Unusual isolation of Pseudoglutamicibacter cumminsii in urine culture.

Sir,

Pseudoglutamicibacter cumminsii is an aerobic, catalase-positive, Gram-positive coccobacillus commonly found in soil. Recently, a change has been made in the taxonomy of this species, which was previously classified as Arthrobacter cumminsii [1]. The literature associated with urinary tract infection (UTI) is rare [2,3], although other cases of infections caused by related species within this genus, such as bacteraemia caused by A. creatinolyticus [4] or endocarditis caused by A. woluwensis [5], have been reported.

A 34-year-old woman with no personal history of interest visited her primary care medical centre with persistent urinary symptoms. She was diagnosed with cystitis and was prescribed Fosfomycin 3 g oral solution, two doses. Two weeks later, she returned to the health centre reporting continued urinary symptoms, without episodes of fever.

The patient was asked to send a urine sample for culture in the microbiology laboratory. The sample was inoculated in CPSO chromogenic medium (Biomerieux®, Marcy L’Etoile, France) and incubated for 24 hours in a 37º atmosphere. After the incubation time, a pure culture count of >100,000 CFU/ml of a yellowish colony was observed (Figure 1).

Figure 1

Colonies of P. cumminsii grown in CPSO® chromogenic agar (Biomerieux®)

Identification of the microorganism was performed by mass spectrometry, MALDI-TOF (Bruker®, Bremen, Germany). Pseudoglutamicibacter cumminsii was obtained with a score of 1.65. The identification was confirmed by using 16S rRNA gene sequence (GenBank accession number: MZ293797). Antibiotic susceptibility was tested by disc diffusion and Corynebacterium cut-off points in EUCAST (European Committee on Antimicrobial Susceptibility Testing) 2021 were taken as a reference for antibiogram interpretation. The susceptibility profile reported was as follows: susceptible to imipenem, linezolid, rifampicin, tetracycline and vancomycin, and resistant to ciprofloxacin, clindamycin, erythromycin, gentamicin, levofloxacin and penicillin.

Subsequently, the patient was treated with doxycycline 100 mg for 7 days with successful results. No new post-treatment control sample was sent.

Few reports have associated this microorganism to urinary tract infection [2,3]. However, the etiology of UTI’s can be very wide ranging, from the most common pathogens such as Escherichia coli, Proteus mirabilis or Klebsiella pneumoniae, to other less frequent pathogens described in the literature [6]. Accurate identification methods and antibiotic susceptibility constitute a fundamental tool in the diagnosis of urinary tract infections caused by underdiagnosed emerging pathogens.