Medicines and the Microbiome

The human body plays host to trillions of microbial cells across the epithelial surfaces of the mouth and gut. These communities of microorganisms – collectively, the human microbiome – have crucial roles in human physiology and organ function, particularly in digestion and immunity. They may also have significant impacts, both positive and negative, on the effectiveness of medicines.

Fortunately, we now have a greater scientific understanding and appreciation for the microbiome than ever before – mostly thanks to the efforts of the Human Microbiome Project (HMP), a US National Institute of Health initiative launched in 2008. HMP’s goal is to identify and characterize the microorganisms associated with both health and disease, and many of the findings have implications for the way that medicines are formulated and the environment in which they are prepared. The truly exciting aspect of this work is that it reveals, for the first time, the extent to which the human body is host to a vast array of different microbes. But this isn’t just an area of academic intrigue; interactions between the human body and its microorganisms are vital for human health.

Understanding the intricacies of co-metabolic activity that occur amongst individual bacterial populations, pharmacologically derived byproducts, and the human gut has become a subject of much research. The microbiome regulates metabolic balance and homeostatic activity, adapting to each individual and their environmental circumstances, which makes all medicines unintentionally ‘personalized’ in a way. Indeed, the extent to which the microbiome influences the relative effectiveness of drugs in different individuals is a fascinating topic with great potential. It is not hard to imagine a new era of personalized medicine, when an individual’s microbiome might be screened to ensure that a particular medicine targets only certain parts of the body, perhaps working in conjunction with some microorganisms whilst avoiding degradation by others.

But that’s the future. One area that has seen immediate increased attention as a result of HMP’s work is contamination. We all know that non-sterile medicines, such as creams and ointments, must be protected from specific pathogens, while any contamination at all of sterile products can be extremely dangerous. However, the HMP has shown that the microbiome of the human skin is more diverse than previously thought, demanding a rethink of several aspects of sterile production, from improvements in the types of cleanroom clothing worn to the way that clean filtered air is provided and circulated. We each shed a billion skin cells per day – that’s 30,000 to 40,000 dead skin cells every minute – and approximately 10 percent of those cells play host to microorganisms. Clearly, those tasked with designing controlled environments must guarantee clean air spaces that effectively remove any contamination dispersed by operators (through turbulent air-flow), verify that disinfectants have appropriate biocidal activity, and ensure that staff changing procedures are sufficiently robust.

Now that the HMP has provided us with new information about the richness and complexity of the bacteria, fungi, viruses and other organisms that live in intimate contact with us, it’s crucial that we apply this knowledge across the board. Deeper knowledge of the human microbiome can help us develop new, optimized or even personalized medicines, but it can also ensure that medicines are not contaminated with microbial populations that might interfere with their action or otherwise cause harm.