Greg Wideman from Southwest Ontario Veterinary Services, Tulathromycin Treatment At Birth Had No Negative Effect On Piglet Microbiota or ARGs

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There continues  to be  a  level  of  concern about  the  effects  of  prudent  antimicrobial use  in  livestock  on  the  development  of antimicrobial  resistance  in  both  pigs  and people.  It  is  important  to  understand  the  extent by which  antimicrobial  interventions  affect  the  pig’s resident   microbiota,   and   their   accompanying antimicrobial  resistance  genes  (ARGs).  While  the antimicrobial resistance profiles of swine pathogens are reasonably well understood there is less known about  the  ARGs  associated  with  the  developing gastrointestinal  microbiota.  These  independent  US researchers  wanted  to  assess  the  impact  of a tulathromycin    (TUL)    (Draxxin)    preventive treatment  given  at  birth  on  the  developmental  of fecal   microbiota   and   their   accompanying antimicrobial  resistome  in  pre-weaned  piglets. Sixteen  litters  were  given  one  of  two  treatments [control  group  (CONT;  saline  1cc  IM)  and  TUL group  (TUL;  2.5  mg/kg  IM)]  directly  after  birth. Shotgun  metagenomic  sequencing  was  performed on  the  extracted  bacterial  DNA,  and  the  fecal microbiota structure and abundance of ARGs were assessed. Across  all  fecal  samples,  a  total  of  127  ARGs related  to  19  different  classes  of  antibiotics  were identified  in  the  microbiota.  The  majority  of identified   ARGs   were   observed   in   both experimental  groups  and  at  all-time  points.  The magnitude  and  extent  of  differences  in  microbial composition  and  abundance  of  ARGs  between  the TUL   and   CONT   groups   were   statistically insignificant.  However,  both  fecal  microbiota composition   and   ARGs   abundance   changed significantly between different sampling days as the pigs matured.

Take Home Message

In  this  study,  a  preventive  treatment  with tulathromycin  at birth  had  no  measurable  effect on  fecal  microbiota  structure  or  the  number  of antimicrobial  resistance  genes  (ARGs)  in  pre-weaned piglets.

The researchers hypothesized that the negligible effect on the microbiota may be associated with the   rapid   absorption   and   distribution   of tulathromycin (TUL) from the injection site and transfer to the target tissues and in particular the respiratory tract.

Even  though  there  is  no  evidence  of  a  negative effect associated with a preventive treatment with tulathromycin  it  is  important  to  recognize  that this  may  not  necessarily  be  true  of  other antimicrobial treatments.

Submitted by Greg Wideman, DVM

Ref: Zeineldin  MM,  Megahed  A,  Blair  B,  Burton  B,  Aldridge  B,  Lowe J.Negligible  Impact  of  Perinatal  Tulathromycin  Metaphylaxis  on  the Developmental  Dynamics  of  Fecal  Microbiota  and  Their  Accompanying Antimicrobial Resistome in Piglets. Front Microbiol. 2019 Apr 5;10:726. doi: 10.3389/fmicb.2019.00726. eCollection 2019

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