Okay, there’s only one thing I dislike writing about more than an animal study. And that’s writing about a bench research study. First, I don’t even pretend to know enough about most of it to make any real sense of it. But even more importantly, the actual translation into clinical practice is far in the future and frequently never happens. So many times it’s just an academic exercise to get a paper published.

But this is another paper with a startling result that begs rapid follow-up and animal or human study. The use of nebulizers and inhaled aerosols is commonplace in ventilated patients in the typical ICU setting. A recent trial of an inhaled cocktail containing heparin, albuterol, and n-acetylcysteine (mucomyst) unexpectedly resulted in a higher incidence of pneumonia. So which one is the offending ingredient?

Since mucomyst is therapeutically used to change the properties of mucus, a group at Wayne State in Detroit looked at its effect on mucus, cytokine response, and bacterial transcytosis in an in vitro model.

Here are the factoids:

• Three groups of monolayers of human bronchial epithelial cells were grown and each was treated with either mucomyst, albuterol, or nothing (control). A mucin analysis was carried out.
• Separately, Klebsiella was added to three groups of monolayers grown as above. Cytokine response and bacterial transcytosis was measured.
• Mucin and its oligosaccharide content decreased significantly only in the mucomyst group, within 15 minutes of administration.
• Cytokine response was decreased in the mucomyst group after exposure to Klebsiella. This did not achieve statistical significance but was impressive.
• Bacterial transcytosis was increased only in the mucomyst + Klebsiella group.

Bottom line: This is startling news that involves a medication we tend to take for granted. Again, animal and/or human studies need to be quickly designed so we can determine whether the use of N-acetylcysteine should be avoided in ventilated patients.

N-acetylcysteine renders airway barrier at risk for bacterial passage and subsequent infection. EAST 2016 Oral abstract #4, resident research competition.