Who ya gonna call? --“Ghostbusters”
We seem to have mostly weathered two-plus years of a pandemic like the world has not seen in our lifetimes. It raced across the globe killing and maiming people, and overwhelming health care capabilities. Sure, we have read the history about the black plague, small pox, and the Spanish flu pandemics, but vicarious experience through books and film is no substitute for first-hand experience. We now have that experience. It was sobering to see the novel SARS-CoV-2 virus ravage country after country while medical experts played a desperate game of catch-up to learn how to retard the spread of a brand new virus and how to treat the brand new COVID-19 disease it spawned. It was sobering seeing and hearing about people we know get very ill and sometimes die, and sobering reading the statistics of millions of deaths that occurred worldwide.
While most of us today have not seen such a pandemic wild-fire before, we have seen other, more smoldering pandemics that do not spread as fast. HIV is a good example. It too is a world-wide disease that, for many years was a death sentence for those who were infected. Now it is a well-managed chronic disease, thanks to medical science.
The world was not as frantic over HIV and AIDS as we were over CoV-2 and COVID. The reasons for this are probably two-fold: First, it was quickly recognized that AIDS was largely limited to homosexual men and IV drug users and, therefore, was not an eminent threat to most of us. It was not necessary to quarantine, mask up, and shut down businesses and schools in order to prevent catching the “gay disease.” Second, despite the world-wide spread of AIDS, it is not easy to catch. You must be in very intimate contact with an infected person to catch it—it is not caught by simply breathing the same air as an infected person like COVID is. Clearly, not all pandemics are created equal. Some smolder like AIDS, others fulminate like COVID. What will our next pandemic be like?
As the global population grows, as the climate changes, as humans push into spaces occupied by wild animals, and as we continue enjoying our ever increasing global connectedness, future pandemics become more likely. We are not guaranteed the luxury of facing just one a century, or even one at a time. As greatly encouraging, even exciting as it was to watch the post-molecular BioX science, as I have called it, roar into life to produce several effective and novel anti-CoV-2 vaccines in record time, there is no guarantee BioX can save us next time.
Well, the “next pandemic” already is upon us and BioX is struggling to deal with it. This pandemic is not as volatile as COVID or the Spanish flu. In fact, compared to COVID, it is a “slow mo’” pandemic, more like AIDS. But, it promises to be more difficult than COVID, even for BioX, to mitigate. It currently kills about 700,000 people annually around the world, but threatens to kill 10 million people a year by 2050 (in contrast, COVID killed ~6 million around the world in 2.5 years).
In March 1942, Anne Miller of New Haven, Connecticut, was near death. A bacterial infection had made its way into her bloodstream, which was a death sentence at that time. Desperate to save her, doctors administered an experimental drug called penicillin, which Alexander Fleming accidentally discovered 14 years earlier. In just hours, she recovered, becoming the first person to ever be saved by an antibiotic. Rather than dying in her thirties, Mrs. Miller lived to be 90 years old and Fleming went on to win the Nobel Prize for his inadvertent discovery.
Today, decades later, germs like the one that infected Mrs. Miller, but easily eradicated with antibiotics, are increasingly becoming resistant to penicillin and the many other antibiotics that have since been developed. There is a very good chance that right now, you have such a “superbug” in or on your body—a resistant germ that, given the opportunity could enthusiastically sicken you leaving medical people at a loss on how to treat you. You would be at the mercy of the bug just as all patients with a microbial infection were before Mrs. Miller.
We are not talking about a new, exotic germ like CoV-2 suddenly appearing and ravishing the world. The antimicrobial resistance crisis stems from the simple fact that new antibiotic development cannot keep pace with the rate that common microbes become resistant to antibiotics. This very slowly growing pandemic we are now in involves run-of-the-mill pathogens, bacteria and fungi that have caused disease since humans first dragged their knuckles on the earth. These are bugs which we had well controlled with antibacterial and antifungal drugs, but there is a very definite trend toward these germs becoming resistant to ALL known antimicrobial medicines we have. Infection with multidrug resistant pathogens is the slow moving pandemic that already is among us but that is growing at a logarithmic rate.
Since multi-drug-resistant infections do not respond to our antibiotics, treatment increasingly involves surgically removing an infected organ. For example, in the case of drug-resistant Clostridioides difficile (aka, “C-diff”) colitis, an emergency colectomy is performed when patients no longer respond to antibiotic therapy. CDC data show C-diff infections occur in half a million patients each year, and at least 29,000 die within one month of initial diagnosis. Up to 30% of patients with severe C-diff colitis develop sepsis require emergency surgery, and still their mortality remains high.
As of 2019, about 18 drug resistant pathogens affected >3 million people in the US, causing 48,000 deaths. These bugs cause pneumonia, septic shock, various GI problems, STDs, urinary tract infections, typhoid fever, TB, and infection with the so-called “flesh eating bacteria.” Compared to COVID, this has received relatively little attention in the popular press, but has been a frequent topic in medical lectures and conferences for the last 20 or more years. These infectious disease lectures tend to scare the bejeebers out my colleagues and me. This smoldering pandemic is that serious.
And it is not just antibiotic-resistant bacteria we have to worry about. Certain fungi, especially of the Candida genus, cause various serious ailments in people. Recently, for the first time, the CDC reported five unrelated cases (two in DC and three in Texas) of people infected with fungi that showed “de novo” resistance to all drugs. Usually, drug resistant fungi only appear after infected patients have been treated with antifungals. But, the patients in these five de novo cases had no prior exposure to antifungal drugs. The fungi were already drug-resistant when they infected the patients; they were picked up from the environment already resistant to our medicines.
Antibiotic resistance is now one of the biggest threats to global health. It occurs naturally in naturally occurring pathogens, but is accelerated by overuse of antibiotics in humans and animals, especially farm animals. What happens is that upon treatment with an antibiotic, a single infectious bug out of a population of millions or billions fortuitously mutates and becomes resistant to the antibiotic. The antibiotic then kills off all the non-resistant population, including beneficial bacteria, opening the door for the drug-resistant pathogen to take over. This resistance can occur via many different mechanisms. The bacteria or fungal cell can stop taking up the drug, it can spit out the drug if it is taken up, it can neutralize the drug once it takes it up, or it can change its internal machinery so that it no longer responds to the drug. This problem can be further exacerbated since bacteria and fungi can pass along their mutations by sharing mobile genetic material with their progeny and even with other bugs in their immediate environment that have never been exposed to the antibiotic. They can even pass along this DNA to microbes of different species. Bacteria can also pick up DNA remnants left over from dead germs. Thus, DNA that confers resistance to anti-microbial drugs can spread to the environment even in treated human and animal waste contaminating lakes and streams and ground water.
Currently, the major problem with drug resistant infections occurs in in-patient clinical settings—perhaps you have seen the heightened infection control efforts (gowns, gloves, masks, and isolation) in hospitals designed to prevent the spread of untreatable pathogens. People receiving health care, especially those with weakened immune systems, are at higher risk for getting an infection. Routine procedures, such as bladder catheterization or kidney dialysis are common ways to introduce drug resistant germs into clinical patients. But, infection can happen in any surgical or invasive procedure. Treatment of diabetes, cancer, and organ transplantation can weaken a person’s immune system making them even more susceptible for infections that either are, or that can become drug resistant.
But, antibiotic infections can also occur in the community outside of clinical settings. There is the case of Mike who needed a month long hospital stay for kidney failure after bringing home a new puppy from which he caught a multidrug-resistant Campylobacter infection. He was one of 113 people across 17 states who was part of an outbreak linked to pet store puppies. He recovered after surgery to remove a dead section of his stomach.
The NIH Hospital Experience. About 10 years ago, the NIH Clinical Center in Bethesda was hit with an epidemic of drug resistant infections that killed a number of patients in just a few months. It was such an intractable problem that NIH finally had to gas rooms with a disinfectant, rip out plumbing, and build a wall to isolate infected patients. Still, over a period of six months it reached 17 patients, 11 of whom died. In this case, the bug was Klebsiella pneumoniae, which arrived in June 2011 with a 43-year-old female lung transplant patient who had just transferred from New York City. NIH nurses noted something startling in her chart: She was carrying an antibiotic-resistant infection.
Desperately trying to contain the superbug before it could spread, the NIH staff quickly isolated the woman in the ICU. Staff members donned disposable gowns and gloves before entering her room and her nurses cared for no other patients. After a month, the patient was discharged and the staff believed that their containment measures had worked. There were no signs that the bacteria had spread. But a few weeks later, they were shocked when a second patient tested positive for resistant Klebsiella. A third and fourth soon followed and all these patients died.
This pattern was baffling since, if the bug had not been cleared, it should have reappeared sooner. Even though it was the same type of bacteria, K. pneumoniae, perhaps it had spontaneously arisen anew in the other three patients. But by reading the genomes of the bacteria isolated from each patient, including the NYC transfer, scientists at NIH’s National Human Genome Research Institute saw that the bacteria in the subsequent patients came from the New York patient.
That meant two unsettling things: The bacteria lingered for weeks unnoticed in the hospital environment; and the hospital’s infection control measures for the New York patient failed. A further search for the bacteria found it on a ventilator that had been bleached twice. They also found it in a sink drain in a patient’s room, so they tore out all the plumbing. Yet, it began popping up it in more patients, at a rate of about one per week.
As hospital staff desperately raced to stanch the outbreak, they also struggled to treat the infected patients. Out of desperation, doctors battling the deadly, drug-resistant superbug turned to colistin, an antibiotic of last resort. It is not a new drug, having been discovered in 1949 in a beaker of fermenting bacteria in Japan. It had quickly fallen out of favor then since it causes significant kidney damage. The fact that the doctors resorted to such an old, dangerous drug highlights the lack of new antibiotics coming out of the pharmaceutical pipeline even in the face of a global epidemic of hospital-acquired bugs that quickly grow resistant to our toughest drugs.
While colistin defeated the superbug in a few patients, in at least four, the bacteria evolved so rapidly it outran colistin, too. Those four died. This was when the wall was built and all new Klebsiella-positive patients were moved into a new isolation unit behind the wall. Blood pressure cuffs and other normally reusable gear were tossed after one use. Clinical monitors were hired to follow doctors and nurses around to ensure that they were donning gowns, gloves and masks, and scrubbing their hands after seeing each patient.
Among the most concerning mutating bacteria are carbapenem-resistant Enterobacteriaceae (CRE). Enterobacteriaceae are a large family of more than 70 bacteria that includes the common E. coli, that normally live in the digestive system and help digest food. But, if conditions allow the bacteria to leave the digestive system, they can cause serious disease that needs to be treated with antibiotics. They too can quickly develop resistance to front-line drugs and become a serious problem. Carbapenem is an antibiotic "drug of last resort" used to treat disease caused by bacteria resistant to other front line antibiotics. Therefore, CRE are resistant to all or nearly all antibiotics and kill up to half the >13,000 patients who get bloodstream infections from them. The CDC first detected this type of antibiotic-resistant bacteria in 2000. Since then, it has been reported in 41 states. In the 10 years between 2001 and 2011, the percentage of Enterobacteriaceae resistant to antibiotics increased almost fourfold according to the CDC. Recently, the CDC tracked one type of CRE from a single health-care facility to facilities in at least 42 states.
The antimicrobial resistance crisis stems from the simple fact that new antibiotic development cannot keep pace with the rate that bacteria become resistant to antibiotics. Between 1945 and 1968, drug companies invented 13 new categories of antibiotics. Between 1968 and today, just two new categories of antibiotics have arrived. In 1980, the FDA approved 4-5 new antibiotics a year, but now only about 1-2 new drugs are submitted annually for approval. Hence, the solution appears quite simple: Develop more novel antibiotics. However, this is quite complicated since BioX science, which led to the rapid development of the novel mRNA anti-COVID vaccines, has not quite caught up to novel antibiotic development. There are two general reasons for this. First, finding a drug that disrupts the metabolism of bacteria or fungi, but that does not interfere with mammalian biochemical pathways is a difficult and narrow path. Second, so far, the market for novel antibiotics has been comparatively small, meaning that the profit incentive for pharma companies has not been large compared to that for so-called lifestyle medications. While a new antibiotic may bring in a billion dollars over its lifetime, a drug for heart disease may net $10 billion. Drugs to treat depression and erectile dysfunction are typically taken for years making them much more profitable than antibiotics that are used short-term.
Even if we could develop new antibiotics faster, their overuse is the primary driver of antibiotic resistance. According to the CDC, in 2018 seven antibiotic prescriptions were written for every 10 Americans. Of these, one-third were unnecessary, and very often were prescribed for viral illnesses that do not respond to antibiotics. Clinicians writing these prescriptions argue that the antibiotic can help prevent the primary viral infection from leading to a secondary bacterial infection. In other words, many antibiotics are prescribed for prophylaxis rather than treatment.
The number of new antibiotics that the FDA approves annually has slowed to a trickle, while the rate of bacterial mutation has grown exponentially. It used to take 21 years on average for bacteria to become resistant when antibiotics were first used. Now it takes just 1 year for bacteria to develop drug resistance because antibiotics are so readily prescribed and used. Today, the CDC lists 18 different types of antibiotic-resistant bacteria, five of which are classified as urgent threats to human health.
Physician-prescribed antibiotics, however, are not the only, or even main, source of our antibiotic resistance crisis. In the U.S., 70%-80% of all antibiotics are given to animals, especially farm animals destined for human consumption. Drug-resistant pathogens from farm animals can spread to the environment providing a gateway through which drug resistant germs can quickly spread across our communities, food supply, and even our soil and water around the world.
Surprisingly, antibiotic use is even rampant in salmon and other fish farms, which is especially concerning, considering that 90% of fresh salmon eaten in the U.S. comes from such farms. Antibiotic-resistant infections also affect petting zoo animals, which can then transfer the germs to people.
Antibiotics clearly have been miracle medicines, saving countless lives; however, anytime they are used, they drive the development of antibiotic resistant pathogens that ultimately defeat their purpose. Developing new antimicrobial drugs to counter the growing resistance to current drugs is not working; it is not keeping pace with the appearance of new antibiotic resistant germs. Without drastic changes in the science and economics behind antibiotic development and business, this will only be a partial solution to the growing pandemic. However, what we can do now is resort to low-tech, less expensive, and more innovative mitigation measures. These include alternative prevention steps such as more judicious use of antibiotics and increased use of isolation and sanitation measures (where have we heard this before?). Isolation and sanitation defenses against infectious diseases have been part of our disease fighting repertoire since the earliest awareness that contagions can spread through communities. It is an ancient remedy, but still the most effective way to protect ourselves against contagious diseases worldwide. Between 2013-2019, these mitigation measures led to an 18% reduction in US deaths from drug resistant infections. It always is better to prevent than treat.
Alternative medical treatment and prevention options. Besides the obvious masks, gloves, sanitation, and quarantine measures, there are other alternative medical (i.e., non-antibiotic) options that can be used to prevent and control drug resistant infection. In fact, these methods are often preferable to using antibiotics, which also deplete the microbiome of “good bacteria” that are critical for good health. These options include vaccines, therapeutic antibodies, and bacteriophages.
From 2000 to 2016, members of the WHO increased the use of the pneumococcal vaccine around the world, thereby decreasing antibiotic use which slowed the development of antibiotic resistant S. pneumoniae saving ~250,000 children from death. Pneumonia caused by secondary infection with other bacteria is a leading cause of complications and death in patients who get the flu. Therefore, the influenza vaccines also are effective tools to decrease the risk of drug-resistant bacterial pneumonias by preventing viral influenza. Since patients with COVID can also develop secondary complications from bacterial pneumonia, COVID vaccination now is another important weapon in the arsenal to prevent the development of antibiotic resistant bacterial lung infection.
In recent years, healthcare providers also have been increasingly using therapeutic antibodies to treat viral and bacterial infection. For example, antibody therapy is often used to treat recurrent C-diff GI infections, and antibodies to prevent and treat bacterial associated pneumonia also are being developed. So far, we have not seen bacteria develop resistance to antibodies.
Finally, a different and very novel approach to dealing with untreatable bacterial infection has recently taken advantage of bacteriophages, which are viruses that can specifically infect and kill bacteria. There are a few cases in which phage therapy has been used to cure people dying of multidrug-resistant bacterial infections. According to Pew Charitable Trusts, as of June 2019, 29 non-antibiotic products like therapeutic antibodies and phages were in clinical development and seven were in Phase 3 clinical trials.
Perhaps BioX is indeed coming to rescue us from the growing pandemic of drug-resistant pathogens.
Notes: 1) By way of disclaimer, your correspondent has consulted for a biotech company that engages in “big genome” research to search for novel antibiotic molecules produced by everyday bacteria and fungi that grow in the soil under your feet. Something like this could be part of the future of novel antibiotic development. 2) In order to have blog updates delivered to your email, see the simple Subscription Instructions here. Remember, you can easily unsubscribe when you want. But, you can’t beat the price.