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Staphylococcus aureus, an opportunistic pathogen, can root several infections viz skin and tissue infections, bacteraemia, food poisoning, pneumonia, and many other clinical conditions with some variations of virulence factors. In treatment of infections, caused by this Gram-positive pathogen, several antibiotics are being used importantly Methicillin and Vancomycin. This pathogen has high capability of antibiotic resistance development and had evolved new strains such as Methicillin-resistant Staphylococcus aureus (MRSA), and Vancomycin-resistant Staphylococcus aureus (VRSA). Meta-analysis in Ethiopia showed that pooled prevalence of MRSA in environment, food, animal, and human was 54%, 77%, 15%, and 38% respectively (2022). Risk of MRSA isolates from burn ICU was 55 % higher (2018). In Bangladesh 37.1% isolates from frozen meat chicken (2021) were identified as MRSA. This problem is being dealt with a novel drug called Linezolid which has been proved effective against both MRSA and VRSA. Exacerbating the situation, this pathogen has shown resistance against this unprecedented drug by means of a number of drug resistance mechanisms. Its prevalence has been reporting since the adoption of the drug, but with a minute ratio at one time/place to the very high percentage at another time/place. This inconsistent prevalence must not be ignored, and its surveillance should be augmented as antibiotic treatment is critical for fighting against microbial infections. This review highlights the worldwide reports in which Staphylococcus aureus of either wildtype or Methicillin or Vancomycin resistance that have shown resistance to Linezolid drug for the past 2 decades. At the same time where incidences of Linezolid Resistant Staphylococcus aureus (LRSA) indications are reporting, there is a call for comprehensive strategies to overcome this challenge of antibiotic resistance. [ABSTRACT FROM AUTHOR]

Drinking water with excessive concentration levels of arsenic (As) is a great threat to human health. A hydrochemical approach was employed in 50 drinking water samples (collected from Kushtia district, Bangladesh) to examine the occurrence of geogenic As and the presence of trace metals (TMs), as well as the factors controlling As release in aquifers. The results reveal that the drinking water of shallow aquifers is highly contaminated by As (6.05–590.7 μg/L); 82% of samples were found to exceed the WHO recommended limit (10 μg/L) for potable water, but the concentrations of Si, B, Mn, Sr, Se, Ba, Fe, Cd, Pb, F, U, Ni, Li, and Cr were within safe limits. The Ca-HCO 3 -type drinking water was identified as having high contents of As, pH and HCO 3 −, a medium-high content EC, and low concentrations of NO 3 −, SO 4 2−, K+, and Cl−. The significant correlation between As and NO 3 − indicates that NO 3 − might be attributed to the use of phosphate fertilizers and a factor responsible for enhancing As in aquifers. The study also reports that the occurrence of high As and the presence of TMs in drinking water may be a result of local anthropogenic activities, such as irrigation, intensive land use and the application of agrochemicals. The insignificant correlation between As and SO 4 2− demonstrated that As is released from SO 4 2− minerals under reducing conditions. An elevated pH value along with decoupling of As and HCO 3 − plays a vital role in mobilizing As to aquifer systems. Moreover, the positive relationship between As and Si indicated that As is transported in the biogeochemical environment. The reductive suspension of Mn(IV)-oxyhydroxides also accelerated the As mobilization process. Over exploitation of tube-well water and the competitive ion exchange process are also responsible for the release of As in aquifers. • Analyzed 82% drinking water contained As more than WHO recommended limit. • Occurrence of other trace metals was within the safe limit. • Ca-HCO 3 -type drinking water was identified having high As, pH and HCO 3 −. • Intensive land use, agrochemicals usage and irrigation are responsible for high As. • As is mobilized in biogeochemical and reduction environment with ion exchange process. [ABSTRACT FROM AUTHOR]

Groundwater with an excessive level of Arsenic (As) is a threat to human health. In Bangladesh, out of 64 districts, the groundwater of 50 and 59 districts contains As exceeding the Bangladesh (50 μg/L) and WHO (10 μg/L) standards for potable water. This review focuses on the occurrence, origin, plausible sources, and mobilization mechanisms of As in the groundwater of Bangladesh to better understand its environmental as well as public health consequences. High As concentrations mainly was mainly occur from the natural origin of the Himalayan orogenic tract. Consequently, sedimentary processes transport the As-loaded sediments from the orogenic tract to the marginal foreland of Bangladesh, and under the favorable biogeochemical circumstances, As is discharged from the sediment to the groundwater. Rock weathering, regular floods, volcanic movement, deposition of hydrochemical ore, and leaching of geological formations in the Himalayan range cause As occurrence in the groundwater of Bangladesh. Redox and desorption processes along with microbe-related reduction are the key geochemical processes for As enrichment. Under reducing conditions, both reductive dissolution of Fe-oxides and desorption of As are the root causes of As mobilization. A medium alkaline and reductive environment, resulting from biochemical reactions, is the major factor mobilizing As in groundwater. An elevated pH value along with decoupling of As and HCO 3 − plays a vital role in mobilizing As. The As mobilization process is related to the reductive solution of metal oxides as well as hydroxides that exists in sporadic sediments in Bangladesh. Other mechanisms, such as pyrite oxidation, redox cycling, and competitive ion exchange processes, are also postulated as probable mechanisms of As mobilization. The reductive dissolution of MnOOH adds dissolved As and redox-sensitive components such as SO 4 2− and oxidized pyrite, which act as the major mechanisms to mobilize As. The reductive suspension of Mn(IV)-oxyhydroxides has also accelerated the As mobilization process in the groundwater of Bangladesh. Infiltration from the irrigation return flow and surface-wash water are also potential factors to remobilize As. Over-exploitation of groundwater and the competitive ion exchange process are also responsible for releasing As into the aquifers of Bangladesh. • Intensive land use, agrochemicals usage and irrigation are responsible for high As. • Elevated As concentrations mainly occurred in shallow Holocene alluvial aquifers. • Strong reducing condition and moderate alkalinity facilitated As release process. • Evaporation was not an important factor responsible for As enrichment. • As is mobilized in biogeochemical and reduction environment with ion exchange process. [ABSTRACT FROM AUTHOR]