person feel better faster is a myth, too, and using them for viral infections could actually make things worse if the patient is allergic to them. They can also cause bad cases of diarrhea.

Antibiotics, he said, are appropriate for treating bacterial infections like pneumonia, urinary tract infections, cellulitis and skin abscess, among others.

Though antibiotics are most closely associated with medical treatment, Carlan said that’s not the only factor in rising resistance.

“A big part of the problem is the use of antibiotics routinely in our food supply,” he said. “We know they’re frequently used to increase production in the food supply — animals tend to grow better and faster when antibiotics are applied to their feed.”

Though the practice is widespread, he said, more public awareness has led to an increased demand for antibiotic-free, organic foods.

“Most of us are young enough to not remember the era before (antibiotics) resisted, and it’s really nice to have drugs that treat common infections and prevent them from becoming severe,” he said, “but resistance is becoming a problem, and we’re seeing it with some regularity.”

To compound the problem, Carlan said, many pharmaceutical companies are not working on new types of antibiotics to replace the ones we have, though many groups, including the Infectious Disease Society of America, have been pushing for the development of new antibiotics.

“Many of us think the reason is financial,” he said. “Antibiotics are relatively small revenue drugs compared to other drugs,” he said.

Carlan said surgical procedures can in some cases stop infections when antibiotics fail, but often nothing can be done except to hope the person’s natural immunity can fight it off.

“As we get older and sicker and have more individuals with cancer and other immune suppressants, the risk that these infections will kill people will go up,” he said.

Tom Relihan can be reached at trelihan@recorder.com.