Case presentation of urinary tract infection by StenotrophomonaS maltophilia

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Introduction

Stenotrophomonas maltophilia is an emerging aerobic, non-fermentative, gram-negative multidrug-resistant global opportunistic bacillus. Usually found in aqueous habitats, as well as in animals, foods and water sources. S. maltophilia causes a wide range of infections including respiratory tract infections, blood stream infections and, less commonly, biliary tract infections, skin and soft tissue infections, as well as bone and joint infections [3, 8]. It is increasingly being reported to cause urinary tract infections (UTIs). The aim of our study is to present a UTI case, caused by S. maltophilia.

Stenotrophomonas maltophilia represents the fourth most common pathogen among nonfermenting gram-negative bacteria (following Pseudomonas aeruginosa, Acinetobacter spp., and Burkholderia cepacia complex), with a reported incidence of 7.1 to 37.7 cases/10 000 discharges (regarding nosocomial infections).

S. maltophilia usually must bypass normal host defenses to cause human infection. For example, if an irrigation solution becomes colonized with this organism, irrigating an open wound can cause colonization or infection of the wound. S. maltophilia is usually incapable of causing disease in healthy hosts without the assistance of invasive medical devices that bypass normal host defenses.

Risk factors associated with S. maltophilia infection have been defined and may include underlying malignancy, immunosuppressant therapy, cystic fibrosis, Chronic obstructive pulmonary disease (COPD), HIV infection, neutropenia, mechanical ventilation, prior colonization with stenotrophomonas, central venous catheter, genitourinary catheter, continuous ambulatory peritoneal dialysis (CAPD), recent surgery, trauma, prolonged hospitalization, ICU admission, and exposure to broad-spectrum antibiotics, third or fourth generation cephalosporins and carbapenems, and hyperalimentation.

Stenotrophomonas (Xanthomonas) maltophilia is a multidrug-resistant gram-negative bacillus that is an opportunistic pathogen particularly among hospitalized patients. S. maltophilia infections have been associated with high morbidity and mortality in severely immunocompromised and debilitated individuals, with overall mortality rates ranging from 21% to 69%.

Treatment of S. maltophilia infections is difficult because this organism presents low susceptibility to antibiotics.

The mainstay of treatment for Stenotrophomonas infections is trimethoprim-sulfamethoxazole (TMP-SMX) and it remains the current drug of choice. Fluoroquinolones (FQs) have in vitro activity against S. maltophilia.

Case report

A 87-year-old male patient visited the Biopathology Laboratory of Nikea Primary Healthcare Center, Piraeus, Greece, for routine examination, being referred by the family doctor. Patient history revealed diabetes mellitus type 2, arterial hypertension, hypercholesterolemia, hypertriglyceridemia, hyperuricemia, chronic obstructive pulmonary disease, diagnosed before 30 years, prostate cancer Gleason grade 6, operated before 15 years, followed by hormone therapy and radiation therapy. Patient history also revealed urinary tract stones with 3 episodes of obstructive pyelonephritis in the last 5 years, followed by hospital admissions and administration of intravenous antibiotic treatment. Τhere were underlying diseases (risk factors) such as: a) diabetes mellitus type 2, b) barterial hypertension, c) hypercholesterolemia, d) hypertriglyceridemia, e) hyperuricemia, f) chronic obstructive pulmonary disease diagnosed 30 years ago, g) prostate cancer Gleason grade 6 operated 15 years ago, h) followed by hormone therapy, i) and radiation therapy, j) urinary tract stones with 3 episodes of obstructive pyelonephritis in the last 5 years and k) urinary incontinence the last 5 years. During the 3 times hospital admissions, he had a permanent bladder catheter and received special antimicrobial treatment, for various microorganisms detected in his urine samples, such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Enterococcus faecalis. During the hospital admissions (3 episodes of obstructive pyelonephritis in the last 5 years) he had a permanent bladder catheter and received special antimicrobial treatment, for various microorganisms detected in his urine samples, such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Enterococcus faecalis. There is no data base for the treatment that he received, because he was treated in hospital. He came to Nikea Primary Healthcare Center afterwards for routine examination, being referred by the family doctor. Urinary incontinence has been a symptom for 15 years, after the prostate cancer surgery. Moreover, the last 5 years the patient faced many difficulties in his daily life because of the urinary incontinence. Patient history, including urinary tract stones, with 3 episodes of obstructive pyelonephritis in the last 5 years, followed by hospital admissions where bladder catheterization was done. The situation was managed by bladder catheterisation, which further worsened his condition with recurrent UTIs and new episodes of pyelonephritis with subsequent hospitalization. The patient had also received a 6 month treatment of chemoprophylaxis with Nitrofurantoin (Furolin). The laboratory performed urinalysis (Multistix 10 SG Reagent Strips, Siemens Healthineers) and urine culture (incubation at 37°C for 24 hours on MacConkey agar, Columbia blood agar, and Sabouraud dextrose agar for fungi). The urinalysis described in the study was taken οn 11 April 2023. Next day, Stenotrophomonas maltophilia was the only pathogen identified. The bacterium was identified by the RapID™ REMEL ONE identification system (Thermo Fisher Scientific) οn 12 April 2023. The patient received treatment with Trimethoprime/Sulfamethoxazole, and he was cured. There were no subsequent tests after the identification by the RapID™ REMEL ONE identification system.

Results

Urinalysis showed proteinuria, intense pyuria, abundance of micro-organisms and abundance of red blood cells. The urine culture grew monomicrobial Stenotrophomonas maltophilia > 10⁵ CFU/ml. The bacterium was identified by the RapID™ REMEL ONE identification system (Thermo Fisher Scientific) (Fig.). Antimicrobial susceptibility testing revealed susceptibility to Trimethoprime/Sulfamethoxazole, Levofloxacin, Ceftriaxone and moderate susceptibility to Ciprofloxacin and Norfloxacin (Kirby-Bauer Disk Diffusion Susceptibility Test Protocol). The patient received treatment with Trimethoprime/Sulfamethoxazole.

 

Figure. Identification of Stenotrophomonas maltophilia by RapID™ REMEL ONE

 

Discussion

Stenotrophomonas maltophilia, formerly named XanthomonaS. maltophilia or Pseudomonas maltophilia, causes various infectious in immunocompromised individuals, which can be complicated by septic shock, respiratory failure, pulmonary hemorrhage, metastatic cellulitis, tissue necrosis that may be extensive, septic thrombophlebitis, disseminated infection, and death [4, 5]. Risk factors for infection by S. maltophilia include malignancy, the presence of indwelling catheters, chronic respiratory disease, chemotherapy, immunosuppressive therapy, prolonged antibiotic use and long-term hospitalization or admission to ICU [6]. Our study is to present a UTI case report, caused by S. maltophilia. Our results are in accordance to the literature references. According to Umar et al., males with mean age between 43 and 85 years, are more prone to developing UTIs caused by S. maltophilia [9]. Moreover, patients with underlying urological or nephrological diseases, such as the patient included in the study, tend to develop a more severe illness [1, 7, 9]. In most cases presented in the literature, the bacterium was sensitive to Trimethoprime/Sulfamethoxazole [2, 9].

Conclusion

Stenotrophomonas maltophilia, formerly named Xanthomonas maltophilia or Pseudomonas maltophilia, causes various infectious in immunocompromised individuals, which can be complicated by septic shock, respiratory failure, pulmonary hemorrhage, metastatic cellulitis, tissue necrosis that may be extensive, septic thrombophlebitis, disseminated infection, and death [4, 5]. Risk factors for infection by S. maltophilia include malignancy, the presence of indwelling catheters, chronic respiratory disease, chemotherapy, immunosuppressive therapy, prolonged antibiotic use and long-term hospitalization or admission to ICU [6]. Our results are in accordance to the literature. According to Umar et al., males with mean age between 43 and 85 years, are more prone to developing UTIs caused by S. maltophilia [9]. Moreover, patients with underlying urological or nephrological diseases, such as the patient included in the study, tend to develop a more severe illness [1, 7, 9]. In most cases presented in the literature, the bacterium was sensitive to Trimethoprime/Sulfamethoxazole [2, 9]. As a conclussion, accurate identification and susceptibility testing of this emerging pathogen are critical for the management of infected patients and prevention of spread of this emerging pathogen. Accurate identification and susceptibility testing of this emerging pathogen are critical for the management of infected patients and prevention of spread of this emerging pathogen.

About the authors

C. Seitopoulou

Nikea Prime Care Center

Email: antoniamour@yahoo.com

MD, MSc in Occupational and Enviromental Health, PhDc, Biopathologist, Laboratory of Biopathology

Греция, Nikea

M. Stamouli

Naval and Veterans Hospital of Athens

Email: antoniamour@yahoo.com

BSc, MSc in Health management, MSc in TQM, EurSpLM, Director of Biochemistry Laboratory

Греция, Athens

G. Kalliora

National and Kapodistrian University of Athens

Email: antoniamour@yahoo.com

Student at Faculty of Biology

Греция, Athens

A. Mourtzikou

GHNP “Agios Panteleimon”

Author for correspondence.
Email: antoniamour@yahoo.com

BSc, MSc in Clinical Chemistry, MPH, MPHM, EurSpLM, PhD, Scientific Senior Supervisor, Laboratory of Molecular Diagnostics

Греция, Piraeus

References

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