Antimicrobial Resistance and Whole-Genome Characterisation of High-Level Ciprofloxacin-Resistant <i>Salmonella</i> Enterica Serovar Kentucky ST 198 Strains Isolated from Human in Poland

• Main Authors: Tomasz Wołkowicz, Katarzyna Zacharczuk, Rafał Gierczyński, Magdalena Nowakowska, Katarzyna Piekarska
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Salmonella</i> Kentucky; antibiotic resistance; multidrug resistance; ciprofloxacin; ST198
• Online Access: https://www.mdpi.com/1422-0067/22/17/9381
• ISSN: 1661-6596; 1422-0067

Background: <i>Salmonella</i> Kentucky belongs to zoonotic serotypes that demonstrate that the high antimicrobial resistance and multidrug resistance (including fluoroquinolones) is an emerging problem. To the best of our knowledge, clinical <i>S.</i> Kentucky strains isolated in Poland remain undescribed. Methods: Eighteen clinical <i>S.</i> Kentucky strains collected in the years 2018–2019 in Poland were investigated. All the strains were tested for susceptibility to 11 antimicrobials using the disc diffusion and E-test methods. Whole genome sequences were analysed for antimicrobial resistance genes, mutations, the presence and structure of SGI1-K (Salmonella Genomic Island and the genetic relationship of the isolates. Results: Sixteen of 18 isolates (88.9%) were assigned as ST198 and were found to be high-level resistant to ampicillin (>256 mg/L) and quinolones (nalidixic acid MIC ≥ 1024 mg/L, ciprofloxacin MIC range 6–16 mg/L). All the 16 strains revealed three mutations in QRDR of GyrA and ParC. The substitutions of Ser83 → Phe and Asp87 → Tyr of the GyrA subunit and Ser80→Ile of the ParC subunit were the most common. One <i>S.</i> Kentucky isolate had <i>qnrS1</i> in addition to the QRDR mutations. Five of the ST198 strains, grouped in cluster A, had multiple resistant determinants like <i>bla</i>TEM1-B, <i>aac(6′)-Iaa</i>, <i>sul1</i> or <i>tetA</i>, mostly in SGI1 K. Seven strains, grouped in cluster B, had shorter SGI1-K with deletions of many regions and with few resistance genes detected. Conclusion: The results of this study demonstrated that a significant part of <i>S.</i> Kentucky isolates from humans in Poland belonged to ST198 and were high-level resistant to ampicillin and quinolones.