To Preserve Human Health, It is Time to Stop Feeding Antibiotics to Farm Animals in the USA and Other Countries

摘要

Antibiotic discovery was a major factor in the increase in life expectancy in the USA from 47 years in 1900 to 74 for males and 80 for women in 2000. However, resistance development in pathogens has become a major problem. Infectious diseases cause 20% of all deaths in the world and are the leading cause of death in children under the age of five. They are the second leading cause of death in the world (13 million deaths) and number three in developed nations. In the USA, 2-2.5 million people are infected each year with antibiotic-resistant bacteria. Hospital-acquired infections in the USA cost the health care system over $20 billion per year and lead to more than eight million additional days in the hospital. In Europe, the numbers of antibiotic-resistant infections are 400,000 per year resulting in 25,000 deaths. Much of the problem deals with hospital-acquired (nosocomial) infections. Each year, there are about two million nosocomial infections in the USA, resulting in 90,000 to 200,000 deaths. About half of these are caused by Staphylococcus aureus. Others are mainly due to infections with Clostridium difficile and Pseudomonas aeruginosa. These three organisms produce septicemia, especially in old and immunecompromised patients. Resistant bacteria which have developed over the years are generally uninhibited by most commercial antibiotics today. For example, some enterococci are resistant to all known antibiotics. Other organisms that are not normally virulent can infect immune-compromised patients. Great concern exists about resistance development among Gram-positive pathogens, such as methicillinresistant bacteria including S. aureus, i.e., the well-known MRSA. The incidence of MRSA infections in U.S. hospitals went from 127,000 in 1999 to 278,000 in 2005 and to 360,000 by 2011. During that time, U.S. deaths from MRSA increased from 11,000 to 19,000. MRSA attacks 150,000 people per year in Europe and kills about the same number of Europeans as Americans. Another serious problem involves clinical isolates of penicillin-resistant Streptococcus pneumoniae, the most common cause of bacterial pneumonia. It increased in the USA from 1987 to 1992 by 60-fold. It causes 1,200,000 cases in the USA each year and 7,000 deaths. Other serious nosocomial infections involve the intestinal bacterium Klebsiella pneumoniae causing pneumonia, blood infections, infections in newborns and intensive-care patients. It can be cured by the beta-lactam carbapenem antibiotics, such as imipenem and meropenem, but carbapenem-resistance is developing rapidly, especially in hospitals. In some countries, half of the patients die from carbapenem-resistant infections. The number of beta-lactamases discovered in clinical isolates is enormous, i.e., about 1300. The most dangerous are the extended spectrum beta-lactamases that hydrolyze most penicillins and cephalosporins. The carbapenases inactivate virtually all beta-lactam drugs. Hospital-acquired pathogens produce multiple beta-lactamases, as high as eight such enzymes per strain. Carbapenem-resistant Enterobacteriaceae increased four-fold in the USA from 2003 to 2013 with a mortality rate of 50%.