Yokenella regensburgei necrotizing fasciitis in an immunocompromised host

Yokenella regensburgei-Past, Present and Future

Yokenella regensburgei is a Gram-negative rod part of the Enterobacteriaceae family (order Enterobacterales) and a rare cause of human infections. Although improved diagnostic methods have led to an increase in reports of this elusive pathogen, information remains limited. In order to provide a better understanding of this bacterium, we developed the first comprehensive review of its biology, biochemical profile, antimicrobial resistance pattern, virulence factors, natural reservoir and involvement in various veterinary and human infections. Human infections with this bacterium are scarcely reported, most probably due to constraints regarding its identification and biochemical similarities to Hafnia alvei. Multiple systematic searches revealed 23 cases of human infection, with a seemingly worldwide distribution, mostly in middle-aged or elderly male patients, often associated with immunosuppression. To date, Y. regensburgei has been reported in skin and soft tissue infections, bacteremia and sepsis, osteoarticular infections and in others such as urinary tract and digestive infections. The unique ability of Y. regensburgei to degrade polystyrene presents a novel and promising avenue for addressing plastic pollution in the near future. However, large-scale applications of this bacterium will undoubtedly increase human exposure, highlighting the necessity for comprehensive research into its role in human and veterinary infections, pathogenicity and antibiotic resistance.

Complete genome sequence of Yokenella regensburgei isolated from a patient with urinary tract infection in India

Yokenella regensburgei, an environmental organism, is an emerging pathogen in patients chiefly with immune suppression. We report the draft genome of Y. regensburgei, strain UU2206353, isolated from the urinary tract of an immunocompetent individual. The assembled genome consisted of 4,669,536 bp distributed over 20 contigs with 4,283 protein-coding genes.

Refractory otitis media and otitis externa in a koala (Phascolarctos cinereus) treated with total ear canal ablation and lateral bulla osteotomy

BACKGROUND

To the authors' knowledge, this is the first report fully describing the surgical and medical management of otitis media and otitis externa in the koala (Phascolarctos cinereus) treated by total ear canal ablation and lateral bulla osteotomy.

CASE REPORT

An adult male koala captured as part of a monitoring project in South East Queensland was diagnosed with chlamydial cystitis. Purulent discharge from the right ear was also observed; diagnostic imaging was consistent with otitis media and otitis externa. Yokenella regensburgei was repeatedly cultured from the site. Clinical signs resolved with topical antibiotic therapy; however, recrudesced following cessation of antibiotics. A total ear canal ablation and lateral bulla osteotomy was performed, followed by an extended period of systemic antibiotic therapy. Mild facial nerve paresis was observed for 4 weeks postoperatively and resolved spontaneously. The koala remained clinically healthy for the 6 months it was monitored following release.

CONCLUSION

Total ear canal ablation combined with lateral bulla osteotomy appears to be an appropriate surgical intervention for otitis media combined with otitis externa refractory to medical management in the koala. Transient postoperative facial nerve paresis is a possible complication, as documented in other species. To the authors' knowledge this is the first case of Yokenella regensburgei infection outside of humans and American alligators (Alligator mississippiensis); the clinical significance of this pathogen in the koala remains unknown.

Yokenella regensburgei urinary tract infection in an immunocompetent patient: a case report

Yokenella regensburgei , belonging to the order Enterobacterales , is a rare and emerging human pathogen reported to cause both superficial and invasive infections. The 13 case reports in the literature worldwide highlight blood, bone and wound infections. To our knowledge this is the first case description of Y. regensburgei causing a urinary tract infection in a 69-year-old immunocompetent patient which was isolated in two separate specimens and identified using matrix-assisted laser desorption ionization time-of-flight MS. It was found to be susceptible to most antimicrobials but resistant to penicillin, amoxicillin-clavulanate, cefoxitin and colistin. Inducible chromosomal ampC resistance was demonstrated on disc approximation testing, and blaYOC-1 class C beta-lactamase, beta lactamase superfamily and MBL fold metallo-hydrolase genes were found on whole genome sequencing.

The Molecular Weaponry Produced by the Bacterium Hafnia alvei in Foods

Hafnia alvei is receiving increasing attention from both a medical and veterinary point of view, but the diversity of molecules it produces has made the interest in this bacterium extend to the field of probiotics, the microbiota, and above all, to its presence and action on consumer foods. The production of Acyl Homoserine Lactones (AHLs), a type of quorum-sensing (QS) signaling molecule, is the most often-studied chemical signaling molecule in Gram-negative bacteria. H. alvei can use this communication mechanism to promote the expression of certain enzymatic activities in fermented foods, where this bacterium is frequently present. H. alvei also produces a series of molecules involved in the modification of the organoleptic properties of different products, especially cheeses, where it shares space with other microorganisms. Although some strains of this species are implicated in infections in humans, many produce antibacterial compounds, such as bacteriocins, that inhibit the growth of true pathogens, so the characterization of these molecules could be very interesting from the point of view of clinical medicine and the food industry. Lastly, in some cases, H. alvei is responsible for the production of biogenic amines or other compounds of special interest in food health. In this article, we will review the most interesting molecules that produce the H. alvei strains and will discuss some of their properties, both from the point of view of their biological activity on other microorganisms and the properties of different food matrices in which this bacterium usually thrives.

Yokenella regensburgei, a novel pathogen in farmed American alligators

Increased acute mortality of farmed American alligators (Alligator mississippiensis) was observed in various pens from 2 different farms in Louisiana over 2 years (2019-2021). A total of 14 alligators from multiple events of increased mortality were subjected to postmortem investigations. Except for one alligator with acute neurologic signs, no premonitory signs were observed. All animals had pneumonia (14/14), coelomitis (14/14), and intravascular short Gram-negative bacilli (14/14). Myocarditis (13/14) was common. Yokenella regensburgei was isolated from all alligators tested (13/13). These data suggest the respiratory tract may be a primary target system and could be involved in transmission, either through exhaled bacteria or through swallowing of contaminated respiratory fluids with passage through the feces. Available sensitivity data for Y. regensburgei in this study indicates in vitro sensitivity to aminoglycosides, fluoroquinolones, chloramphenicol, and trimethoprim/sulphamethoxazole antibiotics. Yokenella regensburgei should be included in the differential diagnosis of septicemia and acute death in alligators.

First report of Yokenella regensburgei isolated from external auditory canal after diving in valley

Yokenella regensburgei is a Gram-negative, oxidase-negative motile rod which is rarely isolated from human caused a few opportunistic infections in immunocompromised patients so far. We report the first case of otitis media combined with externa caused by Y. regensburgei in an immunocompetent patient. A 56-year-old male patient visited the outpatient clinic of the Otolaryngology Department due to otorrhea of the right ear started after diving in mountain valley in Korea 3 days ago. He was immunocompetent adult and clinical examination revealed swelling and debris accumulation in the right external auditory canal with an intact, erythematous tympanic membrane, and clear, odorless otorrhea. Microbiological culture of otorrhea revealed Y. regensburgei by matrix-assisted laser desorption/ionization time-of-flight and PCR-based 16S rRNA gene sequencing. His otorrhea persisted, and a pinpoint perforation occurred in the inferior anterior portion of the tympanic membrane. 50% acetic acid irrigation and 500 mg of oral ciprofloxacin were prescribed, and his infection was cured after 4 weeks. This is the first case of otitis media combined with externa caused by Yokenella regensburgei in an immunocompetent patient. Given that Yokenella species infections are rare, especially in immunocompetent patients, this case highlights the importance of history taking and communication between clinicians and laboratory physicians. Molecular identification methods assist in identifying rare pathogens.

Characterization of a Novel Chromosomal Class C β-Lactamase, YOC-1, and Comparative Genomics Analysis of a Multidrug Resistance Plasmid in Yokenella regensburgei W13

Yokenella regensburgei, a member of the family Enterobacteriaceae, is usually isolated from environmental samples and generally resistant to early generations of cephalosporins. To characterize the resistance mechanism of Y. regensburgei strain W13 isolated from the sewage of an animal farm, whole genome sequencing, comparative genomics analysis and molecular cloning were performed. The results showed that a novel chromosomally encoded class C β-lactamase gene with the ability to confer resistance to β-lactam antibiotics, designated bla YOC - 1, was identified in the genome of Y. regensburgei W13. Kinetic analysis revealed that the β-lactamase YOC-1 has a broad spectrum of substrates, including penicillins, cefazolin, cefoxitin and cefotaxime. The two functionally characterized β-lactamases with the highest amino acid identities to YOC-1 were CDA-1 (71.69%) and CMY-2 (70.65%). The genetic context of the bla YOC - 1 -ampR-encoding region was unique compared with the sequences in the NCBI nucleotide database. The plasmid pRYW13-125 of Y. regensburgei W13 harbored 11 resistance genes (bla OXA - 10, bla LAP - 2, dfrA14, tetA, tetR, cmlA5, floR, sul2, ant(3″)-IIa, arr-2 and qnrS1) within an ∼34 kb multidrug resistance region; these genes were all related to mobile genetic elements. The multidrug resistance region of pYRW13-125 shared the highest identities with those of two plasmids from clinical Klebsiella pneumoniae isolates, indicating the possibility of horizontal transfer of these resistance genes between bacteria of various origins.