Over the next 230 pages Sachs describes the intersection between modern man and mutating microbe, from the evolution of germ theory to revelations about the bacteria (helpful and harmful) that dwell on and in us; from an unhealthy focus on 'hospital level' cleaning to the rise of multi-resistant bacteria; and concluding with three chapters that explore alternatives to the traditional use of antibiotics.
Sachs's meticulously researched work, much of which draws on leading research into an increasingly vital aspect of health, is beautifully synthesised and comprehensive. I was particularly interested in the section where Sachs discusses the evolution of our bacterial colonies over the course of our lives, no two of which are identical. This starts with the way newborn immune systems are boosted by ingesting maternal microbes, from the lactobacilli and bifidobacteria that are created in the mother's vagina and milk ducts respectively, but also from the tail end of her digestive tract:
it's no coincidence, but rather the result of natural selection that a newborn's head typically faces in the direction of its mother's rectum when the head first emerges and remains there until the next contraction delivers the shoulders and the rest of the body.I was surprised to read of the direct link between high stress and intestinal microbe Bacteroides thetaiotamicron or B. theta, a bug associated with gene switching and possibly with how thriftily an individual metabolises energy.
Though slightly familiar with the hygiene hypothesis, the idea that maintaining an environment as close to germ-free as possible increases autoimmune and reactive disorders, I had no idea of the extent to which this was the case. I learned with interest that the kinds of microbes we're exposed to, particularly early in life, have potential lifelong consequences - children who are exposed in day care to many other children in infancy have dramatically lower rates of type 1 diabetes, while rates of multiple sclerosis and inflammatory bowel conditions like ulcerative colitis and Chrone's disease rise as sanitation improves. Similarly, children exposed to livestock, particularly stabled animals, are markedly less likely to develop allergies. Children are also far more likely to develop allergies and asthma if treated with antibiotics at a young age. And twins are more likely to have depression if their identical sibling has either of these conditions.
I have some knowledge of the growing problem of antibiotic resistance, so that aspect was less surprising to me than others, but I was impressed by Sachs's summation of the evolution of the problem, and the way she was able to convey frustration and impotence in the face of poor prescribing practices despite all physicians knowing the dangers of indiscriminate antibiotic use. Some of the findings Sachs reports, from the discovery of multi-resistant flora in never-hospitalised school children to the revelation that antimicrobial chemical triclosan (used widely in antibacterial soaps and other toiletries) can trip a bacterial genetic switch and trigger drug resistance on microbes never exposed to the antibiotics in question, were fascinating.
Antibiotics are used widely and relatively indiscriminately in agriculture, an aspect of the problem that Sachs thoroughly examines
Though recommendations about antibiotic prescribing are emerging - including the stunning (at least to me) revelation that three day courses of amoxycillin are as effective in treating bacterial pneumonia as the traditional ten day course - the outlook seems fairly dire.
But I was heartened by the research that, rather than just focusing on the next silver bullet antibiotic, is exploring alternatives to antibiotic therapies. I was also interested to read about research examining the possibility of using targeted bacteria to 'vaccinate' against cancers, and the idea of using positive strains of bacteria to outnumber harmful (or even less beneficial) varieties - a technique that may help reduce conditions as varied as dental caries and vaginal thrush.
Although I'm cautious about genetic modification of microbes, it sounds as though safety is a significant concern for researchers, and the boards that oversee them - safeguards include non-reproducible mutations and elements essential to the bug's survival that are not naturally available in that environment, meaning that failing to swish around mouthwash twice daily will kill off the tooth-protecting introduced Strep.
Most of all, I was hopeful when I read in the penultimate paragraph that we may one day aspire not to the death of microbes but "a relationship of symbiotic coexistence" with the flora that are so vital to our lives. - Alex