vegetative bacteria readily and the spores more slowly. It is used primarily in
disinfecting nonliving objects, because of its harmful effect on tissue. It is particularly
useful in disinfecting sputum, blood, feces, and other organic discharges.
c. Alcohol. Alcohol is one of the most effective and extensively used
antiseptics. It is interesting to note, however, that it is most effective at strength of 70
percent. At concentrations above 90 percent or below 50 percent, it is distinctively less
d. Halogens. Iodine and chlorine are two of the best known and widely known
disinfectants. Tincture of iodine (two percent in alcohol solution) is used to disinfect
cuts and wounds. Strong or old solutions will burn the skin. Chlorine, in the form of
sodium or calcium hypochlorite, is used in water purification, in sewage treatment, and
in disinfecting food and dairy equipment.
e. Formaldehyde. Formaldehyde is a gas used in fumigation. A one percent
concentration will kill all pathogenic bacteria in a room or chamber. A 37-40 percent
solution in water, known as formalin, is used as a disinfectant, deodorant, and tissue
f. Detergents. Soap and numerous other detergents act upon microorganisms
by reducing the surface tension of the water in which they are used, thereby reducing
the ability of the microbial cell membrane to control the passage of fluids in and out of
the cell by osmosis. Soap tends to neutralize the effect of disinfectants; therefore, it
should be thoroughly rinsed off before an antiseptic or disinfectant is applied.
Hexachlorophene, a phenol derivative, is not affected by soap; therefore, it is
incorporated into soaps and detergents used in scrubbing hands of surgical personnel
and the skin of surgical patients. Detergents are not true disinfectants, but are used as
adjuncts to other agents in order to remove organic matter that might otherwise interfere
with the action of the antiseptic or disinfectant. Detergents are also the principal agents
employed in sanitizing food service equipment, eating utensils, and patient care items
not requiring sterility (bed pans, water pitchers, and so forth).
g. Antibiotics. Numerous chemotherapeutic agents, including penicillin,
streptomycin, tetracycline, the sulfonamides, and many others, are used to inhibit or kill
microorganisms which have already gained entrance into the body of a human or
animal host. This usage, however, falls within the realm of therapy, rather than
disinfection and sterilization.
Section III. PACKING MICROBIOLOGICAL SPECIMENS FOR SHIPMENT
The improper collecting and processing of microbiological specimens are often
responsible for the failure to isolate and identify the agent responsible for a disease.
The specific techniques for collecting various types of specimens do not fall within the