348 
Urinary  Antisepsis. 
Am.  Jour.  Pharm. 
May,  1918. 
to  a  carefully  calibrated  small  syringe  (by  means  of  a  small  rubber 
tip),  it  was  found  that  0.1  Cc.  amounts  could  be  drawn  up  with  re- 
markable accuracy,  irrespective  of  variations  in  the  size  of  the 
capillary  tubes.  These  tubes  were  used  over  and  over  again,  large 
numbers  being  sterilized  together  by  means  of  dry  heat. 
Parallel  tests  were  run  for  each  compound,  sterile  water  being 
used  for  one  series  of  dilutions  and  sterile  urine  for  the  other.  It 
was  found  to  be  unnecessary  to  adopt  any  method  of  sterilizing 
the  urine  to  be  used  for  this  purpose.  Agar  plates  poured  each  day 
containing  0.1  Cc.  of  urine  taken  from  a  specimen  voided  in  a  sterile 
(second)  flask  by  a  normal  individual  were  uniformly  sterile.  The 
factor  of  possible  error  due  to  modification  of  the  urine  through 
the  process  of  sterilization  was  thus  eliminated.  For  example, 
sterilization  of  urine  by  heat  produces  a  marked  change  in  the 
hydrogen  ion  concentration,  the  urine  becoming  much  more  alkaline. 
The  effect  of  the  reaction  of  the  urine  in  aiding  or  hindering  the 
germicidal  activity  of  a  drug  is  an  all-important  factor.  Henderson 
and  Palmer9  have  shown  that  the  hydrogen  ion  concentration  of 
urine  is  normally  subject  to  a  considerable  range  of  variation  (/>h 
4.8  to  pu  7.4),  and  that  the  average  of  this  range  is  pn  6.0  on  the 
hydrogen  ion  scale,  corresponding  to  0.000001  N  acid.10  The  im- 
portance of  the  reaction  of  urine  when  used  as  a  culture  medium 
has  been  pointed  out  by  Shohl  and  Janney,  who  find  that  the  colon 
bacillus  fails  to  grow  in  urine  at  certain  definite  acid  (pn  4.8)  and 
alkaline  (pu  9.2)  end-points.  In  order  to  eliminate  possible  error, 
due  to  strongly  acid  or  alkaline  urine,  the  hydrogen  ion  concentra- 
tion of  each  specimen  of  urine  to  be  used  for  antiseptic  experiments 
was  determined,  and  the  specimen  rejected  if  the  reaction  was  not 
approximately  that  of  average  normal  urine,  that  is,  pu  6.0. 
2.  Antiseptic  Test. — More  important  than  the  determination  of 
the  germicidal  strength  of  these  compounds  was  the  determination 
of  the  highest  dilution  of  each  in  urine  that  will  cause  an  inhibition 
of  bacterial  development.  For  this,  dilutions  in  urine  were  made  in 
10  Cc.  amounts,  sterile  test  tubes  being  used.    Each  tube  was  inocu- 
9  Henderson,  L.  J.,  and  Palmer,  W.  W.,  "  On  the  Intensity  of  Urinary 
Acidity  in  Normal  and  Pathological  Conditions,"  Jour.  Biol.  Chem.,  1913,  13, 
393- 
10  For  discussions  concerning  the  hydrogen  ion  concentration  of  urine,  and 
the  technic  for  colorimetric  estimation,  see  publications  of  Henderson  and 
Palmer,  Clark  and  Lubs,  and  Shohl  and  Janney. 
