clostridium, bacillus anthracis, francisella + vibrio

clostridium facts

Gram-positive, anaerobic, spore-forming rods. The big themes are exotoxins and endospore formation

clostridium disease

diseases range from botulism and tetanus to gas gangrene and antibiotic-associated colitis

group includes C. bot, tet, perf, diff

clostridium human impact

clostridium host rxn

host reaction depends on the species. In C. difficile infection, the colon shows strong inflammation and tissue injury. In toxin-mediated diseases like botulism and tetanus, the host pathology comes mainly from toxin action.

clostridium function

Disease is caused mainly by powerful exotoxins or, for C. difficile, by colonization after microbiota disruption plus toxin-mediated intestinal damage. C. difficile spores germinate in response to bile salts such as taurocholate.

clostridium research paper

whether enhanced trehalose metabolism contributed to the success of epidemic C. difficile strains

clostridium big question

whether adaptation to low levels of trehalose helped hypervirulent strains expand and become more pathogenic

clostridium solution

The authors used gene-expression assays, strain comparisons, genetics, and infection models to show that epidemic strains respond to and use low trehalose more effectively

bacillus info

a Gram-positive, spore-forming bacterium that causes anthrax

bacillus disease

Anthrax can be cutaneous, inhalational, or gastrointestinal

bacillus human impact

inhalational disease can be severe and because the organism is historically important in microbiology and biodefense.

bacilllus function

Its major virulence factors are the capsule and anthrax toxin. The toxin components are protective antigen, edema factor, and lethal factor. Toxin genes are on pXO1 and capsule genes are on pXO2

bacillus host rxn

early innate immune targeting and, in severe disease, widespread systemic damage

bacillus paper

investigated the siderophore petrobactin and asked whether it does more than just collect iron

bacillus big question

whether petrobactin contributes not only to iron acquisition but also to sporulation and stress protection

bacillus solution

authors used mutants, sporulation assays, and fluorescence microscopy reporters to show that petrobactin contributes to late-stage physiology and sporulation success

francisella info

a Gram-negative coccobacillus with a very low infectious dose.

zoonotic

francisella disease

tularemia; flu like symptoms that turn into severe symptoms such as skin ulcers, diarrhea, vomiting

francisella human impact

hard to diagnose bc it acts like the flu

francisella function

 survives in macrophages, avoids early immune recognition with unusual LPS and stealthy surface properties, escapes from phagosomal killing, and replicates intracellularly

francisella host rxn

innate immune activation, but the pathogen is especially good at hiding from or delaying early immune recognition

francisella paper

host nutrient exploitation by francisella

francisella big question

how Francisella gains access to metabolizable host nutrients needed for intracellular growth

francisella solution

authors used confocal microscopy, metabolic inhibitors, Western blotting, and AMPK-deficient cells to show that Francisella uses AMPK activation and host lipolysis to exploit lipid droplets

vibrio info

Gram-negative, comma-shaped rod with a polar flagellum that causes cholera

vibrio disease

Cholera causes severe secretory diarrhea with rice-water stool and can rapidly cause life-threatening dehydration

vibrio human impact

human impact is especially large during outbreaks linked to water and sanitation failures

vibrio function

V. cholerae colonizes the small intestine and causes disease mainly through cholera toxin, which raises cAMP and drives massive water and ion secretion. Another important virulence factor is TCP, the toxin-coregulated pilus, which helps attachment and phage interactions.

vibrio host rxn

rapid fluid loss and dehydration rather than extensive tissue destruction

vibrio paper

the CBASS anti-phage defense system in V. cholerae

vibrio big question

how the CBASS defense system is regulated and activated.

vibrio solution

authors used mutant comparisons, growth/sensitivity assays, signaling analysis, and gene-expression work to connect CBASS function to quorum sensing and folate depletion