Superbug | Annie Lu

Superbug

by Annie Lu

Now that this year’s particularly far-reaching flu season seems to be finally reaching its close, many of us may breathe a sigh of relief. No more days of sniffling, sneezing, and aching throats, we hope. Unfortunately, the common cold and flu aren’t the only things a majority of humankind battles on the field of bacteria and viruses. In fact, things may be getting worse.

Researchers have recently discovered for the first time strains of a multidrug-resistant bacterium. This itself isn’t unusual, for antibiotic resistance is something scientists have been pondering for years, but this particular germ evades even colistin, which is a last-resort antibiotic treatment. This study was published earlier this week by Emory University researchers. These bacteria are carbapenem resistant Klebsiella pneumoniae (CRKP, to most normal humans), members of a family of multidrug-resistant pathogens. These pathogens have a collective mortality rate of almost 50%.

Multiple drug resistance, abbreviated as MDR, are threatening for patients that may end up in the hospital with an infection that just won’t pass, and find that even treatment at the hospital may offer them no salvation. Species of microorganisms have survived for millennia by adapting via spontaneous mutation, enabling them to oppose the attacks of some antibiotics. Many common bacteria that we face now exhibit MDR, including staphylococci, streptococci, and salmonella. Antibiotic resistant bacteria can also transfer copies of their own DNA, which encode their resistance, to other bacteria, which then spread it even further.

CRKP was already reported a superbug decades ago. After infecting a surprisingly high rate of people in Los Angeles in 2010, renewed study of the bacteria began. In a 2008 study, the death rate from previous outbreaks was determined to be about 35%.

The Emory researchers isolated strains of CRKP from patients’ urine, and have since conducted testing to verify that certain strains of the bacteria survived even colistin treatments. This mysterious resistance is often referred to as hetero-resistance. Hetero-resistant populations are unusual in that they may look perfectly susceptible to treatment in standard tests, but with advanced diagnoses, sub-populations of the bacteria appear to be more resistant. This would make sense if some bacteria had a genetic mutation that protected them from the drug treatment, but the strangest part yet is that these resistant sub-populations appear genetically identical to their counterparts.

The answer then must be that the bacteria are activating their genes differently, even if they have the same overall genetic blueprint. The general study of changes in organisms caused by modification of gene expression rather than the code itself is called epigenetics. In the case or CRKP, the Emory researchers hypothesize that a specific sensory system involving proteins in the bacterial membrane is responding to an environmental cue that “switches” genes on and off.

If these bacteria may be inescapable, what can people to do to prevent infection? For one thing, hospitals more than any other entity have responsibility for events like these. According to Dr. Robert Moellering, infectious disease specialist at Harvard, hospitals should identify organisms like CRKP, quarantine them, and follow standard isolation techniques like hand-washing and wearing gowns and gloves. If these guidelines are followed, there is hope that the number of infections will go down. But it won’t be easy.

Sources:

1. Melnick, Meredith. “Q&A With a Superbug Expert: How Dangerous is CRKP?” Time Magazine. 31 March 2011.

2. Mole, Beth. “Deadly superbug just got scarier—it can mysteriously thwart last-resort drug.” ars technica. 9 March 2018.

image source: https://www.cagle.com/daryl-cagle/2013/04/superbug