Update on molecular diversity and multipathogenicity of staphylococcal superantigen toxins

Staphylococcal superantigen(SAg)toxins are the most notable virulence factors associated with Staphylococcus aureus,which is a pathogen associated with serious community and hospital acquired infections in humans and various diseases in animals.Recently,SAg toxins have become a superfamily with 29 types,including staphylococcal enterotoxins(SEs)with emetic activity,SE-like toxins(SEIs)that do not induce emesis in primate models or have yet not been tested,and toxic shock syndrome toxin-1(TSST-1).SEs and SEIs can be subdivided into classical types(SEA to SEE)and novel types(SEG to SEIY,SE01,SE02,SEI26 and SEI27).The genes of SAg toxins are located in diverse accessory genetic elements and share certain structural and biological properties.SAg toxins are heat-stable proteins that exhibit pyrogenicity,superantigenicity and capacity to induce lethal hypersensitivity to endotoxin in humans and animals.They have multiple pathogenicities that can interfere with normal immune function of host,increase the chances of survival and transmission of pathogenic baaeria in host,consequently contribute to the occurrence and development of various infeaions,persistent infeaions or food poisoning.This review focuses on the following aspeas of SAg toxins:(1)superfamily members of classic and novelty discovered staphylococcal SAgs;⑵diversity of gene locations and molecular structural characteristics;(3)biological characteristics and activities;(4)multi-pathogenicity of SAgs in animal and human diseases,including bovine mastitis,swine sepsis,abscesses and skin edema in pig,arthritis and septicemia in poultry,and nosocomial infections and food-borne diseases in humans.

A Study of Prevalence and Pathogenic Activity of Bacteria in the Air of Dhaka City and Their Antimicrobial Resistance Pattern

Bangladesh composes the most polluted air with Dhaka securing the top position. The purpose of the study is the enumeration of the prevalence of pathogenic bacteria in Dhaka city’s air and their antibiotic susceptibility to the common antibiotics. For the sample collection, different selective media was exposed in air where the highest and lowest CFU was 137 and 1 respectively. Pathogens were screened through Hemolysis, DNase and Coagulase test and identified by 16s rRNA sequencing followed by antibiotic susceptibility test. 16s rRNA sequencing revealed that the organisms were Bacillus altitudinis strain 41KF2bT.28, Bacillus licheniformis strain QMA46-2, Bacillus altitudinis, Bacillus pumilis strain BJ-DEBCR-34, Staphylococcus aureus strain TPS3156, Bacillus sp CO16, Pseudomonas sp strain 96LC22 and Shigella dysenteriae strain ATCC 13313. Shigella dysenteriae, Staphylococcus aureus were 81.81% and 54.54% resistant to the antibiotics. Whole-genome sequencing would help to observe mutations in the traits as changes in hemolytic activity were found during pathogenecity tests.