Microbiology Flashcards
Which colour are gram positive and negative organism stained?
Gram positive - purple
Gram negative - pink
Why are gram positive organisms stained purple?
Gram negatives have a thick peptidoglycan layer in the cell wall, which retains the crystal violet in the stain
What are the different shapes of bacteria?
Cocci
Bacilli
Spiral
What are cocci in strips, and what are cocci in clusters?
Strips - streptococci
Clusters - staphylococci
How do bacteria replicate?
Binary fission
Which bacteria secrete endotoxin and exotoxin?
Endo - gram negative
Exo - gram positive
What is an opportunistic pathogen?
One that usually causes problems in immunocompromised patients
What is pathogenicity?
Ability of an organism to cause disease/infect host
What is virulence?
Degree of pathogenicity/severity of disease in host
Are staph and strep gram positive or negative?
Positive
Are staph and strep aerobic or anaerobic?
Aerobic
Which test is done for staph, and which for strep?
Staph - coagulase test
Strep - haemolysis
What are examples of alpha haemolytic strep?
Strep pneumoniae
Strep viridans
What are examples of beta haemolytic strep?
Group A strep
Group B strep
What are examples of non-haemolytic (gamma) strep?
Enterococcus
What are coagulase positive staph?
Just staph aureus
What does staph aureus look like on haemolysis?
Golden cocci in clusters
What are coagulase negative staph?
Staph epidermidis
What does strep pneumoniae cause?
Pneumonia
Meningitis
What does strep viridans cause?
Endocarditis
What does group A strep cause?
Throat and skin infection
What does staph aureus cause?
Wound or skin infection
Lots more
What does staph epidermidis cause?
Skin commensal
IV line infection
Describe clostridium sp
gram positive anaerobic bacilli
What is alpha haemolysis?
Partial haemolysis - green
What is beta haemolysis?
Complete haemolysis
What is gamma haemolysis?
No haemolysis
What are gram negative strict aerobic bacilli?
Legionella
Pseudomonas aeruginosa
What are gram negative aerobic cocci (diplococci)?
Neisseria gonorrhoea
Neisseria meningitides
What are gram negative aerobic bacilli?
Haemophilus influenzae
What are gram negative aerobic coliform (large bacilli)?
E coli
Klebiella
What are microaerophilic gram negative bacilli?
Campylobacter
Helicobacter (spiral)
What is the first line treatment of coliforms?
Gentamicin
What is the process of viral replication?
Attachment Entry Uncoating Nucleic acid and protein synthesis Assembly Release
What do bactericidal and bacteriostatic mean?
Bactericidal - kill bacteria
Bacteriostatic - inhibit bacterial growth
What are the sites that antibiotics can work on?
Cell wall
Ribosome
DNA
Which antibiotics work on the cell wall?
Penicillins
Cephalosporins (e.g. ceftriaxone)
Glycopeptides (e.g. vancomycin)
All bactericidal
When is flucloxacillin used?
Skin and soft tissue infection, wound infection in adults
How do penicillins and cephalosporins work on the cell wall?
Stop cross linking and cause autolysins to degrade cell wall
Are penicillins safe in pregnancy?
Yes
Which antibiotics act on ribosomes?
Macrolides (e.g. erythromycin)
Tetracyclines (e.g. doxycycline)
Aminoglycosides (e.g. gentamicin)
Which organisms does gentamicin generally act against?
Gram negative
Which antibiotics act on bacterial DNA?
Metronidazole
Trimethoprim
Fluroquinolones
What are the 4Cs?
Cephalosporins
Co-amoxiclav
Ciprofloxacin
Clindamycin
