Infection prevention-how can we prevent transmission of community-onset methicillin-resistant Staphylococcus aureus?

Tracking Antimicrobial Resistant Organisms Timely: a workflow validation study for successive core-genome SNP-based nosocomial transmission analysis

Background and Objectives

Effective infection prevention and control (IPC) interventions in hospitals require timely information to determine the potential transmission of antimicrobial-resistant (AMR) organisms. We proposed and developed a successive core-genome SNP (cgSNP)-based phylogenetic analysis workflow, 'Tracking Antimicrobial Resistant Organisms Timely' (TAROT), using the Oxford Nanopore Technologies (ONT) sequencer for MRSA, and compared the results with those obtained using the Illumina sequencer.

Methods

We have developed a TAROT workflow for successive phylogenetic analysis using ONT data. We sequenced 34 MRSA strains isolated from Toho University Omori Medical Center using MinION (ONT) and MiSeq (Illumina). Each strain's ONT data were inputted into TAROT (TAROT-ONT), and successive cgSNP-based phylogenetic analyses were conducted. Illumina data were processed with a batched cgSNP-based phylogenetic analysis. Assembly-based analysis identified AMR genes, AMR mutations and virulence genes.

Results

MinION generated an average sequence depth of 262× for the ST8 reference genome within 3 h. TAROT-ONT successively generated 11 phylogenetic trees for 14 ST8 strains, 7 trees for 10 ST1 strains and 2 trees for 5 ST5 strains. Highly suspected transmission pairs (pairwise cgSNP< 5) were detected in trees #6 through #11 for ST8, trees #3, #5 and #7 for ST1, and tree #2 for ST5. Differences in pairwise cgSNP value between TAROT-ONT and Illumina ranged from zero to two within pairs with fewer than 20 cgSNPs using Illumina. TAROT-ONT bioinformatic analysis for each strain required 5-42 min. The identification of AMR genes, mutations and virulence genes showed high concordance between ONT and Illumina.

Conclusions

TAROT-ONT can facilitate effective IPC intervention for MRSA nosocomial transmissions by providing timely feedback through successive phylogenetic analyses based on cgSNPs.

Recurrence of skin and soft tissue infections: identifying risk factors and treatment strategies

PURPOSE OF REVIEW

Recurrent skin and soft tissue infections (RSSTIs) are challenging for the clinicians due to morbidity and healthcare-related costs. Here, we review updates on risk factors and management.

RECENT FINDINGS

RSSTIs rates range between 7 and 45%. Local and systemic conditions can favour RSSTIs, with comorbidities such as obesity, diabetes, cancer and immunosuppressive disease becoming increasingly relevant. Streptococcus spp . and Staphylococcus aures (including methicillin resistant, MRSA) are the leading causative pathogens of RSSTIs, but also Gram-negative bacteria and polymicrobial infection should be considered. To prevent recurrences, treatment of underlying predisposing factor, complete source control and appropriate antibiotic therapy are crucial. Antibiotic prophylaxis for recurrent erysipelas and decolonization for MRSA carriers demonstrated some advantages, but also long-term loss of efficacy and possible adverse effects. Clinical score and patients risk stratification could be useful tools to target prophylaxis and decolonization strategies. To reduce hospitalization rates and costs, outpatient oral and parenteral antibiotic therapy (OPAT) and long-acting antibiotics are being implemented.

SUMMARY

Management of RSSTIs requires both preventive interventions on modifiable risk factors and pharmacological strategies, with a patient tailored approach.

A 14-amino acid cationic peptide Bolespleenin334-347 from the marine fish mudskipper Boleophthalmus pectinirostris exhibiting potent antimicrobial activity and therapeutic potential

Antimicrobial peptides (AMPs) are an important component of innate immunity in both vertebrates and invertebrates, and some of the unique characteristics of AMPs are usually associated with their living environment. The marine fish, mudskipper Boleophthalmus pectinirostris, usually live amphibiously in intertidal environments that are quite different from other fish species, which would be an exceptional source of new AMPs. In the study, an AMP named Bolespleenin334-347 was identified, which was a truncated peptide derived from a new functional gene found in B. pectinirostris, that was up-regulated in response to bacterial challenge. Bolespleenin334-347 had only 14 amino acid residues, including five consecutive arginine residues. It was found that the peptide had broad-spectrum antibacterial activity, good thermal stability and sodium ion tolerance. Bolespleenin334-347 killed Acinetobacter baumannii and Staphylococcus aureus by disrupting the structural integrity of the bacterial membrane, leading to leakage of the cellular contents, and inducing accumulation of bacterial endogenous reactive oxygen species (ROS). In addition, Bolespleenin334-347 effectively inhibited biofilm formation of A. baumannii and S. aureus and long-term treatment did not lead to the development of resistance. Importantly, Bolespleenin334-347 maintained stable activity against clinically multi-drug resistant bacterial strains. In addition, it was noteworthy that Bolespleenin334-347 showed superior efficacy to LL-37 and vancomycin in a constructed mouse model of MRSA-induced superficial skin infections, as evidenced by a significant reduction in bacterial load and more favorable wound healing. This study provides an effective antimicrobial agent for topical skin infections with potential therapeutic efficacy for infections with drug-resistant bacteria, including MRSA.