114 LABORATORY BACTERIOLOGY 



EXERCISE LI 



A BACTERIOLOGIC EXAMINATION OF THE SKIN FOR 



MICROCOCCUS EPIDERMIDIS ALBUS AND 



OTHER BACTERIA 



167. There is liable to be on or in the skin a number of bac- 

 teria which resist the ordinary methods of cleansing, owing to 

 their being deeply seated in the epidermis. The most impor- 

 tant among these is M. (Staph.) epidermidis albus. 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 this or other species of bac- 

 teria which were on or in the skin itself. The work of this 

 exercise is to demonstrate the presence of these organisms on 

 the skin of supposedly sterilized hands. 



REFERENCES. Dennis' System of Surgery, Vol. I, p. 249. 

 This chapter, written by Professor Welch, contains a summary of 

 the present knowledge of the bacteria of the skin, with references 

 to original articles. 



168. Work for this exercise. Wash the hands thoroughly 

 with soap and water, using a sterilized brush. Then wash 

 them in a solution of i 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 bacteria. 



