But certainly the bacterial mode change inside biofilms is a major factor in protecting bacteria from antibiotics. I read that about 1% of bacteria in biofilms turn into persister cells. These persisters are in a dormant state, and are metabolically inactive, and that protects them from the antibiotics.
persister cell behaviour is another super interesting area of microbiology - as you indicate closely related to biofilm behaviour.
it turns out that the % of persister cells in a population is highly variable - and since its an adaptive behaviour - as you would expect, this percentage depends of a host of factors in any given population
-the bacterial species and or strain involved
-the environmental conditions - eg abx / other drugs/ nutrient availability / oxygen content/quorum sensing/etc
-the age of the microbial community - larger persister cell % correlated with stationary growth phase
in general most bacteria like to grow rapidly - a more or less logarithmic growth trajectory while conditions are favourable - as nutrients start to become more scarce - or other conditions limit or impinge on their growth - or as the community grows biofilm - then the % of cells that are persister cells typically increases.
in some cases this may be 50% of the population or more
if you introduce an antimicrobial - then typically the easy to kill portions of the population are killed off - leaving only the persisters - so in these conditions it can be close to 100%
the persister cells as well as using different genes, and presumably different metabolic pathways - also dramatically reduce their overall metabolism - and stop replicating or at least dramatically slowed down replicating. Most abx mechanisms of action require them to be taken into the bacterial cells as the cell respires, or as it divides, in order to have their effect - so it is this combination of behaviours that make them so much more resilient to the effects of abx. Once they have entered the persister states and susceptible bacterial killed off with normal levels of abx - additional increases in dose of that abx often does little or nothing to this population and in In-Vitro experiments they can often remain viable even at 500-1500x the concentration.
the mechanism for this switch to persister behaviour is complex and multifactorial - but from the studies i have read appears to be driven by cell stress signalling inside the bacteria - which makes a lot of sense - as then any stressor - be it heat, chemical, nutrient reduction etc - will tend to trigger higher transformation into persister states. This has been studied quite well in certain bacteria including things like E. Coli and Borrelia
its also notable that for persister cell behaviour to work as an evolutionary advantage - the cells must, while in their very low metabolic state, still have an ability to sense when the environment has become more suitable again and they can return to log growth behaviour. This they are also able to do.
its an active area of research and there is a great deal we still do not know about how exactly they do some of these things - but in general persister states and biofilm formation tend to go hand in hand.
its important to note that this complex behaviour is not limited to some rare or obscure small subset of bacterial species - persister cells and biofilm formation are present in many common species relevant to human health. eg
Escherichia coli,
Pseudomonas aeruginosa,
Bacillus subtilis, and
Staphylococcus aureus to name just a few.
Estimates i have read are that 90% of bacteria are capable of forming biofilm communities.
This paper says its actually a universal attribute of all bacteria, and wherever we find biofilm we typically find persister cells.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2890205/
and yet - how many of us have been told by a primary care physician that - if we have had a 2-3week course of antibiotics than that will have taken care of whatever infection we may have had .........
hope this is not too far off topic - its something i have been researching recently - and i thought it was relevant to the question of how such an dysbiosis discussed here could remain active in the kidney for so long despite abx treatments