Screening of Elaeocarpus floribundus fruit extracts for bioactive phytocomponents and antibacterial activity against food-borne bacteria

Background: Medicinal plants possess several active components having antimicrobial activity. This study was undertaken to explore the antibacterial activity of Indian olive, Elaeocarpus floribundus, fruit extracts against potential food-borne bacterial isolates.Methods: The ethanolic extracts of olive seed (OSE) and mesocarp-epicarp (OMeE), and the aqueous extracts of olive seed (AqOSE) and mesocarp-epicarp (AqOMeE) were prepared, and analysed qualitatively for phytochemicals. The antibacterial activity of the extracts against food-borne pathogenic bacteria: Bacillus sp., Bacillus cereus, Enterococcus sp. and Corynebacterium sp., was determined by agar-well diffusion method, and minimum inhibitory concentration (MIC) values by agar dilution method.Results: The concentration dependent activity of the extracts against the bacteria was recorded with zone diameter of inhibition 6 - 28 mm for ethanolic extracts, and 7 - 23 mm for aqueous extracts. The ethanolic extracts were confirmed positive for the presence of cardiac glycosides, anthraquinone glycosides, steroids, terpenoids and quinones, while cardiac glycosides, anthraquinone glycosides, steroids, terpenoids, quinones and phenol were detected in the aqueous extracts. The MICs of OSE and OMeE ranged 9.375-12.5mg/ml, and 1.875 - 3.125 mg/ml, respectively, for the test bacteria.Conclusions: The olive fruit extracts contained various bioactive components, and had excellent antibacterial activity against food-borne bacteria. The plant might be useful in the preparation of non-antibiotic antibacterial agents and in the storage of food as well

Plasmid-Encoded Multidrug Resistance of Salmonella typhi and some Enteric Bacteria in and around Kolkata, India: A Preliminary Study

The present study investigates the occurrence of R-plasmid in Salmonella typhi isolates from enteric fever cases in and around Kolkata (1991-2001), India following in vitro conjugation experiments, isolation of plasmid DNAs and agarose gel electrophoretic analysis. The multidrug resistant (MDR) S. typhi strains contained a transferable plasmid conferring resistance to ampicillin, chloramphenicol, cotrimoxazole and tetracycline. The plasmid encoding ACCoT-resistance of Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were conjugative and co-migrated with the plasmid of MDR S. typhi isolates. The antibiotic sensitive S. typhi isolates did not contain any plasmid. Thus the findings of the present study confirmed the instability of the R-plasmid in S. typhi, and that the antibiotic sensitive S. typhi strains acquired the R-plasmid from other enteric bacteria such as E. coli, K. pneumoniae and P.vulgaris to undergo a suitable adaptation for survival in the changing antibiotic environment

Enhancing chloramphenicol and trimethoprim in vitro activity by Ocimum sanctum Linn. (Lamiaceae) leaf extract against Salmonella enterica serovar Typhi

AbstractObjectiveTo evaluate the antibacterial activity of Ocimum sanctum (O. sanctum) leaf extract, alone, and in combination with chloramphenicol (C) and trimethoprim (Tm) against Salmonella enterica serovar Typhi (S. typhi).MethodsThe antibacterial activity of ethanolic extract of tulsi, O. sanctum, leaf (TLE; 500 μg) for 23 S. typhi isolates was determined following agar diffusion. The C (30 μg) and Tm (5 μg) activity alone and in combination with TLE (250 μg) was determined by disk diffusion. The zone diameter of inhibition (ZDI) for the agents was recorded, and growth inhibitory indices (GIIs) were calculated.ResultsThe S. typhi isolates (n=23), which were resistant to both C (ZDI 6 mm) and Tm (ZDI 6 mm), had TLE (500 μg) ZDIs 16-24 mm. The ZDIs of C and Tm were increased up to 15-21 mm and 17-23 mm, respectively, when TLE (250 μg) was added to the C and Tm discs. The GIIs ranged 0.789-1.235 and 0.894-1.352, due to combined activity against S. typhi isolates, of C and TLE and Tm and TLE, respectively.ConclusionsThe data suggest that TLE, in combination with C and Tm, had synergistic activity for S. typhi isolates, and hence O. sanctum is potential in combating S. typhi drug resistance, as well promising in the development of non-antibiotic drug for S. typhi infection

Plasmid-Mediated Dimethoate Degradation by Bacillus licheniformis Isolated From a Fresh Water Fish Labeo rohita

The Bacillus licheniformis strain isolated from the intestine of Labeo rohita by an enrichment technique showed capability of utilizing dimethoate as the sole source of carbon. The bacterium rapidly utilized dimethoate beyond 0.6 mg/mL and showed prolific growth in a mineral salts medium containing 0.45 mg/mL dimethoate. The isolated B licheniformis exhibited high level of tolerance of dimethoate (3.5 mg/mL) in nutrient broth, while its cured mutant did not tolerate dimethoate beyond 0.45 mg/mL and it was unable to utilize dimethoate. The wild B licheniformis strain transferred dimethoate degradation property to E coli C600 (Na(r), F(−)) strain. The transconjugant harbored a plasmid of the same molecular size (approximately 54 kb) as that of the donor plasmid; the cured strain was plasmid less. Thus a single plasmid of approximately 54 kb was involved in dimethoate degradation. Genes encoding resistance to antibiotic and heavy metal were also located on the plasmid

Antibiotic Resistance of Salmonella enterica Serovar Typhi in Kolkata, India, and In Vitro Experiments on Effect of Combined Chemotherapy

This communication states the changing patterns of Salmonella enterica serovar Typhi (S. Typhi) isolates causing enteric fever in and around Kolkata, India. Among the isolates resistance to ampicillin (A), chloramphenicol (C), cotrimoxazole (Co) and tetracycline (T) were plasmid mediated; the plasmid was unstable in S. Typhi, and the other enteric bacteria like Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were found to be the potential source of dissemination of such plasmids into S. Typhi. The infection with such S. Typhi strains were successfully treated with ciprofloxacin (Cp: MICs 0.0075–0.075 μg mL−1) and/or ofloxacin (Ofx: MICs 0.0125–0.075 μg mL−1), but in the later course, the S. Typhi strains, showing resistance to nalidixic acid, developed low level of resistance to Cp and Ofx, causing the treatment failure. Thus, the treatment regimen was shifted to the third generation cephalosporins like ceftriaxone (Ct) and cefotaxime (Cf). Keeping in mind the anticipation of development of resistance to Ct/Cf, we prepared the treatment regimen for MDR enteric fever, based on the double-drug synergy tests in vitro; Cp-gentamycin (FICI 0.121–0.216) and Cp-trimethoprim (FICI 0.14–0.483) combinations were found effective against S. Typhi isolates having decreased sensitivity to cp (MICs: 0.5–1.25 μg mL−1)

Estimating global case fatality rate of coronavirus disease 2019 (COVID-19) pandemic

Background: There is a huge global loss of lives due to COVID-19 pandemic, the primary epicentre of which is China, where the causative agent of the disease, SARS-CoV-2 was first emerged in December 2019. This study aims to explore the severity, in terms of case fatality rate (CFR), of COVID-19 pandemic. Methods: Data of ongoing COVID-19 global pandemic were retrieved from website of the WHO, and processed for the estimation of global (both including and excluding China) CFRs of COVID-19. CFRs were explored following the naive estimates, 14-day delay estimates, and linear regression model analysis, during January 25, 2020 to April 25, 2020, on weekly basis. To explore the current situation, in terms of CFR, data for the next 13 weeks (May 2, 2020 through July 25, 2020), were processed by naive and linear regression model analysis. Results: Mean CFRs, in naive estimates, were 4.59% for the world including China, and 3.62% for the world excluding China. The 14-day delay estimates of CFRs were 15.6% globally, and 21.65% in countries outside China. Following statistical model, global (both including and excluding China) CFRs were 6.81%, by naive estimates, and ~13%, by 14-day delay estimates. Global CFRs of COVID-19 during May 2, 2020 to July 25, 2020, ranged 4.1% – 7.04%, by naive estimates, and by statistical regression analysis the CFR was 3.19%. Conclusion and recommendations: The CFR might help estimate the need of up-to-date hospital supplies and other mitigation measures for COVID-19 ongoing pandemic, and therefore, instantaneous CFR estimations are recommended

Detection of transmission change points during unlock-3 and unlock-4 measures controlling COVID-19 in India

Objective: To evaluate the efficiency of unlock-3 and unlock-4 measure related to COVID-19 transmission change points in India, for projecting the infected population, to help in prospective planning of suitable measures related to future interventions and lifting of restrictions so that the economic settings are not damaged beyond repair. Methods: The SIR model and Bayesian approach combined with Monte Carlo Markov algorithms were applied on the Indian COVID-19 daily new infected cases from 1 August 2020 to 30 September 2020. The effectiveness of unlock-3 and unlock-4 measure were quantified as the change in both effective transmission rates and the basic reproduction number (R0). Results: The study demonstrated that the COVID-19 epidemic declined after implementing unlock-4 measure and the identified change-points were consistent with the timelines of announced unlock-3 and unlock-4 measure, on 1 August 2020 and 1 September 2020, respectively. Conclusions: Changes in the transmission rates with 100% reduction as well as the R0 attaining 1 during unlock-3 and unlock-4 indicated that the measures adopted to control and mitigate the COVID-19 epidemic in India were effective in flattening and receding the epidemic curve. Keywords: COVID-19 in India, epidemiological parameters, unlock-3 and unlock-4, SIR model, Bayesian inference, Monte Carlo Markov samplin

MM-GBSA and QM/MM simulation-based in silico approaches for the inhibition of Acinetobacter baumannii class D OXA-24 β-lactamase using antimicrobial peptides melittin and RP-1

The antimicrobial peptides (AMPs) have been regarded as the next generation antibiotics. This study aimed to explore the AMP inhibitors of β-lactamase enzyme employing computational biology methods. Protein-peptide docking of Acinetobacter baumannii OXA-24 class D β-lactamase with AMPs (melittin and RP-1) were performed using HawkDock webserver. The docked complexes were subjected to energy property analysis through MM/GBSA, and binding affinity (ΔG (kcal/mol)) and stability (dissociation constant, KD (M)) prediction using PRODIGY. Both the AMPs, melittin and RP-1, were well docked with A. baumannii OXA-24. The top ranked OXA-24-melittin and OXA-24-RP-1 complexes were detected on the basis of the HawkDock scores (-2974.08 and -2825.83, respectively), thereafter by rescoring with MM/GBSA-based binding free energy (BFE) of -33.85 and -29.29 kcal/mol, respectively. The PRODIGY-based respective BFE (-8.0 and -10.0 kcal/mol) and KD (1.4 × 10-6 and 5 × 10-8 M) of the complexes revealed excellent protein-peptide binding affinity and complex stability. The iMODS-based molecular dynamic simulation authenticated the stability and molecular motion flexibility of the protein-peptide complexes. The quantum mechanics and molecular mechanics energy estimated using density-functional theory with CP2K software, for the electrostatic interaction of OXA-24-RP-1 (-218862.95 kcal/mol), was more favourable than the H-bonded interaction of OXA-24-melittin (-200620.21 kcal/mol), nevertheless both the peptides were found effective to inhibit OXA-24. Both the AMPs had toxicity profiles within the acceptable limits as predicted through pkCSM. Current findings indicate the potential supplement or replacement of conventionally used antibiotics with melittin and RP-1 to treating or averting A. baumannii infection by escaping the β-lactamases-mediated resistance

Coriander (Coriandrum sativum L.) essential oil: Chemistry and biological activity

Coriandrum sativum L. (C. sativum) is one of the most useful essential oil bearing spices as well as medicinal plants, belonging to the family Umbelliferae/Apiaceae. The leaves and seeds of the plant are widely used in folk medicine in addition to its use as a seasoning in food preparation. The C. sativum essential oil and extracts possess promising antibacterial, antifungal and anti-oxidative activities as various chemical components in different parts of the plant, which thus play a great role in maintaining the shelf-life of foods by preventing their spoilage. This edible plant is non-toxic to humans, and the C. sativum essential oil is thus used in different ways, viz., in foods (like flavouring and preservatives) and in pharmaceutical products (therapeutic action) as well as in perfumes (fragancias and lotions). The current updates on the usefulness of the plant C. sativum are due to scientific research published in different web-based journals