Bacterial profile and prevalence of urinary tract infections in pregnant women in Latin America: a systematic review and meta-analysis.

BACKGROUND: Given the physiological changes during pregnancy, pregnant women are likely to develop recurrent urinary tract infections (UTIs) and pyelonephritis, which may result in adverse obstetric outcomes, including prematurity and low birth weight preeclampsia. However, data on UTI prevalence and bacterial profile in Latin American pregnant women remain scarce, necessitating the present systematic review to address this issue. METHODS: To identify eligible observational studies published up to September 2022, keywords were systematically searched in Medline/PubMed, Cochrane Library, Embase, Web of Science, and Bireme/Lilacs electronic databases and Google Scholar. The systematic review with meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and the quality of studies was classified according to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines. The meta-analysis employed a random-effects method with double-arcsine transformation in the R software. RESULTS: Database and manual searches identified 253,550 citations published until September 2022. Among the identified citations, 67 met the inclusion criteria and were included in the systematic review, corresponding to a sample of 111,249 pregnant women from nine Latin American countries. Among Latin American pregnant women, the prevalence rates of asymptomatic bacteriuria, lower UTI, and pyelonephritis were estimated at 18.45% (95% confidence interval [CI]: 15.45-21.53), 7.54% (95% CI: 4.76-10.87), and 2.34% (95% CI: 0.68-4.85), respectively. Some regional differences were also detected. Among the included studies, Escherichia coli (70%) was identified as the most frequently isolated bacterial species, followed by Klebsiella sp. (6.8%). CONCLUSION: Pregnant women in Latin America exhibit a higher prevalence of bacteriuria, UTI, and pyelonephritis than pregnant women globally. This scenario reinforces the importance of universal screening with urine culture during early prenatal care to ensure improved outcomes. Future investigations should assess the microbial susceptibility profiles of uropathogens isolated from pregnant women in Latin America. TRIAL REGISTRATION: This research was registered at PROSPERO (No. CRD42020212601).

A Meta-Analysis on Clinical Outcomes of Ceftolozane versus Piperacillin in Combination with Tazobactam in Patients with Complicated Urinary Tract Infections.

Objective: To evaluate efficacy and adverse events of ceftolozane/tazobactam in complicated UTI including acute pyelonephritis. Method: Databases that include PubMed, Embase, Scopus, and TRIP were searched. All randomized controlled trials and cohort studies were considered for the study. Statistical analysis was done using a fixed effects model, and results were expressed in proportion for dichotomous data and risk ratio for continuous data with 95% confidence intervals (CI). Results: A clinical cure of ceftolozane/tazobactam was found to be 92% with 95% CI of 90-94 while that of piperacillin/tazobactam was only 78% (95% CI, 74-82) in patients with complicated UTI. Microbiological eradication was still higher in the ceftolozane/tazobactam group (83%, 95% CI 81-88) when compared with piperacillin/tazobactam (63% 95% CI, 58.77-65.2). Ceftolozane/tazobactam was more effective in the treatment of complicated urinary tract infections other than acute pyelonephritis as compared to piperacillin/tazobactam (RR = 1.21, 95% CI, 1.07-1.23). Serious adverse events were found comparable in both groups (RR = 1.15, 95% CI, 0.64-2.09). Conclusion: The analysis showed that ceftolozane/tazobactam has better clinical outcomes including cure rates and low resistance for the treatment of complicated urinary tract infection.

Antibiotic prophylaxis for percutaneous renal biopsy: study protocol for a prospective randomized trial.

BACKGROUND: The major complication of renal biopsy is bleeding. Infection is an extremely rare complication of percutaneous renal biopsy, providing sterile techniques are used and bowel perforation does not occur. However, the questionnaire included in the Kidney Biopsy Guidebook 2020 in Japan reported that antibiotic prophylaxis was administered to patients undergoing percutaneous renal biopsy at 61% of 170 adult institutions and 57% of 54 pediatric institutions. The objective of this study is to show the non-inferiority of not administering antibiotic prophylaxis for percutaneous renal biopsy. METHODS: Patients aged ≥15 years who are scheduled to undergo percutaneous renal biopsy are eligible for inclusion in the study. Three hundred and sixty-four patients will be recruited at 6 hospitals. The patients will be randomly assigned at a 1:1 ratio to receive either a single dose of intravenous cefazolin (1 g) or no antibiotic prophylaxis. The primary outcome is the number of patients that exhibit positive urine cultures (>105 colony-forming units/ml) 3 or 4 days after the renal biopsy, or at which point the patients are diagnosed with pyelonephritis until 3 or 4 days after the renal biopsy. The secondary outcomes are the number of patients who are diagnosed with pyelonephritis within 30 days after the renal biopsy, the number of patients who are diagnosed with puncture site infections within 30 days after the renal biopsy, the number of patients who are diagnosed with an infection other than pyelonephritis or a puncture site infection within 30 days after the renal biopsy, and the number of patients who experience cefazolin-induced side effects. DISCUSSION: This randomized controlled trial aims to show the non-inferiority of not administering antibiotic prophylaxis for percutaneous renal biopsy. If this study shows that antibiotic prophylaxis is not needed, it would help to ensure patient safety and prevent the development of antibiotic-resistant bacteria. TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN-CTR) UMIN000042378 . Registered on 7 Nov 2020.

[Systematic review and Meta-analysis of efficacy and safety of Ningmitai Capsules in treatment of urinary tract infection].

This study aims to evaluate the effectiveness and safety of Ningmitai Capsules in the treatment of urinary tract infection.To be specific, articles on the treatment of urinary tract infection with Ningmitai Capsules were retrieved from China National Know-ledge Infrastructure(CNKI), Wanfang, VIP, SinoMed, Cochrane Library, PubMed, EMbase, and Web of Science(from establishment to October 2021).Eligible randomized controlled trials(RCTs) were screened out, and ROB and RevMan 5.3 of Cochrane were employed for data integration and Meta-analysis.Finally, 17 articles were included, involving 1 972 cases, with 1 045 in the experimental group and 927 in the control group.The Meta-analysis results are as follows.Ningmitai Capsules combined with conventional antibiotics was superior to sensitive antibiotics alone in the treatment of acute pyelonephritis in aspects of clinical cure rate(RR=1.94, 95%CI[1.58, 2.37], P<0.000 01), reduction in the count of red blood cells in the urine(MD=-3.22, 95%CI[-3.23,-3.21], P<0.000 01), decrease in the count of white blood cells in the urine(MD=-2.34, 95%CI[-2.59,-2.10], P<0.000 01), and time for the disappearance of the symptoms(MD_(time for urinary tract irritation disappeared)=-2.19, 95%CI[-2.69,-1.68], P<0.000 01; MD_(time for waist aches disappeared)=-3.58, 95%CI[-4.20,-2.97], P<0.000 01; MD_(time for heating disappeared)=-0.57, 95%CI[-0.81,-0.33], P<0.000 01).The combination of either cephalosporin or quinolone with Ningmitai Capsules can improve clinical cure rate of acute pyelonephritis(RR_(combined with cephalosporin)=1.94, 95%CI[1.56, 2.42], P<0.000 01; RR_(combined with quinolone)=1.91, 95%CI[1.16, 3.15], P=0.01).The clinical cure rate(RR=1.91, 95%CI[1.47, 2.49], P<0.000 01) of diabetes complicated with urinary tract infection by Ningmitai Capsules was higher than that by quinolones.The clinical cure rate(RR=1.22, 95%CI[1.09, 1.37], P=0.000 5) of non-gonococcal urethritis by Ningmitai Capsules combined with conventional tetracycline and macrolide antibiotics was higher than that by conventional antibiotics.Ningmitai Capsules combined with conventional antibiotics/Ningmitai Capsules alone was superior to conventional antibiotics alone in the treatment of urinary tract infection in terms of the clinical cure rate(RR=1.35, 95%CI[1.17, 1.56], P<0.000 1) and incidence of adverse reactions(RR=0.32, 95%CI[0.15, 0.68], P=0.003), particularly the combination with quinolone antibiotics(RR=1.30, 95%CI[1.04, 1.61], P=0.02).The main adverse reactions were mild gastrointestinal discomfort, nausea, vomiting, and dry mouth.In summary, Ningmitai Capsules combined with conventional sensitive antibiotics/Ningmitai Capsules alone can improve the clinical cure rate of patients with urinary tract infection.Ningmitai Capsules combined with conventional sensitive antibiotics can significantly reduce the time for symptom disappearance of acute pyelonephritis and down-regulate the counts of red and white blood cells in the urine compared with antibiotics alone, and no serious adverse reactions have been found.However, in light of the low proportion of quality eligible articles, experiments with rigorous design, large sample size, and complete outcome in-dexes should be carried out in the future to verify the clinical efficacy and safety of Ningmitai Capsules in the treatment of urinary tract infection.

Increased risk of urinary tract infection and pyelonephritis under concomitant use of sodium-dependent glucose cotransporter 2 inhibitors with antidiabetic, antidyslipidemic, and antihypertensive drugs: An observational study.

Urinary tract infection (UTI) and pyelonephritis cause urosepsis, which can become life threating. Sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors, a class of oral anti-diabetic drugs, may increase the risk of UTI and pyelonephritis, as observed from their mechanism of action. Patients with diabetes receiving SGLT2 inhibitors are often concomitantly administered other antidiabetic, antidyslipidemic, or antihypertensive drugs. To determine if drug-drug interactions (DDIs) between SGLT2 inhibitors and these medications increased the risk of UTI and pyelonephritis, we analyzed the Food and Drug Administration Adverse Event Reporting System (FAERS) database. We applied Norén's and Gosho's methods for detecting DDIs. FAERS contains records describing 14 526 398 patient characteristics, 54 290 663 drug properties, and 47 252 416 reactions/events. We found 23 drug combinations that could induce UTI and pyelonephritis, such as SGLT2 inhibitors administered with dipeptidyl peptidase-4 inhibitors, thiazolidinediones, glinides, statins, angiotensin II receptor blockers, and calcium channel blockers. Combination therapy with the drugs detected in our analyses would show potential interactions that could result in UTI and pyelonephritis in patients with diabetes mellitus. However, owing to various limitations, these results must be confirmed by additional analyses.

Consistent alteration of chain length-specific ceramides in human and mouse fibrotic kidneys.

BACKGROUND: Several studies revealed alterations of single sphingolipid species, such as chain length-specific ceramides, in plasma and serum of patients with kidney diseases. Here, we investigated whether such alterations occur in kidney tissue from patients and mice suffering from renal fibrosis, the common endpoint of chronic kidney diseases. METHODS: Human fibrotic kidney samples were collected from nephrectomy specimens with hydronephrosis and/or pyelonephritis. Healthy parts from tumor nephrectomies served as nonfibrotic controls. Mouse fibrotic kidney samples were collected from male C57BL/6J mice treated with an adenine-rich diet for 14 days or were subjected to 7 days of unilateral ureteral obstruction (UUO). Kidneys of untreated mice and contralateral kidneys (UUO) served as respective controls. Sphingolipid levels were detected by LC-MS/MS. Fibrotic markers were analyzed by TaqMan® analysis and immunohistology. RESULTS: Very long-chain ceramides Cer d18:1/24:0 and Cer d18:1/24:1 were significantly downregulated in both fibrotic human kidney cortex and fibrotic murine kidney compared to respective control samples. These effects correlate with upregulation of COL1α1, COL3α1 and αSMA expression in fibrotic human kidney cortex and fibrotic mouse kidney. CONCLUSION: We have shown that very long-chain ceramides Cer d18:1/24:0 and Cer d18:1/24:1 are consistently downregulated in fibrotic kidney samples from human and mouse. Our findings support the use of in vivo murine models as appropriate translational means to understand the involvement of ceramides in human kidney diseases. In addition, our study raises interesting questions about the possible manipulation of ceramide metabolism to prevent progression of fibrosis and the use of ceramides as potential biomarkers of chronic kidney disease.

Lactobacillus plantarum IS-10506 promotes renal tubular regeneration in pyelonephritic rats.

Lactobacillus plantarum IS-10506 is a novel probiotic isolated from Indonesian traditional fermented buffalo milk dadih. Probiotics are clinically proven to be effective in accelerating recovery after urinary tract infection (UTI) and in decreasing recurrent UTI in children with or without structural disorders of the urinary tract. This study aimed to investigate the role of the probiotic L. plantarum IS-10506 in activating and regenerating renal epithelial stem cells in pyelonephritic rats. Fifty-five 20-weeks-old male Sprague-Dawley rats were randomised into control, lipopolysaccharide (LPS) and treatment (LPS and probiotic) groups. Pyelonephritis was induced with Escherichia coli ATCC 25922 LPS administered via a urethral catheter on the first experimental day to the LPS and treatment groups. Microencapsulated L. plantarum IS-10506 was orally administered once daily for up to 14 days to the treatment group. On days 3, 5, 7, 10 and 14, five rats per group were sacrificed and their kidneys were immunohistochemically analysed for production of interleukin (IL)-10, lipocalin-2 and Ki-67 in the renal tubular cells. IL-10 production was upregulated starting from day 3 through day 14 in the treatment group (P<0.05) compared with that in the control and LPS groups. Moreover, treatment with the probiotic led to increased activation of renal tubular stem cell, as indicated by a higher lipocalin-2 production, and further proliferation of renal tubular stem cells was documented by a higher Ki-67 production. Taken together, these results indicate that the anti-inflammatory probiotic L. plantarum IS-10506 improves renal injury in pyelonephritic rats by activating endogenous renal tubular stem cells to proliferate into mature renal tubular epithelial cells.

Host and Bacterial Markers that Differ in Children with Cystitis and Pyelonephritis.

OBJECTIVE: To determine whether treatment for urinary tract infections in children could be individualized using biomarkers for acute pyelonephritis. STUDY DESIGN: We enrolled 61 children with febrile urinary tract infections, collected blood and urine samples, and performed a renal scan within 2 weeks of diagnosis to identify those with pyelonephritis. Renal scans were interpreted centrally by 2 experts. We measured inflammatory proteins in blood and urine using LUMINEX or an enzyme-linked immunosorbent assay. We evaluated serum RNA expression using RNA sequencing in a subset of children. Finally, for children with Escherichia coli isolated from urine cultures, we performed a polymerase chain reaction for 4 previously identified virulence genes. RESULTS: Urinary markers that best differentiated pyelonephritis from cystitis included chemokine (C-X-C motif) ligand (CXCL)1, CXCL9, CXCL12, C-C motif chemokine ligand 2, INF γ, and IL-15. Serum procalcitonin was the best serum marker for pyelonephritis. Genes in the interferon-γ pathway were upregulated in serum of children with pyelonephritis. The presence of E coli virulence genes did not correlate with pyelonephritis. CONCLUSIONS: Immune response to pyelonephritis and cystitis differs quantitatively and qualitatively; this may be useful in differentiating these 2 conditions.

Clinical Assessment of Urinary Tract Damage during Sustained-Release Estrogen Supplementation in Mice.

Estrogen supplementation is a key component of numerous mouse research models but can adversely affect the urinary system. The goal of this study was to develop a clinical scoring system and identify biomarkers of occult urinary tract lesions prior to the development of systemic illness in mice. Ovariectomized or sham-surgery SCID mice were implanted subcutaneously with a placebo pellet or one containing sustained-release estradiol (0.18 mg 60-d release 17ß-estradiol). Mice were assessed twice weekly for 4 to 6 wk by using a clinical scoring system that included body condition, general activity, posture, hair coat, hydration, abdominal distension, urine staining of coat and skin, and ability to urinate. Samples were collected weekly for urinalysis, BUN, creatinine, and serum estradiol levels. Terminal samples were analyzed for histopathologic lesions. Compared with placebo controls, estradiolsupplemented mice had higher serum estradiol levels at weeks 2 and 3; significant differences in total clinical scores by the 3-wk time point; and in body condition, general activity, posture, hair coat, and urine staining scores by the 6-wk terminal time point. Urinary tract lesions included hydronephrosis, pyelonephritis, cystitis, and urolithiasis. All mice with urolithiasis had crystalluria, and 5 of the 6 mice with pyelonephritis or hydroureter had dilute urine (that is, specific gravity less than 1.030). However, these findings were not specific to mice with lesions. A total clinical score of 3.5 (maximum, 24) identified estradiol-supplemented mice with 83% specificity and 50% sensitivity, but no single clinical parameter, biomarker, or the total clinical score accurately predicted occult urinary tract lesions. Considering the lesions we observed, prudence is warranted when using pelleted sustained-release estradiol in mice, and important parameters to monitor for animal health include urine staining, body condition score, urine sediment, and urine specific gravity.

Pyelonephritis following phenazopyridine use.

We present a case of pyelonephritis following the extended andsolitary use of over-the-counter phenazopyridine in a forty-year-oldfemale. The patient initially had uncomplicated cystitis signs andsymptoms which partially resolved with phenazopyridine and therefore she continued use. She presented to the emergency department with systemicsigns and symptoms of acute pyelonephritis. As phenazopyridine is devoidof antibacterial properties this allowed the lower urinary tractinfection to progress to acute pyelonephritis requiring intravenousantibiotics. Better patient education may preclude this complication.

A Case of Septic Shock Due to Serratia marcescens Pyelonephritis and Bacteremia in a Patient Receiving Empagliflozin.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been associated with serious urinary tract infections (UTIs) including pyelonephritis and urosepsis. The Food and Drug Administration (FDA) issued a label change to include this warning in December 2015 due to a small number of cases (n = 19) reported to the FDA Adverse Event Reporting System. Details of these cases are limited and none involved empagliflozin. To date, there has been no published literature comprehensively describing serious UTIs attributed to empagliflozin. We describe a case of septic shock due to Serratia marcescens pyelonephritis and bacteremia that required intensive care unit admission in a well-controlled, type 2 diabetic patient who had begun taking empagliflozin 2 months prior. The patient was treated successfully with intravenous antibiotics followed by oral ciprofloxacin. After discontinuation of empagliflozin and completion of antibiotic therapy, no subsequent UTIs were documented in the following 4 months.

Use of Zolpidem and Risk of Acute Pyelonephritis in Women: A Population-Based Case-Control Study in Taiwan.

The aim of this study was to assess a possible correlation between zolpidem use and acute pyelonephritis (APN) in women in Taiwan. Therefore, we performed a case-control study involving the Taiwan's National Health Insurance Research Database between 2000 and 2011. This study included 3151 female participants aged 20 to 84 years who experienced the first bout of APN (case group) and 6015 randomly selected female participants without APN (control group). Zolpidem use was defined as "current," "early," or "late," if the last remaining 1 tablet for zolpidem was detected within 7 days, between 8 and 14 days, or ≥15 days before the date of APN diagnosis, respectively. The multivariable unconditional logistic regression model was used to calculate the odds ratios (ORs) with 95% confidence intervals (CIs) to assess the correlation between zolpidem use and APN. After adjusting for confounders, the multivariable analysis yielded an adjusted APN OR of 2.2 for participants with current zolpidem use (95%CI 1.7-2.8) compared with participants who never used zolpidem. The adjusted ORs gradually decreased to 1.4 for participants with early zolpidem use (95%CI 0.8-2.5) and 1.1 for participants with late zolpidem use (95%CI 0.9-1.2), but without statistical significance. Only patients with current zolpidem use had a significantly increased relative risk of APN. Additional large confirmatory studies are needed to illustrate a causal relationship. Meanwhile, physicians and pharmacists should be more cautious about the risk of APN when prescribing and dispensing zolpidem in women.

Cyclosporine A impairs nucleotide binding oligomerization domain (Nod1)-mediated innate antibacterial renal defenses in mice and human transplant recipients.

Acute pyelonephritis (APN), which is mainly caused by uropathogenic Escherichia coli (UPEC), is the most common bacterial complication in renal transplant recipients receiving immunosuppressive treatment. However, it remains unclear how immunosuppressive drugs, such as the calcineurin inhibitor cyclosporine A (CsA), decrease renal resistance to UPEC. Here, we investigated the effects of CsA in host defense against UPEC in an experimental model of APN. We show that CsA-treated mice exhibit impaired production of the chemoattractant chemokines CXCL2 and CXCL1, decreased intrarenal recruitment of neutrophils, and greater susceptibility to UPEC than vehicle-treated mice. Strikingly, renal expression of Toll-like receptor 4 (Tlr4) and nucleotide-binding oligomerization domain 1 (Nod1), neutrophil migration capacity, and phagocytic killing of E. coli were significantly reduced in CsA-treated mice. CsA inhibited lipopolysaccharide (LPS)-induced, Tlr4-mediated production of CXCL2 by epithelial collecting duct cells. In addition, CsA markedly inhibited Nod1 expression in neutrophils, macrophages, and renal dendritic cells. CsA, acting through inhibition of the nuclear factor of activated T-cells (NFATs), also markedly downregulated Nod1 in neutrophils and macrophages. Silencing the NFATc1 isoform mRNA, similar to CsA, downregulated Nod1 expression in macrophages, and administration of the 11R-VIVIT peptide inhibitor of NFATs to mice also reduced neutrophil bacterial phagocytosis and renal resistance to UPEC. Conversely, synthetic Nod1 stimulating agonists given to CsA-treated mice significantly increased renal resistance to UPEC. Renal transplant recipients receiving CsA exhibited similar decrease in NOD1 expression and neutrophil phagocytosis of E. coli. The findings suggest that such mechanism of NFATc1-dependent inhibition of Nod1-mediated innate immune response together with the decrease in Tlr4-mediated production of chemoattractant chemokines caused by CsA may contribute to sensitizing kidney grafts to APN.

[Chronic pyelonephritis in workers of chemical industry: pathogenesis and treatment].

The examination of 500 workers engaged in the production of chemicals detected chronic pyelonephritis in 81 (16%) of them. Such occupational hazards as furnace-charge dust, fly-powder, calcium petre in the air, intensify their toxic action on workers in high temperature and humidity (54-67%) at workplace and provoke pyelonephritis. An experimental model of pyelonephritis was developed in animals exposed to the above environmental hazards. Ceruloplasmin added to combined treatment of chronic pyelonephritis relieves endotoxicosis by reducing content of middle-mass molecules in blood plasma.

Caffeic acid phenethyl ester suppresses oxidative stress in Escherichia coli-induced pyelonephritis in rats.

Although oxidative damage is known to be involved in inflammatory-mediated tissue destruction, modulation of oxygen free radical production represents a new approach to the treatment of inflammatory diseases. Caffeic acid phenethyl ester (CAPE), an active component of propolis from honeybee hives, has antioxidant, anti-inflammatory and antibacterial properties. For that reason, we aimed to investigate the efficiency of CAPE administration in preventing oxidative damage in pyelonephritis (PYN) caused by Escherichia coli. In this study, 35 Wistar rats were grouped as follows: control, PYN 24 h, PYN 48 h, PYN 72 h, CAPE 24 h, CAPE 48 h and CAPE 72 h. E. coli (1 x 10(9) c.f.u.) were inoculated into the rats in both PYN and CAPE groups via urethral catheterization. Ten microM/kg-body weight CAPE was injected to the rats in all CAPE groups 24 h before E. coli infection, and injections were repeated at 24-h intervals. Rats were sacrificed 24 h, 48 h and 72 h after infection in both PYN and CAPE groups. Malondialdehyde (MDA) and nitric oxide (NO) levels were significantly increased in kidneys of PYN groups. The activities of the antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and xanthine oxidase (XO) were also elevated by E. coli. However, CAPE administration reduced MDA and NO levels, as well as XO activity, although it increased SOD and GSH-Px activities. Histopathological examination showed that CAPE reduced the inflammation grade induced by E. coli. In conclusion, CAPE administrations decrease the oxidative damage occurring in PYN and therefore could be used for medical management of bacterial nephropathy.

Mesalazine interstitial nephritis presenting as colitis ulcerosa exacerbation.

Mesalazine is the first line treatment in paediatric inflammatory bowel disease (IBD). There are several reports in the literature about nephrotoxicity (1/150 treated patients), from renal insufficiency to reversible nephritis. It is currently advised to follow creatinine in patients treated with mesalazine during the first 5 years of treatment; however this may reveal the problem too late. As demonstrated in this paediatric case, a high degree of clinical suspicion is needed to diagnose the side effects before irreversible kidney damage occurs. Since the treatment of IBD exacerbation and mesalazine induced interstitial nephritis is based upon steroids, delayed diagnosis of the latter is at risk.

Effect of a selective cyclooxygenase-2 inhibitor on renal scarring.

BACKGROUND: Scarring is one of the steps of excessive wound healing, causing dysfunction of the involved tissues and clinically poor cosmetics. The aim of this study was to examine the effect of a highly selective cyclooxygenase-2 (COX-2) inhibitor on renal scar formation in experimental pyelonephritis. MATERIALS AND METHODS: Four groups of 10 Balb/C mice were formed. In groups I and II following the inoculation of lipopolysaccharide (LPS) into both kidneys, 0.18 and 0.36 mg/day of rofecoxib was given respectively via intraperitoneal route for 5 days. No medication was applied following physiological saline solution injection to both kidneys of the mice in group III (negative control group). After group IV's LPS inoculation on the first day, saline solution (1 ml/day) was given intraperitoneally for 5 days (positive control group). Following the exposure of both kidneys, LPS of Escherichia coli (5 mg/kg) was injected into the kidneys of groups I, II, and IV. In group III, saline solution (0.1 ml) was used instead of LPS. Three days after the inoculation of LPS, solutions containing 0.18 and 0.36 mg of COX-2 inhibitor were given intraperitoneally for 5 days in groups I and II. No medication was used for the mice in group III. Six weeks after the inoculation of LPS and saline solution, all mice were humanely euthanized. Bilateral nephrectomies were done on each group of mice, and histopathological examination was performed. RESULTS: Inoculation of LPS into the renal parenchyma caused pyelonephritis and scar formation in all groups. The degree of pyelonephritis and scar formation was lesser in groups in which COX-2 inhibitors were used. The degree of scar formation was lesser in group II, in which 0.36 mg more of COX-2 inhibitor was used than in group I (0.18 mg of COX-2 inhibitor). CONCLUSION: In our study model, direct inoculation of LPS to kidneys caused experimentally induced pyelonephritis. Renal scar formation was effectively prevented through the utilization of rofecoxib at 0.36-mg doses.