Antimicrobial resistance in equine faecal Escherichia coli isolates from North West England

Table 3 Summary of results showing the identification and distribution of antibiotic resistance genes in E. coli isolates from equine faecal samples taken from hospital and livery premises.

*Antibiotic(No. of resistant* *isolates investigated)*	*Source and number(N) of isolates*	*Identified by PCR*	*Not identified by* *PCR*	*Antibiotic resistance gene composition tested by PCR (details in table legend)*
AMP (191)	Hospital n = 177 Livery n = 14	169 5	8 9	TEM & SHV β-lactamase genes
CHL (102)	Hospital n = 97 Livery n = 5	75 0	22 5	*catI* catII catIII cmlA
TET (198)	Hospital n = 177 Livery n = 21	154 18	23 3	*tetB tetA* tetC tetD tetE tetG
TRI (279)	Hospital n = 209 Livery n = 70	195 65	14 5	*dfrA1 dfrA17 dfrA12 dfrA9* dfrA7, dfrA13

All genes listed were tested by PCR amplification using gene-specific primer pairs listed in Table 1. Genes positively identified by PCR are shown in bold, and are listed according to their frequency of occurrence within each resistance group: AMP, TEM lactamase genes 91%, SHV β-lactamase genes 0.6%; CHL, catI 73.5%; TET, tetB 71%, tetA 18%,tetA+B 11%; TRI, dfrA1 40.3%, dfrA17 28%, dfrA12 17.3%, dfrA9 0.3%. Those genes failed to give rise to detectable levels of PCR product are listed in normal type.
Abbreviations: AMP, ampicillin; CHL, chloramphenicol; TET, tetracycline; TRI, trimethoprim

ISSN: 1476-0711