High frequency of azole resistant Candida spp. colonization among presumptive multidrug resistant tuberculosis (MDR-TB) patients

Clinical and microbiological characteristics of a hospital outbreak of Candida auris in a referral hospital in Lima, Peru

BACKGROUND

Candida auris, a multidrug-resistant fungal pathogen, has received considerable attention owing to its recent surge, especially in South America, which coincides with the ongoing global COVID-19 pandemic. Understanding the clinical and microbiological characteristics of outbreaks is crucial for their effective management and control.

OBJECTIVE

This retrospective observational study aimed to characterize a C. auris outbreak at a Peruvian referral hospital between January 2021 and July 2023.

METHODS

Data were collected from hospitalized patients with positive C. auris culture results. Microbiological data and antifungal susceptibility test results were analysed. Additionally, infection prevention and control measures have been described. Statistical analysis was used to compare the characteristics between the infected and colonized patients.

RESULTS

Thirty-three patients were identified, mostly male (66.7%), with a median age of 53 years. Among them, 18 (54.5%) were colonized, and 15 (45.5%) were infected. Fungemia was the predominant presentation (80%), with notable cases of fungemia in tuberculosis patients with long-stay devices for parenteral anti-tuberculosis therapy. Seventy-five percent of the isolates exhibited fluconazole resistance. Echinocandins were the primary treatment, preventing fungemia recurrence within 30 days. Infected patients had significantly longer hospital stays than colonized patients (100 vs. 45 days; p = .023). Hospital mortality rates were 46.7% and 25% in the infected and fungemia patients, respectively. Simultaneous outbreaks of multidrug-resistant bacteria were documented.

CONCLUSIONS

This study underscores the severity of a C. auris outbreak at a referral hospital in Peru, highlighting its significant impact on patient outcomes and healthcare resources. The high prevalence of fluconazole-resistant isolates, leading to prolonged hospital stay and high mortality rates, particularly in cases of fungemia, underscores the critical need for effective infection prevention and control strategies.

Mechanistic Insights into Cellular and Molecular Targets of Zinc Oxide Quantum Dots (ZnO QDs) in Fungal Pathogen, Candida albicans: One Drug Multi-Targeted Therapeutic Approach

Rationally designed multitargeted drugs, known as network therapeutics/multimodal drugs, have emerged as versatile therapeutic solutions to combat drug-resistant microbes. Here, we report novel mechanistic insights into cellular and molecular targets of ZnO quantum dots (QDs) against Candida albicans, a representative of fungal pathogens. Stable, monodispersed 4-6 nm ZnO QDs were synthesized using a wet chemical route, which exhibited dose-dependent inhibition on the growth dynamics of Candida. Treatment with 200 μg/mL ZnO QDs revealed an aberrant morphology and a disrupted cellular ultrastructure in electron microscopy and led to a 23% reduction in ergosterol content and a 53% increase in intracellular reactive oxygen species. Significant increase in steady-state fluorescence polarization and fluorescence lifetime decay of membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in treated cells, respectively, implied reduction in membrane fluidity and enhanced microviscosity. The observed reduction in passive diffusion of fluorescent Rhodamine 6G across the membrane validated the intricate relationship between ergosterol, membrane fluidity, and microviscosity. An inverse relationship existing between ergosterol biosynthetic genes, ERG11 and ERG3 in treated cells, related well with displayed higher susceptibilities. Furthermore, treated cells exhibited impaired functionality and downregulation of ABC drug efflux pumps. Multiple cellular targets of ZnO QDs in Candida were validated by in silico molecular docking. Thus, targeting ERG11, ERG3, and ABC drug efflux pumps might emerge as a versatile, nano-ZnO-based strategy in fungal therapeutics to address the challenges of drug resistance.

Drug resistance in Candida albicans isolates and related changes in the structural domain of Mdr1 protein

BACKGROUND

The increasing azole drug resistance in fungal pathogens poses a pressing threat to global health care. The coexistence of drug-resistant Candida albicans with tuberculosis patients and the failure of several drugs to treat C. albicans infection extend hospital stay, economic burden, and death. The misuse or abuse of azole-derived antifungals, chronic use of TB drugs, different immune-suppressive drugs, and diseases like HIV, COVID-19, etc., have aggravated the situation. So it is vital to understand the molecular changes in drug-resistant genes to modify the treatment to design an alternative mechanism.

METHOD

C. albicans isolated from chronic tuberculosis patients were screened for antifungal sensitivity studies using disk diffusion assay. The multidrug-resistant C. albicans were further screened for molecular-level changes in drug resistance using MDR1 gene sequencing and compared with Gen bank data of similar species using the BLAST tool.

RESULTS

The investigation proved that the isolated C. albicans from TB patients are significantly resistant to the action of six drugs. The molecular changes in MDR1 genes showed differences in seven nucleotide base pairs that interfered with the efflux pump.

In vitro study on the potential fungicidal effects of atorvastatin in combination with some azole drugs against multidrug resistant Candida albicans

The resistance of Candida albicans to azole drugs represents a great global challenge. This study investigates the potential fungicidal effects of atorvastatin (ATO) combinations with fluconazole (FLU), itraconazole (ITR), ketoconazole (KET) and voriconazole (VOR) against thirty-four multidrug-resistant (MDR) C. albicans using checkerboard and time-kill methods. Results showed that 94.12% of these isolates were MDR to ≥ two azole drugs, whereas 5.88% of them were susceptible to azole drugs. The tested isolates exhibited high resistance rates to FLU (58.82%), ITR (52.94%), VOR (47.06%) and KET (35.29%), whereas only three representative (8.82%) isolates were resistant to all tested azoles. Remarkably, the inhibition zones of these isolates were increased at least twofold with the presence of ATO, which interacted in a synergistic (FIC index ≤ 0.5) manner with tested azoles. In silico docking study of ATO and the four azole drugs were performed against the Lanosterol 14-alpha demethylase enzyme (ERG11) of C. albicans. Results showed that the mechanism of action of ATO against C. albicans is similar to that of azole compounds, with a docking score (−4.901) lower than azole drugs (≥5.0) due to the formation a single H-bond with Asp 225 and a pi–pi interaction with Thr 229. Importantly, ATO combinations with ITR, VOR and KET achieved fungicidal effects (≥ 3 Log₁₀ cfu/ml reduction) against the representative isolates, whereas a fungistatic effect (≤ 3 Log₁₀ cfu/ml reduction) was observed with FLU combination. Thus, the combination of ATO with azole drugs could be promising options for treating C. albicans infection.