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This paper provides a United States (US) perspective on the issue of antibiotic resistance as it pertains to the use of antibiotics in animals. A recent National Research Council (NRC, 1999) report concludes that drug residue issues are being effectively addressed in the US. The report also found that antibiotic use in food and animals is related to antibiotic resistance and the development of a set of diseases that exhibit resistance in humans. Although there is an urgent need to find alternatives to the use of antibiotics in animal production, an outright ban is unwarranted, and is likely to come down to a political issue. Scientific risk assessment, impact assessment, and a pragmatic recognition of existing conditions are important inputs in the political process. ; Includes bibliographical references

AbstractMany common bacterial pathogens have become increasingly resistant to the antibiotics used to treat them. The evidence suggests that the essential cause of the problem is the extensive and often inappropriate use of antibiotics, a practice that encourages the proliferation of resistant mutant strains of bacteria while suppressing the susceptible strains. However, it is not clear to what extent antibiotic use must be reduced to avoid or reverse an epidemic of antibiotic resistance, and how early the interventions must be made to be effective. To investigate these questions, we have developed a small system dynamics model that portrays changes over a period of years to three subsets of a bacterial population— antibiotic‐susceptible, intermediately resistant, and highly resistant. The details and continuing refinement of this model are based on a case study of Streptococcus pneumoniae, a leading cause of illness and death worldwide. The paper presents the model's structure and behavior and identifies open questions for future work. Copyright © 2000 John Wiley & Sons, Ltd.

A number of resistant bacterial pathogens have become the focus of recent concern in human medicine. Studies and facts on use of antibiotics in animals suggest that animal sources contribute little to the problem. The current pursuit of zero risk by banning some antibiotics in Europe is not a sensible precaution but rather an abdication of responsibility based on science. ; Includes bibliographical references

Daily and Ehrlich have described the current state of our epidemiological environment in chilling detail. While their point is that human beings interact and affect the epidemiological environment in a variety of ways, the development of antibiotic resistance in bacteria strikes us as one aspect that we can begin to analyse immediately. The evolution of resistance to antibiotics is a function of their use by humans. The more we use, the more selective pressure is placed upon bacteria to develop resistance. This is further complicated by how they are used. Both the duration and the amounts used affect the change in the level of resistance. Finally, the primary feature driving the concern over the use of these drugs is that the evolution of resistance makes these 'miracle' drugs exhaustible. We can try to develop new and better antibiotics, but it is uncertain how successful we will be and how expensive they will be if we are successful.

Changes in the drug susceptibility pattern were observed in Vibrio cholerae O1 isolated in the Lao People's Democratic Republic during 1993 to 2000. In this study, 50 V. cholerae O1 strains were selected during this period for studying the presence of class I integron and SXT constin. Twenty-four streptomycin-resistant strains out of 26 isolated before 1997 contained a class I integron harboring the aadA1 gene cassette. Twenty-four strains isolated after 1997 contained an SXT constin (a large conjugative element). Twenty of the strains were resistant to chloramphenicol, tetracycline, streptomycin, and trimethoprim-sulfamethoxazole, while four strains were susceptible to the antibiotic tested. The resistance genes included in the SXT constins were floR, tetA, strAB, and sulII, which encode resistance to chloramphenicol, tetracycline, streptomycin, and sulfamethoxazole, respectively. The antibiotic resistance gene cluster was found to be deleted in the four susceptible strains. SXTLAOS did not contain dfrA1 or dfr18, which confer resistance to trimethoprim in SXTET and SXTMO10, respectively. A hot spot region of SXTLAOS was sequenced, and we identified two novel open reading frames showing homology to sO24 (exonuclease) and sO23 (helicase) of the genomic island associated with the multidrug resistance region of Salmonella enterica serovar Typhimurium DT104. Analysis of SXTLAOS showed that there is a continuous flux of genes among V. cholerae SXT constins which should be carefully monitored.

Antibiotic resistance and emm gene types were examined from 692 Group A streptococci isolates from eight United States military basic training sites between 1998 and 2001. Macrolide resistance was associated with geographic sites and emm type. These data are useful for vaccine development initiatives and antimicrobial treatment considerations.

To address the public health problem of antibiotic resistance, the European Union (EU) founded the European Antimicrobial Resistance Surveillance System. A network of 40 hospitals that serve approximately 30% of the Spanish population (about 12 million) participated. Each laboratory reported data on antimicrobial susceptibility testing using standard laboratory procedures that were evaluated by an external quality control program. The antibiotic consumption data were obtained from the National Health System. We compared the antibiotic susceptibility of Spanish isolates of invasive Streptococcus pneumoniae (2001 to 2003) with antibiotic consumption. Invasive S. pneumoniae was isolated from 1,968 patients, 20% of whom were children at or below the age of 14 years. Of non-penicillin-susceptible strains (35.6%; 95% confidence interval, 34 to 37.2), 26.4% were considered intermediate and 9.2% were considered resistant. Between 2001 and 2003, penicillin resistance decreased from 39.5 to 33% overall and from 60.4 to 41.2% in children at or below the age of 14 years (P = 0.002). Resistance to erythromycin was at 26.6%, and coresistance with penicillin was at 19.1%. Of total isolates, the ciprofloxacin MIC was >2 μg/ml for 2.1%, with numbers increasing from 0.4% (2001) to 3.9% (2003). Total antibiotic use decreased from 21.66 to 19.71 defined daily doses/1,000 inhabitants/day between 1998 and 2002. While consumption of broad-spectrum penicillins, cephalosporins, and erythromycin declined, use of amoxicillin-clavulanate and quinolones increased by 17.5 and 27%, respectively. The frequency of antibiotic resistance in invasive S. pneumoniae in Spain was among the highest in the EU. However, a significant decrease in penicillin resistance was observed in children. This decrease coincided with the introduction of a heptavalent conjugate pneumoccocal vaccine (June 2001) and with a global reduction in antibiotic consumption levels.

Recent qualitative analyses warn of potential future human health risks from emergence of antibiotic resistance in food‐borne pathogens due to the use of similar antimicrobial drugs in both food animals and human medicine. While historical data suggest that human health risks from some animal antimicrobials, such as virginiamycin (VM), have remained low (McDonald et al., 2001), there is a widespread concern that "resistance epidemics" or endemics could arise in the future. How reassuring is the past about the future? This article applies quantitative risk assessment methods to help find out, using human health risks from VM and the nearly identical human antimicrobial quinupristin‐dalfopristin (QD) as a case study. A dynamic simulation model is used to predict the risks of emerging resistance to human antimicrobials in human populations from given input assumptions. Bayesian Monte Carlo uncertainty analysis allows past data to constrain and inform selection of input parameter values, and thus to predict the possible future resistance patterns that are consistent with historical data. The results show that health risks from VM use in food animals are highly sensitive to the human prescription rate of QD. For realistic prescription rates, quantitative risks are less than 1 × 10−6 even for members of the most‐threatened (ICU patient) population, while societal risks are <1 excess statistical death per year for the whole U.S. population. Such quantitative estimates complement more qualitative assessments that discuss the possibility of future "resistance epidemics" (or endemics) without quantifying their probabilities.

Emerging respiratory disease agents, increased antibiotic resistance, and the loss of effective vaccines threaten to increase the incidence of respiratory disease in military personnel. We examine six respiratory pathogens (adenoviruses, influenza viruses, Streptococcus pneumoniae, Streptococcus pyogenes, Mycoplasma pneumoniae, and Bordetella pertussis) and review the impact of the diseases they cause, past efforts to control these diseases in U.S. military personnel, as well as current treatment and surveillance strategies, limitations in diagnostic testing, and vaccine needs.

10.3201/eid0503.990308 ; Emerging Infectious Diseases ; 5 ; 3 ; 379-387

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO provided information on antibiotic resistance issues that may stem from the use of antibiotics in agriculture, focusing on the: (1) use of antibiotics in agriculture and the implications of that use for human health; (2) federal roles and responsibilities for overseeing the use of antibiotics in agriculture; and (3) issues surrounding the debate over whether to further regulate or restrict the use of antibiotics in agriculture."

Epidemiological environment (EE) could be denned as a set of conditions and processes, both physical and social, that influence the interaction between human beings and disease agents. The human epidemiological environment is shaped by various aspects of development and global change, viz. the influences of human population size, mobility, geographic distribution, urbanization, and nutrition status; modernization (macro-and microeconomic enterprise); loss of indigenous medicinal knowledge; microbial evolution of antibiotic resistance; land conversion and biodiversity loss; agricultural intensification; stratospheric ozone depletion; and climatic change (Daily and Ehrlich, 1995). Health status is affected greatly not only by economic development (e.g. by policies influencing per capita income and its distribution), but also through changes in EE.

AbstractAlthough improvements in human health represent a crucial aspect of development worldwide, many trends associated with development and global change appear to be reducing health security. In this article, we define the human epidemiological environment and describe key biophysical, economic, sociocultural, and political factors that shape it. The potential impact upon the epidemiological environment of aspects of both development and global change are then examined: the influences of human population size, mobility, geographic distribution, and nutritional status; modernization; loss of indigenous medicinal knowledge; microbial evolution of antibiotic resistance; land conversion and biodiversity loss; agricultural intensification; stratospheric ozone depletion; and climate change. Human vulnerability to infectious disease is often strongly and deleteriously influenced by ongoing, intensifying changes in these factors. An unprecedented level of communication and cooperation between experts, institutions, and nations is required to respond to the increasing threat of epidemic disease, which points to a promising area for enhanced interdisciplinary collaboration.

The intensive and inappropriate use of antibiotics in both medicine and agriculture has selected for antibiotic resistant bacteria that cause severe problems in antibiotic therapy. In animal husbandry, antibiotics are used for therapeutic and preventive treatments of infectious diseases and as growth promoters. In Europe, many antibiotics used as growth promoters were of the same classes as important antibiotics used in human medicine. The European Union withdrew the authorization for the use of the major antimicrobial growth promoters between 1996 and 1999. In 1999 Switzerland decided to ban the use of all antimicrobials as growthpromoting feed additives. The regulations concerning antibiotic use in animal husbandry and the chronological reasons for the ban of antimicrobial growth promoters are described. This ban led to a decrease of the antibiotic volume deployed in agriculture. This measure helps to reduce the amount of antibiotic resistant bacteria in food-producing animals. However, the use of medicated feed is still a common practice to prevent and to remedy bacterial infections and thus still leads to resistant pathogens. Surveillance programs, single animal treatment, good manufacturing practices and vaccinations are additional measures to be taken to keep the level of resistances in bacteria low.