Fatemeh Maghsood Ahmadi, Arash Arash Mahboubi, Farzaneh Hosseini, Davoud Esmaeili, Bahareh Hajikhani,
Volume 19, Issue 5 (9-2025)
Abstract
ABSTRACT
Background and objectives: Lactic acid bacteria (LAB) are potential candidates for the mucosal vaccine. Staphylococcal enterotoxin B (SEB), as a potent superantigen exotoxin is associated with widespread dietary poisoning and induction of toxic shock syndrome. Also, cholera toxin is the most important virulence factor in Vibrio cholera pathogenicity. CTB, a well-known immune adjuvant, enhances immunity and is mainly used to produce recombinant vaccines as antigen immunization enhancers. This study aimed to produce recombinant Lactobacillus Plantarum as a candidate vaccine against Vibrio cholera producing Cholera toxin and Staphylococcus aureus producing enterotoxin SEB. Methods: A gene sequence encoding SEB, devoid of superantigenic activity, and CTB were successfully designed, synthesized, cloned, and then expressed in a secreted form in the Lactobacillus Plantarum. The recombinant protein containing His-Tag was purified by Ni-NTA Agarose ion-exchange chromatography column. The purified protein was confirmed by Western blotting. Results: The result of this study demonstrated the expression of this recombinant protein in the Lactobacillus Plantarum system by pnz7021 expression vector. The protein electrophoresis showed that the molecular weight of recombinant fusion protein was 52 kDa. Western blot analysis also confirmed the production of recombinant protein. The use of recombinant vaccines has received a great deal of attention today. LP-pnz7021–SP-rseb-ctxB can be used as a suitable candidate in recombinant vaccines against Vibrio cholera producing Cholera toxin and Staphylococcus aureus producing enterotoxin SEB.
Apurba Sankar Sastry , Shuruthi Kirubakaran , Sarumathi Dhandapani , Ketan Priyadarshi,
Volume 19, Issue 5 (9-2025)
Abstract
Background: The emergence of multidrug-resistant organisms has limited the choice of therapeutic options to treat infections. The lack of development of new antimicrobials paved the way for considering the reassessment of older antibiotics like fosfomycin. In this context, we assessed the in-vitro effect of fosfomycin against carbapenem-resistant Enterobacterales and methicillin-resistant Staphylococcus aureus (MRSA) bloodstream isolates by agar dilution, disk diffusion, and screen agar.
Methods: In this study, 141 consecutive blood isolates resistant to carbapenem and 62 MRSA blood culture isolates were collected over a period of 8 months. The methods used were fosfomycin agar dilution (0.25 µg/ml to 512 µg/ml), Kirby-Bauer disk diffusion (150 µg of fosfomycin + 50 µg of glucose-6-phosphate), and fosfomycin screen agar (32 µg/ml, 48 µg/ml, and 64 µg/ml). All three methods were interpreted using the European Committee on Antimicrobial Susceptibility Testing guidelines. The agreement between the new method and the reference method was calculated.
Results: Among the tested isolates, 100% of MRSA, followed by Escherichia coli (E. coli) (86.4%), Klebsiella pneumonia (K. pneumonia) (65.2%), and E. cloacae (50%) were susceptible to fosfomycin. The MIC50 and MIC90 of fosfomycin were 0.5 µg/ml and 2 µg/ml for MRSA, 16 µg/ml and 32 µg/ml for K. pneumoniae, 4 µg/ml and 16 µg/ml for E. coli, and 8 µg/ml and 32 µg/ml for E. cloacae, respectively.
Conclusion: Fosfomycin demonstrated a good in-vitro effect on most of the carbapenem-resistant Enterobacterales and MRSA isolates tested.
Naila Begum, Karvi Agarwal, Amit Garg,
Volume 19, Issue 5 (9-2025)
Abstract
Background and Objectives:Colistin is regarded as the final resort for managing infections caused by multi-drug resistance (MDR) gram-negative bacilli (GNB). Minimum inhibitory concentration (MIC) is used to monitor the development of colistin resistance. This study aimed to assess the performance of Broth Microdilution Method (BMD) against routine Kirby-Bauer disk diffusion (KBDD) and automated BD Phoenix for the detection of in vitro activity of colistin against GNB
Methods: A cross-sectional study was done in the Department of Microbiology, LLRM Medical College, Meerut Uttar Pradesh from September 2023 to January 2024. KBDD method, BMD method & BD Phoenix (Becton Dickinson, USA) automated system were used in 320 GNB isolated from various clinical samples to detect Colistin susceptibility. MIC determined by BMD method was interpreted according to Clinical Laboratory Standards Institute (CLSI) 2023 guidelines.
Results: In our study,320 isolates of GNB were identified from the patients with a mean age of 45.34 years. A total of 320 isolates [145(45.31%) Escherichia coli, 124(38.75%) Klebsiella pneumoniae, 32(10.0%) Pseudomonas aeruginosa, and 19(5.93%) Acinetobacter baumannii complex] were tested simultaneously with all three methods for colistin susceptibility. The overall resistance to Colistin amongst GNB was found to be 17.18% by the gold standard BMD method, 15.31% by BD Phoenix, and 14.37% by KBDD.
Conclusion: BMD is the most cost-effective, authentic method for routine testing of colistin susceptibility as compared to other methods. The comparative analysis revealed that BMD is superior to other methods in detecting colistin susceptibility emphasizing its potential role in guiding clinicians for treatment decisions
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