Flashcards in Microbiology Deck (260)
Treatment of COPD infection?
amoxicillin with clavulanate, tetracycline, trimethoprim
Likely organisms to cause pneumonia?
Treatment of pneumonia?
B lactams, erythromycin
Likely organisms in a wound?
staph aureus, strep pyogenes, anaerobes
Treatment of a wound?
flucloxacillin, erythromycin, co-amoxiclav
How can antibiotics be misused?
use broad spectrum when narrow are just as effective, treat for too long, treating with IV when oral is as effective, using combination when one is a effective, failure to use a dose appropriate for renal and hepatic function, using antibiotics for highly unlikely organisms, failure to step down organism once known
Dangers of antibiotic misuse?
adverse drug reactions which increases with multiple drug prescribing, harmful drug interactions, errors in prescribing monitoring, can cause super infection and antibiotic resistance
What is the difference between bacteriostatic and bactericidal?
bacteriostatic - prevents bacteria growth by inhibiting protein synthesis, DNA replication or metabolism, reduces toxin production
bactericidal - kills bacteria by inhibiting cell wall synthesis, good if poor penetration
Why do antimicrobials want a large MIC?
minimum inhibitory conc - to attach to more binding sites to inhibit bacteria
What factors must be considered in drug administration choice?
will it penetrate, pH of the site, is antimicrobial lipid soluble
How do bacteria resist antimicrobials?
change antimicrobial site by changing binding site configuration, destroy or inactivate the antimicrobal, prevent antimicrobial etery by modifying bacterial membrane porin channel site, numbers or selectivity, remove antimicrobial from bacterium using export pumps
How does bacterial resistance develop?
intrinsically naturally resistant so subpopulations can develop it too
acquired - not all subpopulations are equally resistant
Gram positive antimicrobial resistant bacteria?
Gram negative antimicrobial resistant bacteria?
B lactamases, ESBL, carbapenenases, AmpC B lactamase resistant
What methods can be used to test antimicrobial resistance?
antimicrobial sensitivity testing, chromogenic plates, mechanism specific tests, genotypic methods, breakpoint plates
What is a pathogen?
an organism that is capable of causing disease
What is a commensal?
an organism which colonises the host but causes disease in normal circumsatnces
What is an opportunist pathogen?
only causes disease if host defences are compromiseed
What is pathogenicity?
the degree to which an organism is pathogenic
What is asymptomatic carnage?
when a pathogen is carried harmlessly at a tissue site where it causes no disease
Components to a bacteria?
capsule, cell wall, outer and inner membrane, pili, chromosome, may also have plasmids
What is the function of a capsule on bacteria?
super coated so difficult for phagocytes to ingest
What is used to stain acid fast bacilli?
Ziehl Neelsen stain
What colour is a gram positive stain?
What colour is a gram negative stain?
What is the difference in gram positive and negative cell wall composition?
n = more lipopolysaccharide, with lipoprotein, less peptidoglycan with inner and out membrane
p = more peptidoglucan with lipoteichoic acid and cytoplasmic membrane
What is the idea bacterial environment?
What are the 4 stages of bacterial life?
lag, exponential (log), stationary, death
What is endotoxin?
component of outer membrane of bacteria produced by lipopolysaccharide gram negative, has non specific action, stable effect of heat, weak antigenicity and not convertable to toxoid