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Letter
Antimicrobial Drug Consumption
in Companion Animals
Ole E. Heuer,*
Vibeke Frøkjær Jensen,* and Anette M. Hammerum†
*Danish Institute for Food and Veterinary Research, Søborg, Denmark; and
†National Centre for Antimicrobials and Infection Control, Copenhagen,
Denmark
Suggested
citation for this article
To the Editor: During the last decade, use of antimicrobial drugs
for growth promotion and therapeutic treatment in food animals has received
much attention. The reservoir of resistant bacteria in food animals implies
a potential risk for transfer of resistant bacteria, or resistance genes,
from food animals to humans. Subsequent emergence of infections in humans,
caused by resistant bacteria originating from the animal reservoir, is
of great concern. These unintended consequences of antimicrobial drug
use in animals led to termination of antimicrobial growth promoters in
food animals in countries in the European Union, including Denmark, where
the consumption of antimicrobial drugs by production animals was reduced
by 50% from 1994 to 2003 (1).
In Denmark, the VetStat program monitors all veterinary use of medicines
for animals. VetStat is based on reporting from the pharmacies and from
veterinary practitioners and contains detailed information, such as animal
species, reason for prescription, and dosage on each prescription. In
Denmark, antimicrobial drugs can be obtained only by prescription and
only at pharmacies.
So far, use of antimicrobial drugs in companion animals has received
little attention; monitoring programs have focused on antimicrobial drug
consumption in food animals. According to data generated by the VetStat
program in 2003, consumption of fluoroquinolones and cephalosporins in
companion animals was substantial when compared to consumption in food
animals (1). Fluoroquinolones and cephalosporins are
antimicrobial drugs ranked by the U.S. Food and Drug Administration as
critically important in human medicine, and for which emergence of resistant
bacteria is especially undesirable (2). Considering the
shared environment of humans and companion animals, transfer of resistant
bacteria or mobile resistance determinants from companion animals to humans
would be possible, and emergence of resistance to fluoroquinolones and
cephalosporins in companion animals should be a matter of concern.
Several scientific publications have reported the occurrence of the same
resistance genes in companion animals and in humans (3–6)
and the possible transfer of bacteria between companion animals and humans
(3–9). Companion animal owners and their families are
likely in close contact with their animals daily, which provides the opportunity
for transfer of bacteria between companion animals and humans. A large
proportion of the human population presumably has daily contact with companion
animals, not only in Denmark but also in other countries. In Denmark,
20% of families own dogs and 16% own cats (10).
In 2002, legal restrictions aimed to reduce the usage of fluoroquinolones
in food animals were imposed in Denmark. The total annual consumption
of fluoroquinolones in animals (companion and food animals) in Denmark
was reduced from 183 kg in 2001 to 53 kg in 2003 (1).
Of these 53 kg of fluoroquinolones, almost half (24 kg) was used in companion
animals (data based on reporting on use in veterinary practice and sales
from pharmacies on prescription). These data document that fluoroquinolones
remain widely used for infections in companion animals, even though the
emergence of fluoroquinolone resistance in bacteria is especially undesirable
and regarded as a human health hazard. A similar situation exists with
cephalosporins. The total consumption of cephalosporins in animals (companion
and food animals) in Denmark in 2003 was 461 kg, of which more than half
(254 kg) was consumed by companion animals (1).
Thus, a comparatively small number of companion animals (550,000 dogs
and 650,000 cats) (10) consume approximately the same
amount of fluoroquinolones and cephalosporins as consumed annually in
the much larger population of food animals in Denmark (23 million slaughter
pigs, 130 million broiler chickens, and 1.2 million cattle and dairy cows)
(10). We do not believe that antimicrobial drugs are
more generously prescribed for companion animals in Denmark than in other
industrialized countries. Rather, the data presented here reflect the
apparent contrast between policies of antimicrobial drug use for food
animals and policies for companion animals. The use of these antimicrobial
drugs is avoided or restricted in food animals to minimize spread of resistance,
while in companion animals prescription continues unimpeded. This situation
may create undesirable antimicrobial drug resistance in bacteria, which
may subsequently spread to humans from the previously neglected reservoir
in companion animals.
This work is a part
of The Danish Integrated Antimicrobial Resistance Monitoring and Research
Programme (DANMAP), and was funded by the Danish Ministry of Food, Agriculture
and Fisheries and the Danish Ministry of the Interior and Health.
References
- DANMAP 2003: use of antimicrobial agents and occurrence
of antimicrobial resistance in bacteria from food animals, foods and
humans in Denmark. Sørborg, Denmark: Danish Zoonoses Center; 2004.
- S. Food and Drug Administration. FDA guidance (152): Guidance for
industry: evaluating the safety of antimicrobial new animal drugs with
regard to their microbiological effects on bacteria of human health
concern. Fed Reg. 2003;68:61221.
- Butaye P, Devriese LA, Haesebrouck F. Differences
in antibiotic resistance patterns of Enterococcus faecalis and
Enterococcus faecium strains isolated from farm and pet animals.
Antimicrob Agents Chemother. 2001;45:1374–8.
- Lanz R, Kuhnert P, Boerlin P. Antimicrobial
resistance and resistance gene determinants in clinical Escherichia
coli from different animal species in Switzerland. Vet Microbiol.
2003;91:73–84.
- Simjee S, White DG, McDermott PF, Wagner DD, Zervos MJ, Donabedian
SM, et al. Characterization
of Tn1546 in vancomycin-resistant Enterococcus faecium isolated
from canine urinary tract infections: evidence of gene exchange between
human and animal enterococci. J Clin Microbiol. 2002;40:4659–65.
- van Belkun A, van den Braak N, Thomassen R, Verbrugh H, Endtz H. Vancomycin-resistant
enterococci in cats and dogs. Lancet. 1996;348:1038–9.
- Rodrigues J, Thomazini CM, Lopes CA, Dantas LO. Concurrent
infection in a dog and colonization in a child with a human enteropathogenic
Escherichia coli clone. J Clin Microbiol. 2004;42:1388–9.
- Damborg P, Olsen KE, Moller, Nielsen E, Guardabassi L. Occurrence
of Campylobacter jejuni in pets living with human patients infected
with C. jejuni. J Clin Microbiol. 2004;42:1363–4.
- Guardabassi L, Loeber ME, Jacobson A. Transmission
of multiple antimicrobial-resistant Staphylococcus intermedius between
dogs affected by deep pyoderma and their owners. Vet Microbiol.
2004;98:23–7.
- Nyt fra Danmarks Statistik: No. 499. Titel, Denmark: Familiernes Kæledyr
(publication in Danish); 2000.
Suggested citation
for this article:
Heuer OE, Jensen VF,
Hammerum AM. Antimicrobial drug consumption in companion animals [letter].
Emerg Infect Dis [serial on the Internet]. 2005 Feb [date cited]. Available
from http://www.cdc.gov/ncidod/EID/vol11no02/04-0827.htm
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