Rare UTI Case Linked To Raoultella Planticola In Healthy Woman

A 56-year-old woman with no major health issues presented with recurrent urinary tract infections (UTIs) over a two-year period. During this time, her urine culture consistently revealed the presence of Raoultella planticola, an unusual pathogen rarely linked to UTIs. Typically, recurrent UTIs are defined as two or more infections within six months or three or more within a year, prompting further investigation to identify potential causes. This case emphasizes the rarity of R. planticola as a UTI culprit and underscores the importance of thorough microbiological testing in patients with persistent infections. After treatment with trimethoprim-sulfamethoxazole, the patient fully recovered with no recurrence after one month.

Raoultella planticola is a gram-negative, nonmotile bacterium from the Enterobacteriaceae family. Initially classified as Klebsiella planticola, it was reclassified in 2001 after advances in molecular genetics. This bacterium is usually found in environmental sources such as water, soil, and plants and is often considered nonpathogenic. However, this case highlights a rare instance of R. planticola causing a urinary tract infection, an uncommon event that prompts a deeper investigation into its potential as a uropathogen.

Case Presentation

The patient, a 56-year-old postmenopausal woman, sought help for recurrent UTIs over a two-year span. Previous infections were caused by Enterococcus faecalis and Klebsiella pneumoniae. At presentation, she complained of dysuria, left-sided abdominal pain, malodorous urine, hematuria, and mucus in the urine. Physical exam revealed mild tenderness in the left lower abdomen, but no fever or other alarming signs. Her medical history included diverticulosis, nephrolithiasis, and chronic constipation, with previous surgeries for rectocele and cystocele repair.

To rule out nephrolithiasis, a CT scan was performed, which showed no renal stones, and a prior cystoscopy had normal results. Urinalysis showed leukocyte esterase, nitrites, and moderate pyuria, consistent with a UTI. The urine culture identified R. planticola at a high concentration of >100,000 CFU/mL. Based on antibiotic susceptibility, she was treated with trimethoprim-sulfamethoxazole for seven days, leading to full symptom resolution and no recurrence at the one-month follow-up.

Discussion

UTIs can range from mild to severe, potentially leading to sepsis. Raoultella planticola, while genetically and phenotypically similar to Klebsiella, is infrequently associated with UTIs. Colonization rates in humans are between 9% and 18%, with most cases arising from the gastrointestinal and upper respiratory tracts. Despite its rarity, cystitis is the most common manifestation of R. planticola infection.

R. planticola shares virulence factors with Klebsiella, such as type 1 fimbriae, which contribute to UTI development. Differentiating between these two bacteria can be challenging in routine clinical practice due to their similarities, but biochemical and molecular techniques can aid in accurate identification. Notably, R. planticola ferments lactose, produces urease, and can grow at 4°C, distinguishing it from Klebsiella.

Although older age and immunocompromised conditions are known risk factors for R. planticola UTIs, our patient was healthy and without significant risk factors, making this case unusual. The absence of common environmental exposure further reduces the likelihood of R. planticola being acquired from external sources. This case challenges the conventional understanding of R. planticola as a pathogen primarily affecting immunocompromised hosts.

While R. planticola has been linked to a variety of infections, its pathogenesis remains poorly understood. Infections such as pneumonia, cholangitis, and soft tissue infections have been reported. Importantly, R. planticola exhibits intrinsic resistance to ampicillin, but remains susceptible to other antibiotics, such as aminoglycosides, carbapenems, and fluoroquinolones, making these viable treatment options.

Conclusion:

This case adds to the growing but limited body of literature linking R. planticola to UTIs, even in healthy individuals. While rare, it underscores the need for heightened clinical awareness of this pathogen, especially in cases of recurrent or unexplained UTIs. As diagnostic techniques improve, clinicians should be alert to the possibility of R. planticola as a uropathogen, particularly when conventional pathogens are not identified.