Molecular epidemiology ofEnterococcus cecorumisolates recovered from enterococcal spondylitis outbreaks in the southeastern United States

Abstract

Enterococcus cecorum, a normal intestinal inhabitant, is increasingly responsible for outbreaks of arthritis and osteomyelitis in chickens worldwide. Enterococcal spondylitis (ES) is a specific manifestation of E. cecorum-associated disease in which increased flock morbidity and mortality result from chronic infection involving the free thoracic vertebra. In this study the genetic relatedness and antimicrobial resistance of isolates recovered from ES-affected flocks in the southeastern United States were determined. ES outbreaks from 2007 to 2011 were investigated in North Carolina (15 flocks, 13 farms, four integrators), South Carolina (one flock, one farm, one integrator) and Alabama (six flocks, six farms, one integrator). From these 22 epidemiologically distinct outbreaks, 326 isolates of E. cecorum were recovered. Isolates from spinal lesions and caeca of affected birds (cases) and caeca of unaffected birds (controls) were genotyped using pulsed-field gel electrophoresis; phenotyped using both GenIII MicroPlate TM (Biolog; Hayward, CA, USA) microbial identification plates and antimicrobial sensitivity testing; and compared with each other. Isolates from spinal lesions were incapable of mannitol metabolism and the majority of these isolates were genetically clonal. In contrast, caecal isolates from control birds varied in their ability to metabolize mannitol and were genetically diverse. Isolates from both case and control birds had high levels of antimicrobial resistance. These findings indicate that the increase in E. cecorum-associated disease in the southeast United States is due to the emergence of new clones with increased pathogenicity and multidrug resistance.

Antimicrobial resistance, virulence determinants and genetic profiles of clinical and nonclinical E nterococcus cecorum from poultry

“…cecorum from clinical and nonclinical birds has not been previously described, antimicrobial resistance results from other studies indicated that the use of antimicrobials in poultry may have selected for isolates that are resistant to a broader range of antimicrobials than the nonpathogenic isolates and those strains may also harbour more resistance genes (Borst et al . ). This was not evident in this study as no significant difference in MDR between Ent.…”

“…; Borst et al . ; Wijetunge et al . ), cross‐clustering of some of the isolates in this study suggests that there are shared genetic attributes among some of the isolates and not all isolates can be distinguished as clinical and nonclinical based on this method.…”

“…; Borst et al . ); however, additional studies are needed to fully characterize antimicrobial resistance differences among clinical and nonclinical isolates (Agunos et al . ).…”

Culture methods impact recovery of antibiotic-resistant Enterococci includingEnterococcus cecorumfrom pre- and postharvest chicken

“…Both pathogenic and commensal EC demonstrated decreased susceptibility to multiple antimicrobials, including enrofloxacin, novobiocin, spectinomycin, streptomycin, sulfathiazole, sulfadimethoxine and tylosin tartrate (Borst et al . ).…”

Disease surveillance in England and Wales, December 2016

“…Enterococci are normal inhabitants of the intestinal flora of poultry, but are increasingly recognised as causing a range of diseases, such as those described in this case. The possibility has been reported of spinal lesions being associated with newly emerging clones of E cecorum with increased pathogenicity (Borst and others 2012). …”