We share the world with trillions of microbes, many of which can be found in the human body. But only a few thousand of the bacteria in the world have been well-characterized. A new study has shown just how much we don't know about bacterial cells. This work, which was reported in BMC Microbiology, analyzed samples taken from patients at University Hospital Basel. After assessing samples taken since 2014, the researchers identified thirty species of bacteria that were previously unknown. Some of these microbes are linked to patient infections as well.
For this study, the researchers focused on 61 pathogens that were found in samples of patient blood or tissue; these patients were affected by a variety of different health conditions. While bacteria had been isolated from the individuals, the microbes had not been identified with standard methods like mass spectroscopy or by analyzing a portion of the bacterial genome.
The investigators instead sequenced the entire genomes of these bacteria. The sequence data was compared to known bacterial genomes, which showed that 35 of them had never been described before. Of the 35, there were 26 that the study suggested are challenging to classify because they have only recently been found and few samples have been sequenced.
Seven of the 35 bacteria were found to be clinically relevant - they study authors noted that they might cause human infections.
"Such direct links between newly identified species of bacteria and their clinical relevance have rarely been published in the past," said corresponding study author Daniel Goldenberger.
Some of the bacteria do seem to belong in genera called Corynebacterium, or Schaali, which are both bacteria with gram-positive walls and rod shapes. These genera are full of microbes that are typically part of the human skin or mucosal microbiomes, noted Goldenberger. "This is why they are frequently underestimated, and research into them is sparse." But they have been associated with some infections as well.
Another bacterial pathogen found in this study was isolated from the thumb of a patient who was experiencing inflammation after they were bitten there by a dog. Another study, which named the microbe Vandammella animalimorsus in 2022, has linked it to dog and cat bite wounds.
"This has led us to assume that it is an emerging pathogen which we need to monitor," said Goldenberger.
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The team continues to monitor bacteria that are isolated from patients at University Hospital Basel. New species have already been found. Goldeberger noted that this is due to technological advancements, which are also going to improve the diagnosis and treatment of infections due to rare pathogens.
Sources: University of Basel, BMC Microbiology