I've worked for many years in our TB lab (before we were downsized and
outsourced). I would say that if they want different cultures they MUST
provide different swabs - 1 each for the TB, the Fungus and the Routine
Bact cultures. It is not only a matter of inhibitors in some of the
media, but also sample quantity. You make a good point about non
sterile slides, but if a GS is necessary then you should attempt to
sterilize the slides. And another question - if this is "tissue" from
the OR then why not send real tissue that can be cut and ground up and
distributed to the different labs - a whole lot better for the quantity
of the specimen and also able to get the organisms IN the tissue not
just ON the tissue.

I am not an expert - I've just worked in micro a helluva long time
[sigh/smile].

Our laboratory does NOT accept swabs for acid fast culture - period. We
reject them. Docs aren't happy, but if they're in the OR, it's easy to
suck up fluids in syringes or send a bit of tissue, which are superior
to swabs in all cases. They are much better specimens. We are slowly
working on our OR's to send liquid or tissue for ALL cultures but it is
an uphill battle. You can grind the tissue, plate the bacterial
cultures, and send the grindings on for AFB.

All fluids must be spun at centifugation appropriate for AFB cultures -
15 minutes at 2500 rpm (not sure of the rpm's - check your AFB
procedures). At a previous lab I worked at, our Ph.D. had us take off
200 ml (if one of those big bottles of pleural fluid or thoracentesis
fluid came down) into four 50 ml conical tubes. We would spin all four,
pour off the supernatant, and combine sediments for culturing (all
performed under a BSC). At my current job, we don't do that, and I think
we should. Obviously you don't get that kind of volume with some fluids.
If specimens are obviously contaminated with bacteria, then we run the
specimen through decontamination procedures.

If your facility insists on accepting swabs, I would insist on the OR
sending you a separate swab for AFB. If they don't, another thing you
can do is this, which actually is a superior way for plating all swab
cultures: vortex the swab in about 0.5 ml saline (a bit more if you're
doing AFB and fungus off of them). Remove the swab. Then, using a
sterile squeegee pipette, use this saline for inoculating your plates
and making your smears. The vortexing loosens the bacteria from the swab
fibers and you will get good recovery this way. That way you can send on
the saline that's left to the main lab for AFB/fungus and you don't have
to worry about contaminating the swab. We were doing this for awhile
(don't really know why we stopped) and had a rack of sterile salines
made up for this purpose ahead of time.

Hope this helps.

Judy Dilworth, M.T. (ASCP)
Microbiology

We occasionally get tissue "swabs" from the OR.