Healthy Hooha

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Seriously!

Here’s the TLDR summary: Lactobacillus do not have the ability to take up and metabolize (process) a bunch of antibiotics. It’s like using a weed killer safe for lawns, the weeds (bacteria) are susceptible to the killing agent, but the grass (lactobacillus) is left unharmed.

There are certain antibiotics that act like Round Up and kill EVERYTHING, but science has identified, and known for DECADES, that certain antibiotics are not harmful to your vaginal lactobacillus.

Those are:

*Flagyl (Metronidazole), Tindamax (Tinidazole), Solosec (Secnidazole), Bactrim (sulfamethoxazole+trimethoprim), and some other lesser known/lesser used ones.

Macrobid (nitrofurantoin) is another one but with nuance- Macrobid’s (nitrofurantoin) mechanism of action is technically harmful to lactobacillus, however, Macrobid has very poor systemic absorption meaning there is very little risk of the vaginal lactobacillus coming into contact with Macrobid. The risk isn’t ZERO so some individuals may notice a change in their vaginal microbiome, while others may not experience any noticeable difference. Those who already have a low lactobacillus count might find themselves more sensitive to these effects.

Now, I know what you are thinking “but I developed a yeast infection after using one of these antibiotics.” Your yeast infection was not the result of the antibiotic killing your lactobacillus. Your yeast infection while/after using one of the above listed antibiotics is typically due to these 2 reasons:

1. Your lactobacillus was already low before your bacterial infection started, this is one of the biggest reasons vaginal infections are able to start in the first place. When you killed off the pathogenic bacteria there was a void left in your vaginal microbiome environment. Starting with low/no lactobacillus + a void left behind from killing the bad bacteria (+ angry tissues from the destruction caused by the bad bacteria) = a hospitable and inviting environment for the candida we normally have just hanging out without incidence to turn pathogenic and reproduce, taking over unopposed.
2. You had a low-level yeast infection at the same time as the bacterial infection.  A lot of times the symptoms that the pathogenic bacteria cause are more front and center than those of a yeast infection. Also, most bacterial infections also cause the same symptoms as a yeast infection (dermatitis, redness, and itching from irritation) which make it very difficult to recognize that you have both infections happening at the same time since the discharge from a bacterial infection is preventing the cottage cheese discharge from developing.

I realize this isn’t the current narrative. I know doctors and (most) of the internet says “antibiotics harm lactobacillus”, but I PROMISE you that this is just the result of people regurgitating someone else’s incorrect, and over generalized, information instead of verifying this information via scientific study results which are a simple and quick PubMed/Google Scholar search away.  Science has known that there are numerous antibiotics that don’t harm lactobacillus (including vaginal lacto) FOR DECADES, like 40+ years! Yet no one, but a few, have taken the time to look up and verify this information to share it with the people who need it the most.

The amount of information that is either completely missing from a doctors toolbox or possibly worse, is incorrect, is inexcusable. Such as, even some reputable online medical resources going so far as calling out metronidazole specifically as harmful to lactobacillus when we have empirical scientific proof that lactobacillus literally cannot metabolize and convert metronidazole to it’s active form. It is inexcusable for trusted organization we rely on for guidance to convey something so utterly untrue. Metronidazole either just sits inside the lacto basically as an inert substance OR the lacto actively pumps back the metronidazole back out since it’s not needed, leaving the lacto completely unharmed.

As a reminder, I always put my citations and sources (which are always the sources of the study data) at the end of my articles for others to check and verify the information I provide.

The mechanism of action of Metronidazole, the most commonly prescribed antibiotic for bacterial vaginosis, kills the bacteria by disrupting the DNA and causing strand breakage, ultimately leading to cell death via what’s called PFOR enzyme activity. Lactobacillus also have this PFOR enzymes but are less reliant on it and perform it’s metabolism for energy via other avenues, making it not susceptible to the antibiotic.

Furthermore, lactobacillus is generally less susceptible to DNA strand breakage via various prevention and repair mechanisms, and they have something called efflux pumps that pump out of its cell things it doesn’t want or need.

There are STACKS of scientific papers that have been peer reviewed, reproduced, verified, conducted on multiple human lactobacillus strains, including the 3 main vaginal strains, so it’s time to stop the spread of the misconception that all antibiotics harm your beneficial lactobacillus populations. The evidence, spanning decades of scientific research, overwhelmingly supports the idea that certain antibiotics, like Metronidazole, Tinidazole, Secnidazole, sulfamethoxazole+trimethoprim, and some others, do not harm lactobacillus- including those in the vagina. This misconception has persisted despite the wealth of readily available scientific data confirming otherwise due to the medical community and online resources perpetuating inaccurate information about antibiotic effects on lactobacillus.

The scientific evidence firmly demonstrates that lactobacillus populations either remain unaffected or even flourish in the presence of certain antibiotics, including oral and vaginal Metronidazole. This resilience can be attributed to the unique metabolic pathways and protective mechanisms employed by lacto.

The fact that some reputable sources incorrectly label Metronidazole specifically as harmful to lactobacillus highlights the need for a more rigorous and evidence-based approach to disseminating medical information not only to patient facing websites and resources but evidently, to health care providers as well.

It is crucial to challenge and correct these misconceptions to ensure that accurate and evidence-based information guides medical decisions. I encourage everyone to verify information and advocate for a more informed approach to healthcare. The disparity between the available data and common misconceptions is not only unfortunate but also inexcusable in a world where accurate information can significantly impact our well-being.  A good way to verify if information is true and consistent via published scientific research is to simply type into your internet search bar or Google Scholar the keywords or statement you wish to learn about and type NIH at the end. You might not understand all of the scientific/medical jargon, but that’s ok, most papers write their conclusions in accessible language.

This misconception has made so many of us afraid to take the medications necessary in order to get our vaginal health back on track, sometimes this fear even causes us to try remedies that end up causing us more harm than good, and while we are still struggling globally to cure and prevent future BV infections, hopefully this new knowledge lessens your fears, and empowers you to make informed choices about your health with confidence and peace of mind.

Citations:

Armstrong E, Hemmerling A, Miller S, Burke KE, Newmann SJ, Morris SR, Reno H, Huibner S, Kulikova M, Liu R, Crawford ED, Castañeda GR, Nagelkerke N, Coburn B, Cohen CR, Kaul R. Metronidazole treatment rapidly reduces genital inflammation through effects on bacterial vaginosis-associated bacteria rather than lactobacilli. J Clin Invest. 2022 Mar 15;132(6):e152930. doi: 10.1172/JCI152930. PMID: 35113809; PMCID: PMC8920324.

Mayer BT, Srinivasan S, Fiedler TL, Marrazzo JM, Fredricks DN, Schiffer JT. Rapid and Profound Shifts in the Vaginal Microbiota Following Antibiotic Treatment for Bacterial Vaginosis. J Infect Dis. 2015 Sep 1;212(5):793-802. doi: 10.1093/infdis/jiv079. Epub 2015 Feb 12. PMID: 25676470; PMCID: PMC4539900.

Lagenaur LA, Hemmerling A, Chiu C, Miller S, Lee PP, Cohen CR, Parks TP. Connecting the Dots: Translating the Vaginal Microbiome Into a Drug. J Infect Dis. 2021 Jun 16;223(12 Suppl 2):S296-S306. doi: 10.1093/infdis/jiaa676. PMID: 33330916; PMCID: PMC8502429.

Armstrong NR, Wilson JD. Tinidazole in the treatment of bacterial vaginosis. Int J Womens Health. 2010 Aug 9;1:59-65. doi: 10.2147/ijwh.s4455. PMID: 21072275; PMCID: PMC2971702.

Er, S., Erim, Ü. C., Koç, F., & Kıvanç, M.. (2019). Identifying probiotic characteristics of Lactobacillus crispatus isolated from the vagina. Brazilian Journal of Pharmaceutical Sciences, 55, e17507. https://doi.org/10.1590/s2175-97902019000117507

M. Álvarez-Cisneros, Y., & Ponce-Alquicira, E. (2019). Antibiotic Resistance in Lactic Acid Bacteria. IntechOpen. doi: 10.5772/intechopen.80624

Oluwatosin Goje, Elizabeth O. Shay, Metabel Markwei, Roshan Padmanabhan, Charis Eng, The effect of oral Metronidazole on the vaginal microbiome of patients with recurrent bacterial vaginosis: A pilot investigational study,Human Microbiome Journal,Volume 20,2021,100081,ISSN 24522317,  https://doi.org/10.1016/j.humic.2021.100081. (https://www.sciencedirect.com/science/article/pii/S245223172100004X)

Simoes JA, Aroutcheva AA, Shott S, Faro S. Effect of metronidazole on the growth of vaginal lactobacilli in vitro. Infect Dis Obstet Gynecol. 2001;9(1):41-5. doi: 10.1155/S1064744901000072. PMID: 11368258; PMCID: PMC1784636.

Samuelson J. Why metronidazole is active against both bacteria and parasites. Antimicrob Agents Chemother. 1999 Jul;43(7):1533-41. doi: 10.1128/AAC.43.7.1533. PMID: 10390199; PMCID: PMC89320.

Edwards DI. Nitroimidazole drugs–action and resistance mechanisms. I. Mechanisms of action. J Antimicrob Chemother. 1993 Jan;31(1):9-20. doi: 10.1093/jac/31.1.9. PMID: 8444678.

Verwijs MC, Agaba SK, Darby AC, van de Wijgert JHHM. Impact of oral metronidazole treatment on the vaginal microbiota and correlates of treatment failure. Am J Obstet Gynecol. 2020 Feb;222(2):157.e1-157.e13. doi: 10.1016/j.ajog.2019.08.008. Epub 2019 Aug 9. PMID: 31404542; PMCID: PMC6995998.

Virginia Ocaña, Clara Silva, María Elena Nader-Macías, “Antibiotic Susceptibility of Potentially Probiotic Vaginal Lactobacilli”, Infectious Diseases in Obstetrics and Gynecology, vol. 2006, Article ID 018182, 6 pages, 2006. https://doi.org/10.1155/IDOG/2006/18182