microbiology Flashcards
what colour do gram +ive stain and why
purple, thick peptidoglycan layer
what colour do gram -ive stain and why
pink, think peptidoglycan layer
exotoxin is produced by..
gram +ive, produced inside and released
endotoxin is produced by…
gram -ive, part of the cell wall
what shape is staphylococcus
gram +ive clusters of balls
what is the test for staph A
coagulase test, +ive = staph A, -ive = another staph
what is streptococcus
gram +ive chain of balls
what does alpha heamolysis show
partial, strep pneumonia and viridans
what does beta heamolysis show
complete, group A (pyogens) and group B
what does gamma heamolysis show
none, is enterococcus
what are enterococci
chained cocci, gram +ive, often found in the gut as commensal bacteria but can cause UTI’s
descrive gram -ive cocci
diplococci (pairs) and are aerobic
what are the 2 main types of -ive cocci
neisseria meningitidis and gonorrhoea
describe coliforms of the GI tract
grow best aerobically but can be anaerobic. are gram -ive bacilli commensal bacteria. can cause infection in sterile places eg UTI
name common GI coliforms
E. coli, klebsiella, proteus
name gut pathogens
salmonella, shigella, E. coli 0157 (verotoxin)
what is the antibiotic for GI coliforms and and pathogens
gentamicin
what are strict aerobes, name some
need O2, pseudomonas (-ive bacilli), legionella (-ive bacilli)
what are strict anaerobes, name some
need CO2: clostridia - produces spores and can cause C diff (+ive bacilli), bacteriodes (-ive bacilli)
how do you treat anaerobes
metronidazole
name some gram -ive bacilli
camplobacter (food poisoning), H pylori (gastritis), H. influenza
what are the 2 types of fungal infections
yeast eg candida, moulds that produce spores eg aspergillus
name a protozoan
malaria
describe the virus structue
DNA or RNA, protein coat surrounded by envelope with protein spikes
describe how viruses infecta cell
virus uncoats and nucleic acid is released to produce viral proteins, they are released via budding or lysis
what does cytotoxic T lymphocyte do in virus infection
recognised foreign proteins and induces apoptosis
what does IgG and IgM do
neutralise and prevent viruses infecting other cells
once viruses had infected can they become reactivated
yes - eg herpes
name some common viral infections
HIV, hep C, herpes
what do bactericidal drugs do
kill bacteria
what do bacteriostatic drugs do
inhibit bacterial growth
what antibiotics attack the cell wall
penicillin, cephalosporins, glycopeptides
what are the 3 types of penicillin and how must they be administered
benzylpenicillin (pen G, IV) phenoxymethyl penicillin (pwn V, oral) benzathine penicillin (IM)
describe the gram +ive penicillin
flucloxacillin for staph and strep
describe the gram +ive/-ive penicillin
amoxicillin (destroyed by B-lactamase) and co-amoxiclav (everything but MRSA and pseudomonas)
describe the gram -ive penicillin
temicillin, resistant to B-lactamase, acts on coliforms eg e. coli
describe cephlasporins
excreted via kidneys and urine, safe in pregnancy, bactericidal, can promote C diff
descrive glycopeptides
excreted in kidneys and kidneys, bactericidal resistant to B-lactamase, gram +ive eg vancomycin
describe penicillin
safe in pregnancy, people can be hypersensitive, excreted in kidneys, bactericidal
name the 3 antibiotics that attack ribosomes
aminoglycosides, tetracyclines, macrolides
describe aminoglycocides
bacteriocidal, gram -ive eg gentamycin, excreted in urine and can damage kidneys, not safe in pregnancy
describe tetracyclines
broad spectrum, bacteriostatic
describe macrolides
erythrmoycin, clarithromycin, azithromycin, used for pen allergies, excreted via liver, erythromycin safe in pregnancy
name the 3 nucleic acid antibiotics
metronidazole, trimethroprim, fluoroquinolones
describe metronidazole
anaerobic infections eg clostridium and bacteroides, dafe in pregnancy, bactericidal
describe trimethroprim
if you add sulphonamide = co-trimoxazole, can cause UTI’s, bacteriostatic
describe fluroquinolones
gram +ive or -ive, bacteriocidal, excreted via urine, levofloxacin and ciprofloxacin
what 4 C’s can cause C diff
co-amoxiclac, cephlosporins, clindomycin and ciprofloxacin
what 5 I’s spread infection
inhalation, ingestion, intercourse, inoculation, mother to Infant
how does the body cause a fever
antigen interacts with macrophages which release cytokines, they travel to hypothalamus and stimulate PGE, PGE increases body temp –> shiver
