Adesh Ramsubhag

Multidrug-resistant (MDR) Gram-negative pathogens continue to threaten patient outcomes in intensive care units (ICUs) worldwide, particularly in regions where genomic surveillance is limited. Understanding intra-host genomic diversity and mobility of resistance determinants remain essential for mitigating global antimicrobial resistance (AMR) threats. Whole genome sequencing and molecular analysis were performed on three selected isolates to identify resistance and virulence determinants. The isolates exhibited complex and heterogenous resistomes shaped by extensive antimicrobial exposure during prolonged ICU care. Two genetically distinct Klebsiella pneumoniae strains (ST11 and ST15) demonstrating intra-patient strain diversity, an emerging trend in high-risk clinical settings globally, along with an Acinetobacter baumannii strain (ST944) were recovered from the same patient. Key resistance genes linked to mobile genetic elements (MGEs) were identified, including bla _CTX-M-15 and bla _NDM-5 in K. pneumoniae ST11 and bla _ADC-152 in A. baumannii . A plasmid-associated contig harbouring bla _DHA-1 and qnr resistance genes represented a ‘high-risk’ mobile platform with international similarity in K. pneumoniae , highlighting the global circulation of resistance plasmids. Virulence profiling revealed conserved and unique determinants, including biofilm, siderophore, and secretion loci, with one isolate carrying a complete Yersiniabactin locus associated with MGEs. This study provides the first genome-resolved case from the Caribbean demonstrating intra-host co-existence of globally important MDR lineages and plasmid-mediated dissemination of key resistance genes. Within the global AMR challenge, this analysis offers novel insight into the convergence of resistance and virulence traits and highlights the value of localized genomic surveillance in understanding pathogen adaptation, mobility, and persistence under high antimicrobial pressure. These findings emphasize the importance of incorporating genomic data from diverse geographic regions into global AMR networks to better manage MDR ESKAPE pathogens in ICU environments.

The study explored Sargassum valorization through the production of a fermented extract for its application as a crop biostimulant. The dried and ground Sargassum (S. natans and S. fluitans) was subjected to anaerobic fermentation utilizing the endogenous microorganisms already present in the seaweed. During the fermentation process, samples were periodically taken (5, 15, 20, 27, 30, and 35) for 16S rRNA and ITS paired-end amplicon metataxonomics. Microbiome profiling revealed distinct temporal microbiome shifts over the 35 days of fermentation, with Firmicutes, Bacteroidota, and Nectriaceae emerging as the core microbiome. Furthermore, microbial network analysis identified Clostridiaceae, Sporolactobacillaceae, and Pirellulaceae as dominant bacterial families, while Gibberella and Aspergillus showed up as prevalent fungal genera. Beta-diversity analyses showed a significant shift in microbial composition on Day 35. Extracts were screened for their antimicrobial properties against plant pathogens (Xanthomonas campestris pv. vesicatoria and Alternaria solani), however results indicated no antimicrobial effect. Plant growth trials were conducted using Capsicum annuum L. plants and the extracts were applied as foliar application sprays at 0.5-1% v/v concentrations under greenhouse conditions. All parameters measured (chlorophyll content, root and shoot length, and root and shoot weights were all significantly greater than Control-treated plants. Chlorophyll content, root length, shoot length, fresh root and shoot weight, and dry root and shoot weight all had significant increases of up to 28.82%, 60.13%, 15.95%, 67.95%, 53.90%, 82.05%, and 95.86% respectively. The result of the study promotes the usage of fermented Sargassum extracts as an organic biostimulant and aligns with sustainable agricultural practices. The online version contains supplementary material available at 10.1007/s13205-026-04811-1.

Cowpea ( Vigna unguiculata ) is an important vegetable crop in Trinidad and Tobago as well as the entire Caribbean region. Recently, farmers have reported considerable reduction in crop yield due to diseases, particularly those suspected to be caused by viruses. There were very few reports of cowpea viruses from the Caribbean region, which necessitated the need to look into the emerging viral pathogens that can cause significant crop losses. PCR and nucleic acid sequencing‐based techniques were employed to detect viruses from cowpea plant samples from the farmers' fields in Trinidad. The prevalence of cowpea mosaic virus (CPMV) and potato yellow mosaic virus (PYMV) was detected and characterised through sequencing of the genomes. Whole‐genome sequencing using primer walking revealed that the CPMV‐TnT isolate comprised two RNA segments of 5889 nt (RNA‐1) and 3481 nt (RNA‐2), showing notable divergence in start and stop positions compared to reference genomes. The PYMV‐TnT genome consisted of DNA‐A (2,593 bp) and DNA‐B (2,547 bp), with high similarity to regional isolates and evidence of recombination events, suggesting ongoing genetic diversification within established Caribbean lineages. Phylogenetic analysis confirmed both viruses clustered with Caribbean and South American relatives, though the CPMV RNA‐2 and PYMV DNA‐B sequences displayed distinct branching patterns. Furthermore, absolute qPCR analysis revealed a progressive increase in viral titre throughout the stages of plant development for CPMV and PYMV. The study provides genome‐level characterisation of CPMV and PYMV isolates infecting cowpea in Trinidad, offering updated molecular epidemiological insight into viruses previously reported in the region and thus highlights the need for strategic management and continuous viral surveillance in crops.

Antimicrobial resistance poses a critical global threat, with carbapenem-resistant pathogens representing a significant challenge to healthcare systems. This study aimed to characterize carbapenem-resistant pathogens isolated from wound infections in patients from a major hospital in Trinidad using a combination of traditional microbiological and molecular techniques. A total of 25 Gram-negative bacterial isolates were analyzed phenotypically for antimicrobial resistance and genetically profiled for resistance mechanisms using polymerase chain reaction and whole genome sequencing. Analysis of the data revealed most of the isolates were Acinetobacter baumannii (A. baumannii) (56%; n = 14) and Klebsiella pneumoniae (K. pneumoniae) (28%; n = 7), but a small number of Enterobacter (12%; n = 3), and Pseudomonas (4%; n = 1) were also identified. While the isolates were determined to be carbapenem resistant, 32% (n = 8) also exhibited extended spectrum beta-lactamases characteristics. Key resistance determinants identified from whole genome sequencing included bla_OXA-23 (n = 2), bla_OXA-90 (n = 2), and bla_OXA-72 (n = 1) in A. baumannii and bla_NDM-5 (n = 1) in K. pneumoniae. The co-occurrence of carbapenemase and extended spectrum beta-lactamase genes, such as bla_CTXM-124 in A. baumannii and bla_TEM-1B and bla_CMY-4 in K. pneumoniae, emphasized the complexity of resistance mechanisms that limits therapeutic options. Notably, this is the first study to report on the occurrence of bla_SPM and bla_SME in A. baumannii in Trinidad. By contributing critical insights into the molecular epidemiology of antimicrobial resistance in the setting of the Caribbean, this study offers a foundation for region-specific interventions to mitigate the clinical and economic impact of resistant infections. It will also help improve antimicrobial stewardship, and control efforts, and therefore supports the need for investment in diagnostic stewardship.