Up to a half of infections after surgery and over a quarter of infections after chemotherapy are caused by organisms already resistant to standard antibiotics in the US, according to new estimates published in The Lancet Infectious Diseases.
Antibiotics are key to modern health care. Without them, life-giving invasive medical procedures become extremely risky.
Prophylactic antibiotics are used routinely in surgery, organ transplantation and cancer chemotherapy to prevent infections.
Increasing antibiotic resistance threatens the safety of these procedures and could result in increased rates of morbidity, amputation or death.
In the US, an estimated 157,500 surgical site infections resulted during inpatient surgery in 2011. A 3% mortality rate is associated with surgical site infections, and patients who develop such infections have between two and 11 times higher mortality rate than those who do not.
- Over 2 million people a year in the US acquire serious infections due to antibiotic resistance
- More than 23,000 people die of such infections
- Use of antibiotics is the single most important cause of antibiotic resistance.
The Centers for Disease Control and Prevention (CDC) estimate that around 650,000 patients a year receive chemotherapy for cancer in the US; approximately 10% acquire an infection that requires a hospital visit.
Previous studies have investigated how increasing antibiotic resistance has reduced the efficacy of antibiotic prophylaxis, but a global estimate of the decline was lacking.
Dr. Ramanan Laxminarayan, director of the Center for Disease Dynamics, Economics & Policy in Washington, DC, and colleagues reviewed all the meta-analyses of randomized controlled trials conducted between 1968 and 2011 to establish the severity of the situation.
They looked at the efficacy of antibiotic prophylaxis in preventing infections and infection-related deaths after 10 of the most common surgical procedures and blood cancer chemotherapy in the US, and they calculated the additional number of infections and deaths that a decline in efficacy could lead to.
The researchers also estimated the proportion of infections caused by bacteria that are resistant to currently used standard prophylactic antibiotics.
They found that between 39% (after cesarean section) and 50-90% (after transrectal prostate biopsy) of surgical site infections are caused by organisms that are resistant to recommended antibiotic prophylactic regimens. Another 27% of infections following blood cancer chemotherapy are resistant to standard antibiotics.
They estimate that a 10% drop in the efficacy of antibiotic prophylaxis could lead to 40,000 additional deaths in the US, rising to 280,000 in the case of a 70% drop. Deaths from infections could number an extra 2,100, rising to 15,000 in a pessimistic scenario.
Dr. Laxminarayan notes that this is the first study to estimate the impact of antibiotic resistance on broader medical care in the US.
“A lot of common surgical procedures and cancer chemotherapy will be virtually impossible if antibiotic resistance is not tackled urgently. Not only is there an immediate need for up-to-date information to establish how antibiotic prophylaxis recommendations should be modified in the face of increasing resistance, but we also need new strategies for the prevention and control of antibiotic resistance at national and international levels.”
Limitations include the fact that the trials reported in the meta-analyses were done over a long period (1968-2011). As resistance levels rise and newer antibiotic regimens come into use, the results of older studies might no longer be applicable to present-day hospital settings with better infection control standards than in the past.
Nevertheless, there is a stark warning in the results. The researchers call for further studies investigating antibiotic resistance across a range of medical procedures.
In a linked Comment, Dr. Joshua Wolf, from St. Jude Children’s Research Hospital in Memphis, TN, foresees a future where patients who need surgery or chemotherapy can no longer be protected from life-threatening infections by antibiotic prophylaxis. He calls for efforts to prevent this by supporting careful use of antibiotics through means such as clinical education and restriction of use of antibiotics.
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