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AgVetLink February 2003

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Antibiotic resistance management

In response to the direction of the Animal Remedies Board (December 1999), the ACVM Group has been refining its regulatory control on antibiotic products used as veterinary medicines. The changes have been made to minimise the likelihood that the use of antibiotics in animals may contribute to the development of antibiotic resistance in human pathogens (i.e. bacteria causing disease in humans).

Progress on review of antibiotic product registrations

It was intended that the registrations for antibiotic products would be reissued with conditions designed to manage the antibiotic resistance problem before the commencement of the ACVM (Transitional Provisions) Regulations 2002. In almost all cases this was achieved. However, there were a few products for which the reissuing of registrations was delayed because of unrelated matters. When the registrations of these few products are updated, all antibiotics of significance to the antibiotic resistance problem will be prescription only medicines.

All antibiotic products will also have a stratified prescription animal remedy (PAR) I level based on the public health significance of the antibiotic. This will introduce additional obligations on the prescribing veterinarian to limit the use of significant antibiotics to cases in which alternative antibiotic are not likely to be effective. The effects of these changes should begin to appear in the 2002 sales statistics.

Antibiotic group	Non-food animals (in kilograms)	Food animals	Total	Unspecified animals	Total 2001	Total 2000
penicillins	265	5161	5426	4997	13747	10423
cephalosporins	15	674	689	150	879	839
aminoglycosides	77	690	767	1355	1692	2122
macrolides/lincosamides	-	6358	6358	243	5293	6601
tetracyclines	42	2168	2210	957	2840	3167
sulphonamides	1380	731	2111	3460	5930	5571
ionophores	-	36215	36215	-	50169	36215
others	46	15176	15222	239	25013	15461
Totals	1825	67173	68998	11401	105563	80399

Sales of antibiotics

Pharmaceutical companies have voluntarily provided sales statistics for the last two years. The collective statistics (in kilograms of active ingredient grouped into antibiotic families) are shown in the table below.

The totals must be considered only indicative because of the variability in calculating and recording quantities by different companies. Therefore, little significance can be attributed to minor differences in totals from year to year.

In addition, actual use relative to kinds of animals treated may be different than reported by the companies because veterinarians may have prescribed antibiotics for a group of animals other than what a company had anticipated. Consequently, the 'unspecified animals' column is based on an undetermined ratio of non-food animals to food animals.

Given the statistical limitations, the table indicates an overall increase in the total sales of antibiotics. However, when the statistics were examined by species of animals treated in either feed or water, there was either no significant change or a decrease in sales of those antibiotics that are assessed as significant for use in humans (e.g. aminoglycosides and macrolides/lincosamides).

The statistics indicate an increase in the sales of antibiotics assessed as not relevant to the potential antibiotic resistance problem (i.e. ionophores, zinc bacitracin and avilamycin). Almost all of the increase in the 'other' antibiotics group relates to an increase in sales of in-feed zinc bacitracin, which the expert panel considered unlikely to contribute to the antibiotic resistance problem.

There were increases in sales of penicillins, cephalosporins and sulphonamides administered by injection. This administration route is considered unlikely to contribute to antibiotic resistance in human pathogens.

It must be noted that the collection of the survey information is still undergoing refinement. Recording and reporting the information is improving. This means that with only two years' data over a period of such marked regulatory and industry change, the variations in amounts must be taken as indicative at best. Analysis of the data is also hampered by variations in animal health challenges from one year to the next. It is expected to take a number of years before this compounding factor can be addressed in any meaningful analysis.

It must also be noted that sales during 2001 were based on the regulatory requirements at the time. The changes in the conditions of registrations that will give effect to:

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