Peer Reviewed

Case In Point

An Atypical Case of Raoultella planticola Urinary Tract Infection

Volume 60 - Issue 8 - August 2020

AUTHORS:
Harielle Deshommes and Pete Papapanos, MD

AFFILIATION:
Florida State University College of Medicine, Tallahassee, Florida

CITATION:
Deshommes H, Papapanos P. An atypical case of Raoultella planticola urinary tract infection. Consultant. 2020;60(8):14-16. doi:10.25270/con.2020.03.00016

Received February 12, 2020. Accepted February 15, 2020.

CORRESPONDENCE:
Harielle Deshommes, Florida State University College of Medicine, 2498 S 35th St, Fort Pierce, FL 34981 (hjd17@med.fsu.edu)

DISCLOSURES:
The authors report no relevant financial relationships.

An 87-year-old gravida 2, para 2, postmenopausal woman with a history of vaginal vault prolapse and cystocele presented for a pessary fitting. She recently had been fitted for a size 5 pessary ring; however, the ring was too large, and the patient returned to the clinic to have a size 4 ring pessary fitted.

In addition to pelvic organ prolapse, the patient had stress urinary incontinence, urge urinary incontinence, atrophic vaginitis, hypertension, and osteopenia. Her surgical history included hysterectomy with bladder repair. She had no history of abnormal Papanicolaou test results, cervical dysplasia, or sexually transmitted infections. She was not sexually active and had no known drug allergies.

The patient’s medication list included estradiol vaginal cream for atrophic vaginitis and extended-release oxybutynin for urinary urge incontinence. The patient reported improvement of her urinary urge incontinence symptoms with anticholinergic medication. Review of symptoms at the time of this visit was significant only for urinary frequency, urgency, and incontinence. The patient’s pelvic examination findings were significant for a grade 2 cystocele but were otherwise unremarkable. No erosion was noted upon removal of the pessary, and it was replaced without difficulty.

The patient returned to the clinic for a routine pessary check 24 days later. Review of systems was significant for worsening urinary frequency, urgency, and incontinence. She also reported that she had been experiencing pain with urination. However, she stated that she was satisfied with her current size 4 ring pessary. Similar to findings at her previous visit, the patient’s pelvic examination findings were significant for a grade 2 cystocele but were otherwise unremarkable. Again, the pessary was replaced without difficulty. To address the patient’s painful micturition, a dipstick urinalysis was performed in the office (Table 1), and a routine urine culture was ordered.

Table 1

The patient was told that she was tolerating her new pessary well, and she was instructed to continue to apply the vaginal estrogen cream twice weekly for atrophic vaginitis symptoms. The decision was made to defer treatment until the results of the urine culture were received.

The final report of the routine urine culture was significant for a growth of Raoultella planticola. The growth was greater than 100,000 colony-forming units/mL. Antimicrobial susceptibility results are shown in Table 2. The patient was informed of her culture results and was prescribed amoxicillin-clavulanate, 500 mg/125 mg twice a day for 7 days.

Table 2

Seventeen days later, the patient presented for a follow-up visit and reported that her symptoms of dysuria and worsening urinary incontinence had resolved since taking the antibiotic. Table 3 shows the results of the patient’s dipstick urinalysis performed in the office that day. The results of the patient’s follow-up urine culture showed successful eradication of R planticola.

Table 3

DISCUSSION

Raoultella are gram-negative, aerobic, encapsulated, nonmotile bacilli.1 The bacteria are a member of the Enterobacteriaceae family and are commonly found in water, soil, and plants.2 Four species of the genus have been identified—R planticola, Raoultella terrigena, Raoultella electrica, and Raoultella ornithinolytica. The bacteria had been originally classified as a member of the genus Klebsiella but were reclassified as a separate genus in 2001.3 R planticola and R ornithinolytica have been most often reported to be pathogenic.1 Specifically, R planticola has become an emerging pathogen in humans. It is estimated that 9% to 18% of human populations are colonized with R planticola.4

Raoultella species are known to colonize the gastrointestinal and upper respiratory tracts in humans.2 However, because Raoultella species are opportunistic pathogens, they can cause infections of the biliary tract, the blood, and the lung parenchyma in immunocompromised individuals.2,5

The factors that might have contributed to the development of our patient’s R planticola infection include age, gender, medications, pelvic organ prolapse, the use of a pessary, atrophic vaginitis, urinary incontinence, and medication use. Women (particularly elderly women) are more prone to developing UTIs. Furthermore, this patient was taking an anticholinergic medication for urinary incontinence. Because the desired side effect of this class of medication is to induce urinary retention in cases of urinary incontinence, urinary stasis may have been a precipitating factor for this infection. It is equally important to consider the role that atrophic vaginitis and cystoceles play in the role of precipitating a UTI. Atrophic vaginitis is the result of a hypoestrogenic state in which the urogenital epithelium becomes more susceptible to injury and infection such as urinary incontinence and recurrent UTI. Due to the loss of elasticity and turgor of vulvovaginal tissues, the urethra does not have the ability to efficiently close and results in the opportunity for bacteria to travel up the urethra. A cystocele can cause anatomic kinking of the urethra and/or urinary stasis in the prolapsed segment of the bladder. Additionally, a vaginal pessary is a foreign body that can act as a nidus for infection.

R planticola is the source of various infections, including bacteremia, pancreatitis, pneumonia, UTI, appendicitis, necrotizing fasciitis, cholangitis, peritonitis, conjunctivitis, and prostatitis.3 Our review of the literature identified a total of 10 reported cases of UTI caused by Raoultella species, including 9 cases caused by R planticola (Table 4),3,6-13 and 1 case caused by R terrigena.14 Each patient’s infection was successfully treated.

Table 4

Compared with other reported cases, our patient’s case is unique in that the patient had unremarkable urinalysis results while infected with R planticola. In the other 9 reported cases, urinalysis results were significant for infection, including evidence of white blood cells, blood, and nitrites. In addition, in most of the reported R planticola UTI cases, the patients experienced fever, leukocytosis, and/or pain to abdominal palpation. However, our patient denied recent fevers and did not elicit tenderness to deep palpation of the lower abdomen. Results of in-office dipstick urinalysis showed no signs of infection. Moreover, the patient did not exhibit costovertebral angle tenderness and had no visible signs of genitourinary tract infection such as erythema, discharge, and tenderness. This patient’s case demonstrates that negative urinalysis results do not necessary rule out R planticola UTI.

Based on antimicrobial susceptibility results, the patient was treated with amoxicillin-clavulanic acid, 500 mg/125 mg twice a day for 7 days. Antimicrobial susceptibility for Raoultella species includes gram-negative antibiotics such as amoxicillin-clavulanic acid, second- to fourth-generation cephalosporins, aminoglycosides, fluoroquinolones, and tigecycline, among others.2 Although most strains of Raoultella species can be treated with antibiotics with gram-negative coverage, the documented cases of R planticola infections have demonstrated the species’ increasing resistance to antibiotics. The close resemblance of Raoultella species to Klebsiella species suggests an increased potential for multidrug-resistant strains over time,4 as well as difficulty identifying the organism accurately.2 Each reported case of R planticola UTI, including our patient’s case, had varying degrees of antimicrobial susceptibility.

In conclusion, although considered to be of low pathogenicity in immunocompetent individuals, Raoultella species have emerged as a source of infection. The low incidence of infections caused by R planticola may be due to the close resemblance to Klebsiella species.13 Although this emerging pathogen requires further investigation, it is important to consider R planticola as a source of infection and be informed about the treatment options.

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