mystery bug

Phil jorge2 at
Sat Mar 21 14:03:05 EST 1998

TEvers wrote:
> Had an interesting bug last week.  Could hardley get this bad boy to
> grow.  Here's a little history for you all, and maybe you can give me
> some suggestions.  (I work in a small hospital lab w/ limited resources
> as far as specialized media, etc...)
> The doc admitted this man to an isolation room and began doing acid fast
> sputum cultures x 3 and two routine cultures.  On the day of admission,
> the patient had not been on antibiotics and the first AF culture and
> routine sputum culture was collected.  The Q score on the first routine
> culture was 2+ and the predominant org. was gram positive diplococci and
> what looked like staph.  Very few gram negative anything.
> The patient was put on Zinacef after that first sputum was collected but
> remained in isolation, as the doc was highly suspicious.
> The second set of AF and routine cultures was collected the next day.
> It was a copious amount and very pirulent.  The gram stain was 3+ and
> there were LARGE number of gram negative rods.  They were large long
> gram negative rods.  There were still gram positive diplos and staph,
> but the predominant org. was DEFINATELY the gram negative rods.  I
> called this to the doc, and he put the patient on Genta.
> The next day, the third spec for AFB came down and I (on a whim) gram
> stained, mostly to make sure this was the correct patient, and some
> mislabeling hadn't occured.   Again...large number gram negative rods w/
> diplo's and staph.
> All three AFB smears were negative.
> The  1st routine culture on the first spec grew....alpha streps and
> staph.
> The 2nd routine culture grew moderate amt. of Staph. aureus and some
> normal resp. flora as well.  The first day, no gram negatives appeared.
> The second day, the mac plate showed a very small amount of a very dry,
> crumbly gram negative lactose fermenter (oxidase positive).  Nothing
> grew on the mic plate.  We plated/subbed that gnr to everything we could
> think of, just to keep it alive and send it to the state for ID.
> Nothing grew on any other media.  ZERO.  I even on a whim tried an
> anerobic culture.
> I have seen this typical colony morph at least twice before, and could
> not keep it alive then, EITHER.  I think it's time for us to find out
> what this bug is so that we can make sure the patient is being treated
> accordingly.  I looked in the books, and had no luck in getting to a
> description of this bug.
> Any thoughts on this?  I would be happy to hear them.
> The patient did begin feeling better on the third day and the WBC count
> dropped from 21 to 18.
> T. Evers.

What were the media used for culture and specific methods used for AF
and Gram stains?
Slow growing, friable colony, lactose fermenting, oxidase positive, Gram
neg bug.  This is an odd collection of characteristics that don't seem
to point at any of the typical isolates.  Mycobacterium fortuitum grows
slowly and, I recall, as friable colonies on Mac - not sure how well it
stains acid fast and don't have ref's here for lactose/oxidase
reactions. What about this one as your culprit?

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