Genomic characterization of a mobile-element-associated resistance island in trimethoprim-sulfamethoxazoleresistant Stenotrophomonas maltophilia isolates sharing the same PFGE genotype

Altan G., Rakıcı E., Dündar D., Özgümüş O. B.

FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY, cilt.16, sa.1926102, ss.1-14, 2026 (SCI-Expanded, Scopus)

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 16 Sayı: 1926102
  • Basım Tarihi: 2026
  • Doi Numarası: 10.3389/fcimb.2026.1926102
  • Dergi Adı: FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY
  • Derginin Tarandığı İndeksler: Natural Science Collection (ProQuest), Biological Science Database (ProQuest), Health Research Premium Collection (ProQuest), Scopus, Science Citation Index Expanded (SCI-EXPANDED), BIOSIS, EMBASE, MEDLINE, Directory of Open Access Journals, Zoological Record
  • Sayfa Sayıları: ss.1-14
  • Recep Tayyip Erdoğan Üniversitesi Adresli: Evet

Özet

Background: Stenotrophomonas maltophilia is an opportunistic nosocomial

pathogen with intrinsic multidrug resistance and limited therapeutic options.

This study integrated phenotypic susceptibility testing, targeted molecular

screening, PFGE and short-read whole-genome sequencing (WGS) to

characterize resistance determinants and their local genomic context in

clinical-culture isolates.

Methods: Thirty-four non-duplicate clinical-culture isolates were analyzed.

Susceptibility to trimethoprim-sulfamethoxazole (TMP-SMX), levofloxacin and

minocycline was determined by disk diffusion. Minocycline testing was repeated

with acceptable quality control, and the repeat-run zone records were reassessed

using current CLSI breakpoints. A predefined, hypothesis-driven PCR panel was

used to screen selected resistance-, efflux- and biofilm-associated targets, and

gyrA, gyrB, parC and parE were sequenced. Genetic relatedness was assessed by

XbaI-PFGE. Three selected isolates (S05, S08 and S25) underwent WGS as a

targeted genomic-context analysis rather than a whole-collection populationgenomic

study.

Results: Resistance rates were 5.9% for TMP-SMX, 8.8% for levofloxacin and 11.8%

for minocycline after reassessment using current CLSI minocycline breakpoints.

Smqnr- and sul1-target PCR positivity was observed in 61.8% and 8.8% of isolates,

respectively. A dfrA27-target PCR amplicon was observed in 82.4% of isolates but

was not associated with TMP-SMX resistance and was not confirmed in the three

sequenced genomes. No QRDR hotspot mutations were identified. The two TMPSMX-

resistant isolates, S05 and S08, shared the same PFGE genotype. Short-read

WGS identified an identical 19,361-bp mobile-element-associated resistance

region in these isolates, containing a putative Sul-family/folP-like

dihydropteroate synthase (DHPS) annotation, two assembly-predicted hits each

of blaOXA-2 and ant(3’’), multiple insertion sequences and a mercury-resistance

module; the region was absent from S25.

Frontiers