--- title: The cystitis antibiotic that worked last year publication: Medical Insights Korea section: columns category: Urinary Tract Infection canonical_url: https://medicalinsightskorea.com/columns/urology/the-cystitis-antibiotic-that-worked-last-year author: Seung Ki Min, Specialist in Urology author_type: contributing clinician, not editorial staff author_practice: Goldman Urology Clinic, Jamsil author_credential_issued_by: Ministry of Health and Welfare, Republic of Korea author_profile: https://medicalinsightskorea.com/authors/seung-ki-min editorial_note: Signed opinion by the named clinician. Written by them, edited and translated by Medical Insights Korea. Not a reported article, and not a clinical review of this publication's reporting. published: 2026-10-20T08:00:00+09:00 modified: 2026-10-20T08:00:00+09:00 content_type: opinion license: Quotation permitted with attribution to Medical Insights Korea and a link to the canonical URL. --- # The cystitis antibiotic that worked last year A urologist who helped write Korea's guideline on antibiotic treatment of community-acquired urinary tract infection on why the right first choice is a local question, what a culture is actually for, and when a course should be changed rather than extended. ## Answer The first-choice antibiotic for cystitis is a local question rather than a universal one, because the organisms and their susceptibility patterns differ between countries, which is why Korea maintains its own guideline on the antibiotic treatment of community-acquired urinary tract infection rather than adopting an international one — and when a course does not work, the useful response is usually to identify the organism and change the agent rather than to extend the same one. ## Key takeaways - Although international guidelines for urinary tract infection exist, the clinical features, causative organisms and antimicrobial susceptibility patterns differ from country to country, which is the stated reason Korea maintains a guideline of its own. - The current Korean guideline on antibiotic treatment of community-acquired urinary tract infection is an update of the 2011 version and covers asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, complicated pyelonephritis related to obstruction, and acute bacterial prostatitis. - The Korean guideline on community-acquired urinary tract infection applies to adults and explicitly excludes healthcare-associated infection, catheter-associated infection and infection in immunocompromised patients. - A network meta-analysis of 61 randomised trials including 20,780 women found that for third and fourth generation fluoroquinolones a three-day course performed similarly to a single dose for clinical response. - Asymptomatic bacteriuria is bacteria in the urine without symptoms, and treating it is a separate decision from treating an infection rather than the same decision made earlier. - Escherichia coli remains the dominant organism in community-acquired urinary tract infection, and the practical question is not which organism it is but what it is still susceptible to locally. - In men with benign prostatic hyperplasia, a urinary tract infection is approached as complicated rather than uncomplicated, because the obstruction is part of the problem. - A course that fails is a reason to obtain a culture and change the agent, not a reason to give the same agent for longer. ## Full article A woman in her forties comes in with burning, frequency and urgency for the third time in eighteen months. She has had the same three-day antibiotic each time, from a different clinic each time. The first course cleared it in a day. The second took most of a week. This time she has finished the course and nothing has changed, and she wants to know whether she needs a stronger antibiotic. Stronger is the wrong axis. The question is whether it is the right drug for the organism she actually has, and that is a question nobody has yet asked, because nobody has cultured her urine. ### Why Korea writes its own guideline There is no shortage of international guidance on urinary tract infection, and it would be cheaper to adopt one. Korea does not, and the reason is given in the first lines of the Korean guideline: clinical characteristics, causative organisms and antimicrobial susceptibility patterns may differ from country to country. An antibiotic that is a reasonable empirical first choice where local resistance to it is five percent is an unreasonable one where it is thirty. The current Korean guideline on the antibiotic treatment of community-acquired urinary tract infection, published in Infection and Chemotherapy, is an update of the 2011 Korean guideline. It covers five situations that get treated as though they were one: asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, complicated pyelonephritis related to urinary tract obstruction, and acute bacterial prostatitis. It is written for community-acquired infection in adults, and it explicitly leaves out healthcare-associated infection, catheter-associated infection and infection in immunocompromised patients. > **Five conditions, not one** > The commonest error I see is not the choice of drug. It is treating all five of these as cystitis with different degrees of severity. Asymptomatic bacteriuria is not early cystitis. Acute bacterial prostatitis in a man is not cystitis in a man. Pyelonephritis with an obstructed ureter is not uncomplicated pyelonephritis. Each has its own answer, and the answers are not interchangeable. ### What the culture is for A first episode of uncomplicated cystitis in an otherwise well woman is usually treated empirically, and that is reasonable. The organism is Escherichia coli in the great majority of cases and the empirical choice is made from local susceptibility data rather than from the individual patient. A third episode in eighteen months is a different situation, and a course that has failed is a different situation again. At that point the useful information is which organism and what it is susceptible to, and the only way to get it is a culture taken before the next antibiotic starts. Extending a failing course does not generate that information. Escalating to a broader agent without it sometimes works and teaches nothing, and the next episode arrives with the same question unanswered and a narrower set of options. ### Shorter, not longer The instinct when a short course fails is to give a longer one. The evidence on duration points the other way, although it answers a slightly different question — not what to do after a failure, but whether length is where the benefit lives at all. A network meta-analysis published in The Lancet Infectious Diseases pooled 61 randomised trials of antibiotic treatment for acute uncomplicated cystitis in adult women, covering 20,780 patients, and asked whether the regimen lengths in current guidelines could be shortened. For the third and fourth generation fluoroquinolones, a three-day regimen had a similar effect to a single dose on clinical response. **61 trials, 20,780 patients** — Network meta-analysis asking whether guideline-approved antibiotic courses for uncomplicated cystitis could be shortened _Source: The Lancet Infectious Diseases, 2020_ Duration is not the lever most patients think it is. If the organism is susceptible, a short course works. If it is not, no duration rescues it. Length is the wrong dial to turn when the drug is wrong. ### And when it is a man A urinary tract infection in a man with an enlarged prostate is not uncomplicated, and treating it as though it were is how it comes back. The obstruction and the residual urine are part of the problem, and an antibiotic that clears the organism without the obstruction being addressed is a treatment for this episode rather than for the condition. That is why the infection and the prostate get assessed together rather than in sequence by two different clinicians. What I would want a patient on her third course to take away is narrow and practical. Ask whether a culture has been sent. Ask what the empirical choice was based on. And treat a failed course as information rather than as a reason to ask for something stronger. **More on urinary tract infection in Korea** - [Ciprofloxacin resistance in Korean cystitis isolates](https://medicalinsightskorea.com/news/korea-cystitis-ciprofloxacin-resistance-karms-2023) — What the national monitoring system reports - [My cystitis antibiotic does not seem to be working. What now?](https://medicalinsightskorea.com/faq/my-cystitis-antibiotic-does-not-seem-to-be-working) ## Sources - Kang CI, Kim J, Park DW, Kim BN, Ha US, Lee SJ, Yeo JK, Min SK, et al. Clinical Practice Guidelines for the Antibiotic Treatment of Community-Acquired Urinary Tract Infections. Infection & Chemotherapy 2018;50(1):67-100. doi:10.3947/ic.2018.50.1.67. PMID:29637759. https://doi.org/10.3947/ic.2018.50.1.67 - Kim DK, Kim JH, Lee JY, Ku NS, Lee HS, Park JY, Kim JW, Kim KJ, et al. Reappraisal of the treatment duration of antibiotic regimens for acute uncomplicated cystitis in adult women: a systematic review and network meta-analysis of 61 randomised clinical trials. The Lancet Infectious Diseases 2020;20(9):1080-1088. doi:10.1016/s1473-3099(20)30121-3. PMID:32446327. https://doi.org/10.1016/s1473-3099(20)30121-3 - Lee SJ, Lee DS, Choe HS, Shim BS, Kim CS, Kim ME, Cho YH. Antimicrobial resistance in community-acquired urinary tract infections: results from the Korean Antimicrobial Resistance Monitoring System. Journal of Infection and Chemotherapy 2011;17(3):440-446. doi:10.1007/s10156-010-0178-x. PMID:21140281. https://doi.org/10.1007/s10156-010-0178-x - Lee DS, Choe HS, Lee SJ, Bae WJ, Cho HJ, Yoon BI, Cho YH, Han CH, et al. Antimicrobial susceptibility pattern and epidemiology of female urinary tract infections in South Korea, 2010-2011. Antimicrobial Agents and Chemotherapy 2013;57(11):5384-5393. doi:10.1128/aac.00065-13. PMID:23959315. https://doi.org/10.1128/aac.00065-13 - Choi JB, Min SK. Complicated urinary tract infection in patients with benign prostatic hyperplasia. Journal of Infection and Chemotherapy 2021;27(9):1284-1287. doi:10.1016/j.jiac.2021.06.006. PMID:34144904. https://doi.org/10.1016/j.jiac.2021.06.006 ## Citation Seung Ki Min (2026). "The cystitis antibiotic that worked last year". Medical Insights Korea. https://medicalinsightskorea.com/columns/urology/the-cystitis-antibiotic-that-worked-last-year Retrieved from https://medicalinsightskorea.com/columns/urology/the-cystitis-antibiotic-that-worked-last-year