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The onset of mandatory public reporting of HAI has contributed to the sense of urgency to improve hand hygiene practices. In the United States, it is estimated that two million HAI occur per year in hospitals, and 90,000 deaths can be directly related to these infections. Healthcare costs to manage these infections are calculated to be in excess of 4.5 billion dollars. The personal cost to the patients who develop these infections cannot be measured. Hand hygiene is considered to be the most straightforward and most effective intervention for preventing HAIs.¹

An antiseptic agent is an antimicrobial substance that is applied to the skin to reduce the number of microbial flora. In the United States, the most commonly used antiseptic agents are alcohol, iodophors, chloroxylenol, chlorhexidine gluconate and triclosan.²

Figure 1

Triclosan is a synthetic, broad-spectrum antiseptic agent that was first described in the literature in 1967.³ It has been used extensively for more than 20 years in personal care products such as toothpaste and deodorants, and in
antibacterial handwash products that are sold in the consumer market. Triclosan is also an antiseptic ingredient included in healthcare personnel handwash (HCPH- a term used by FDA) formulations that are intended to be used in healthcare facilities. Does this mean that all triclosan-containing hand hygiene products perform equally well against pathogenic microorganisms?

The mere presence of an antiseptic agent in a hand hygiene product does not guarantee that there is significant antimicrobial efficacy against pathogens. Antiseptic hand hygiene products marketed in the healthcare arena should meet the proposed rigorous performance standards issued by the Food and Drug Administration (FDA).⁴ The performance standards specify required in vitro (in a test tube or container) tests in addition to the minimum criteria for in vivo (with a living organism) tests such as those used for a HCPH. According to FDA, a HCPH must have fast-acting, broad-spectrum antimicrobial activity to reduce the number of transient flora on intact skin. Commercially available antibacterial hand hygiene products are not appropriate substitutes in the healthcare setting because they are not formulated to meet the testing standards of the TFM.

A time-kill study is the most commonly used method to prove the fast-acting, broad-spectrum antimicrobial activity of an antiseptic-containing hand hygiene product. A time-kill study is an in vitro test in which a test product is challenged to kill pathogenic microorganisms in a designated time period (usually seconds) with an expected substantial reduction of microorganisms at the end of the time period.⁵

The procedure begins with specific amounts of the test product being placed in the testing container.

Next, specified amounts of microbial suspensions (microorganisms in a medium) are added to the test product to determine the antimicrobial activity of the antiseptic agent in the hand hygiene product. The contact time between test product and microorganism can vary depending on the objective of the study. In most time-kill studies, the contact time is 15 seconds.

After the contact time has been reached, a neutralizer is added to stop the antimicrobial activity of the test product. The test product will continue to interact with the microorganisms if it is not neutralized.

The final step in the process is to determine the antimicrobial efficacy of the test product by comparing the number of viable microorganisms from the original culture, known as the baseline count, to the number of microorganisms after exposure to the test product. The results are determined by standard microbiological plate counts. (See Figure 1)

In a recent time-kill study, a triclosan-containing HCPH formulated to meet the performance standards of FDA was compared to a triclosan-containing antibacterial soap intended for household use. The products were both challenged with 17 pathogenic microorganisms commonly found in healthcare facilities. Antimicrobial activity was evaluated at contact times of 15, 30, and 60 seconds.

Results Product A, the HCPH, demonstrated exceptional antimicrobial efficacy when compared to the performance of a triclosan-containing antibacterial household soap (Product B). Product A reduced the bacterial counts of 14 of the 17 test microorganisms by > 99.999% within 15 seconds. The remaining three test microorganisms were reduced by > 99.999% at 30 seconds. Product B achieved 99.999% reduction of only three of the 17 microorganisms tested in 15 seconds. Table 1 illustrates the average performance of Product B.

• Product B demonstrated zero activity against Escherichia coli at 15, 30, and 60 second contact time

• Against Pseudomonas aeruginosa, Product B reduced the count by only 18% in 15 seconds. Baseline bacterial counts of the test microorganisms were approximately six million. An 18% reduction of six million bacteria would mean that there are 4,920,000 Pseudomonas aeruginosa remaining after contact with Product B.

• The antimicrobial activity of Product B did not significantly improve against most of the test microorganisms even when evaluated at the longest exposure time, 60 seconds. See Table 1 for all of the antimicrobial efficacy results for Product B.

Product A demonstrated superior antimicrobial activity against all of the test microorganisms including two strains of methicillin-resistant Staphylococcus aureus (MRSA) and one strain of vancomycin-resistant enterococci (VRE). The results are shown in Figure 2.

Product A also demonstrated superior antimicrobial efficacy against a new threat in the healthcare environment – community-acquired methicillin-resistant Staphylococcus aureus (CA- MRSA). In a 15-second contact time, Product A reduced CA-MRSA by 99.8%, as compared to Product B, which reduced the count by 8.7%. See Figure 3.

Percent reduction of MRSA and VRE at 15 seconds by products A and B.	Percent reduction of CA-MRSA USA 300 at 15 seconds by products A and B.
Figure 2	Figure 3

Antimicrobial-resistant pathogens such as MRSA and VRE have contributed significantly to the magnitude of HAIs in acute care and long-term care facilities. Currently, more that 50% of Staphylococcus aureus isolates causing infections in intensive care units are resistant to methicillin, and more than 40% of the infectious organisms found in other hospital units are resistant. VRE emerged in the late 1980s and is now endemic in many hospitals. In many healthcare settings, more than 25% of enterococcal infections are caused by vancomycin-resistant strains.⁶ It is imperative that healthcare workers use a hand hygiene product with optimum antimicrobial efficacy, to reduce the risk of cross-contamination with these potentially life-threatening antimicrobial-resistant pathogens.

References

1. Pittet, D. Compliance with hand disinfection and its impact on hospital-acquired infections. J Hosp Infect 2001; 48 (Supplement A): S40-S46.

2. Boyce, JM, Pittet, D. Guideline for Hand Hygiene in Health-Care Settings. Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force. MMWR 2002; 51 (RR-16): 1-45.

3. Jungermann, E., Taber, D. A new broad spectrum antibacterial soap, general properties. J Am Oil Chem 1971; 48: 18-25.

4. Food and Drug Administration. Topical antimicrobial drug products for over-the-counter human use; tentative final monograph for health-care antiseptic drug products (TFM) Federal Register, Parts 333 and 369, Vol. 59, No.116, June 17, 1994.

5. Stone, PS, Newman, J, Jampani, H, Jones, R. Interpreting antimicrobial activity test data: a powerful tool for product selection. Infect Control Today 199: 35-36.

6. Fridkin, SK, Gaynes, RP. Antimicrobial resistance in intensive care units. Clinics in Chest Med 1999; 20:305.