From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med
Subject: Re: Traveler's diarrhea
Date: 29 Apr 1998 12:53:44 GMT

In <6i71ri$l84$1@news-t.computek.net> gnee@marlin.utmb.edu (Greg Nee)
writes:

>1. Most infectious causes of diarrhea are viral (rotavirus, etc.) so
>antibiotics have absolutely no effect on them.


Is that true?  I thought they were varients of normal flora, such as E
coli.



>2. Even those bacterial causes of diarrhea are often not caused by the
>bacteria themselves, but by toxins produced by bacteria that you ingest
>preformed (in contaminated water or foods). These bacteria can sit in
>you intestines (where most antibiotics cannot affect them) and keep
>producing these toxins for a while.

    Well, you're talking about food poisoning, which is NOT the same
thing as traveler's diarrhea.  Traveler's diarrhea in pure form happens
even in countries where the food is not contaminated (at least no more
than anywhere else).  It's just that people have a different set of
germs.  Go somewhere, and after a time you catch them, sooner or later.
 During that time your stools are loose.  That's it.


>3. The biggie. The bacteria that live in your intestines normally (some
>of which you need to digest food and nutrients properly) live with each
>other in a careful balance. Powerful broad-spectrum antibiotics like
>Augmentin can disturb that balance by selectively killing off certain
>bacteria. This then allows other bacteria to grow unchecked, itself
>causing an infectious diarrhea known as pseudomembranous colitis.


    Right. That's why you never want to give a drug which kills
anaerobes, like Augmentin, for this.  A good non-well-absorbed
fluoroquinolone, like Noroxin, works fine.

>The best way to  prevent traveler's diarrhea is to only drink bottled
>water when in doubt and only eat at reputable establishments.

    Won't save you.  Obviously you've done little serious traveling!
Or thought you were making mistakes.  Probably not.


                                      Steve Harris, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med
Subject: Re: Traveler's diarrhea
Date: 19 May 1998 08:48:58 GMT

In <6jr805$2056$1@newssvr04-int.news.prodigy.com> "Andrea L Boyd"
<GANDAB@xprodigy.net> writes:

>>Really? That's something I didn't know. What's special about clavulinic
>>acid? We never get to use it alone, so this hadn't occurred to me.
>>Clearly amoxicillin is quite enough to disturb gut flora (or do
>>something) on it's own, though.
>>
>>                                   Steve Harris, M.D.
>
>Aren't the macrolides especially nasty on the gut as well?
>
>A


    Erythromycin is famously bad as a local stomach irritant.  But
that's a chemical effect.  In general macrolides don't seem to disturb
gut flora nearly so much as many others.  To do a good job screwing up
gut flora (causing diarrhea and vaginal or skin candidiasis), an
antibiotic generally has to kill some E. Coli and Klebsiella, and some
anaerobes. Macrolides, like fluoroquinolones, don't kill anaerobes too
well.  And at least one drug (metronidazole) kills anaerobes but not
enough the enterobacter spp.  So these all seem to be a bit less
diarrhea-ogenic. No hard and fast rules in this, though.  Another
famously bad oral antibiotic is clindamycin, because it doesn't kill C.
difficile (an anaerobe with a nasty toxin), but kills enough other bugs
to make it easier for C. difficile to grow.

                                        Steve Harris, M.D.

From: gnee@marlin.utmb.edu (Greg Nee)
Subject: Re: Traveler's diarrhea
Date: 30 Apr 1998
Newsgroups: sci.med

In article <6i77so$i64@dfw-ixnews9.ix.netcom.com>, sbharris@ix.netcom.co
says...
>>1. Most infectious causes of diarrhea are viral (rotavirus, etc.) so
>>antibiotics have absolutely no effect on them.
>
>Is that true?  I thought they were varients of normal flora, such as E
>coli.

Most traveler's diarrhea is presumed to be caused by enterotoxigenic E.
coli, but overall the most common causes of diarrhea are viral, with
enteroviruses the most common I believe with some other common pathogens
thrown in. At least that's what I've been told.

>    Well, you're talking about food poisoning, which is NOT the same
>thing as traveler's diarrhea.  Traveler's diarrhea in pure form happens

You're quite correct that true "traveler's diarrhea" is not caused by food
poisoning. But I assumed that when a layperson asked about traveler's
diarrhea, they were referring to all causes of diarrhea when traveling.


>    Won't save you.  Obviously you've done little serious traveling!
>Or thought you were making mistakes.  Probably not.

May not save you from true traveler's diarrhea, but if the poster was
concerned about diarrhea while traveling, normal precautions are a good
recommendation. I haven't done much traveling recently (medical school
does that to you). The only time I had diarrhea while traveling was
definitely a food poisoning incident while backpacking through Spain. Man
I thought I was going to die.

Anyway, the basic message was that taking antibiotics in hopes of staving
off Traveler's Diarrhea is a bad idea. Won't help prevent it and can cause
some problems of its own.