May 30th, 2011 by Mark Crislip, M.D. in Health Tips
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It is hard to get infected. The immune system is robust and has a multitude of interlinking defenses that are extremely efficient in beating off most pathogens. Most of the time.
Fortunately, it is a minority of microbes that have evolved to be virulent in humans. Bacteremia is common with our own microbiome. When you brush or floss, bacteria leak into the blood stream:
We identified oral bacterial species in blood cultures following single-tooth extraction and tooth brushing. Sequence analysis of 16S rRNA genes identified 98 different bacterial species recovered from 151 bacteremic subjects. Of interest, 48 of the isolates represented 19 novel species of Prevotella, Fusobacterium, Streptococcus, Actinomyces, Capnocytophaga, Selenomonas, and Veillonella.
but with a good immune system, low virulence bacteria and no place to go, unfortunately the bacteria rarely cause infections.
Even heroin users rarely get infection. Heroin is a rich melange of bacteria and, on occasion, yeasts (I hate to say contaminated, since avoiding microbes is hardly a worry of heroin manufacturers), and the water used for injection is rarely sterile, yet infections are relatively rare despite the filth in which many heroin users exist.
I used to be somewhat fatalistic about hospital acquired infections. However, as the institutions in which I have worked have proven, almost all infections in the hospital are preventable if the institutions aggressively pursue high standards of care.
There are many systems in place in society to prevent infections: flush toilets, good nutrition, public health, vaccines, antibiotics, good hygiene, and an understanding of disease epidemiology, and I suspect people forget there are bugs out there that are pathogenic, just waiting to sicken and kill us. At least a couple of times a year I see patients come into the hospital, previously healthy, who rapidly die of acute infections. But for most people, most of the time, it takes a lot of effort to get an infection.
From my perspective we are Charlie Chaplain on skates , mostly unaware of the infections that awaits us if we do something silly, Read more »
*This blog post was originally published at Science-Based Medicine*
January 14th, 2009 by Dr. Val Jones in Expert Interviews, News
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Photo Credit: Dr. Crippen
I recently listened in to a Webinar related to infectious disease prevention strategies in elementary schools. The lead speaker (Dr. Thomas Sandora) was the principal investigator of a research study that was sponsored by Clorox and published in the Journal, Pediatrics a few months ago. I thought the results were interesting.
Study Design
This study was a randomized, controlled trial of 285 third to fifth graders in a school in Avon, Ohio. The study took place over a two-month period: from March to May, 2006. Half of the classrooms were randomized to the intervention group (which included having the kids apply hand sanitizer before and after lunch, and the teachers perform a sanitary wipe down of all their desks once/day), the other half were observed during their “business as usual” daily routine without sanitizers. The primary outcome measure was “days of school missed due to illness – either upper respiratory or gastrointestinal.” Swabs of surfaces in both the intervention and control groups were taken.
Results
Interestingly, there was no difference in the groups in terms of days of school missed due to upper respiratory type illnesses. There was a small but significant (9%) reduction in gastrointestinal-related illnesses absenteeism in the intervention group. Surface swabs picked up norovirus with higher frequency in the control group classrooms. No MRSA was detected during the study.
Discussion
Upper respiratory tract infections (URIs) are highly contagious, and are commonly spread by droplets in the air as well as surface contact (some viruses and bacteria can survive for 2 hours or more outside the body). Due to an infected child’s continuous contact with their own nasal secretions (sorry for the graphic photo), it is difficult to reduce the spread of URIs through the occasional hand washing or sanitizing. One would have to wash a child’s hands after each time they touched their mouth or nose.
On the other hand, gastrointestinal infections like norovirus are spread via the fecal-oral route, and are therefore not dripped and sneezed all over the place the way URI-causing viruses tend to be. Instead, GI infections are spread when hands are not washed thoroughly after a trip to the bathroom – and then food is touched and ingested.
So it’s not all that surprising that the transmission of GI-related infections were particularly susceptible to this study’s intervention: hand sanitizing before and after lunch, and a daily desk surface wipe.
An interesting point that Dr. Sandora made was that alcohol-based hand sanitizers don’t contribute to antibiotic resistance, because their killing mechanism is not related to antibiotics. I guess it’s like saying that humans don’t become resistant to knife injuries when exposed to attacks with greater frequency.
Conclusions
Hand sanitizer and surface disinfectant strategies may be more effective in reducing the transmission of gastrointestinal illnesses than respiratory tract illnesses in elementary school children. But since compliance is challenging – the total reduction in GI illness transmission remains modest though probably worth the hygiene effort. One glance at the photo above tells you all you need to know.
