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Wednesday, 07 February 2018 21:45

TWiM 170 Letters

Written by 
Published in Letters

Anthony writes:

Late last night in that little interval between exhaustion and sleep after showering, I take a cat for a little walk in the hallway,  I then sit on the steps with her for a few minutes.  My thoughts strayed to Chimpanzees, wondering how they bear a tropical climate without bathing.  Might there be something in their skin microbiome that naturally cleansed?  Might here be the means to wage war against MRSA, analogous to the Merck's goldmine found just under the green of a Japanese golf course?

I'd forgotten my conversation with myself until you mentioned in TWiM 168 about the dairy farmers showering less a day.  Might the richness of their superficial flora extend past the nose?  Might that make less frequent bathing possible?


Answer… “Only in the last hundred years have we made bathing a daily practice. Are we overdoing it? According to Dr. Richard Gallo, chief of the dermatology division at the University of California, San Diego,“Good bacteria are educating your own skin cells to make your own antibiotics. . . and they produce their own antibiotics that kills off bad bacteria.” (NY Times “The Great Unwashed“)  Gallo believes showering not only removes lipids and oils that keep your skin from drying out, showering also removes some of the good bacteria.  Commensal skin bacteria as the probiotic of the cutaneous immune response, Expert Review of Dermatology, 5:3, 251-253, DOI: 10.1586/ edm.10.24


Anthony writes:

E. coli deaths from romaine contamination

Would rinsing help?

From USDA…Washing Produce

Before eating or preparing fresh fruits and vegetables, wash the produce under cold running tap water to remove any lingering dirt. This reduces bacteria that may be present. If there is a firm surface, such as on apples or potatoes, the surface can be scrubbed with a brush. Consumers should not wash fruits and vegetables with detergent or soap. These products are not approved or labeled by the U.S. Food and Drug Administration (FDA) for use on foods. You could ingest residues from soap or detergent absorbed on the produce.

When preparing fruits and vegetables, cut away any damaged or bruised areas because bacteria that cause illness can thrive in those places. Immediately refrigerate any fresh-cut items such as salad or fruit for best quality and food safety.





Shinichiro Enomoto writes:

Thank you for discussing our paper. I used to listen to TWIV and TWIM regularly when I had a long commute. I would have loved to hear Elio’s thoughts on our work. I am his fan and do not mean any disrespect towards Dickson. As per Dickson, we would love to know where Sodalis praecaptivus lives after injection.  

However, injection into the thoracic cavity is artificial and we don’t know the true lifestyle of the S. praecaptivus. With these caveats, I imagine that the bacteria live throughout the hemolymph, as I have recovered colonies from an amputated leg. We don’t know if they are intracellular, though we have preliminary data that suggests that the bacteria can survive for few days in mouse lymphocytes.

We regard the S. praecaptivus as a “protosymbiont” and consider it  ancestral to many of the insect symbionts.   The two relatively “young”  symbionts, S. glossinidius
(of tsetse fly) and Candidatus Sodalis peirantonious (of rice weevil) have different homes and lifestyles.  Ca S. pierantonius lives in bacteriomes, near the gut and near the ovaries, it is suspected that the one near the ovaries gets transmitted and one near the gut provides amino acids (

In contrast S. gossinidius, lives in the hemolymph and bacteriomes have not been detected. And this bacterium is facultative and has been cultured without the host.  Moreover it was recently shown that even paternal transmission can occur ( Given enough time, S. praecaptivus
appears capable of evolving into different lifestyles. But it is also possible that there are many protosymbionts that are already specialized towards different insect hosts.

Shin Enomoto

Last modified on Wednesday, 07 February 2018 21:47
Vincent Racaniello

Vincent Racaniello, Ph.D. is Professor of Microbiology at Columbia University Medical Center. As principal investigator of his laboratory, he oversees the research that is carried out by Ph.D. students and postdoctoral fellows. He also teaches virology to graduate students, as well as medical, dental, and nursing students.

Vincent entered the world of social media in 2004 with virology blog, followed by This Week in Virology. Videocasts of lectures from his undergraduate virology course are on iTunes University and virology blog. You can find him on WikipediaTwitter, Facebook, and Instagram. His goal is to be Earth’s virology professor. In recognition of his contribution to microbiology education, he was awarded the Peter Wildy Prize for Microbiology Education by the Society for General Microbiology. His Wildy Lecture provides an overview of how he uses social media for science communication.