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Some time ago, one of my colleagues and I stared at the test results of a patient in awe. It's not uncommon for us to work up drug-resistant organisms. What was unusual was the specimen we had to conduct repeat analysis on. It wasn't my first time seeing a super resistant organism, but it was always a special occasional.
A 30-year-old female patient had a persistent urinary tract infection (UTI) caused by E. coli. Patient did not have recent travel history outside of the state.
First round of analysis found the organism to be multi-drug resistant via MicroScan. Repeat analysis through BD Phoenix and other turbidimetric method displayed the same results.
Not only was it a multi-drug resistant organism (MDRO), it had extreme resistance. The bacteria was resistant to Avycaz, Vabomere, and Zerbaxa!
Why is that significant?
The drugs mentioned are "combination drugs" designed to take care of resistant bacteria. In this case, ones that produce beta-lactamase and even carbapenemase. The drugs work by inhibiting enzyme activities in conjunction with antibiotics.
Without going into insane details about their mechanisms, here's an easier primer: https://www.idstewardship.com/comparison-avycaz-vabomere-zerbaxa/.
By this point, you could only fear the worst for the patient. If left to persist, it was only a matter of time it could become septic and fatal. When all the drugs fail, the only hope is a miracle from your immune system.
When the drugs don't work
All was not lost for our patient. There were still a few drugs left available to treat her ailment.
The physician only had choices between nitrofurantoin, tigecycline, and Zosyn. It's interesting to note that these drugs are much older than the combination drugs. The MDRO had most likely never encountered them before. They are usually not on the first choice list where I work.
Further research
With an organism this resistant, the medical director demanded molecular tests. What we found was both fascinating and disturbing. It would appear the E. coli had the New Delhi metallo-β-lactamase variant 1 gene (NDM-1). This is an emerging infectious disease phenomenon.
The CDC actually has entries for these nasty organisms. One of such is here: https://wwwnc.cdc.gov/eid/article/21/6/14-1578_article
As you can see, it came from the Indian subcontinent. In context of the patient, it didn't quite make sense. The patient did not have travel history to that area. In fact, she's not even of the ethnicity from the region.
In the end
I never knew what became of the patient or her treatment. I hope things worked out for her. While the world is battling Covid, they don't realize there are much scarier fiends in the abyss. And, they are getting stronger as time passes.