Sphingobacterium spiritivorum septicaemia associated with cellulitis in a patient with Parkinson's disease

Development of a candidate multi-epitope vaccine against Sphingobacterium spiritivorum : Reverse vaccinology and immunoinformatics approach

OBJECTIVES

To develop a candidate vaccine aginst the Sphingobacterium spiritivorum.

METHODS

Since there is currently no vaccine against this pathogen, we employed in-silico methods to extensively explore the outer membrane toxin-producing proteins found specifically in S. spiritivorum to forecast a multi-epitope chimeric vaccine design. This computational study was conducted in Saudi Arabia in 2022 (study design: computational; ethical approval not applicable).

RESULTS

TThe vaccine peptide comprises multiple linear and conformational B-cell epitopes, which have the potential to elicit humoral immunity. Projected B-cell- derived T-cell epitopes for outer membrane proteins are present in the produced protein. The docking and molecular dynamic simulation results indicating that the chimeric vaccine had adequate binding stability with TLR-4. Following the immunological simulation, significant levels of immune cell expression were observed as immunoglobulin (Ig) M and IgG, IgM, IgM1, and IgM2, and independently IgG1 and IgG2.

CONCLUSION

The developed vaccine candidate is suitable for further testing and can assist experimental vaccinologists in developing an effective vaccine against S. spiritivorum.

Microbial landscapes of the rhizosphere soils and roots of Luffa cylindrica plant associated with Meloidogyne incognita

Introduction

The root-knot nematodes (RKN), especially Meloidogyne spp., are globally emerging harmful animals for many agricultural crops.

Methods

To explore microbial agents for biological control of these nematodes, the microbial communities of the rhizosphere soils and roots of sponge gourd (Luffa cylindrica) infected and non-infected by M. incognita nematodes, were investigated using culture-dependent and -independent methods.

Results

Thirty-two culturable bacterial and eight fungal species, along with 10,561 bacterial and 2,427 fungal operational taxonomic units (OTUs), were identified. Nine culturable bacterial species, 955 bacterial and 701 fungal OTUs were shared in both four groups. More culturable bacterial and fungal isolates were detected from the uninfected soils and roots than from the infected soils and roots (except no fungi detected from the uninfected roots), and among all samples, nine bacterial species (Arthrobacter sp., Bacillus sp., Burkholderia ambifaria, Enterobacteriaceae sp., Fictibacillus barbaricus, Microbacterium sp., Micrococcaceae sp., Rhizobiaceae sp., and Serratia sp.) were shared, with Arthrobacter sp. and Bacillus sp. being dominant. Pseudomonas nitroreducens was exclusively present in the infested soils, while Mammaliicoccus sciuri, Microbacterium azadirachtae, and Priestia sp., together with Mucor irregularis, Penicillium sp., P. commune, and Sordariomycetes sp. were found only in the uninfected soils. Cupriavidus metallidurans, Gordonia sp., Streptomyces viridobrunneus, and Terribacillus sp. were only in the uninfected roots while Aspergillus sp. only in infected roots. After M. incognita infestation, 319 bacterial OTUs (such as Chryseobacterium) and 171 fungal OTUs (such as Spizellomyces) were increased in rhizosphere soils, while 181 bacterial OTUs (such as Pasteuria) and 166 fungal OTUs (such as Exophiala) rose their abundance in plant roots. Meanwhile, much more decreased bacterial or fungal OTUs were identified from rhizosphere soils rather than from plant roots, exhibiting the protective effects of host plant on endophytes. Among the detected bacterial isolates, Streptomyces sp. TR27 was discovered to exhibit nematocidal activity, and B. amyloliquefaciens, Bacillus sp. P35, and M. azadirachtae to show repellent potentials for the second stage M. incognita juveniles, which can be used to develop RKN bio-control agents.

Discussion

These findings provided insights into the interactions among root-knot nematodes, host plants, and microorganisms, which will inspire explorations of novel nematicides.

Sphingobacterium Spritivorum Associated With Spontaneous Bacterial Peritonitis in a Cirrhotic Patient With Gram-Positive Bacteremia

Sphingobacterium spritivorum (SS) is a ubiquitous gram-negative organism and an uncommon cause of infection in humans. To our knowledge, there are no reported cases of this bacterium causing spontaneous bacterial peritonitis (SBP) in patients with cirrhosis. In this report, we discuss a case of a male patient in his late 60s who presented with severe sepsis from methicillin-resistant staphylococcus aureus (MRSA), in whom SS was subsequently identified via ascitic fluid culture. This unusual organism is known to have an innate resistance to multiple antibiotics and can cause life-threatening sepsis in cases of delayed or missed diagnosis. Clinicians should not be weighed down by anchoring bias and look for alternative, uncommon gram-negative organisms in cases of progressive sepsis in patients with ascites.

Scrub Typhus Complicated by Rare Human Pathogen Sphingobacterium spiritivorum

Sphingobacterium spiritivorum is a rare cause of human infections worldwide. After reviewing the literature, we could find only eight case reports to date. The majority of cases were of cellulitis and septicemia. Most of these patients were immunocompromised and the recovery rate was lesser. We present a case of a young female diagnosed with scrub typhus complicated by acute respiratory distress syndrome who developed septicemia and septic shock due to S. spiritivorum. She was managed with sensitive antibiotic levofloxacin, clinically improved, and discharged in satisfactory condition.

Cellulitis Complicated with Bacteremia Due to Sphingobacterium Species: A Report of Two Cases and a Literature Review

Sphingobacterium species rarely cause human infection. We herein report two cases of cellulitis complicated with bacteremia due to this genus. The patients, both in their 70s and receiving corticosteroid therapy for their underlying diseases, had antecedent skin injuries in their affected limbs. The patients' symptoms improved promptly and completely with the administration of cefazolin, which did not inhibit the growth of isolated organisms at a concentration of 4 μg/mL.

Sphingobacterium spiritivorum bacteremia due to cellulitis in an elderly man with chronic obstructive pulmonary disease and congestive heart failure: a case report

Background

Sphingobacterium spiritivorum is a glucose non-fermenting Gram-negative rod, formerly classified as one of the Flavobacterium species. It is characterized by a large number of cellular membrane sphingophospholipids. Sphingobacterium species are ubiquitous and isolated from natural environments, such as soil and water. However, they rarely cause infections in humans. Only a limited number of cases have been reported in elderly and immunocompromised patients with underlying diseases and predisposing factors.

Case presentation

An 80-year-old Japanese man with chronic obstructive pulmonary disease and congestive heart failure visited the Kariya Toyota General Hospital, Aichi, Japan with the chief complaint of fever accompanied by chills and left leg pain. At initial presentation, he was distressed and dyspneic. He was febrile (38.8 °C), and his left foot was swollen with reddening and tenderness. We diagnosed him as having cellulitis, and he was hospitalized for antibiotic therapy. Initially, he was treated with intravenously administered cefazolin, but after the isolation of a glucose non-fermenting Gram-negative rod from blood cultures, we decided to switch cefazolin to intravenously administered meropenem on day 4, considering the antibiotic resistance of the causative organism. The causative organism was identified as S. spiritivorum on day 6. His condition gradually stabilized after admission. Meropenem was switched to orally administered levofloxacin on day 12. He was discharged on day 16 and treated successfully without any complications.

Conclusions

Although S. spiritivorum is rare, with limited cases isolated from cellulitis, it should be considered as a causative organism in elderly and immunocompromised patients with cellulitis. Blood cultures are the key to correct diagnosis and appropriate treatment.