Drug Resistance-Associated Mutations in ERG11 of Multidrug-Resistant Candida auris in a Tertiary Care Hospital of Eastern Saudi Arabia

Abstract

Candida auris is an emerging multi-drug resistant pathogen with high mortality rate; nosocomial infections have been reported worldwide, causing a major challenge for clinicians and microbiological laboratories. The study aims to describe new cases of C. auris and detect drug resistance-associated mutations of C. auris by the sequencing of ERG11 and FKS1 genes. A total of six specimens were collected from blood, urine, ear swab, and groin screening samples. Isolates were incubated for 48 h on Sabouraud Dextrose agar (SDA) at 42 °C, then confirmed by MALDI-TOF MS. Furthermore, antifungal susceptibility testing was performed using the Vitek 2 system to detect Minimum Inhibitory Concentrations (MICs) of six antifungals. Sequences of 18S rRNA gene and ITS regions from isolates and phylogenetic analysis were performed. Gene sequencing was analysed to detect drug resistance-associated mutations by FKS1 and ERG11 genes sequencing. All C. auris isolates were confirmed by MALDI-TOF MS, and evolutionary analyses using sequences of 18S rRNA gene and ITS region. Antifungal susceptibility testing showed that all isolates were resistant to fluconazole. Sequencing of ERG11 and FKS1 genes from the isolates revealed the presence of two (F132Y and K143R) drug resistance-associated mutations in ERG11, however, FKS1 gene was devoid of mutations. The study sheds light on a public health threat of an emerging pathogen, and the hospital implemented strict contact screening and infection control precautions to prevent C. auris infection. Finally, there is a critical need to monitor the antifungal resistance in different geographical areas and implementation of efficient guidelines for treatment.

Candida auris: A Quick Review on Identification, Current Treatments, and Challenges

“…Using an in vitro diagnostic library of VITEK ® MS, 96.7% of the isolates were correctly identified [ 44 ]. As another example, isolates collected from blood, urine, ear swab, and groin were confirmed by MALDI-TOF MS and antifungal susceptibility testing was performed using the VITEK ® 2 system to detect MICs of six antifungals [ 45 ].…”

“…It is clear how necessary it is to reliably identify C. auris by molecular methods—polymerase chain reaction (PCR) amplification and/or PCR-sequencing of ribosomal DNA (rDNA). The methods are based on sequencing of the D1–D2 region of the 28s rDNA; however, the internal transcribed spacer (ITS) region can also dependably identify C. auris [ 32 , 39 , 45 , 49 ]. Another option is sequences of 18S rRNA gene and phylogenetic analysis for C. auris detection [ 45 ].…”

“…The methods are based on sequencing of the D1–D2 region of the 28s rDNA; however, the internal transcribed spacer (ITS) region can also dependably identify C. auris [ 32 , 39 , 45 , 49 ]. Another option is sequences of 18S rRNA gene and phylogenetic analysis for C. auris detection [ 45 ]. Sequencing of genetic loci and PCR/qPCR assays have successfully been applied for identification of C. auris .…”

“…Setting the MICs of antifungals against C. auris strains has also been requested, since elevated MICs are severe problem [ 79 ]. Importantly, it is equally critical to monitor the antifungal resistance in different geographical areas and implement efficient guidelines for treatment [ 45 ].…”

“…Isolates with the K143R mutation were resistant to Vcz [ 32 ]. Research of AlJindan and colleagues showed that all selected C. auris isolates were resistant to Flu and sequencing of ERG11 revealed the same mutation (F132Y and K143R) in ERG11 [ 45 ]. Similarly, another only two-hour-lasting assay identified mutations Y132F and K143R in ERG11 , and S639F in FKS1 HS1, and results were 100% concordant with DNA sequencing results [ 78 ].…”