Without more info, what suggests itself is this:
Heat sterilization of bulk containers of media is a dicey thing. Assuming
they do so by autoclaving a set-up bulk bottle of TSB, with all the
necessary fill pipes, vent filters, etc., attached and wrapped: Perhaps
the heat transfer by the container itself and via the fill pipe (metal?)
to the bottom of the vessel, is more efficient and faster, resulting in
LOCALIZED overheating of media-- which would happen to be the FIRST media
that would see the final containers.
This could explain why the FIRST containers from B might fail, whereas
all the bulks, all the A-line samples (filtered), and the end-of-run B
samples, don't show this problem-- in the absence of CIP or sanitizer
Long shot? maybe. Depends on the volumes of media in bulk and per
container, how much is purged during set-up and priming of the filling
machine, etc.- but possible?
Also, could be aeration (or lack thereof) of the media? Hard to say.
Have passed around to some cohorts and comrades- we'll see if other
[log in to unmask]
On Tue, 16 Dec 2003 10:20:50 -0600 Scott Sutton
<[log in to unmask]> writes:
> Here is an interesting case study I have been asked to post
> Two aseptic filling lines:
> Line A - Product is filtered sterile immediately before aseptic
> Line B - Product is bulk sterilized (heat) and then aseptically
> The problem:
> Filled bottles (Line B) from the beginning of the run fail GPQ
> for B
> subtilis (and continue to fail on subsequent challenges of
> Bulk media from both lines pass GPQ for all organisms
> Filled units from the end of the run (Line B) pass GPQ
> Filled units from Line A always pass GPQ, no matter from
> beginning or end
> of run
> Both media fills used same manufacturer's lot of TSB
> CIP is validated
> No evidence of sanitizers can be found in the media filled
> When I first saw this question I thought that the CIP was suspect,
> but have
> been assured that all is in place, and there is no evidence of
> sanitizer being washed off the equipment into the filled units.
> thought was that they had baked the TSB too much to support B
> subtilis (Line
> B remember is sterilized in bulk by heat). If so, then why do
> samples from
> the bulk and the end of the fill run support growth? Unfortunately,
> are no retains from the different sampling events to evaluate.
> BTW - all other organisms used for GPQ (based on Sterility Test B/F
> environmental) were fine.
> Anyway, I held this post a couple of days to get the above
> Does anyone have any ideas?
> Scott Sutton
> Moderator, PMFList
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