Yes, it’s LOLStaphylococcus. They don’t call me the Mad Biologist for nuthin’
A colleague of mind sent along this paper, “Nose Picking and Nasal Carriage of Staphylococcus aureus“:
OBJECTIVE. Nasal carriage of Staphylococcus aureus is an important risk factor for S. aureus infection and a reservoir for methicillin-resistant S. aureus [MRSA]. We investigated whether nose picking was among the determinants of S. aureus nasal carriage.
SETTING AND PARTICIPANTS. The study cohort comprised 238 patients who visited the ear, nose, and throat (ENT) disease outpatient clinic of a tertiary care hospital and did not have a nose-specific complaint (defined as ENT patients) and 86 healthy hospital employees (including medical students and laboratory personnel).
MEASUREMENTS. All participants completed a questionnaire on behavior regarding the nose and were screened for S. aureus nasal carriage; only ENT patients underwent nasal examination by an ear, nose, and throat physician for clinical signs of nose picking.
RESULTS. Among ENT patients, nose pickers were significantly more likely than non-nose pickers to carry S. aureus (37 [53.6%] of 69 vs 60 [35.5%] of 169 patients; relative risk, 1.51 [95% confidence interval, 1.03-2.19]). Among healthy volunteers, there was a statistically significant positive correlation between the self-perceived frequency of nose picking and both the frequency of positive culture results (R = 0.31; P = .004) and the load of S. aureus present in the nose (R = 0.32; P = .003).
CONCLUSION. Nose picking is associated with S. aureus nasal carriage. The role of nose picking in nasal carriage may well be causal in certain cases. Overcoming the habit of nose picking may aid S. aureus decolonization strategies.
This isn’t as absurd as it seems. Most people are transient carriers of S. aureus, but we don’t really have a good understanding of what factors affect nasal colonization (most staph live up your nose, and don’t cause disease). Of course, we also don’t know why staph vanishes from your nose either. Onto the paper. First, they asked the study volunteers a bunch of questions about their nose picking habits:
Then they stuck nasal swabs up the subjects’ noses, and tried to culture S. aureus:
They also reported a rough estimate of the number of ‘colony forming units’ per schnozz (basically, the number of colonies that grew per swab):
So, nose picking does increase the likelihood of S. aureus carriage. But this conclusion hadn’t occurred to me (italics mine):
We conclude that nose picking is associated with nasal carriage of S. aureus and may well be causal. Future studies should reveal whether nose picking is a cause or a consequence of S. aureus nasal carriage and whether stopping the habit of nose picking prevents nasal colonization with S. aureus.
It would be really interesting if S. aureus somehow modified human behavior so as to increase its own transmission. Regardless, the authors are correct about this:
Understanding the pathogenesis of S. aureus nasal carriage will help optimize prophylactic strategies to prevent S. aureus disease and the spread of MRSA.
Now if they only had done an experiment where they eliminate S. aureus with mupirocin, and then see if nose picking is causal….