Severe Skin Infections Due to Serratia marcescens: A Case Associated With Cat Scratch in a Patient With Liver Disease and Review of the Literature

Molecular insights into flavone-mediated quorum sensing interference: A novel strategy against Serratiamarcescens biofilm-induced antibiotic resistance"

Antibiotic resistance poses a significant challenge in modern medicine, urging the exploration of innovative approaches to combat bacterial infections. Biofilms, complex bacterial communities encased in a protective matrix, contribute to resistance by impeding antibiotic efficacy and promoting genetic exchange. Understanding biofilm dynamics is crucial for developing effective antimicrobial therapies against antibiotic resistance. This study explores the potential of flavone to combat biofilm-induced antibiotic resistance by employing in-vitro biochemical, cell biology, and Insilico (MD simulation), approaches. Flavone exhibited potent antibacterial effects with a low minimum inhibitory concentration by inducing intracellular reactive oxygen species. Flavones further inhibited the formation of biofilms by 50-60 % and disrupted the pre-formed biofilms by reducing the extracellular polysaccharide substance protective layer formed on the biofilm by 80 %. Quorum sensing (QS) plays a crucial role in bacterial pathogenicity and flavone significantly attenuated the production of QS-induced virulence factors like urease, protease, lipase, hemolysin and prodigiosin pigment in a dose-dependent manner. Further Insilico molecular docking studies along with molecular dynamic simulations run for 100 ns proved the stable binding affinity of flavone with QS-specific proteins which are crucial for biofilm formation. This study demonstrates the therapeutic potential of flavone to target QS-signaling pathway to combat S.marcescens biofilms.

Bacterial community profiles within the water samples of leptospirosis outbreak areas

Background

Leptospirosis is a water-related zoonotic disease. The disease is primarily transmitted from animals to humans through pathogenic Leptospira bacteria in contaminated water and soil. Rivers have a critical role in Leptospira transmissions, while co-infection potentials with other waterborne bacteria might increase the severity and death risk of the disease.

Methods

The water samples evaluated in this study were collected from four recreational forest rivers, Sungai Congkak, Sungai Lopo, Hulu Perdik, and Gunung Nuang. The samples were subjected to next-generation sequencing (NGS) for the 16S rRNA and in-depth metagenomic analysis of the bacterial communities.

Results

The water samples recorded various bacterial diversity. The samples from the Hulu Perdik and Sungai Lopo downstream sampling sites had a more significant diversity, followed by Sungai Congkak. Conversely, the upstream samples from Gunung Nuang exhibited the lowest bacterial diversity. Proteobacteria, Firmicutes, and Acidobacteria were the dominant phyla detected in downstream areas. Potential pathogenic bacteria belonging to the genera Burkholderiales and Serratia were also identified, raising concerns about co-infection possibilities. Nevertheless, Leptospira pathogenic bacteria were absent from all sites, which is attributable to its limited persistence. The bacteria might also be washed to other locations, contributing to the reduced environmental bacterial load.

Conclusion

The present study established the presence of pathogenic bacteria in the river ecosystems assessed. The findings offer valuable insights for designing strategies for preventing pathogenic bacteria environmental contamination and managing leptospirosis co-infections with other human diseases. Furthermore, closely monitoring water sample compositions with diverse approaches, including sentinel programs, wastewater-based epidemiology, and clinical surveillance, enables disease transmission and outbreak early detections. The data also provides valuable information for suitable treatments and long-term strategies for combating infectious diseases.

Identification and Characterization of Non-protein Coding RNA Homologs in Serratia Marcescens by Comparative Transcriptomics

The Serratia marcescens is a Gram-negative bacterium from the Enterobacteriaceae family. Recently, S. marcescens have evolved to become a versatile and opportunistic pathogen. Furthermore, this bacterium is also a multi-drug resistant pathogen exhibiting Extended-Spectrum Beta-Lactamases (ESBL) activity. This bacterium is highly associated with infections in healthcare settings and even leads to death. Hence, an advanced approach based on non-protein coding RNA (npcRNA) of S. marcescens was considered in this study to understand its regulatory roles in virulence, pathogenesis, and the differential expression of these transcripts in various growth phases of the bacterium. BLASTn search of known npcRNAs from Salmonella typhi, Escherichia coli, and Yersinia pestis against S. marcescens was performed to discover putative conserved homologous transcripts. The novelty of these putative homologous npcRNAs was verified by screening through the Rfam web tool. The target mRNA for the homologs was predicted via the TargetRNA2 webtool to understand the possible regulatory roles of these transcripts. The npcRNA homologs, which were predicted to regulate virulence target mRNA were assessed for their expression profile at different growth stages via reverse transcription PCR and the band intensity was quantitatively analysed using the Image J tool. The known npcRNA ssrS, from S. typhi showed expression in S. marcescens during three growth stages (lag, log, and stationary). Expression was observed to be high during the lag phase followed by a similarly low-level expression during the log and no expression during stationary phase. This ssrS homolog was predicted to regulate mRNA that encodes for protein FliR, which is associated with virulence. This is a preliminary study that lay the foundation for further elucidation of more virulence-associated npcRNAs that are yet to be discovered from S. marcescens, which can be useful for diagnostics and therapeutic applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01160-y.

Serratia marcescens causing recurrent superficial skin infections in an immunosuppressed patient

Serratia marcescens is a gram-negative bacterium found commonly in water and soil. Initially thought to be non-pathogenic, it is now recognised as an important cause of nosocomial and opportunistic infections. Skin infections are rare, but cases of S. marcescens causing ulcers, abscesses and necrotizing fasciitis have been reported. We report an unusual cutaneous presentation of S. marcescens in an immunosuppressed patient. A 77-year-old man under review for non-melanoma skin cancer in the context of a previous cardiac transplant, presented with an asymptomatic scalp eruption. Immunosuppressive medications included ciclosporin 90 mg twice daily (2.5 mg/kg/day) and mycophenolate mofetil 1 g twice daily. Physical examination revealed well-defined annular and polycyclic patches with brownish crusting across his scalp. Bacterial culture demonstrated a heavy growth of Staphylococcus aureus sensitive to flucloxacillin. The patient was treated with 7 days of flucloxacillin 500 mg four times daily. Despite this, the eruption extended. Skin biopsy demonstrated epidermal spongiosis, florid dermal inflammatory cell infiltrate and abundant bacteria and neutrophils in the parakeratotic crust. Fungal stains were negative as was direct immunofluorescence. Repeat culture demonstrated heavy growth of S. marcescens sensitive to ciprofloxacin. The patient was treated with 10 days of oral ciprofloxacin 500 mg twice daily along with 1% hydrogen peroxide cream topically with significant clinical improvement. Microbiological review indicated that a gram-negative organism was present in the initial scalp swab. In addition, S. marcescens had been detected previously on a skin swab from a recent transient eruption on the torso. Further, a heavy growth of a coliform bacillus was demonstrated in a similar eruption on the chest in 2013. It was concluded that the patient was likely colonised with S. marcescens which appeared to have caused recurrent superficial skin infections over several years. We report this case to highlight an unusual clinical presentation of cutaneous S. marcescens infection. This should be considered in the differential diagnosis of skin eruptions in immunocompromised patients. Clinical information detailing a patient's immunosuppressed state must be supplied on microbiology requests to allow accurate interpretation of results, and consideration of organisms which may otherwise be overlooked or considered contaminants.