PFGE-analysis of ESBL-producing <i>E</i>. <i>coli</i> isolated from specimens obtained from horses at hospital admission.

<p>Dendrogram (percent similarity) showing DNA restriction pattern after digestion with XbaI for 41 <i>E</i>. <i>coli</i> isolated from horses directly at hospital admission. PFGE analysis by use of bionumerics® (unweighted-pair group method using average linkages), dice coefficient, 1.5% tolerance and 0.5% optimization indicated limited clonal relatedness. Antimicrobial susceptibility testing results VITEK®2 system (BioMérieux, Germany) for all ESBL-producing isolates revealed that multi-drug resistance is common. Plain numbers = susceptible-, bold = resistant-, underlined = intermediate phenotype. Abbreviations: Horse ID, individual number for each enrolled equine patient; OW, horse of the open wound group; C, horse of the colic group; IMT ID, strain collection number at IMT; ST, sequence type; AMP, ampicillin; AMC, amoxicillin-clavulanic acid; PIP, piperacillin; CFL, cephalexin; CPD, cefpodoxim; CEF, cephalexin; AN, amikacin; GM, gentamicin; ENR, enrofloxacin; MAR, marbofloxacin; TET, tetracycline; FM, nitrofurantoin; C, chloramphenicol; SXT, trimethoprim-sulfamethoxazole.</p

Results from Gram-negative indicator pathogen screening of equine patients at hospital admission.

<p>Results from Gram-negative indicator pathogen screening of equine patients at hospital admission.</p

Extended-spectrum beta-lactamase (ESBL)-producing <i>Escherichia coli</i> and <i>Acinetobacter baumannii</i> among horses entering a veterinary teaching hospital: The contemporary "Trojan Horse"

<div><p>Pathogens frequently associated with multi-drug resistant (MDR) phenotypes, including extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) and <i>Acinetobacter baumannii</i> isolated from horses admitted to horse clinics, pose a risk for animal patients and personnel in horse clinics. To estimate current rates of colonization, a total of 341 equine patients were screened for carriage of zoonotic indicator pathogens at hospital admission. Horses showing clinical signs associated with colic (n = 233) or open wounds (n = 108) were selected for microbiological examination of nostril swabs, faecal samples and wound swabs taken from the open wound group. The results showed alarming carriage rates of Gram-negative MDR pathogens in equine patients: 10.7% (34 of 318) of validated faecal specimens were positive for ESBL-E (94%: ESBL-producing <i>Escherichia coli</i>), with recorded rates of 10.5% for the colic and 11% for the open wound group. 92.7% of the ESBL-producing <i>E</i>. <i>coli</i> were phenotypically resistant to three or more classes of antimicrobials. <i>A</i>. <i>baumannii</i> was rarely detected (0.9%), and all faecal samples investigated were negative for <i>Salmonella</i>, both directly and after two enrichment steps. Screening results for the equine nostril swabs showed detection rates for ESBL-E of 3.4% among colic patients and 0.9% in the open wound group, with an average rate of 2.6% (9/340) for both indications. For all 41 ESBL-producing <i>E</i>. <i>coli</i> isolated, a broad heterogeneity was revealed using pulsed-field gel electrophoresis (PFGE) patterns and whole genome sequencing (WGS) -analysis. However, a predominance of sequence type complex (STC)10 and STC1250 was observed, including several novel STs. The most common genes associated with ESBL-production were identified as <i>bla</i>_CTX-M-1 (31/41; 75.6%) and <i>bla</i>_SHV-12 (24.4%).</p><p>The results of this study reveal a disturbingly large fraction of multi-drug resistant and ESBL-producing <i>E</i>. <i>coli</i> among equine patients, posing a clear threat to established hygiene management systems and work-place safety of veterinary staff in horse clinics.</p></div

Antibiotic susceptibility testing results for <i>Acinetobacter baumannii</i> isolated from horses.

<p>Antibiotic susceptibility testing results for <i>Acinetobacter baumannii</i> isolated from horses.</p

Maximum likelihood tree based on the maximum common genome (MCG).

<p>Maximum likelihood tree showing the relatedness of the strains based on their genome sequences together with their corresponding Sequence Type Complex (STC). The occurrences and distribution of <i>bla</i>_CTX-M-1, <i>bla</i>_CTX-M-24 and <i>bla</i>_SHV-12 in ESBL-producing <i>E</i>. <i>coli</i> obtained from horses at hospital admission is marked with black squares. While a general broad genomic heterogenicity is obvious, two genetic backgrounds are dominating (STC10 and STC1250).</p