Methicillin-Resistant Staphylococcus aureus Endocarditis from a Diabetic Foot Ulcer Understanding and Mitigating the Risk

Distant metastatic foci of infection in adult patients with diabetic foot - not as rare as we think?: case series and review of the literature

BACKGROUND

Diabetic foot is one of the common complications of diabetes mellitus. We report clinical and microbiological characteristics and outcomes of cases with distant metastatic foci of infection arising from diabetic foot.

METHODS

Retrospective review of adult patients with diabetic foot infection or diabetic foot ulcer who demonstrated distant metastatic foci of infection between August 2017 and December 2019. We performed a literature search of similar cases published until June 2020.

RESULTS

Twelve patients with diabetic foot infection or diabetic foot ulcer with distant metastatic foci of infection were identified. The median age of patients was 67.5 years (range 60.5-73.5 years) and 11 males. The most common distant metastatic foci of infection included endocarditis (n = 7) followed by septic arthritis (n = 3) and spine infections (n = 2). Five patients had multiple site and organ involvement. Staphylococcus aureus was the only organism isolated from blood (n = 11), diabetic foot (n = 7), and metastatic foci (n = 8) sources. Three patients died and three had a relapse of distant metastatic foci of infection. Thirty-eight cases were identified in the literature with similar characteristics.

CONCLUSIONS

Prevalence of distant metastatic foci of infection in adult patients with diabetic foot and burden of illness, in terms of mortality, morbidity, and length of hospital stay, appears to be underreported in the literature. A large prospective study is needed to assess the true prevalence of complications, associated risk factors, outcomes and prognostic factors.

Immunization with a Bacterial Lipoprotein Establishes an Immuno-Protective Response with Upregulation of Effector CD4+ T Cells and Neutrophils Against Methicillin-Resistant Staphylococcus aureus Infection

Staphylococcus aureus (S. aureus) is a commensal bacterium in the human body; however, the bacterium frequently generates serious inflammation and infectious diseases. Some strains of S. aureus, such as methicillin-resistant Staphylococcus aureus (MRSA), are still a serious problem in public health facilities. Thus, an effective protection strategy is eagerly expected for the prevention and cure of MRSA infection. Here, we report that a specific fraction of an S. aureus lipoprotein (SA-LP) established a protective response against MRSA infection. The fractionated S. aureus lipoprotein SA-LP-F2, which is contained in 30–50 kDa of crude S. aureus lipoprotein (SA-LP-C), effectively activated dendritic cells (DCs) and the SA-LP-F2-pulsed DCs generated IFN-γ+CD4+ T (Th1) and IL-17A+CD4+ T (Th17) cells by in vitro antigen presentation. The SA-LP-F2 immunization upregulated the Th1 and Th17 populations so that MRSA colonization on the skin was suppressed during the challenge phase with MRSA. By following the effector T cell upregulation, the neutrophil function, which was a substantial effector cell against MRSA, was also enhanced in the SA-LP-F2-immunized mice. Finally, we found that the protective effect of SA-LP-F2 immunization was maintained for at least 90 days because the immunized mice continued to show a protective response during the MRSA challenge period. In the MRSA challenge, reactivated Th1 and Th17 populations were maintained in the SA-LP-F2-immunized mice as compared to naive mice. In addition, the neutrophil population was also upregulated in the mice. The memory CD4+ T cell (central memory T; T_CM and effector memory T; T_EM) population was established by SA-LP-F2 immunization and was maintained at higher levels than usual. Taken together, our findings may provide a breakthrough in the establishment of an immunization strategy against MRSA infection.

Biopolymer K-carrageenan wrapped ZnO nanoparticles as drug delivery vehicles for anti MRSA therapy

Kappa-Carrageenan wrapped ZnO nanoparticles (KC-ZnO NPs) was synthesized, physico-chemically characterized and evaluated their biocompatibility and antimicrobial therapy against MRSA. XRD showed the highly crystalline and hexagonal phase structure of ZnO NPs. FETEM confirmed the spherical and hexagonal shaped particle with the mean size of 97.03 ± 9.05 nm. The synthesized KC-ZnO NPs exhibited significant antibacterial activity against MRSA. The biofilm growth of MRSA was greatly inhibited at 100 μg/ml as observed through live and dead cell assay. KC-ZnO NPs have shown invitro anti-inflammatory activity (82%) at 500 μg/ml. KC-ZnO NPs was non-toxic to NIH3T3 mouse embryonic fibroblasts cell lines. Further, no apoptotic and necrotic mediated death in NIH3T3 mouse embryonic fibroblasts cells were noticed by flow cytometric analysis. KC-ZnO NPs have good biocompatibility as recorded by the least hemolysis percentage (<3%) up to 100 μg/ml, which is much lesser than the acceptable limit. In addition, ecosafety analysis has shown that KC-ZnO NPs and kappa karrageenan (0-500 μg/ml) caused no mortality of A. salina after 48 h. However, bare zinc acetate has shown 35% mortality of A. salina after 48 h. The results conclude that KC-ZnO NPs could be a novel antibacterial therapy for the treatment of MRSA associated infectious.