100 LABORATORY BACTERIOLOGY 
EXERCISE XLI 
A BACTERIOLOGIC EXAMINATION OF THE SKIN AND 
FINGER NAILS 
153. There is liable to be on or in the skin of the hands 
and about the finger nails a number of bacteria which resist 
the ordinary methods of cleansing and which often cause infec- 
tion. The most important among these are pyogenic strep- 
tococci and micrococci. These organisms often infect wounds 
in surgical operations. An abrasion of the skin with a sterile 
instrument may be followed by the infection of the wound with 
these or other species of bacteria. The work of this exercise 
is to demonstrate the presence of these organisms on the skin 
of supposedly sterilized hands. 
154. Work for this exercise. Wash the hands thoroughly 
with soap and water, using a sterilized brush. Then wash them 
in a solution of 1 to 1000 corrosive sublimate for 5 minutes, 
rinse thoroughly in boiled water, and wipe with a sterilized 
towel (furnished). 
With a flamed and cooled scalpel scrape the epidermis over 
a small area about the finger nails, and with these scrapings 
inoculate a tube of bouillon and make a series of 2 agar plate 
cultures. 
Make a similar series of cultures with the scrapings from the 
back or palm of the hand. 
At the next exercise describe these cultures and examine 
the colonies microscopically to determine the genera of the 
bacteria. Indicate in the notes the number of colonies of bac- 
teria which developed in the plate cultures and the genera 
which appear in the bouillon culture. 
