Original Research

Multilocus sequence typing of azole-resistant Candida auris strains, South Africa

Rindidzani Magobo, Mabatho Mhlanga, Craig Corcoran, Nelesh P. Govender
Southern African Journal of Infectious Diseases | Vol 35, No 1 | a116 | DOI: https://doi.org/10.4102/sajid.v35i1.116 | © 2020 Rindidzani Magobo, Mabatho Mhlanga, Craig Corcoran, Nelesh P. Govender | This work is licensed under CC Attribution 4.0
Submitted: 28 May 2019 | Published: 23 March 2020

About the author(s)

Rindidzani Magobo, Centre for Healthcare-associated Infections, Antimicrobial Resistance and Mycoses, Division of the National Health Laboratory Service, National Institute for Communicable Diseases, Johannesburg, South Africa; and Ampath National Reference Laboratory, Pretoria, South Africa
Mabatho Mhlanga, Centre for Healthcare-associated Infections, Antimicrobial Resistance and Mycoses, Division of the National Health Laboratory Service, National Institute for Communicable Diseases, Johannesburg, South Africa
Craig Corcoran, Ampath National Reference Laboratory, Pretoria, South Africa
Nelesh P. Govender, Centre for Healthcare-associated Infections, Antimicrobial Resistance and Mycoses, Division of the National Health Laboratory Service, National Institute for Communicable Diseases, Johannesburg, South Africa


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Abstract

Background: Candida auris is an emerging multidrug-resistant fungal pathogen associated with high mortality.

Methods: We investigated the genetic relatedness of clinical C. auris isolates from patients admitted to either public- or private-sector hospitals, which were submitted to a reference laboratory from 2012 to 2015. Patient demographics and clinical details were recorded. We performed antifungal susceptibility testing, sequencing of the hotspot 1 and 2 regions of the FKS1 and FKS2 genes for all isolates with an echinocandin minimum inhibitory concentration (MIC) of ≥1 µg/mL and cluster analysis using multilocus sequence typing.

Results: Eighty-five isolates were confirmed as C. auris. The median patient age was 59 years [inter-quartile range (IQR): 48–68 years], with male patients accounting for 68% of cases. Specimen types included urine (29%), blood (27%), central venous catheter tips (25%), irrigation fluid (7%), tissue (5%), respiratory tract specimens (4%) and other (3%). Ninety-seven per cent of isolates were resistant to fluconazole, 7% were resistant to both fluconazole and voriconazole, 8% were resistant to both fluconazole and echinocandins (considered multidrug resistant) and all were susceptible to amphotericin B. Of the 15 randomly selected fluconazole-resistant isolates, 14 isolates had an isavuconazole MIC ≤ 1 µg/mL. No FKS mutations were detected. Multilocus sequence typing (MLST) analysis grouped isolates into two clusters: cluster 1 and cluster 2 comprising 83 and 2 isolates, respectively.

Conclusions: Azole-resistant C. auris strains circulating in South African hospitals were related by MLST, but the possibility of nosocomial transmission should be explored using a more discriminatory technique, for example, whole genome sequencing.


Keywords

Candida auris; azole resistant; multilocus sequence typing; FKS sequencing; South Africa.

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