Studies with topical antiseptics against bacteria and viruses inform the choice of rapid kill agents for hand sanitization.

The United States Pharmacopeia describes the use of antiseptics and disinfectants in chapter 1072 as important components of a contamination control program, especially for aseptic processing.¹ In a section entitled, “Selection of an Antiseptic for Hand and Surgical Site Disinfection,” the chapter lists the following antiseptic agents for use in a program of hand hygiene as well as by cleanroom operators in the pharmaceutical industry: isopropyl alcohol, hexachlorophene, chlorhexidine, povidone-iodine, and chlorhexidine alcohol. Of these, only isopropyl alcohol and povidone iodine have universal acceptance for safety and efficacy for use in industry (pharmaceutical, vaccine, tissue bank) or healthcare practice.^2,3,4 Ethyl alcohol solution, the most frequently used hand antiseptic,⁵ is not mentioned by the USP in this connection.

We have performed a series of comparative experiments on the speed and range of activity of antiseptics likely to be used in areas requiring aseptic or sanitary practice, including the less frequently studied effects against viruses. The fact that these agents are “narrow spectrum” (and not “broad spectrum” as with bacteria) is important information that will be discussed in this paper. This knowledge may well discourage their use when there is a transmission danger regarding certain respiratory or enteric viruses.

Even though it is recognized that antiseptics can decrease cross-contamination in pharmaceutical production areas, R & D labs, cleanrooms, and support areas,⁵ it is the purpose of this paper to analyze the laboratory methods that researchers use in the development of such agents.

METHODS
Methods for the kill time experiments and procedures were based on modified ASTM E-2135⁶ and ASTM E- 1052⁷ methods for bacteria and viruses, respectively, as well as by methods developed at Gibraltar Laboratories, Inc. The basic technique, known as the plate count log reduction method, was introduced in USP 18 (1970).

Antiseptics
(PVP-I) 10%, ethanol 62% w/w [EtOH], isopropanol 62% w/w [IPA], Triclosan liquid soap 0.15% and Benzethonium chloride [BC] 0.3% were tested. Tweenlecithin and casein-soy bean digest broth were used as neutralizers. For the viruses, 20% fetal bovine serum (FBS) and dilution were the neutralization entities for viral recovery (recorded as dilutions beyond the toxic doses). Chlorhexidine and hexachlorophene, although mentioned in USP 31, were not tested since they are deemed by FDA as inappropriate for OTC use either for efficacy or safety issues.²