A comparative analysis of the second and third wave of the Covid-19 pandemic: an experience from a tertiary care hospital in Western India.

Introduction. As the world was still recovering from the 2020 pandemic, the devastating impact of Covid-19 driven by the Delta variant shook the world in 2021. As the second wave was declining, there was an unusual surge in Covid-19 positive cases by the end of 2021 which led to global concern about the change in virus characteristics.Hypothesis/gap statement. Whole genome sequencing is critical for understanding a rapidly progressing pandemic.Aim. To provide an insight into the major differences encountered in the changing characteristics between the second and third waves of the pandemic at a tertiary care hospital in India.Methods. A retrospective observational cohort analysis was conducted on Covid-positive patients during the second wave of the Covid-19 pandemic (from March 2021 to April 2021) and the third wave of the Covid-19 pandemic (from December 2021 to January 2022).Results. Out of 303 Covid-19 positive cases, 52 samples were tested by whole genome sequencing during the second wave and 108 during the third wave. A decline of 18.5 % was observed in the case fatality rate from the second wave to the third wave. There was a 5 % decline in the number of patients admitted with ARDS and a 16.3 % decline in the number of patients with co-morbidities.In total, 51.9 percent of cases were due to the Delta variant during the second wave and 95 percent due to the Omicron variant during the third wave. We found that 36.5 % of Covid-positive patients during the second wave had been vaccinated compared to 40 % in the third wave.Conclusion. Whole genome sequencing of clinical samples from a wide range of individuals during a viral epidemic will enable us to develop a more rapid public health response to new variants and identify the required vaccine modifications more quickly.

SARS-CoV-2 variants: Impact on biological and clinical outcome.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) that was first identified in December 2019, in Wuhan, China was found to be the etiological agent for a novel respiratory infection that led to a Coronavirus Induced Disease named COVID-19. The disease spread to pandemic magnitudes within a few weeks and since then we have been dealing with several waves across the world, due to the emergence of variants and novel mutations in this RNA virus. A direct outcome of these variants apart from the spike of cases is the diverse disease presentation and difficulty in employing effective diagnostic tools apart from confusing disease outcomes. Transmissibility rates of the variants, host response, and virus evolution are some of the features found to impact COVID-19 disease management. In this review, we will discuss the emerging variants of SARS-CoV-2, notable mutations in the viral genome, the possible impact of these mutations on detection, disease presentation, and management as well as the recent findings in the mechanisms that underlie virus-host interaction. Our aim is to invigorate a scientific debate on how pathogenic potential of the new pandemic viral strains contributes toward development in the field of virology in general and COVID-19 disease in particular.

Efficiency of Biosynthesized Silver and Zinc Nanoparticles Against Multi-Drug Resistant Pathogens.

Biosynthesis of metallic nanoparticles has acquired particular attention due to its economic feasibility, low toxicity, and simplicity of the process. In this study, extracellular synthesis of silver and zinc nanoparticle was carried out by Pseudomonas hibiscicola isolated from the effluent of an electroplating industry in Mumbai. Characterization studies revealed synthesis of 40 and 60 nm nanoparticles of silver (AgNP) and zinc (ZnNP), respectively, with distinct morphology as observed in TEM and its crystalline nature confirmed by XRD. DLS, zeta potential, NTA, and FTIR studies further characterized nanoparticles giving data about its size, stability, and functional groups. Considering the toxicity of nanoparticles the evaluation of antimicrobial activity was studied in the range of non-toxic concentration for normal cell lines. Silver nanoparticles were found to be the most effective antimicrobial against all tested strains and drug-resistant clinical isolates of MRSA, VRE, ESBL, MDR, Pseudomonas aeruginosa with MIC in the range of 1.25-5 mg/ml. Zinc nanoparticles were found to be specifically active against Gram-positive bacteria like Staphylococcus aureus including its drug-resistant variant MRSA. Both AgNP and ZnNP were found to be effective against Mycobacterium tuberculosis and its MDR strain with MIC of 1.25 mg/ml. The synergistic action of nanoparticles assessed in combination with a common antibiotic gentamicin (590 µg/mg) used for the treatment of various bacterial infections by Checker board assay. Silver nanoparticles profoundly exhibited synergistic antimicrobial activity against drug-resistant strains of MRSA, ESBL, VRE, and MDR P. aeruginosa while ZnNP were found to give synergism with gentamicin only against MRSA. The MRSA, ESBL, and P. aeruginosa strains exhibited MIC of 2.5 mg/ml except VRE which was 10 mg/ml for both AgNPs and ZnNPs. These results prove the great antimicrobial potential of AgNP and ZnNP against drug-resistant strains of community and hospital-acquired infections and opens a new arena of antimicrobials for treatment, supplementary prophylaxis, and prevention therapy.

Evaluation of HiaureusTM Coagulase Confirmation Kit in Identification of Staphylococcus aureus.

INTRODUCTION: Staphylococcus aureus is a facultative anaerobic Gram positive coccal bacterium whose incidence ranges to different infections. It is a cause of various uncomplicated skin infections, abscesses, septicaemia/bacteraemia, gastroenteritis, endocarditis, toxic shock syndrome and food intoxications. Various methods with varied time, sensitivities, specificities and costs are available, but may not be used as a reliable test for the identification and differentiation of S. aureus. Therefore, there is a need to evaluate newer tests. AIM: To compare the conventional tests with a commercial available kit for reliable, cost effective identification and confirmation of S. aureus. MATERIALS AND METHODS: The current prospective study was conducted in the Department of Clinical Pathology, Haffkine Institute for a period of six months. A total of 341 clinical isolates of staphylococci isolated from pus, urine, blood culture and sterile body fluids were subjected to conventional tests like Tube Coagulase Test (TCT) using Rabbit Plasma (RP) and Human Plasma (HP), culture media such as Mannitol Salt Agar (MSA) and Deoxyribonuclease (DNase) media in parallel to HiaureusTM Coagulase Confirmation Kit (HACCK), a commercially available kit for identification of S. aureus. Amplification of the femA gene was used as a comparative reference point test to calculate the sensitivity, specificity and concordance values of the conventional tests. RESULTS: Amongst the coagulase based tests, HACCK was 100% sensitive and specific. The TCT using RP was 98.58% sensitive while TCT using HP was less sensitive (95.37%). A total of 100% specificity was observed for TCT using RP while TCT using HP was 96.68% specific. The MSA and DNase media were 97.86% vs 96.44% and 96.67% vs 91.67% sensitive and specific respectively. The combination tests had varying sensitivity and specificity ranges. The HACCK demonstrated 100% concordance with femA amplification and was labelled as an ideal perfect test (κ=1) with MSA as an alternative test for S. aureus identification. CONCLUSION: The HACCK can be used as an exclusive, reliable and cost effective test for identification of S. aureus. Alternatively, in view of the cost factor MSA either as a single test or in combination with TCT using HP could be used as screening tests and confirm discordant results with HACCK.