Sequence Analysis and Preliminary X-ray Crystallographic Analysis of an Acetylesterase (LgEstI) from Lactococcus garvieae

A gene encoding LgEstI was cloned from a bacterial fish pathogen, Lactococcus garvieae. Sequence and bioinformatic analysis revealed that LgEstI is close to the acetyl esterase family and had maximum similarity to a hydrolase (UniProt: Q5UQ83) from Acanthamoeba polyphaga mimivirus (APMV). Here, we present the results of LgEstI overexpression and purification, and its preliminary X-ray crystallographic analysis. The wild-type LgEstI protein was overexpressed in Escherichia coli, and its enzymatic activity was tested using p-nitrophenyl of varying lengths. LgEstI protein exhibited higher esterase activity toward p-nitrophenyl acetate. To better understand the mechanism underlying LgEstI activity and subject it to protein engineering, we determined the high-resolution crystal structure of LgEstI. First, the wild-type LgEstI protein was crystallized in 0.1 M Tris-HCl buffer (pH 7.1), 0.2 M calcium acetate hydrate, and 19% (w/v) PEG 3000, and the native X-ray diffraction dataset was collected up to 2.0 Å resolution. The crystal structure was successfully determined using a molecular replacement method, and structure refinement and model building are underway. The upcoming complete structural information of LgEstI may elucidate the substrate-binding mechanism and provide novel strategies for subjecting LgEstI to protein engineering.

Fasciitis by Lactococcus garvieae on an immunosuppressed patient by Diabetes Mellitus

Lactococcus garvieae, a gram-positive anaerobe facultative coccus, is a well-known pathogen in the aquaculture and cattle sector, being extremely rare for human beings. There are some case reports of infections caused by this microorganism, however, there are no fasciitis cases up to date. This is a case of a 24-year-old patient with uncontrolled diabetes mellitus and previous COVID-19 pneumonia without sequelae, admitted to the emergency room for a case compatible with fasciitis. Three cultures for L. garvieae were obtained from surgical debridement and microbiological studies were performed using automated VITEK-2 equipment. No posterior complications were documented. The patient went through a skin graft with a favorable response without evidence of clinical relapse.

Genome Sequences of Lactococcus garvieae and Lactococcus petauri Strains Isolated from Traditional Montenegrin Brine Cheeses

Lactococcus garvieae and Lactococcus petauri cause lactococcosis in fish. Both species have also been isolated from various food products and are considered emerging zoonotic pathogens. Here, we report the genomes of L. garvieae INF126 and L. petauri INF110, obtained from traditional Montenegrin brine cheeses.

Lactococcus garvieae: An Uncommon Human Pathogen Causing Infective Endocarditis in a Valve-in-Valve Transcatheter Aortic Valve Replacement

Lactococcus garvieae is a fish pathogen and an uncommon cause of human infections. There is a growing body of evidence showing its potential for causing endocarditis especially in those with prior valve surgery. In this case report, we present what we believe is the first case of endocarditis by L. garvieae affecting a valve-in-valve transcatheter aortic valve replacement that was successfully treated. Specific guidelines for the management of these patients are lacking. Our experience can contribute to the current knowledge regarding this life-threatening infection as well as to the future care of these patients. We aim to emphasize that despite not being recognized as a typical endocarditis microorganism by the Duke Criteria, the possibility of endocarditis needs to be highly entertained in patients with L. garvieae bacteremia, especially when prosthetic valves are present. Consequently, clinicians should pursue further this diagnosis with transesophageal echocardiogram and/or alternative imaging modalities (e.g., PET-CT scan and MRI) regardless of an initial negative transthoracic echocardiogram. Reaching a diagnosis of L. garvieae endocarditis led us to the decision of prolonging the antibiotic course for 6 weeks with successful results. Ultimately, surgery was not required owing to the absence of prosthetic aortic valve dysfunction and paravalvular extension of the infection.