A convergent evolutionary pathway attenuating cellulose production drives enhanced virulence of some bacteria.

Bacteria adapt to selective pressure in their immediate environment in multiple ways. One mechanism involves the acquisition of independent mutations that disable or modify a key pathway, providing a signature of adaptation via convergent evolution. Extra-intestinal pathogenic Escherichia coli (ExPEC) belonging to sequence type 95 (ST95) represent a global clone frequently associated with severe human infections including acute pyelonephritis, sepsis, and neonatal meningitis. Here, we analysed a publicly available dataset of 613 ST95 genomes and identified a series of loss-of-function mutations that disrupt cellulose production or its modification in 55.3% of strains. We show the inability to produce cellulose significantly enhances ST95 invasive infection in a rat model of neonatal meningitis, leading to the disruption of intestinal barrier integrity in newborn pups and enhanced dissemination to the liver, spleen and brain. Consistent with these observations, disruption of cellulose production in ST95 augmented innate immune signalling and tissue neutrophil infiltration in a mouse model of urinary tract infection. Mutations that disrupt cellulose production were also identified in other virulent ExPEC STs, Shigella and Salmonella, suggesting a correlative association with many Enterobacteriaceae that cause severe human infection. Together, our findings provide an explanation for the emergence of hypervirulent Enterobacteriaceae clones.

Presence of heavy metals in over the counter teeth whitening products- An evaluative study.

Background: Dentistry plays a crucial role in shaping the facial aesthetics of a person and thus boosts self-esteem. Tooth discolouration is one of the significant cosmetic problems and hence, many teeth whitening products are widely used for discolouration. However, these products may have heavy metals or chemicals that can affect the tooth and other organs. Aim: The aim is to estimate the amount of heavy metals present in teeth whitening products available for purchase over-the-counter in the pharmacies. Materials and Method: A cross-sectional study of teeth whitening products available Over the Counter (OTC) in pharmacies in Chennai and adjoining districts of Tamil Nadu was conducted during the period from December 2019 to February 2020. The Flame Atomic Absorption Spectrometry (FAAS) method was used to measure the heavy metals such as inorganic lead, chromium, cobalt, arsenic, cadmium, nickel and mercury in the products. Results: We collected 39 products and finalized nine for analysis. These products were available as tablet (n = 1), liquids (n = 2) and powders (n = 6). All products were mentioned as herbal or natural. Three products contained inorganic lead levels in parts per million (ppm) of 759 (product 2); 39.4 (product 3) and 28.1 (product 7), way above the permitted levels. None of the other heavy metals were detected from these products. Conclusion: After analysis with the FAAS method, inorganic lead over and above the permissible levels was observed. Dental professionals and community need to be aware of the availability of such products and its detrimental effects on oral and general health.

Zona pellucida glycoproteins based immunocontraceptive vaccines: strategies for development and their applications.

The mammalian oocyte is surrounded by an extra-cellular matrix, the zona pellucida (ZP), composed of three major glycoproteins (ZP1, ZP2 and ZP3). The ZP glycoproteins, by virtue of their tissue specificity and critical role during mammalian fertilization, have emerged as potential candidate antigens for the development of an immunocontraceptive vaccine. Molecular characterization of ZP glycoproteins from several species, reveals a variable degree of homology among the deduced primary amino acid sequences, which provided an opportunity to undertake active immunization studies in heterologous animal models. Active immunization of various animal species with either native ZP glycoproteins or those obtained by recombinant DNA technology led to the inhibition of fertility. Thus ZP glycoproteins based immunocontraceptive vaccines offer an attractive proposition for controlling wild life population. To make it a practical proposition, additional research inputs are required to optimize and devise novel strategies for vaccine delivery. Observed ovarian dysfunction, often associated with immunization by ZP glycoproteins is one of the major stumbling blocks for their use in humans. Ongoing studies to delineate appropriate B cell epitopes of ZP glycoproteins that are devoid of oophoritogenic T-cell epitopes, which will inhibit fertility without concomitant oophoritis, will be critical to determine their feasibility for human use.