Discussion on Research Summary: Ceftiofur resistance in Salmonella a growing problem
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Robert N. Oglesby DVM
Moderator
Username: dro
Post Number: 18646
Registered: 1-1997
| | Posted on Wednesday, Jun 6, 2007 - 10:40 am: |   |
Horseadvice.com has a strong editorial policy counseling against the indiscriminate use of antibiotics. Here is a new problem we see growing with cetiofur, what many of you may know best as Naxcel. I have seen the routine use of this antibiotic against uncomplicated upper respiratory infections in horses and cringe every time I do. First the vast majority are viruses and will get well no quicker with the use of an antibiotic, and they almost always do get well so use of the antibiotic becomes "justified". Second, even when it is bacterial, most often these are streptococcal organisms that remain very sensitive to procaine penicillin.
It makes great sense to target the strep with penicillin and preserve the efficacy of this excellent wide spectrum antibiotic for other infections resistant to penicillin or TMP-SMZ. As the following summary outlines, it is not just your horse's health you are protecting but yours and your children too.
DrO
Int J Antimicrob Agents. 2007 May 23; Prevalence, distribution and characterisation of ceftiofur resistance in Salmonella enterica isolated from animals in the USA from 1999 to 2003.
Frye JG, Fedorka-Cray PJ.
Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. Department of Agriculture, Agriculture Research Service, Richard B. Russell Research Center, 950 College Station Road, Athens, GA 30605, USA.
Third-generation cephalosporin (3GC) antimicrobials are the drugs of choice for treatment of salmonellosis in children. Salmonella isolated in the USA are assayed by the National Antimicrobial Resistance Monitoring System (NARMS) for resistance to antimicrobials including first-, second- and third-generation cephalosporins. >From 1999 to 2003, 34,411 Salmonella were isolated from animals in the USA, of which 10.9% were found to be resistant to ceftiofur, a 3GC used in animals, whilst only 0.3% were resistant to ceftriaxone, a 3GC used in human medicine. Ceftiofur resistance rose from 4.0% in 1999 to 18.8% in 2003. Isolates from diagnostic laboratories had higher levels of resistance (18.5%), whereas levels in isolates from on-farm (3.4%) and slaughter (7.1%) sources were lower. Animals with a higher than average proportion of resistant Salmonella included cattle (17.6%), horses (19.2%) and dogs (20.8%). Levels in turkeys (6.8%), chickens (7.1%), eggs (3.6%) and swine (4.6%) were lower. Resistance varied between Salmonella serotypes. A few serotypes had significantly high levels, e.g. S. Newport was 70.4% ceftiofur resistant. Resistance was predominantly associated with bla(CMY-2)-encoding plasmids. These data suggest that the acquisition of resistance plasmids and the spread of specific serotypes harbouring these plasmids are driving the observed resistance to ceftiofur in Salmonella animal isolates. |
