Malassezia spp. microorganisms also inhabit skin during acne

Most people experience acne at some point in their life, and the AMI has discussed the microbiome’s role in this skin condition many times in our blog and podcasts.  Cutaneous inflammation is observed in people with acne, as well as increased amounts of the Propionibacterium acnes (P. acnes) bacteria.  However, a recent study conducted by dermatologists in Japan quantitatively examined microbiota in follicular skin contents, and providing more evidence that Malassezia spp. fungi may also be present during facial acne episodes in addition to P. acnes. 

15 untreated acne patients were selected for the study, all of whom had not received previous treatments with topical and/or steroid/antibiotic regiments.  A comedo extractor was used to collect follicular contents from inflammatory acne lesions from the cheek and foreheads of patients, and these samples were subject to DNA extraction and subsequent PCR analysis to characterize microbiota species.  Staphylococcus and Propionibacterium were found in follicular contents, but interestingly Malassezia spp. fungi were also observed.  Furthermore, Malassezia spp. fungi in follicular contents were correlated with inflammatory acne and with content on the skin surface, while Staphylococcus and Propionibacterium were not. 

These findings suggest that Propionibacterium acnes may not be the only microbiota skin residents related to acne.  While this was not the first paper to point to Malassezia spp. fungi as implicated in acne, these researchers addressed prior experimental method concerns and utilized advanced quantitation methods such as PCR rather than culture-methods.

We all emit our own 'microbial cloud'

Every individual has a microbiome compiled of millions of bacteria, fungi, viruses, and other microorganisms that is unique for each one of us. Whenever we travel to a new location and sit down or touch something, we are spreading our microbiome to that new location. A lot of research has gone into this phenomenon and is called the microbiome of the built environment. A new study out of the University of Oregon has expanded on this understanding and has described what they call a “microbial cloud”.

The scientists found that individuals not only spread their microbiome to new locations through direct contact but the microorganisms on our body are also dispersed into the air making up this microbial cloud. To better understand this, the scientists had 11 individuals sit in an enclosed room for 4 hours and they analyzed the DNA from the bacteria in the air. They found that when each individual sat in the room, there were thousands of bacteria in the room and everyone’s was distinct. They were able to identify specific characteristics of the people such as if it was a man or a woman.

The bacterial combinations found in the room could be linked back to specific individuals even after the person inhabited the room for only 4 hours. There were specific groups of bacteria like Streptococcus, often found in the mouth, as well as Propionibacterium and Corynebacterium, often found on the skin, that were most useful in identifying the individuals. While these bacteria were found around all the study participants it was the combination of bacteria that was key to identifying the individuals.

This finding could have several important applications. One often-discussed application of the microbiome is its use in forensic applications. It may be possible to use this ability to identify people and know if they were in a room or not to see if someone committed a crime, though it is not clear if it will be possible to identify people in a crowd of other individuals. Other applications include understanding the spread of infectious disease between individuals and within buildings. This is an exciting new development and I am certain we will see more research looking at our microbial clouds in the future.

Understanding the nasal microbiome

Electron micrography of Staphylococcus aureus.

The nasal microbiome remains largely unstudied despite its potential importance to many diseases, such as rhinosinusitis, allergies, and staph infection (incuding MRSA).  Staphylococcus aureus is probably the most well-known nasal resident, but simple questions, such as which species of bacteria are most prevalent in the nose, are still not answered.  Understanding all the residents of the nasal microbiome, the influence of our genetics and the environment on defining their populations, and the influence each one has on others may be critically important to preventing diseases such as staph infection, and more research is needed.  Fortunately, a new study out of Johns Hopkins that investigated sets of twins shed light on many of these questions, and was published in Science Advances last week.

The scientists sequenced the nasal microbiomes of 46 identical and 43 fraternal pairs of twins.  First, thy learned that these people’s nasal microbiomes could be classified into 7 different phenotypes or community state types (CST) which broadly described their nasal microbiomes.  These 7 types are defined by their most abundant bacteria, and are as follows: CST1 – S. aureus, CST2 - Escherichia spp., Proteus spp., and Klebsiella spp., CST3 - Staphylococcus epidermidis, CST4 - Propionibacterium spp., CST5 - Corynebacterium spp., CST6 - Moraxella spp., and CST7 - Dolosigranulum spp.   The most common CTS was CTS4 with 29% of the sampled population having that CTS, whereas CTS4 was the least popular, coming in at 6% of the individuals tested.  The researchers noted that many of these bacteria, such as Proteus, were not considered to be important to the nasal microbiome at all, so their dominance in some noses was surprising.  The scientists learned that genetics plays nearly no role in the microbiome community composition, but does influence the overall microbiome population.  In addition, gender influenced the overall population, with women having about half as many total bacteria in their noses as men.

With regards to S. aureus, while it existed in 56% of the individuals studied, it was associated with other bacterial.   For example, the researchers discovered that Dolosigranulum, and Propionibacterium granulosum were negatively correlated to the existence of S. aureus, whereas S. epidermidis was positively correlated with S. aureus abundance.  This lends itself to the idea that specific bacteria can create colonization resistance against S. aureus, and thus could be used to prevent the disease.  The researchers suggest a probiotic should be tested for its therapeutic value in preventing S. aureus colonization, and hopefully they move forward with those trials.

Do you smell bad? Just throw on some bacteria

When you’re next to someone on the subway or on the street who smells bad, do you ever  wonder what it is on his or her body that is making him or her smell that way? I don’t. I usually just walk away and I’m done with it.  But after reading a new study out of Switzerland and published in Microbiome, the next time I’m standing next to a smelly person on the subway, I might ask him or her about the bacterial makeup of his or her armpit. While body odor has long been attributed to the degradation of bodily fluids by bacteria in armpit sweat glands, this new study sought to identify which bacteria cause body odor.

The study consisted of 24 test subjects, both male and female, of which 13 used an antiperspirant and 11 did not, as well as four trained assessors tasked with smelling and analyzing the test subjects' underarms (talk about a fun job). Unsurprisingly, the researchers found that sweat odor intensity was much higher in non-antiperspirant users.  In addition, the non-antiperspirant users' odors were more likely to be described as sulfury-cat urine, acid-spicy, and fresh onion as compared to those that used antiperspirant.  After analyzing the amount of bacteria in the armpit of all the individuals, they found that those not using an antiperspirant had 50 times more bacteria than those using one.

The researchers were able to associate specific groups of bacteria with body odor: Corynebacterium, for example, had higher abundances in the smelly pits, while Propionibacterium had higher abundances in the non-smelly pits.  Overall, bacteria from the Firmicutes and Actinobacteria phyla were the most prevalent in all the arm pits, which makes sense as they are typically the most prevalent bacteria on the skin.  Finally, some bacteria were found to be more prevalent in men than in women, evidence that lends itself to the belief that men and women have different odors.

The identification of the smelly arm-pit bacteria provides an opportunity for microbiome interventions to combat body odor, and several companies, like AOBiome, are currently trying to do this.  They have developed products that are meant to put bacteria on the body that will help control body odors.  There are people out there (some that I know!) that rarely if ever take showers or use antiperspirants…and they actually smell just fine. Talk about dedication to the microbiome!