Enteroaggregative Escherichia coli (EAEC) is highly heterogeneous in virulence; we wanted to understand the pathogenic potential of EAEC isolated from various clinical and non-clinical sources in an animal model. We infected male BALB/c mice in six mice/groups with 50 EAEC isolates isolated from clinical and non-clinical sources. We studied colonization, weight loss, stool shedding, and inflammatory markers and their relationship with 21 virulence genes and phylogroups, EAEC organ burden, and histopathological changes. We detected significantly more inflammatory changes and fecal lactoferrin and calprotectin levels in mice infected with EAEC isolated from symptomatic cases. In clinical EAEC isolates, the presence of chromosomal genes (aap (46%), aaiC (23.3%), SPATEs (pet (13.3%), sat (20%), sigA, and pic (6.6%)), the adhesive variantsof EAEC (agg4A (53.3%), aggA (53.3%), aafA (36.6%), andagg3A (40%)), and the master regulator gene aggR (66.6%) were associated with higher levels of lactoferrin and calprotectin. Additionally, 70% (9/13) of EAEC isolated from acute diarrheal cases bearing chuA (70%) in our study were assigned to groups B2 (4 isolates) and D (5 isolates). Real-time PCR analysis revealed that colonization by EAEC strains from different clinical and non-clinical sources occurs up to 10–15 days of life. Even from non-diarrheal stools and non-clinical sources, EAEC strainshad the potential to cause prolonged colonization, weight loss, and inflammation in the intestine, though the degree varied. Moreover, a better understanding of EAEC pathogenic pathways is desperately needed in different clinical scenarios.

Cholera, a disease of antiquity, is still festering in developing countries that lack safe drinking water and sewage disposal. Vibrio cholerae, the causative agent of cholera, has developed multi-drug resistance to many antimicrobial agents. In aquatic habitats, phages are known to influence the occurrence and dispersion of pathogenic V. cholerae. We isolated Vibrio phage VMJ710 from a community sewage water sample of Manimajra, Chandigarh, in 2015 during an outbreak of cholera. It lysed 46% of multidrug-resistant V. cholerae O1 strains. It had significantly reduced the bacterial density within the first 4–6 h of treatment at the three multiplicity of infection (MOI 0.01, 0.1, and 1.0) values used. No bacterial resistance was observed against phage VMJ710 for 20 h in the time–kill assay. It is nearest to an ICP1 phage, i.e., Vibrio phage ICP1_2012 (MH310936.1), belonging to the class Caudoviricetes. ICP1 phages have been the dominant bacteriophages found in cholera patients’ stools since 2001. Comparative genome analysis of phage VMJ710 and related phages indicated a high level of genetic conservation. The phage was stable over a wide range of temperatures and pH, which will be an advantage for applications in different environmental settings. The phage VMJ710 showed a reduction in biofilm mass growth, bacterial dispersal, and a clear disruption of bacterial biofilm structure. We further tested the phage VMJ710 for its potential therapeutic and prophylactic properties using infant BALB/c mice. Bacterial counts were reduced significantly when phages were administered before and after the challenge of orogastric inoculation with V. cholerae serotype O1. A comprehensive whole genome study revealed no indication of lysogenic genes, genes associated with possible virulence factors, or antibiotic resistance. Based on all these properties, phage VMJ710 can be a suitable candidate for oral phage administration and could be a viable method of combatting cholera infection caused by MDR V. cholerae pathogenic strains.

Urinary tract infections (UTIs) are one of the most frequent bacterial infections in the world, both in the hospital and community settings. Uropathogenic Escherichia coli (UPEC) are the predominant etiological agents causing UTIs. Extended-spectrum beta-lactamase (ESBL) production is a prominent mechanism of resistance that hinders the antimicrobial treatment of UTIs caused by UPEC and poses a substantial danger to the arsenal of antibiotics now in use. As bacteria have several methods to counteract the effects of antibiotics, identifying new potential drug targets may help in the design of new antimicrobial agents, and in the control of the rising trend of antimicrobial resistance (AMR). The public availability of the entire genome sequences of humans and many disease-causing organisms has accelerated the hunt for viable therapeutic targets. Using a unique, hierarchical, in silico technique using computational tools, we discovered and described potential therapeutic drug targets against the ESBL-producing UPEC strain NA114. Three different sets of proteins (chokepoint, virulence, and resistance genes) were explored in phase 1. In phase 2, proteins shortlisted from phase 1 were analyzed for their essentiality, non-homology to the human genome, and gut flora. In phase 3, the further shortlisted putative drug targets were qualitatively characterized, including their subcellular location, broad-spectrum potential, and druggability evaluations. We found seven distinct targets for the pathogen that showed no similarity to the human proteome. Thus, possibilities for cross-reactivity between a target-specific antibacterial and human proteins were minimized. The subcellular locations of two targets, ECNA114_0085 and ECNA114_1060, were predicted as cytoplasmic and periplasmic, respectively. These proteins play an important role in bacterial peptidoglycan biosynthesis and inositol phosphate metabolism, and can be used in the design of drugs against these bacteria. Inhibition of these proteins will be helpful to combat infections caused by MDR UPEC.

Globally, urinary tract infections (UTIs) are one of the most frequent bacterial infections. Uropathogenic Escherichia coli (UPEC) are the predominant etiological agents causing community and healthcare-associated UTIs. Biofilm formation is an important pathogenetic mechanism of UPEC responsible for chronic and recurrent infections. The development of high levels of antimicrobial resistance (AMR) among UPEC has complicated therapeutic management. Newer antimicrobial agents are needed to tackle the increasing trend of AMR and inhibit biofilms. Heraclenol is a natural furocoumarin compound that inhibits histidine biosynthesis selectively. In this study, for the first time, we have demonstrated the antimicrobial and antibiofilm activity of heraclenol against UPEC. The drug reduced the bacterial load in the murine catheter UTI model by ≥4 logs. The drug effectively reduced bacterial loads in kidney, bladder, and urine samples. On histopathological examination, heraclenol treatment showed a reversal of inflammatory changes in the bladder and kidney tissues. It reduced the biofilm formation by 70%. The MIC value of heraclenol was observed to be high (1024 µg/mL), though the drug at MIC concentration did not have significant cytotoxicity on the Vero cell line. Further molecular docking revealed that heraclenol binds to the active site of the HisC, thereby preventing its activation by native substrate, which might be responsible for its antibacterial and antibiofilm activity. Since the high MIC of heraclenol is not achievable clinically in human tissues, further chemical modifications will be required to lower the drug’s MIC value and increase its potency. Alternatively, its synergistic action with other antimicrobials may also be studied.