Analysis of the Adaptation Capacity of <b><i>Staphylococcus aureus</i></b> to Commonly Used Antiseptics by Microplate Laser Nephelometry

Abstract

Background: Bacterial colonization and infection are important factors in compromised wound healing. Antiseptics have become an alternative for antimicrobial applications as antibiotic resistance is increasing; they have multiple targets with a broad spectrum of activity. Hence, the risk for developing resistance should be low. However, concerns have been raised that their growing use may result in bacteria that are less susceptible. Methods: The capacity of common antiseptics such as silver nitrate, polihexanide, octenidine, chlorhexidine and polyvinylpyrrolidone (PVP)-iodine to induce adaptation in a Staphylococcus aureus strain was analyzed in vitro using microplate laser nephelometry. S. aureus was repeatedly incubated with the respective half maximal inhibitory concentration (IC₅₀) over a time period of 100 days. The influence of the continued treatment was determined by in situ monitoring of changes in the dose-response curves and calculation of the current IC₅₀ values for the substances tested. Results: During the experiment, S. aureus quickly adapted to high concentrations of the antibiotic mupirocin during repeated treatment. Moreover, a significant increase of the IC₅₀ for silver nitrate was observed over time. On the other hand, no significant difference was observed for polihexanide or chlorhexidine. While the IC₅₀ for octenidine was also found to increase significantly, although the change was only marginal, reiterated incubation with PVP-iodine led to a decrease in the IC₅₀. Conclusion: Repeated treatment of S. aureus with polihexanide, chlorhexidine, octenidine and PVP-iodine did not trigger bacterial adaptation to these substances.

Antimicrobial functionalization of bacterial nanocellulose by loading with polihexanide and povidone-iodine

“…Furthermore, PVP-iodine shows high bactericidal activity against resistant bacteria strains, e.g. MRSA or Enterococcus faecium [33] and it was shown that it does not induce adaptation in bacteria [34,35]. Yet, its application in wound treatment remains controversial as it may have potential systemic side effects and exert possible cytotoxic effects leading to impaired wound healing [36,37].…”

Skin-protective effects of a zinc oxide-functionalized textile and its relevance for atopic dermatitis

“…However, negative effects on cells of both silver ions21,27 and chitosan formulations22,28,29 have been observed in vitro. Moreover, the use of silver compounds has been associated with the risk of inducing bacterial adaptation 30–32. Hence, there is a demand for alternative effective compounds.…”

Coherent Fluctuation Nephelometry: A Rapid Method for Urine Screening for Bacterial Contamination

“…photometry [6,12]. Alifax automated nephelometric microbiological analyzers carry out a rapid microbiological analysis within just several hours, including rapid screening of urine for contamination [4,7].…”