Oxacillinases and antimicrobial susceptibility of Ralstonia pickettii from pharmaceutical water systems in Croatia

• Published in: Letters in applied microbiology Vol. 75; no. 1; pp. 103 - 113
• Main Authors: Batarilo, I., Maravic‐Vlahovicek, G., Bedenic, B., Kazazic, S., Bingulac‐Popovic, J., Slade‐Vitkovic, M., Katić, S., Jukic, I.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.07.2022
• Subjects: Aminoglycosides; antibiotic susceptibility; Antibiotics; Antiinfectives and antibacterials; Aztreonam; bla OXA22; bla OXA60; Cefepime; Cefotaxime; Ceftazidime; Ceftriaxone; Ciprofloxacin; Electrophoresis; Gel electrophoresis; Genes; High resistance; Imipenem; Meropenem; Nosocomial infection; Piperacillin; Polymerase chain reaction; Ralstonia pickettii; resistance; Soil bacteria; Strains (organisms); Susceptibility; Tazobactam; Ticarcillin; Trimethoprim; Water purification; Croatia; Ralstonia pickettii; bla OXA60; bla OXA22; antibiotic susceptibility; resistance
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1111/lam.13711

This study evaluated antibiotic susceptibility and presence of blaOXA22 and blaOXA60 genes in 81 isolates of Ralstonia pickettii obtained from different purified and ultra‐pure water systems in two different geographical areas of Croatia. E‐test and disc diffusion test were performed to determine antibiotic susceptibility. Polymerase chain reaction was applied to detect genes encoding OXA‐22 and OXA‐60 oxacillinases previously identified in R. pickettii. The isolates were genotyped by pulsed‐field gel electrophoresis. The results revealed variable susceptibility/resistance profiles. Our isolates exhibited high susceptibility rates to ceftriaxone, cefotaxime, piperacillin‐tazobactam, ciprofloxacin, imipenem, cefepime and in lesser extent to ceftazidime. High rates of susceptibility were also observed for sulphamethoxazole‐trimethoprim and piperacillin. High resistance rates were noticed for ticarcillin‐clavulanate, aztreonam and meropenem, as well as for all aminoglycosides tested. Modified Hodge test was positive in 51·9% strains, indicating production of carbapenemases. blaOXA22 and blaOXA60 genes were detected in 37·0 and 80·3% strains, respectively. Pulsed‐field gel electrophoresis identified three major clusters containing subclusters. R. pickettii should be taken seriously as a possible cause of nosocomial infections to ensure adequate therapy, to prevent the development of resistant strains and to try to reduce the possibility of R. pickettii surviving in clean and ultra clean water systems. Significance and Impact of the Study: Ralstonia pickettii can form biofilm in pharmaceutical water systems and contaminate parenteral sterile solutions. Studies on antimicrobial susceptibility and systematic monitoring of R. pickettii both in environment and in clinics are very limited, especially on a larger number of isolates. We therefore analysed antibiotic resistance profiles in 81 isolates from different pharmaceutical water systems. Most isolates were resistant to aminoglycosides, aztreonam and meropenem with widespread presence of blaOXA22 and blaOXA60 genes, indicating that ‘sterile’ water represents a vast environmental reservoir of resistance genes that could be transmitted into clinical settings and pose a threat to successful treatment of infections.