Antibiotic-resistant germs on the rise


Courtesy photo

Carbapenem-resistant enterobacteriaceae, or CRE, is the overarching name for the group of bacteria who show resistance to carbapenem and does not refer to a single strain of bacteria.

Bailey Mcgrath

Once heralded as a breakthrough in modern medicine, scientists believe that overuse of antibiotics is to blame for the cause of new strains of bacteria that are difficult for doctors to treat and are spread through hospitals. Carbapenem, the last resort treatment for most bacterial infections, is taking a hard hit from these new strains.

These bacteria, believed to contribute to the death of half their victims, are called carbapenem-resistant enterobacteriaceae (CRE). CRE is the overarching name for the group of bacteria who show resistance to carbapenem and does not refer to a single strain of bacteria.

According to the Centers of Disease Control and Prevention there have been 42 states to see one type of these bacteria over the past 10 years.

Dr. Ricardo Arbulu, infectious diseases director of Mary Greeley Medical Center, says CRE are resistant to a large majority of antibiotics.

“20 years ago [carbapenem] was considered the most potent way to kill bacteria. CRE are resistant to that,” Arbulu said. “Usually when [bacteria] are resistant to carbapenem they are resistant to more commonly used and less strong antibiotics. There are still a few [antibiotics] that can kill them, but some of the CRE are absolutely resistant to everything.” 

Arbulu explains why these new strains of bacteria can become resistant to antibiotics.

“Say you have E. coli in your gut and it becomes carbapenem-resistant, the reason it became a CRE is because the germs have a tiny piece of DNA called a plasmid,” Arbulu said. “In the plasmid, the E. coli has all the information it requires to resist the carbapenem.” 

CRE spreads easily; not only between the same species of bacteria, but between different species as well. When different bacteria share plasmid they are able to pass along the genes that resist antibiotics.

“The plasmid is like an additional USB drive that can be put in and out,” Arbulu said. “It can hang out with a different kind of bacteria and pass it to them.” 

It is not clear yet to scientists how prevalent these new strains of bacteria are in Iowa.

“We don’t really have a feel for how relevant it is. This is not a reportable disease,” said Dr. Patricia Quinlisk, the State Epidemiologist for Iowa Department of Public Health.

Arbulu estimated that Mary Greeley Medical Center has seen only one case of CRE in the past couple of years.

“They tend to cluster in larger institutions. We are a relatively small hospital like 250 beds,” Arbulu. “The larger hospitals with 800 or more beds are more likely to end up with CRE.”

There are precautions hospitals can take to prevent the spread or occurrence of CRE; Mary Greeley Medical Center has three key measures.

“The first is hand washing. Second thing is antibiotic stewardship or using antibiotics wisely,” Arbulu said. “If we do get a CRE case, we isolate the patient.”

Although Arbulu does not know of CRE spreading outside of hospitals, there are precautions individuals can take as well.

“There are a lot of things individuals can do. If you have diarrhea, one thing is to make sure you stay home and don’t touch anybody’s food,” Quinlisk said. “Then, because this is spread on hands, wash your hands after you go to the bathroom.”