On the Waterfront

Mark A. Crislip, MD


June 09, 2021

Getting old? Stinks. On ice. Last week I had night call and then on-call this weekend. And I am pooped. I have nowhere near the stamina I did even last year. And time off does not energize me for work; it only makes me want more time off.

My big mistake was marrying a younger woman. She is not Medicare eligible until 2024, so I am working for healthcare for the next several years. I so hope Biden lowers the age of eligibility to 60. If so? As much as I like ID, I'm outta here. Someday you youngsters will understand.

The past 24 hours gave me a twofer.

Both patients were obese with chronic edema. Both had chronic skin breakdown. One has cirrhosis, the other diabetes.

Both are admitted for SIRS and a lower-extremity cellulitis.

Both had gram-negative rods in the blood.

In my youth, I had been taught that gram-negative rods do not cause cellulitis in normal hosts, and when they do, it is a necrotizing infection. Not so.

Over the years, I have seen an assortment of cellulitises (celluliti?), diffuse erythroderma, in relatively normal hosts. What they all had in common was obesity, although I can't find this association in the PubMeds.

For erysipelas, 4.6% of 607 patients had positive blood cultures, of which …11% were Gram-negative organisms. For cellulitis, 7.9% of 1578 patients had positive blood cultures of which … 28% were Gram-negative organisms.

But what is the difference as a clinician between a cellulitis and an erysipelas? Cellulitis is deeper than erysipelas, but I can't tell that on the exam.

The most characteristic finding in erysipelas, the sharply defined and slightly elevated border, helps to differentiate this entity from cellulitis, which has an indistinct border.

In chronic edema patients, no one can tell. I do not find it a useful distinction. Is it diffuse erythroderma, abscess, or a necrotizing infection? That is what I care about. I agree with the uselessness of

the current distinction between cellulitis and erysipelas

for predicting the microbiology.

The diabetic grew Pseudomonas aeruginosa; the cirrhotic Stenotrophomonas maltophilia.

What do those have in common? Water. So I bet my resident that the Stenotrophomonas maltophilia patient bathed in untreated well water.


As did the Pseudomonas aeruginosa patient.

Stenotrophomonas maltophilia hospital outbreaks traced to tap water are common, but I was surprised to find no cases associated with wells. There are many articles on Pseudomonas in well water, and while water exposure is classic for a variety of pseudomonal infections, none are specifically from well water.

Wells are a common water source outside the Portland metro, and the water is never treated, but I have yet to get confirmatory cultures from the well. I probably have half a dozen odd gram-negative soft tissue infections over the years that I have blamed on bathing in untreated well water.

So maybe it is not the thing I think it is. Or perhaps I'm the only one who routinely asks about water sources?


Gunderson CG, Martinello RA. A systematic review of bacteremias in cellulitis and erysipelas. J Infection. 2012;64:148-155. Source

Ioannou P, Tsagkaraki E, Athanasaki A, Tsioutis C, Gikas A. Gram-negative bacteria as emerging pathogens affecting mortality in skin and soft tissue infections. Hippokratia. 2018;22:23-28. Source

Izadi Amoli R, Nowroozi J, Sabokbar A, Fattahi S, Amirbozorgi G. Isolation of Stenotrophomonas maltophilia from water and water tap. Biomed Res. 2017;28. Source

CDC. Overview of Water-related Diseases and Contaminants in Private Wells. January 27, 2021. Source

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About Dr Mark Crislip
Mark A. Crislip, MD, has been practicing infectious diseases in Portland, Oregon, since 1990. He is nobody from nowhere but has an enormous ego that leads him to think someone might care about what he has to say about infectious diseases. He has been blogging on the most endlessly fascinating specialty in all of medicine since 2008 and has yet to run out of material. Or perhaps he is just a slow learner. His multimedia empire is at


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