Microbiology Flashcards
Which are the two amino acids which contain sulphur?
Methionine and Cysteine
Which has a thicker peptidoglycan layer - gram positive or negative bacteria?
Gram positive bacteria.
Which causes the greatest number of deaths - gram positive, negative or mycobacteria?
Mycobacteria
Which bacteria causes necrotizing fasciitis?
Streptococcus pyogenes
Is Neisseria gram positive or gram negative?
Gram negative bacteria
Name x3 extracellular bacteria
Streptococcus, Staphylococcus, Neisseria
Does Listeria have a flagellum?
No; it only uses invasion as a method of entry through actin polymerisation.
What are the four mechanisms by which antimicrobial resistance can occur?
Altered target site, inactivation of antibiotic (beta lactamase), altered metabolic pathways, decreased drug accumulation (quicker efflux).
What is the method of action of erythromycin and streptomycin?
Inhibits Protein Synthesis.
What is the method of action of cephalosporins?
Inhibits cell wall synthesis.
What type of antibiotic is Prontosil?
A sulphonamide antibiotic.
Prontosil is only effective against which bacteria type?
Gram positive bacteria.
What is the difference between bactericidal and bacteriostatic?
Bactericidal = kills bacteria Bacteriostatic = stops bacterial growth
What are selection pressures?
External agents which affect an organism’s ability to survive in a given environment. Positive selection pressure = helps bacteria survive as they outcompete antibiotics.
What type of selection pressure will actually help the resistant bacteria survive?
Positive selection pressure.
Name one of the more toxic antibiotics.
Vancomycin
How does Rifampicin target bacteria?
Targets RNA polymerase. Makes secretions RED.
What is the mechanism of Vancomycin?
Inhibits cell wall synthesis.
Name x3 drugs which inhibit cell wall synthesis in bacteria.
Penicillin, Vancomycin and Cephalosporins.
Name x3 drugs which inhibit protein synthesis
Erythromycin, Streptomycin and Chloramphenicol.
Name x2 drugs which inhibit DNA replication and DNA transcription
Quinolone and Rifampicin.
Penicillins are effective against both gram negative and gram positive bacteria. True or false.
False. Penicillins are only effective against gram positive bacteria.
Describe the process of Transduction
Horizontal gene transfer. Phage mediated DNA transfer.
Give an example of a commensal organism.
Lactobacillus in vagina and gastrointestinal tract.
