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Characterization of Multi-Drug Resistant Enterococcus faecalis Isolated from Cephalic Recording Chambers in Research
Stephanie E Woods1, Mia T Lieberman1,2, Francois Lebreton3
1Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
Abstract:
Nonhuman primates are commonly used for cognitive neuroscience research and often surgically implanted with cephalic recording chambers for electrophysiological recording. Aerobic bacterial cultures from 25 macaques identified 72 bacterial isolates, including 15 Enterococcus faecalis isolates. The E. faecalis isolates displayed multi-drug resistant phenotypes, with resistance to ciprofloxacin, enrofloxacin, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, bacitracin, and erythromycin, as well as high-level aminoglycoside resistance. Multi-locus sequence typing showed that most belonged to two E. faecalis sequence types (ST): ST 4 and ST 55. The genomes of three representative isolates were sequenced to identify genes encoding antimicrobial resistances and other traits. Antimicrobial resistance genes identified included aac(6')-aph(2"), aph(3')-III, str, ant(6)-Ia, tetM, tetS, tetL, ermB, bcrABR, cat, and dfrG, and polymorphisms in parC (S80I) and gyrA (S83I) were observed. These isolates also harbored virulence factors including the cytolysin toxin genes in ST 4 isolates, as well as multiple biofilm-associated genes (esp, agg, ace, SrtA, gelE, ebpABC), hyaluronidases (hylA, hylB), and other survival genes (ElrA, tpx). Crystal violet biofilm assays confirmed that ST 4 isolates produced more biofilm than ST 55 isolates. The abundance of antimicrobial resistance and virulence factor genes in the ST 4 isolates likely relates to the loss of CRISPR-cas. This macaque colony represents a unique model for studying E. faecalis infection associated with indwelling devices, and provides an opportunity to understand the basis of persistence of this pathogen in a healthcare setting.
Insights
Multi-drug resistant Enterococcus faecalis, common in macaques with implants, poses infection risks. ST 4 isolates showed more virulence and biofilm, suggesting a model for studying device-associated infections in healthcare settings.
Area of Science:
- Microbiology
- Genomics
- Veterinary Medicine
Background:
- Nonhuman primates are crucial models in cognitive neuroscience, often requiring implanted devices.
- Enterococcus faecalis is a significant opportunistic pathogen, particularly in healthcare settings.
- Understanding antimicrobial resistance and virulence in E. faecalis is critical for infection control.
Purpose of the Study:
- To characterize Enterococcus faecalis isolates from macaques with cephalic recording chambers.
- To identify antimicrobial resistance genes and virulence factors in these isolates.
- To evaluate the potential of this macaque colony as a model for studying device-associated E. faecalis infections.
Main Methods:
- Bacterial cultures from 25 macaques yielded 72 isolates, including 15 Enterococcus faecalis.
- Multi-locus sequence typing (MLST) was used to determine sequence types (ST).
- Whole-genome sequencing and antimicrobial resistance gene identification were performed.
- Crystal violet biofilm assays assessed biofilm formation.
Main Results:
- Fifteen Enterococcus faecalis isolates exhibited multi-drug resistance to common antibiotics.
- Two main sequence types, ST 4 and ST 55, were identified.
- ST 4 isolates possessed more virulence factors (cytolysin, biofilm genes) and formed more biofilm than ST 55.
- Numerous antimicrobial resistance genes (e.g., aac(6")-aph(2"), tetM, ermB) and virulence genes were identified.
Conclusions:
- Macaque E. faecalis isolates harbor significant antimicrobial resistance and virulence traits.
- ST 4 isolates demonstrate enhanced biofilm formation and virulence, potentially linked to CRISPR-cas loss.
- This macaque model offers a valuable platform for studying E. faecalis persistence and device-associated infections.
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