34 
Modem  Surgical  Dressings. 
( Am.  Jour.  Pharm. 
\     January,  1897. 
portion  of  the  infected  material  is  then  passed  through  the  steriliza- 
tion process,  care  being  taken  that  it  passes  through  like  conditions 
as  would  the  sterilized  dressings. 
In  the  case  of  gauze  or  cotton,  the  writer's  practice  is  to  wrap 
the  test  material  in  the  centre  of  the  package. 
In  testing  catgut  ligatures,  the  ligatures  are  moistened  and 
untwisted  ;  the  infected  material  is  then  rolled  up  within  the  tissue 
and  dried.  After  the  infected  material  has  passed  through  the 
sterilization  processes,  it  is  placed  in  nutrient  media  in  a  culture 
chamber.  After  a  suitable  time  (at  least  three  days)  if  a  growth  is 
found  in  the  check  experiment,  we  are  certain  that  our  test  material 
was  infected.  If  no  growth  has  taken  place  in  the  infected  material, 
that  has  passed  through  the  sterilization  processes,  we  are  certain 
that  sterilization  has  been  complete  in  all  the  dressings.  This  con- 
clusion needs  no  verification.  The  dressings  have  been  prepared 
and  sterilized  by  methods  which  exclude  contamination.  If  a  cer- 
tain portion  of  material  purposely  infected,  in  passing  through  the 
sterilization  process  with  them,  is  rendered  sterile,  it  is  conclusive 
proof  that  the  whole  of  the  dressings  cannot  fail  to  be  sterile  and 
aseptic. 
The  above  method  of  procedure  applies  particularly  to  dressings 
containing  no  chemical  antiseptic.  Where  the  dressings  are  so 
impregnated,  the  process  is  varied  as  follows : 
To  avoid  the  restraining  influence  of  the  antiseptic  upon  the 
growth  of  the  test  organism,  portions  of  the  infected  material,  after 
passing  through  the  sterilization  processes,  are  placed  in  quite  a 
large  body  of  liquid  nutrient  media,  which  is  shaken  to  dilute  the 
antiseptic  below  its  normal  antiseptic  potency;  to  carry  this  dilution 
still  farther,  a  few  drops  from  the  first  dilution  are  passed  on  to  a 
second  tube  of  culture  media. 
It  has  been  found  in  the  use  of  antiseptics  that  enough  may 
adhere  to  the  organism  (especially  to  spores)  to  restrain  develop- 
ment, though  not  destroying  their  vitality.  This  is  obviated  even 
in  the  use  of  strong  solutions  of  an  antiseptic  by  the  dilution  above 
mentioned. 
In  testing  with  antiseptics  the  test  material  is  kept  under  a  culti- 
vation for  at  least  a  week.  Development  is  often  so  retarded  by 
the  antiseptic  tending  to  make  hasty  conclusions  erroneous.  In 
these  tests  with  antiseptics,  liquefied  flesh — peptone — gelatine  of 
Koch  is  usually  employed. 
