Clonal expansion of colistin-resistant Acinetobacter baumannii isolates in Cape Town, South Africa
Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Objectives: To describe colistin-resistant Acinetobacter baumannii isolates in Cape Town, South Africa.
Methods: A. baumannii isolates identified on Vitek 2 Advanced Expert System were collected from
Tygerberg Hospital referral laboratory between 2016 and 2017. Colistin resistance was confirmed using
broth microdilution and SensiTest. mcr-1–5 were detected using PCR and strain typing was performed by
rep-PCR. Whole genome sequencing (WGS) was performed on a subset of isolates to identify
chromosomal colistin resistance mechanisms and strain diversity using multilocus sequence typing
(MLST) and pairwise single nucleotide polymorphism analyses.
Results: Twenty-six colistin-resistant and six colistin-susceptible A. baumannii were collected separately
based on Vitek susceptibility; 20/26 (77%) were confirmed colistin-resistant by broth microdilution. Four
colistin-resistant isolates were isolated in 2016 and 16 in 2017, from
five healthcare facilities. Thirteen
colistin-resistant isolates and eight colistin-susceptible isolates were identical by rep-PCR and MLST
(ST1), all from patients admitted to a tertiary hospital during 2017. The remaining colistin-resistant
isolates were unrelated.
Conclusions: An increase in colistin-resistant A. baumannii isolates from a tertiary hospital in 2017
appears to be clonal expansion of an emerging colistin-resistant strain. This strain was not detected in
2016 or from other hospitals. Identical colistin-susceptible isolates were also isolated, suggesting
relatively recent acquisition of colistin resistance.
Description
CITATION: Snyman, Y., et al. 2020. Clonal expansion of colistin-resistant Acinetobacter baumannii isolates in Cape Town, South Africa. International Journal of Infectious Diseases, 91:94-100, doi:10.1016/j.ijid.2019.11.021.
The original publication is available at https://www.journals.elsevier.com/international-journal-of-infectious-diseases
Publication of this article was funded by the Stellenbosch University Open Access Fund
The original publication is available at https://www.journals.elsevier.com/international-journal-of-infectious-diseases
Publication of this article was funded by the Stellenbosch University Open Access Fund
Keywords
Colistin resistance, Acinetobacter, Antibiotics, Multidrug resistance, Gram-negative bacteria
Citation
Snyman, Y., et al. 2020. Clonal expansion of colistin-resistant Acinetobacter baumannii isolates in Cape Town, South Africa. International Journal of Infectious Diseases, 91:94-100, doi:10.1016/j.ijid.2019.11.021