Journal of Global Antimicrobial Resistance (Dec 2020)

Antibiotic resistance mechanisms in Acinetobacter spp. strains isolated from patients in a paediatric hospital in Mexico

  • Elena Bello-López,
  • Rosa del Carmen Rocha-Gracia,
  • Semiramis Castro-Jaimes,
  • Miguel Ángel Cevallos,
  • Michelle Vargas-Cruz,
  • Ricardo Verdugo-Yocupicio,
  • Yolanda Sáenz,
  • Carmen Torres,
  • Zita Gutiérrez-Cázarez,
  • Margarita María de la Paz Arenas-Hernández,
  • Patricia Lozano-Zarain

Journal volume & issue
Vol. 23
pp. 120 – 129

Abstract

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Objectives: The aim of this study was to identify Acinetobacter spp. strains from paediatric patients, to determine their genetic relationship, to detect antibiotic resistance genes and to evaluate the role of efflux pumps in antibiotic resistance. Methods: A total of 54 non-duplicate, non-consecutive Acinetobacter spp. isolates were collected from paediatric patients. Their genetic relationship, antibiotic resistance profile, efflux pump activity, antibiotic resistance genes and plasmid profile were determined. Results: The isolates were identified as 24 Acinetobacter haemolyticus, 24 Acinetobacter calcoaceticus–baumannii (Acb) complex and 1 strain each of Acinetobacter junii, Acinetobacter radioresistens, Acinetobacter indicus, Acinetobacter lwoffii, Acinetobacter ursingii and Acinetobacter venetianus. The 24 A. haemolyticus were considered genetically unrelated. One strain was resistant to carbapenems, two to cephalosporins, two to ciprofloxacin and sixteen to aminoglycosides. The antibiotic resistance genes blaOXA-214 (29%), blaOXA-215 (4%), blaOXA-264 (8%), blaOXA-265 (29%), blaNDM-1 (4%), aac(6ʹ)-Ig (38%) and the novel variants blaOXA-575 (13%), blaTEM-229 (75%), aac(6ʹ)-Iga (4%), aac(6ʹ)-Igb (13%) and aac(6ʹ)-Igc (42%) were detected. Among 24 Acb complex, 5 were multidrug-resistant, carbapenem-resistant strains carrying blaOXA-51 and blaOXA-23; they were genetically related and had the same plasmid profile. Other species were susceptible. In some strains of A. haemolyticus and Acb complex, the role of RND efflux pumps was evidenced by a decrease in the MICs for cefotaxime, amikacin and ciprofloxacin in the presence of an efflux pump inhibitor. Conclusions: This study identified isolates of A. haemolyticus carrying new β-lactamase variants and shows for the first time the contribution of efflux pumps to antibiotic resistance in this species.

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