Development and validation of a neutralizer system for in vitro evaluation of some antiseptics

Abstract

A neutralizer system was developed and validated for use in the in vitro bactericidal evaluation of three commonly used antiseptics, namely, Hibiclens (4% [wt/vol] chlorhexidine gluconate), Betadine (7.5% [wt/vol] povidone-iodine), and pHisoHex (3% [wt/vol] hexachlorophene). The neutralizer finally selected after a screening of 12 potential candidates consisted of 3% Asolectin, 10% Tween 80, and 0.3% sodium thiosulfate in diluent, and 0.3% Asolectin, 1% Tween 80, and 0.3% sodium thiosulfate in the recovery agar. This neutralizer system was tested and validated for its neutralizing capacity for the three antiseptics, as well as for its lack of inherent bactericidal action against Staphylococcus aureus and a number of gram-negative bacteria of clinical significance. With no more than a 10-fold dilution of the antiseptic, the selected neutralizer system was 100% effective in neutralizing all the bacteriostatic carry-over of the three antiseptics and was also completely without any inherent bactericidal action against all the test organisms used. Sodium sulfite (considered to be a potential inactivator for iodophores such as Betadine), even in concentrations as low as 0.1%, was found to be ineffective or inherently bactericidal, whereas 0.3% sodium thiosulfate, in combination with Asolectin and Tween 80, was adequate (effective as well as nonbactericidal) and was considered to be essential for the neutralization of the three test antiseptics, namely, Hibiclens, Betadine, and pHisoHex.Chemical agents commonly known as inactivators or neutralizers are often used for (i) the bactericidal evaluation of antimicrobial agents, antiseptics, and disinfectants; (ii) the evaluation of preservative efficacy in many pharmaceuticals, toiletries, and cosmetic products; and (iii) the microbial limit testing ofproducts containing antimicrobial agents. The need for an adequate neutralizer in some of these applications is well documented and rightfully stressed (2-4, 11-14). The selected neutralizer should not only be able to completely inactivate all of the bacteriostatic activity of the residual antimicrobial agent likely to be carried over into recovery media, but also be inherently non-bactericidal to the test organisms (4).As

Killing of Enterococcus faecalis by MTAD and Chlorhexidine Digluconate with or without Cetrimide in the Presence or Absence of Dentine Powder or BSA

“…It seems that Tween 80 itself has limited antibacterial activity, but it is known to increase the antibacterial effect of various substances (19). However, it may also neutralize the antibacterial properties of disinfecting agents, including chlorhexidine and povidone-iodine (20,21).…”

Prevention of Drug Carryover Effects in Studies Assessing Antimycobacterial Efficacy of TMC207

“…The drug carryover phenomenon has been described for several antibiotics, e.g., ␤-lactams, fluoroquinolones, and clofazimine, and also for antiseptics, such as betadine, chlorhexidine, and niacinamide (2,3,4,7,9). Some methods that can be used to overcome this phenomenon are available, but none of them can be universally applied.…”

Comparative efficacy of three antiseptics as surgical skin preparations in dogs

“…25,117 It is however also essential that the neutralizer should not affect the test organisms that are to be cultured. 120 Kampf has subsequently described protocols to validate neutralization agents and quotes two international test methods (EN 13727 and ASTM 1054-02). 119 Various compounds are used as neutralizers in different combinations of which polysorbate 80, saponin, histidine, sodium thiosulphate ether sulphate and lecithin are examples.…”