UTI Comes Back After Antibiotics: Why Biofilm May Be the Reason | Ruth Kriz, Part 1

Ruth Kriz is a nurse practitioner who spent 35 years inside the interstitial cystitis community, including a funded national study presented at an NIH technical conference. She has spent it on the cases that didn’t resolve.

What a urine culture can and can’t see

Standard cultures grow what grows fast. Ruth says the culture media favors E. coli because it’s rapid growing, so it’s what turns up inside 24 hours. Slow growing bacteria haven’t started. Cell wall deficient bacteria won’t grow at all. Anaerobes die the moment the urine hits air.

There’s a second problem. When a lab finds more than two organisms it often calls the specimen contaminated. Ruth’s point is that a biofilm is a community of pathogens, so more than two may be the finding, not the error.

In specimens from chronic patients she cites, E. coli turned up in 28 percent of cases. If your antibiotic was chosen on the assumption of E. coli, that may have been wrong most of the time.

Why interstitial cystitis may be a chronic infection

If you’ve been handed an interstitial cystitis diagnosis, you may also have been handed a diet sheet and told there is no infection. Ruth sees it differently. She describes IC as an infection going on so long it has embedded in the bladder wall, where it no longer responds the way an acute one does.

That reframe has consequences. A mystery condition gets managed. An infection gets treated.

What a biofilm actually is

Bacteria float free in the bladder, then attach to the wall and build a structure to protect themselves. Some of it is fibrin, the protein we all make so we don’t bleed to death, and it cross-links into a three-dimensional web. Ruth says roughly 20 percent of people either make too much fibrin or don’t break it down well. In her chronic UTI patients she found one of four genetic issues around 70 percent of the time.

Bacteria build their own too. E. coli and Klebsiella make amyloid fibres called curli. H. pylori uses extracellular DNA. Which type you have changes what breaks it down.

Why antibiotics may not reach every bacterium

Deep inside a mature biofilm, some bacteria stop getting nutrients and go dormant. Ruth calls these persister cells. Antibiotics work on growing cells, so even a drug that penetrates the biofilm may leave them untouched.

She uses a walled city for it. If you only fight the raiding party that comes out, you never touch what’s inside the walls. Every month or two the biofilm spills bacteria and it looks like a fresh infection. Your doctor treats it as new. It may be the same one.

Why the most commonly prescribed UTI antibiotic may not work

Macrobid is the brand name for the macrocrystals of nitrofurantoin, the drug most often prescribed for UTI. Plain nitrofurantoin has a half life of 20 to 30 minutes. The macrocrystal form takes that to about 45 minutes.

Ruth’s point is about the chronic patient. Twice a day may be enough for an acute infection. For an established biofilm, that window may be too short to do much. She also notes the product insert calls for an acid pH to work, and this population often doesn’t have one.

Where reinfection may be coming from

For women with chronic UTIs, Ruth often finds the vaginal tract colonised with bacteria that keep seeding the bladder. Macrobid clears through the urinary tract almost entirely, so it may never reach the vagina. The bladder gets treated. The reservoir doesn’t.

Then there’s your partner. She says around 25 percent of these women’s partners have an undiagnosed, symptomless prostatitis, and she doesn’t soften it: you must treat your partners. If your symptoms flare after sex and nobody has looked at him, name it at your next appointment.

Why treatment gets sequenced rather than stacked

Ruth doesn’t go after everything at once. Clear the dominant pathogen and the smaller ones come out of the biofilm and compete to replace it. Exposing them to an antibiotic before you know what they are is, in her words, how drug resistance happens.

So the order matters. Take a biofilm disruptor first, then test, so what’s embedded actually shows up. Find out what is there and what kind of biofilm it builds, then match the treatment to that. She is blunt that this takes more than one course.

For people who can’t tolerate oral antibiotics, or where resistance is the problem, she describes a compounded preparation delivered into the bladder through a small catheter and held a couple of hours. More thorough, and expensive. None of it is a recommendation for you, and it needs the right practitioner.

If you’ve been told your cultures are clean while you still feel ill, you aren’t imagining it and you didn’t cause it. This has nothing to do with how clean you are, whatever anyone implied. Ask what the culture tested for. Ask whether anyone has looked at your partner. Ask whether a biofilm should be broken down before you test rather than after. Be your own detective on this one.

In Part 2, episode 018, Ruth goes into ammonia and what it does to the bladder wall overnight, the first morning urine pH to aim for, and what the standard test misses on bacterial vaginosis.