By Kelly A. Reynolds, MSPH, PhD
Repeatedly, the CDC recommends consumption of safe food and water as primary defenses against antibiotic-resistant pathogen exposures. Hand washing and proper food preparation practices are key measures in prevention, as is access to clean water and effective treatment.
A recent report from the US Centers for Disease Control and Prevention (CDC) calls for immediate and urgent action toward improved stewardship relative to antibiotic use. The spread of drug-resistant infections extends beyond hospitals and includes food and waterborne routes as well. Given millions of infections and tens of thousands of deaths per year, the time to act is now. Top on the list of solutions is to prevent exposure to the disease-causing organisms—that is where the water treatment industry can play a key role.
Nowhere to hide
As microbes continue to evolve in the presence of selective pressures (i.e., repeated exposure to non-lethal concentrations of antibiotics in the environment), they develop resistance to the treatments, rendering them ineffective. Numerous bacteria circulating in the environment (including drinking water supplies)are already resistant to multiple antibiotics. Eventually, we will run out of options for treating these bacterial infections.
According to CDC Director Thomas Frieden, MD, MPH, new antibiotic drugs could be a decade away from development and use. He further warns that unless care is taken, we will be living in a post-antibiotic era. No one is immune to the risks of antibiotic-resistant infections. Patients with co-morbidities, such as diabetes, cancer, rheumatoid arthritis, organ transplant and those undergoing dialysis treatment or complex surgeries, are especially at risk, as these patients are more vulnerable to secondary infections and illness. Based on conservative assumptions, a minimum of 23,000 people die from antibiotic-resistant infections in the US each year, with 2,049,442 estimated cases of illness where the causative agent is resistant to one or more antibiotic. The economic burden of antibiotic-resistant infections is estimated at $20 to $35 billion (USD) per year.
In the CDC’s call to action, numerous antibiotic-resistant infectious agents were identified and further categorized into: 1) urgent; 2) serious and 3) concerning risks. Three pathogens were listed under urgent threats with two being potential waterborne pathogens: carbapenem-resistant Enterobacteriaceae or CRE and Clostridium difficile, also known as C. diff. Concern over CRE in drinking water supplies was recently reported in this publicaion (On Tap, March 2013).
Carbapenems are some of the strongest antibiotics in the treatment arsenal. Infections from CRE are associated with very high mortality rates. Up to 50 percent of those infected will die from the disease. More than 9,300 annual cases of CRE are thought to occur resulting in over 600 deaths. C. diff causes a serious and sometimes deadly diarrhea. While not yet broadly resistant to antibiotics, the use of antibiotics is a strong precursor to C. diff infections. The presumption is that use of antibiotics disrupts the gut microbiome, allowing for C. diff to proliferate in the absence of competing bacteria, which leads to the deleterious effect. Nearly 250,000 cases of C. diff result in hospitalization with 14,000 dying each year.
Listed under serious threats were Campylobacter, Salmonella, Shigella, Candida (a fungal pathogen) and Pseudomonas aeruginosa. All are commonly found in either contaminated waters or as part of indigenous aqueous communities.
Campylobacter causes diarrhea that is often bloody and may also result in temporary paralysis. Some strains are resistant to azithromycin or ciprofloxacin. While cases are estimated to be very high (n = 310,000), mortality rates are relatively low, with about 28 deaths per year. Similarly, deaths are relatively rare with Shigella infections but more than 27,000 cases are estimated to occur with the drug-resistant organism.
Candida, a common cause of bloodstream infections, have caused an estimated 3,400 cases and 220 deaths in acute-care hospitals but are also known to cause infections in nursing homes. The database on antibiotic-resistant infections is largely limited to acute-care settings and thus, the estimates of illness and death are largely underestimated.
Some of the most broadly resistant pathogens include drug-resistant Salmonella, which can be resistant to five or more antibiotic classes, and Pseudomonas aeruginosa, resistant to three or more. Drug-resistant, non-typhoidal Salmonella causes an estimated 100,000 US cases with symptoms of diarrhea, fever and cramps and 40 deaths per year, typically from blood infections. Pseudomonas aeruginosa causes approximately 6,700 cases and 440 deaths from pneumonia and bloodstream and wound infections. As dramatic as these morbidity and mortality values sound currently, they are expected to get worse given that bacteria are on a steady evolutionary path toward resistance.
Repeatedly, the CDC recommends consumption of safe food and water as primary defenses against antibiotic-resistant pathogen exposures. Hand-washing and proper food preparation practices are key measures in prevention, as is access to clean water and effective treatment.
Preventing future resistance
The CDC lists four core actions needed to prevent antibiotic-resistant infections: 1) prevent infections and prevent the spread of resistance; 2) track resistant bacteria; 3) improve the use of today’s antibiotics and 4) promote the development of new antibiotics and new diagnostics for resistant bacteria. Vaccines are being developed for some antibiotic-resistant bacteria. Preventing infections today goes beyond vaccinations and requires consideration of each route of pathogen transmission: food, air, water, person-to-person. Repeatedly, the CDC recommends consumption of safe food and water as primary defenses against antibiotic-resistant pathogen exposures. Hand-washing and proper food preparation practices are key measures in prevention, as is access to clean water and effective treatment. Bacteria are relatively easy to remove from water supplies as they are susceptible to conventional methods of municipal treatment, including chlorination. Contamination can occur post-treatment, however, leading to the need for POU treatment and purification.
Tracking the risk factors associated with exposures, infections and the severity of health outcomes will also help experts to develop the most effective solutions. An estimated 50 percent of all prescribed antibiotics are not needed for the patient’s recovery. Prescribing antibiotics for viral infections, for example, is not effective and could cause unnecessary side effects in patients. Rampant use of antibiotics in agriculture (i.e., for prophylactic control of disease and to promote growth) also add to the unnecessary overuse of the medicines. According to the CDC, the single most critical action is to greatly limit the use of antibiotics, but consumption of safe food and water and avoiding others who are ill are also important safeguards to collectively address the growing threat of antibiotic-resistant pathogens in the environment.
- CDC, Antibiotic Resistance Threats in the United States, 2013, US Department of Health and Human Services, Atlanta, 2013.
- Healio, CDC: Antibiotic resistance a serious health threat, requires urgent action, Healio Pediatrics Infectious Diseases in Children, 16 09 2013. [Online]. Available: www.healio.com/pediatrics/emerging-diseases/news/online/%7B9281c885-88ae-4c55-bc99-9f25b3946432%7D/cdc-antibiotic-resistance-a-serious-health-threat-requires-urgent-action. [Accessed 12 05 2014].
About the author
Dr. Kelly A. Reynolds is an Associate Profes- sor at the University of Arizona College of Public Health. She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a doctorate in microbiology from the University of Arizona. Reynolds is WC&P’s Public Health Editor and a former member of the Technical Review Committee. She can be reached via email at email@example.com