Home
Resources
Publications
In Vitro Antimicrobial Activity Against Equine Lawsonia Intracellularis Strains

In Vitro Antimicrobial Activity Against Equine Lawsonia Intracellularis Strains

C E R Pereira, T P Resende, E Vasquez, L Marshall-Lund, R M C Guedes, C J Gebhart

Equine Vet J. 2019 Sep;51(5):665-668.

PMID: 30629755

Abstract:

Background:
Lawsonia intracellularis is the aetiologic agent of equine proliferative enteropathy (EPE). This emerging equine disease leads to diarrhoea, severe protein loss and can result in death if left untreated. Timely treatment of EPE is critical for recovery from the disease, and hence, information about antimicrobial susceptibilities of equine L. intracellularis strains to antimicrobials used in horses is needed. However, L. intracellularis is an obligate intracellular bacterium and so must be isolated and maintained in cell cultures.
Objectives:
To determine the in vitro antimicrobial activity of 14 antimicrobials against two equine L. intracellularis strains.
Study design:
In vitro experiments.
Methods:
This study was designed to compare the relative in vitro susceptibility of each strain of L. intracellularis to different antimicrobials which included metronidazole, minocycline hydrochloride, erythromycin, cephalothin sodium salt, combination (4:1) of sulfamethazine and trimethoprim, chloramphenicol, rifampicin, penicillin, ampicillin, doxycycline hydrochloride, cefazolin sodium salt, clarithromycin, ceftiofur hydrochloride and enrofloxacin. The minimum inhibitory concentration (MIC) was based on intracellular and extracellular activity that inhibited 99% of L. intracellularis growth in cell culture as compared to the antimicrobial-free control.
Results:
Rifampicin and clarithromycin were the most active antimicrobials against the two L. intracellularis strains tested, with MICs of ≤0.125 when tested both intracellularly and extracellularly. Doxycycline, minocycline, erythromycin, chloramphenicol and enrofloxacin showed intermediate to high activity, and activity was generally higher when evaluating intracellular activity. Sulfamethazine/trimethoprim showed variable results. Ampicillin, penicillin and metronidazole had low to moderate activity. L. intracellularis was resistant to cefazolin, cephalothin and ceftiofur in in vitro conditions.
Main limitations:
Only two equine isolates of L. intracellularis were available for this study due to the difficulty in isolating this obligate intracellular species from intestinal samples.
Conclusions:
This is the first report of antimicrobial susceptibility patterns for equine L. intracellularis strains.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP58719	Cephalothin sodium		58-71-9	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: