Pyelonephritis caused by Massilia timonae in a diabetic patient: a rare cause of urinary tract infection: a case report

¹Laboratory of Microbiology, Faculty of Medicine and Pharmacy, University Mohammed First, Oujda, Morocco, ²Laboratory of Microbiology, Mohammed VI University Hospital, Oujda, Morocco, ³Laboratory of Bioresources, Biotechnology, Ethnopharmacology and Health, Faculty of Sciences, University Mohammed the First, Oujda, Morocco, ⁴Department of Bacteriology, Mohammed V Teaching Military Hospital, Rabat, Morocco, ⁵Epidemiology and Bacterial Resistance Research Team/BIO-INOVA Centre, Faculty of Medicine and Pharmacy, University Mohammed V, Rabat, Morocco

^&Corresponding author
Asmae Kidoun, Laboratory of Microbiology, Faculty of Medicine and Pharmacy, University Mohammed First, Oujda, Morocco

Introduction    

Urinary tract infections (UTIs) are among the most common bacterial infections. Although most are caused by Enterobacteriaceae, consider rare pathogens in elderly or immunocompromised patients. Massilia timonae, a non-fermenting aerobic Gram-negative bacillus, was first described in 1998 [1]. Fewer than fifteen human cases have been reported, with no previously documented urinary tract involvement. We report the first case of acute pyelonephritis due to M. timonae, identified by MALDI-TOF mass spectrometry.

Patient and observation     

Patient information: an elderly woman in her eighties with type 2 diabetes mellitus, hypertension, and a history of ischemic stroke with residual hemiplegia was admitted for acute kidney injury (AKI). All patient data were fully anonymized. The patient died during hospitalization; no next of kin could be reached for informed consent.

Clinical findings: on admission: creatinine 74 mg/L, urea 2.2 g/L, C-reactive protein 53 mg/L, white blood cell count 8,240/mm³ with neutrophilia (5,040/mm³). Cytobacteriological urine examination (CBEU) revealed turbid yellow urine with marked leukocyturia (1,600,000/mL) and fine granular casts on microscopy, consistent with upper urinary tract infection.

Timeline: day 1: admission for AKI with inflammatory syndrome (CRP 53 mg/L, leukocyturia). Day 2–3: urine culture yielding mucoid oxidase-positive Gram-negative bacilli. Day 3: MALDI-TOF identification of Massilia timonae; antibiogram performed. Day 4: transfer to intensive care unit. Day 5–7: fatal outcome despite appropriate management.

Diagnostic assessment: culture on cystine-lactose-electrolyte-deficient agar (CLED) and blood agar (48h, 37°C, aerobic) yielded mucoid, opaque, glistening colonies with a positive oxidase reaction, atypical for common uropathogens. Gram staining showed Gram-negative bacilli. MALDI-TOF mass spectrometry (Bruker Biotyper) confirmed identification with a high-confidence score for Massilia timonae. The main diagnostic challenge was the unusual morphology of the colonies, which could have led to misclassification as a contaminant by conventional methods alone (Figure 1).

Therapeutic interventions and follow-up: antimicrobial susceptibility testing (disk diffusion, EUCAST criteria) showed sensitivity to meropenem, ciprofloxacin, levofloxacin, amikacin, and tobramycin, with dose-dependent sensitivity to imipenem, cefepime, ceftazidime, and piperacillin-tazobactam. Appropriate antibiotic therapy was initiated. The patient was transferred to the intensive care unit; despite supportive management, the outcome was fatal. The fatal outcome reflects the severity of underlying comorbidities rather than intrinsic pathogen virulence, given the broad antibiotic sensitivity profile demonstrated.

Patient perspective: the patient died during hospitalization before any formal assessment of her perspective could be obtained. No next of kin could be reached. Therefore, patient perspective is not applicable in this case report.

Informed consent: this case report was conducted in accordance with the Declaration of Helsinki. The patient died during hospitalization, and no next of kin could be reached for informed consent. All patient data have been fully anonymized. The case is reported solely for its scientific and educational value. Written informed consent was waived due to the patient's death and the absence of reachable next of kin.

Discussion     

To our knowledge, this is the first documented case of urinary tract infection caused by M. timonae. Since its initial description [1], twelve cases have been published: septicemia [1,3,4], bone infections [2,3], central nervous system (CNS) involvement [3], corneal abscess [5], wound infection [6], septic abortion [7], and embryo culture contamination [8] (Table 1). Our case adds acute pyelonephritis to this spectrum. Massilia species are distributed in environmental reservoirs including soil, drinking water, and ambient air [9,10], suggesting a possible environmental route. Our patient had advanced age and diabetes mellitus as recognized risk factors for opportunistic infections. MALDI-TOF mass spectrometry was decisive for identification — conventional biochemical methods would likely have classified this isolate as an unidentified non-fermenting bacillus, potentially leading to misclassification or delayed diagnosis.

Conclusion     

This case documents the first urinary tract infection caused by Massilia timonae, expanding its clinical spectrum. Clinicians and microbiologists should consider non-fermenting Gram-negative bacilli in atypical UTIs in elderly diabetic patients. MALDI-TOF mass spectrometry is indispensable for accurate identification of such rare organisms.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Asmae Kidoun: case identification, microbiological analysis, manuscript drafting. Abderrazak Saddari, Imane Douichi, Said Ezrari, Mohammed Lahmer: data collection, manuscript revision. Elmostapha Benaissa, Yassine Ben Lahlou, Mostafa Elouennass: critical revision. Adil Maleb: supervision and final approval. All authors read and approved the final manuscript.

Acknowledgements     

The authors thank the laboratory staff of Mohammed VI University Hospital, Oujda, for their support.

Tables and figure     

Table 1: published human infections due to Massilia timonae

Figure 1: cultural characteristics of Massilia timonae on CLED agar after 48 hours of aerobic incubation at 37°C. Mucoid, opaque, circular, and glistening colonies are visible, morphologically atypical for common uropathogens

References