The cdr1B efflux transporter is associated with non-cyp51a-mediated itraconazole resistance in Aspergillus fumigatus

Fraczek, Marcin G.; Bromley, Michael; Buied, A.; Moore, Caroline B.; Rajendran, Ranjith; Rautemaa, Riina; Ramage, Gordon; Denning, David W.; Bowyer, Paul

doi:10.1093/jac/dkt075

Cited by 267 publications

(282 citation statements)

References 46 publications

Supporting

Mentioning

272

Contrasting

Unclassified

Order By: Relevance

“…In this study, we have extended our understanding of this ABC transporter protein with the finding that Cdr1B/AbcB is critical for azole resistance in several common laboratory strains, detecting the polypeptide chain for the first time, localizing the protein to the plasma membrane, and providing evidence that this protein may be required in pathogenesis. Combined with the previous study (21), these data implicate Cdr1B/AbcB as an important participant in the biology of drug resistance in A. fumigatus.…”

Section: Discussionsupporting

confidence: 77%

“…More recent surveys of azole-resistant clinical isolates found that a large fraction of these organisms contained no detectable change at their cyp51A locus (1,20). Importantly, overexpression of a gene encoding a Pdr5 homologue was found to be required for azole resistance in a strain with a normal cyp51A gene (21). Together, these findings support the view that, as in other fungal pathogens, transcriptional upregulation of ABC transporter gene expression is an important contributor to this clinically key phenotype.…”

mentioning

confidence: 53%

“…We selected these for further analyses and designated them AbcA and AbcB, respectively. The abcB gene has also been designated cdr1B by Fraczek and colleagues (21).…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Contributions of Aspergillus fumigatus ATP-Binding Cassette Transporter Proteins to Drug Resistance and Virulence

2013

View full text Add to dashboard Cite

In yeast cells such as those of Saccharomyces cerevisiae, expression of ATP-binding cassette (ABC) transporter proteins has been found to be increased and correlates with a concomitant elevation in azole drug resistance. In this study, we investigated the roles of two Aspergillus fumigatus proteins that share high sequence similarity with S. cerevisiae Pdr5, an ABC transporter protein that is commonly overproduced in azole-resistant isolates in this yeast. The two A. fumigatus genes encoding the ABC transporters sharing the highest sequence similarity to S. cerevisiae Pdr5 are called abcA and abcB here. We constructed deletion alleles of these two different ABC transporter-encoding genes in three different strains of A. fumigatus. Loss of abcB invariably elicited increased azole susceptibility, while abcA disruption alleles had variable phenotypes. Specific antibodies were raised to both AbcA and AbcB proteins. These antisera allowed detection of AbcB in wild-type cells, while AbcA could be visualized only when overproduced from the hspA promoter in A. fumigatus. Overproduction of AbcA also yielded increased azole resistance. Green fluorescent protein fusions were used to provide evidence that both AbcA and AbcB are localized to the plasma membrane in A. fumigatus. Promoter fusions to firefly luciferase suggested that expression of both ABC transporter-encoding genes is inducible by azole challenge. Virulence assays implicated AbcB as a possible factor required for normal pathogenesis. This work provides important new insights into the physiological roles of ABC transporters in this major fungal pathogen.

show abstract

Section: Discussionsupporting

confidence: 77%

mentioning

confidence: 53%

See 1 more Smart Citation

Contributions of Aspergillus fumigatus ATP-Binding Cassette Transporter Proteins to Drug Resistance and Virulence

2013

View full text Add to dashboard Cite

show abstract

“…Whereas the impact of specific transporters on azole resistance of A. fumigatus remains largely enigmatic, ABC transporter genes are up-regulated in response to azole exposure (AfuMDR1, AfuMDR2, and five genes designated abcA-E) (Tobin et al 1997;da Silva Ferreira et al 2006), and in resistant clinical isolates (Slaven et al 2002;Nascimento et al 2003). AfuMDR1, renamed CDR1B, encodes the only transporter implicated directly in A. fumigatus azole resistance (Fraczek et al 2013).…”

Section: Drug Effluxmentioning

confidence: 99%

Mechanisms of Antifungal Drug Resistance

Cowen

Sanglard

Howard

et al. 2014

Cold Spring Harb Perspect Med

492

399

View full text Add to dashboard Cite

Antifungal therapy is a central component of patient management for acute and chronic mycoses. Yet, treatment choices are restricted because of the sparse number of antifungal drug classes. Clinical management of fungal diseases is further compromised by the emergence of antifungal drug resistance, which eliminates available drug classes as treatment options. Once considered a rare occurrence, antifungal drug resistance is on the rise in many high-risk medical centers. Most concerning is the evolution of multidrug-resistant organisms refractory to several different classes of antifungal agents, especially among common Candida species. The mechanisms responsible are mostly shared by both resistant strains displaying inherently reduced susceptibility and those acquiring resistance during therapy. The molecular mechanisms include altered drug affinity and target abundance, reduced intracellular drug levels caused by efflux pumps, and formation of biofilms. New insights into genetic factors regulating these mechanisms, as well as cellular factors important for stress adaptation, provide a foundation to better understand the emergence of antifungal drug resistance.

show abstract

“…The high-level pan-azole-resistant phenotype, particularly the high posaconazole MIC, suggests that these isolates have accumulated additional non-cyp51A resistance mechanisms. These could include the recently described overexpression of cyp51A, cyp51B, and the cdr1B efflux pump; for these three mechanisms, MICs of Ն8 mg/liter for itraconazole, 1 to 8 mg/liter for voriconazole, and 0.125 to 2 mg/ liter for posaconazole have been measured (9)(10)(11). Based on these reported phenotypes, particularly the low-level posaconazole resistance, these mechanisms are unlikely responsible for the highlevel pan-azole-resistant phenotype observed in these four patients' isolates.…”

mentioning

confidence: 99%

High-Level Pan-Azole-Resistant Aspergillosis

et al. 2015

View full text Add to dashboard Cite

High-level pan-azole-resistant Aspergillus fumigatus was recovered from four patients with chronic lung disease. In one patient, the development of progressive resistance followed long-term azole therapy and switching between antifungal azoles. The highlevel pan-azole-resistant phenotypes were not associated with a specific cyp51A gene mutation. New strategies that avoid the development of progressive azole resistance are needed.A zole resistance in Aspergillus fumigatus is an emerging problem which is associated with treatment failure in patients with aspergillus diseases (1). Resistance is commonly due to mutations in the cyp51A gene (1) that typically lead to high-level resistance (MIC, Ն8 mg/liter) against one azole and low-level resistance (MICs close to the resistance breakpoint) against others (2, 3).We identified four A. fumigatus isolates with MIC of Ն8 mg/ liter for all mold-active azoles, measured using EUCAST methodology (4). We labeled this unique phenotype high-level pan-azole resistance. We analyzed the cyp51A gene sequence of the isolates, using previously published algorithms (5), and retrieved clinical data for these four patients (Table 1).The first patient was a 22-year-old male with cystic fibrosis. After being diagnosed with allergic bronchopulmonary aspergillosis (ABPA), he commenced itraconazole and steroid maintenance therapy. Fungal sputum cultures after 8 months of itraconazole therapy revealed an A. fumigatus isolate with the high-level pan-azole-resistant phenotype. The patient continued itraconazole maintenance therapy, and the high-level pan-azole-resistant isolate was not recovered from repeat cultures.The second patient was a 71-year-old male with a medical history of asthma, bronchiectasis, and intermittent culture positivity with itraconazole-and voriconazole-susceptible A. fumigatus. The patient did not meet diagnostic criteria for ABPA and was never treated with azoles. The high-level pan-azole-resistant A. fumigatus isolate was isolated once from a sputum sample; follow-up sputum cultures yielded azole-susceptible A. fumigatus.The third patient was a 47-year-old female with severe pulmonary sarcoidosis, complicated by a pneumothorax with subsequent pleural empyema. From this empyema, an azole-susceptible A. fumigatus isolate was cultured (itraconazole and voriconazole MICs, 0.5 mg/ liter; posaconazole MIC, 0.063 mg/liter). Treatment with itraconazole was started, later changed to voriconazole, and ultimately changed to posaconazole as a chronic suppressive therapy. After 18 months of azole therapy, the patient's disease progressed, and a sputum sample was ordered for fungal culture. This sample grew the high-level pan-azole-resistant isolate and induced a switch to liposomal amphotericin B therapy. Despite treatment, the patient's condition deteriorated, and she died of respiratory failure.The fourth patient was a 39-year-old male diagnosed with chronic granulomatous disease and ABPA. The patient had been treated for multiple episodes of invasive pulmonary aspergillosis, and...

show abstract

The cdr1B efflux transporter is associated with non-cyp51a-mediated itraconazole resistance in Aspergillus fumigatus

Cited by 267 publications

References 46 publications

Contributions of Aspergillus fumigatus ATP-Binding Cassette Transporter Proteins to Drug Resistance and Virulence

Contributions of Aspergillus fumigatus ATP-Binding Cassette Transporter Proteins to Drug Resistance and Virulence

Mechanisms of Antifungal Drug Resistance

High-Level Pan-Azole-Resistant Aspergillosis

Contact Info

Product

Resources

About