It has always been assumed that antimicrobial resistance would only develop in response to the use of antibiotics, but newer data suggest that antiseptics, disinfectants and other antibacterial approaches are even worse at creating resistance. Data namely indicate that these chemicals cause the bacteria to become tolerant or resistant not only to a specific antiseptic or disinfectant, but also to other types of antiseptics and disinfectants and even to antibiotics, a phenomenon called cross-tolerance. These chemicals therefore cause the bacteria to develop a general tolerance to these approaches with the result that all our anti-infection tools become worthless and this is a process that occurs rapidly, i.e. within days to weeks.
Tolerance means that an organism, e.g. a bacterium can be exposed to higher levels of a chemical than previously without being affected. There is a limit to how much our organism can tolerate of antiseptics and antibiotics without being damaged, so the development of tolerance by a bacterium may mean that it can withstand higher levels than us. This situation results in “clinical resistance” because sufficient levels of the antiseptic or the antibiotic cannot be reached in a human for the purpose of killing the bacterium without damaging the person.
There are 3 recent studies demonstrating how serious this development of cross-tolerance is:
1. Shepard et al. (2018) from Public Health England found that exposure to sublethal doses of the antiseptic octenidine allowed several different strains of Pseudomonas aeruginosa to develop cross-tolerance to other antiseptics and in one strain - which was isolated from a wound - this cross-tolerance extended to several antibiotics. The level of tolerance was quite substantial as it in some cases meant that a 32-fold increase in concentrations of antiseptics was needed to reach the Minimum Inhibitory Concentration - causing de facto clinical resistance. The changes seen occurred within days and the changes were permanent.
2. Wand et al. (2016) also from Public Health England, found that Klebsiella pneumoniae, a bacterium that can cause pneumonia, wound infections and sepsis (blood poisoning), was able to develop tolerance to chlorhexidine, an antiseptic commonly used to clean the skin prior to surgery and in wound care, and that 5 out of 6 strains showed cross-resistance to the last-resort antibiotic colistin.
3. Pidot et al. (2018) found that E. faecium is developing resistance to alcohol-based disinfectants, e.g. hand rubs which are a key way to control hospital infections worldwide. These are the ones seen at any hospital entrance and in many offices. The study found that the bacteria have become better at breaking down the alcohol in the gels, thereby rendering the use of alcohol useless for infection prevention.
The probability of these processes happening is very high because they do not require new mutations to happen for a bacterium to become resistant – instead the changes are based on already existing tolerance mechanisms that every bacterium possesses and the tolerance will therefore develop very quickly.
Antiseptics are very commonly used in wound care for infected wounds, but the above show that the use of antiseptics in a wound will make that person resistant to other antiseptics and antibiotics and this will in turn lead to a rapid increase in the number of treatment resistant infections. The FDA in 2016 concluded that wound dressings for infected wounds that contain antibiotics and antiseptics are ineffective – it therefore seems all they are doing is to make the person resistant to antibiotics.
Currently, the only wound treatment available that can remove a wound infection without the use of antibiotics or antiseptics, is MPPT. Furthermore, because MPPT uses a technology and approach completely different to the conventional dressings, it is able to remove resistant wound infections and it will not contribute to the development of resistance.
A study (Cassini et al. 2019) reported that in the EU in 2015 over 35,000 died from antimicrobial resistant infections, an increase of almost a factor of 3 since 2007. So, this is a problem that needs to be taken seriously.