Abstract The emergence of tmexCD-toprJ, coding for a transmissible multidrug resistance efflux pump of the resistance-nodulation-division (RND) family has compromised the usefulness of tigecycline in the treatment of infections caused by multidrug resistant Gram-negative bacteria. Here, we describe the presence of tmexCD3-toprJ3 in a novel chromosomal context in Pseudomonas sediminis CRE-TB-54 isolated from a toilet in a university dormitory in southwestern Nigeria. Antimicrobial susceptibility testing and whole genome sequencing showed that CRE-TB-54 displayed intermediate level resistance to tigecycline and haboured multiple antibiotic resistance genes, including tmexCD3-toprJ3 flanked upstream and downstream by genetic structures not previously reported in association with tmexCD-toprJ. These include insertion sequences IS4 and IS30, and the metal resistance gene czcD upstream, the prophage integrase IntA, the competence associated DNA binding protein gene comEA, and the double stranded DNA repair and homologous recombination gene cluster recBCD downstream. These results provide new insight into the genetic structures surrounding the tmexCD-toprJ cluster and raises concern about toilets as a potential environmental reservoir of bacteria carrying this clinically important gene in a resource-limited setting where tigecycline is not currently used in human or animals.
Enterobacteriaceae represent a clinically challenging bacterial family owing to the global emergence of multidrug resistance. Bacteriophages, the natural predators of these bacteria, have emerged as powerful tools for detecting, targeting, and inhibiting these pathogens. This review provides a comprehensive overview of bacteriophages targeting Enterobacteriaceae hosts, focusing on their diversity, virion architecture, and the molecular determinants of host specificity. The dynamic co-evolution between bacterial defence strategies and phage counter-defences is discussed to illustrate the complexity of the phage-Enterobacteriaceae host interactions. Translational applications of Enterobacteriaceae phages, including phage therapy, engineered phages, phage-derived lysins as antimicrobials, and phage-based diagnostics for rapid and specific pathogen detection is also explored alongside their limitations including limited large-scale clinical trials, regulatory and manufacturing hurdles, and the need for robust host-range prediction and standardization. Overall, this review elaborates implications of bacteriophage-Enterobacteriaceae interactions to combat antimicrobial resistance and support the development of next-generation antibacterial therapies and diagnostics.
Abstract Crude oil contamination threatens environmental quality due to the persistence and toxicity of petroleum hydrocarbons. Bioremediation using indigenous microorganisms offers an effective and environmentally friendly solution. This study isolated and characterized indigenous hydrocarbon-degrading bacteria from crude oil-contaminated soil collected from a refinery in Port Dickson, Malaysia, and assessed their biodegradation capability individually and as a co-culture. Soil samples were enriched in Bushnell-Haas medium supplemented with crude oil as sole carbon source to isolate potential hydrocarbon-degrading bacteria. Among ten isolates, two superior growth and biosurfactant activity isolates were selected and identified as Klebsiella pneumoniae (isolate OB) and Pseudomonas aeruginosa (isolate SC) using 16S rRNA gene sequencing. Biodegradation efficiency was determined gravimetrically after 21 days, while changes in the residual crude oil profile were examined by GC-MS. Individual degradation efficiencies reached 39.56% for K. pneumoniae and 43.41% for P. aeruginosa, while their mixed co-culture achieved substantially higher efficiency (54.67%), indicating synergistic interactions. GC–MS analysis further supported the crude-oil degradation results, revealing alterations in the residual hydrocarbon profile, including reductions in selected hydrocarbon-associated compounds and changes in the relative abundance of individual components. These findings demonstrate that indigenous biosurfactant-producing bacteria, particularly in co-culture, reveal enhanced crude oil degradation.
Abstract Climate change is increasing the frequency and scale of turf disease outbreaks, yet systems for rapid and accurate disease diagnosis in the field remain limited. Existing microscopic examination methods require skilled professionals. And by the time visible symptoms appear, the optimal window for prevention is often missed. Rhizoctonia solani is a destructive pathogen causing severe turfgrass diseases. To address this, we report a rapid, field-deployable loop-mediated isothermal amplification (LAMP) assay targeting a fungal-specific ITS-5.8S rDNA sequence. The amplification reaction was optimized at 65 °C for 20 minutes, achieving an analytical sensitivity with a limit of detection (LoD) of 1 fg per reaction. The assay exhibited 100% analytical specificity with no cross-reactivity, validated across a panel of 31 fungal isolates comprising target Rhizoctonia species and non-target taxa, as well as successfully tested on artificially contaminated turf and soil matrices. Overall, this highly sensitive and specific LAMP-based system provides a reliable and practical tool for the rapid, on-site detection of R. solani in turf management.
The xerophilic fungal genus Wallemia is an important cause of fungal contamination in bread manufacturing environments, but its detection by conventional culture-based methods is often difficult because of slow growth and competitive overgrowth by other fungi. Here, we report the development of a genus-specific TaqMan real-time polymerase chain reaction assay targeting the internal transcribed spacer (ITS) region for rapid detection of Wallemia. Primer and probe sequences were designed based on comparative ITS analysis of all nine recognized Wallemia species and non-target fungi commonly encountered in bakery environments. The probe-binding region was fully conserved among all Wallemia ITS reference sequences evaluated. Analytical specificity was confirmed using synthetic DNA fragments representing predicted amplicon groups, with amplification observed exclusively in Wallemia. The assay demonstrated excellent linearity over 10 & sup2;-10(6) copies per reaction (R & sup2; = 0.9988), with an amplification efficiency of 102.7%. Analytical sensitivity evaluation yielded an estimated LOD95 of 9.46 copies per reaction. Application to environmental swab samples from an operational bakery production line enabled culture-independent detection of Wallemia, including in samples in which culture-based identification was obscured by fungal overgrowth. This assay provides a rapid and specific molecular tool for culture-independent monitoring of Wallemia contamination and may support improved hygienic control in bakery manufacturing environments.
