A study in Brazil, which looked at levels of anti-fungal drug resistance in 228 Aspergillus isolates from patients has found that 27% of Aspergillus fumigatus isolates showed resistance to Amphotericin B.
Aspergillosis is the most common acute invasive fungal infection, affecting 200,000 people worldwide every year. In patients with underlying conditions which affect the immune system, such as organ transplant recipients or chemotherapy patients, the infection can be particularly serious and is associated with high mortality rates.
There has been good news in recent years as improved treatment and diagnostics have led to increased survival rates. However, drug resistance in Aspergillus species , especially A. fumigatus and A. flavus. are being identified and are causing concern.
The standard treatment for Aspergillus is currently a group of drugs called ‘azoles’ and resistance to all of these drugs is being increasingly reported. Where resistance to azoles is encountered, Amphotericin B (AmB) is often used for treatment -however resistance to AmB is now also rising.
Resistance has been observed in patients with chronic Aspergillosis who are undergoing long term azole treatment. It has also been observed in patients with acute Aspergillosis who have not had any treatment, suggesting that their infection was caused by an already-resistant environmental strain.
Resistance to both azoles and Amphotericin B leaves clinicians with very limited treatment options. This study highlights the need for continuing surveillance for drug resistance, the reduction of environmental sources of azole resistance, further research into understanding the mechanisms of Amphotericin B resistance and urgent work to develop new antifungal drugs.