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Nosocomial outbreaks due to amikacin-resistant tobramycin-sensitive Acinetobacter species: correlation with amikacin
Y Buisson1, G Tran Van Nhieu, L Ginot
1Laboratoire de Biologie Clinique, Hôpital d'Instruction des Armées du Val-de-Grâce, Paris, France.
Abstract:
Fifty-seven patients in the Val-de-Grâce hospital were infected or colonized with amikacin-resistant, tobramycin-sensitive Acinetobacter spp. between January 1985 and December 1987. This resistance phenotype was attributed to the recently described 3'-O-aminoglycoside phosphotransferase (APH(3')-VI), on the basis of substrate profile and DNA-DNA hybridization, and was mainly encountered in various biotypes of A. baumannii isolated from patients. It was also encountered in saprophytic A. johnsonii isolates from the hands of 11 healthy workers among the medical staff, which provided evidence for the dissemination of an epidemic gene among different biotypes and species of Acinetobacter. A retrospective epidemiological survey showed a significant correlation between amikacin consumption and case incidence in the wards where cross-infection had occurred.
Insights
Amikacin-resistant Acinetobacter spp. emerged due to the APH(3’)-VI enzyme, spreading between patients and staff. Amikacin use correlated with increased infections, highlighting the need for antimicrobial stewardship.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Acinetobacter spp. are opportunistic pathogens.
- Antimicrobial resistance in Acinetobacter is a growing concern.
- The emergence of amikacin resistance in Acinetobacter spp. was observed.
Purpose of the Study:
- To investigate the mechanism and epidemiology of amikacin resistance in Acinetobacter spp.
- To identify the genetic basis of this resistance phenotype.
- To determine the correlation between amikacin consumption and infection rates.
Main Methods:
- Phenotypic characterization of resistance.
- Enzyme substrate profiling.
- DNA-DNA hybridization for gene identification.
- Retrospective epidemiological survey.
- Analysis of amikacin consumption data.
Main Results:
- Fifty-seven cases of infection/colonization with amikacin-resistant, tobramycin-sensitive Acinetobacter spp. were identified.
- The resistance was linked to the 3'-O-aminoglycoside phosphotransferase (APH(3')-VI) enzyme.
- This resistance was found in Acinetobacter baumannii and Acinetobacter johnsonii isolates.
- A significant correlation was found between amikacin consumption and case incidence.
Conclusions:
- The APH(3')-VI enzyme is responsible for amikacin resistance in Acinetobacter spp.
- The gene conferring resistance has disseminated among different Acinetobacter biotypes and species.
- Hospital amikacin consumption is a risk factor for the emergence and spread of resistant Acinetobacter infections.