LOS ANGELES – Fungi might play a far larger role in asthma and chronic sinusitis than previously thought, according to investigators at Baylor College of Medicine in Houston.
With the help of a special culturing technique to wash antifungal elements out of sputum samples, six or more fungal colony-forming units grew out of the sputum of 112 of 134 patients (83.5%) at the Houston Veterans Affairs Medical Center; about a third of the patients had asthma, a third had chronic sinusitis, and a third had both. Although Aspergillus and Candida species were common, more than 30 fungal species were identified. Only a handful of patients had positive results on IgE testing.
Dr. David Corry
Of 62 patients treated with standard-dose voriconazole or terbinafine, sometimes for more than a year, 54 (87%) reported symptomatic benefit including 31 (50%) with decreased sputum production, 24 (39%) with improved breathing, 20 (32%) with less cough, and nine (14.5%) with less rescue inhaler use.
At Baylor, prescribing antifungals for patients with recalcitrant asthma and chronic sinusitis “has evolved into something we pretty much do all the time now regardless of sensitivity results. I’m pretty certain we are the only institution that does this,” said allergy and immunology fellow Dr. Evan Li.
“Fungi, we think, are important initiating factors in many cases of asthma. They set up chronic mucosal infection. Our [treatment] experience is extremely positive; it may be in the future that if you have significant asthma or sinusitis, you just go on an antifungal, but more research and clinical trials are needed,” said senior investigator Dr. David Corry, professor and chief of medical immunology, allergy, and rheumatology at Baylor.
“The standard culture techniques that have been used for 100 years are inadequate when it comes to culturing fungi from sputum, and why results almost invariably come back negative,” Dr. Corry said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
The problem is that “almost everything in sputum” – eosinophils, macrophages, cytokines, and so on – “is designed to kill fungi.” Those elements have to be removed before plating. At Baylor, “we solubilize [sputum] with the reducing agent dithiothreitol, and vigorously stir the mixture to disperse the organisms and wash away the cellular elements and the other things.” The process leaves behind “a sandy material that’s basically fibrin clots mixed with a lot of fungal elements. You spread that on a plate, and it grows like wildfire,” he said.
“It’s easy to do, but time consuming. People are actually shipping their samples to us now from around the country, and we are happy to do those cultures,” Dr. Corry said. There’s no patent on the technique because “we want the community to use it. We want people to be helped,” he said.
Voriconazole seems to be the most effective option, and the team opts for it when possible, Dr. Corry noted. Terbinafine is the go-to drug for patients who can’t tolerate voriconazole. Fluconazole is sometimes added when monotherapy doesn’t seem to be doing the trick.
The work began as a search for household proteases. “One of our first discoveries was that” most are fungal. “The twist is that you are not inhaling the proteases, you are inhaling the fungus,” Dr. Corry said.
There have been both positive and negative results from the few prior investigations of antifungals for asthma. The team suspects that negative findings were a result of patients not being treated long enough, among other reasons.
The Baylor team is looking for funding for a prospective trial. The investigators hope to develop a protocol for diagnosis and treatment of fungal airway disease, but “there’s a lot of work that needs to get done,” Dr. Corry said.
The investigators had no relevant financial disclosures, and there was no outside funding for the work.