Bacillus thuringiensis (Bt) is the most successful, environmentally-friendly, and intensively studied microbial insecticide. The major characteristic of Bt is the production of proteinaceous crystals containing toxins with specific activity against many pests including dipteran, lepidopteran, and coleopteran insects, as well as nematodes, protozoa, flukes, and mites. These crystals allow large quantities of the protein toxins to remain stable in the environment until ingested by a susceptible host. It has been previously established that 135 kDa Cry proteins have a crystallization domain at their C-terminal end. In the absence of this domain, Cry proteins often need helper proteins or other factors for crystallization. In this review, we classify the Cry proteins based on their requirements for crystallization.

Background: Urinary tract infections (UTIs) caused by Escherichia coli remain a primary global health concern, with increasing multidrug resistance posing significant diagnostic and therapeutic challenges. Molecular techniques such as 16S rRNA sequencing provide a reliable approach for accurate identification and phylogenetic characterization of resistant strains. Objective: To isolate and identify multidrug-resistant (MDR) Escherichia coli strains from urinary tract infection patients in District Sialkot, Pakistan, using 16S rRNA sequencing. Study Design: Cross-sectional molecular study. Setting: Department of Microbiology, tertiary care hospital in Sialkot, Pakistan. Duration of Study: From July 2023 to December 2023. Methods: Twenty E. coli isolates were obtained from urine samples of patients with clinically diagnosed UTIs. Identification was performed using standard microbiological techniques. Antibiotic susceptibility testing was conducted using the Kirby–Bauer disc diffusion method against commonly used antibiotics. The isolate exhibiting multidrug resistance was subjected to molecular identification via 16S rRNA gene sequencing and phylogenetic analysis. Sequence data were compared with reference strains using BLAST and submitted to GenBank. Results: Antibiotic susceptibility testing revealed high levels of resistance to ceftriaxone (95.2%), cefoperazone (93.5%), ciprofloxacin (86.5%), cefotaxime (84.6%), and cefixime (86%). Molecular analysis confirmed the isolate as Escherichia coli, with phylogenetic analysis showing close homology to previously reported E. coli strains. The sequence of the multidrug-resistant strain was submitted to GenBank under the accession number Escherichia coli strain KS8861 (PP897401.1). Conclusion: 16S rRNA sequencing serves as a robust and accurate method for identifying multidrug-resistant E. coli strains associated with UTIs. Incorporating molecular diagnostics into routine microbiological workflows can enhance early detection and guide effective antimicrobial therapy.

Escherichia coli strains are among the key contributors to urinary tract infections (UTIs) around the world, presenting a significant health challenge globally. Objectives: This cross-sectional study aims to isolate multidrug-resistant (MDR) Escherichia coli strains from UTI patients in Sialkot, Pakistan, and to investigate their biofilm-forming ability, exploring the possible association between biofilm formation and antibiotic resistance. Methods: A total of 131 E. coli isolates were isolated and identified. Their ability to form biofilms was confirmed using the tube method, and their antibiotic susceptibility patterns were evaluated using the disc diffusion method. Fisher's exact test was applied to investigate the association between biofilm production and antibiotic resistance. Results: The findings revealed that 65.6% isolates (n = 88) were biofilm producers, while 34.4% (n = 43) were non-biofilm producers. Antibiotic sensitivity testing indicated high levels of resistance among isolates to several antibiotics, notably ceftriaxone (91.6%), cefoperazone (86.3%), ciprofloxacin (85.5%), cefotaxime (82.4%), and cefixime (81.7%). A significant association was observed between biofilm formation and resistance to most antibiotics, including nitrofurantoin, amoxicillin-clavulanate, amikacin, piperacillin-tazobactam, and sulfamethoxazole-trimethoprim, among others. Conclusion: These findings suggest that E. coli isolates resistant to these certain antibiotics are more likely to form biofilms. This research highlights the critical need to explore biofilm formation, along with antibiotic susceptibility patterns of isolates, to help select appropriate antibiotics and facilitate effective treatment approaches.