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Antifungal Susceptibility Profile of Aspergillus Strains Isolated From the Lower Respiratory Tract in Eastern Indian
Aishwarya Nikhil1, Sradha Choudhury1, Mohit Bhatia2
1Mycology research group, Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Abstract:
Respiratory aspergillosis refers to a range of infections, from allergic to chronic and invasive, which can be life-threatening and are primarily caused by Aspergillus fumigatus and Aspergillus flavus. Other species, including Aspergillus terreus, Aspergillus nidulans, and Aspergillus versicolor, have also been implicated in respiratory infections. Treatment for chronic to invasive pulmonary aspergillosis typically involves azole antifungal drugs, although studies have shown varying minimum inhibitory concentrations (MIC) for these medications, with a growing concern over voriconazole resistance. During the period from August 2022 to May 2024, characteristic hyphae were detected in 7.2% of lower respiratory samples, with culture positivity in 12.8%, including early morning sputum and bronchoalveolar lavage fluid samples. A. flavus (n = 282) was the most frequently isolated species, followed by A. fumigatus (n = 86). Additionally, a seasonal trend was observed for Aspergillus infections, with peaks in April and September. The MIC of itraconazole, voriconazole, posaconazole, amphotericin B, ravuconazole, and caspofungin were assessed for the isolated Aspergillus species. A higher MIC of amphotericin B was observed against A. flavus and A. terreus, whereas azoles exhibited a relatively lower MIC. Caspofungin and posaconazole exhibited the lowest MIC against the isolated Aspergillus species. Therefore, it is crucial to identify the causative fungi and determine the antifungal MIC for Aspergillus species responsible for lower respiratory tract infections. This study emphasizes the significance of respiratory aspergillosis in TB-endemic regions of Eastern India.
Insights
Respiratory aspergillosis, caused by Aspergillus species, is a serious lung infection. This study found Aspergillus flavus most common and highlights the need for antifungal susceptibility testing in Eastern India.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Respiratory aspergillosis encompasses diverse infections, from allergic to invasive, often life-threatening and primarily caused by Aspergillus fumigatus and Aspergillus flavus.
- Emerging concerns exist regarding voriconazole resistance in treating chronic to invasive pulmonary aspergillosis, necessitating evaluation of antifungal minimum inhibitory concentrations (MICs).
Purpose of the Study:
- To investigate the prevalence and species distribution of Aspergillus in lower respiratory tract infections.
- To assess the antifungal susceptibility profiles of isolated Aspergillus species, focusing on azoles, amphotericin B, and echinocandins.
- To determine the clinical significance of respiratory aspergillosis in TB-endemic regions of Eastern India.
Main Methods:
- Analysis of lower respiratory samples (sputum, bronchoalveolar lavage) for characteristic hyphae and fungal cultures from August 2022 to May 2024.
- Identification of isolated Aspergillus species, with subsequent determination of MICs for itraconazole, voriconazole, posaconazole, amphotericin B, ravuconazole, and caspofungin.
- Correlation of findings with seasonal trends and geographical context (TB-endemic Eastern India).
Main Results:
- Characteristic hyphae detected in 7.2% and culture positivity in 12.8% of lower respiratory samples.
- Aspergillus flavus (n=282) was the most frequent isolate, followed by Aspergillus fumigatus (n=86).
- Higher MICs for amphotericin B against A. flavus and A. terreus; azoles showed lower MICs. Caspofungin and posaconazole demonstrated the lowest MICs against most isolates. Seasonal peaks in April and September were observed.
Conclusions:
- Accurate identification of causative Aspergillus species and determination of antifungal susceptibility are crucial for effective treatment of lower respiratory tract infections.
- The study underscores the significant burden of respiratory aspergillosis in Eastern India, particularly in TB-endemic areas.
- Findings support the use of caspofungin and posaconazole, while highlighting potential challenges with voriconazole resistance and amphotericin B efficacy against specific species.
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