Background: The dissemination of extensively drug-resistant Pseudomonas aeruginosa strains across the human–food interface represents a critical threat to global public health, complicating empirical therapeutic choices and challenging traditional nosocomial restriction paradigms. Objective: This study investigated the prevalence, phenotypic resistome landscapes, and underlying integron-mediated mobilization mechanics of P. aeruginosa across the One Health continuum using an optimized real-time quantitative PCR (qPCR) platform. Methods: A total of 116 samples comprising human clinical specimens (n = 61) and retail food matrices (n = 55) were screened. Phenotypic resistance was profiled against 16 antipseudomonal agents, with polymyxin and colistin resistance validated via reference broth microdilution. A novel real-time SYBR Green qPCR assay backed by derivative melting curve analysis was developed to track Class 1 (intI1) and Class 2 (intI2) integrons. Results: Pseudomonas aeruginosa was recovered from 36.2% (n = 42/116) of total samples, exhibiting a homogeneous distribution across clinical (32.8%) and retail food matrices (40.0%, p = 0.445). Antibiogram characterization revealed a critical resistance burden: 100% of isolates fell into extreme epidemiological tiers, with 71.4% (n = 30) exhibiting an extensively drug-resistant (XDR) phenotype and 28.6% (n = 12) reaching absolute pandrug-resistant (PDR) status. Absolute phenotypic resistance (100%) was recorded across both cohorts for meropenem, ceftazidime, aztreonam, tobramycin, polymyxins, and novel combination therapeutics (ceftazidime–avibactam and ceftolozane–tazobactam). Pairwise tracking demonstrated an exceptionally strong positive correlation in resistance distribution patterns between human and food isolates (Spearman’s rho = 0.948, p < 0.001). Analytical validation of the qPCR assay demonstrated tight, reproducible specific derivative melting peaks (T_m) at 83.2 °C for intI1 and 83.8 °C for intI2. Genotypic screening revealed universal conservation of plasmid-borne intI1 (100%), whereas plasmidic intI2 was variably distributed (61.9%). Crucially, intI2 carriage served as a definitive marker for the transition to complete pandrug resistance, being detected in 100% (n = 12/12) of PDR isolates compared to 46.7% (n = 14/30) of XDR strains (p = 0.001), supported by a strong positive correlation with the PDR phenotype (rho = 0.496, p = 0.0008). Conclusions: These findings reveal an overlapping, extreme resistome across the food-clinical interface and identify intI2 as a genetic tipping point for absolute pandrug resistance. The validated real-time assay provides a highly sensitive, proactive molecular surveillance framework capable of mapping high-risk mobile genetic platforms before they manifest as catastrophic empirical treatment failures.

Bacterial pathogens employ a diverse array of virulence factors to colonize and subsequently elicit disease in their host. These factors are often subject to extensive regulation at the transcriptional level to ensure that their expression is timely. Although many pathogens use bespoke transcription factors that primarily target virulence genes, global transcription factors also sometimes play a role in controlling these genes. Enteroaggregative Escherichia coli (EAEC) is a significant cause of watery and mucoid diarrhoea globally. The organism colonizes the small intestine before producing toxins that elicit disease, using a multitude of virulence factors that are encoded both chromosomally and on virulence plasmids. In this work, we have studied the cAMP receptor protein (CRP), a well-characterized bacterial global transcription factor, focusing on its role in the pathogenicity of the prototype EAEC strain 042. We show that, although most functional CRP binding sites on the chromosome are conserved between E. coli K-12 and 042, CRP has been co-opted to couple the expression of some virulence genes to the nutritional state of the cell. We report novel mechanisms for CRP-dependent regulation of genes whose products contribute to the maturation of a bacterial antibiotic, export of a polysaccharide capsule and production of a putative adhesin.

Escherichia coli is an important human pathogen that is able to cause a variety of infections, which can result in diarrhoea, urinary tract infections, sepsis, and even meningitis, depending on the pathotype of the infecting strain. Like many Gram-negative bacteria, E. coli is becoming increasingly resistant to many frontline antibiotics, including third-generation cephalosporins and carbapenems, which are often considered the antibiotics of last resort for these infections. This is particularly the case in Egypt, where multidrug-resistant (MDR) E. coli is highly prevalent. However, in spite of this, few Egyptian MDR E. coli strains have been fully characterised by genome sequencing. Here, we present the genome sequences of ten highly MDR E. coli strains, which were isolated from children who presented with diarrhoea at the Outpatients Clinic of Assiut University Children’s Hospital in Assiut, Egypt. We report that they carry multiple antimicrobial resistance genes, which includes extended spectrum β-lactamase genes, as well as bla_NDM and bla_OXA carbapenemase genes, likely encoded on IncX3 and IncF plasmids. Many of these strains were also found to be high-risk extra-intestinal pathogenic E. coli (ExPEC) clones belonging to sequence types ST167, ST410, and ST617. Thus, their presence in the Egyptian paediatric population is particularly worrying, and this highlights the need for increased surveillance of high-priority pathogens in this part of the world.