rational atb use Flashcards
antimicrobial agent
chemical compound that kills or inhibits the growth of a microorganism
antibiotic
only natural compound of microbial origin
antimicrobial resistance
bacterial ability to survive antimicrobial treatment
quantitative property
rational antimicrobial use
suggests a responsible attitude to antimicrobial use, optimising clinical efficacy while minimising development of resistance
MRSA/MRSP
Methylin resistant staphylococcus aureus/pseudointermedius
contain mecA gene conferring resistance to all beta lactams (penicillins and cephalosporins) detection using oxacillin/cefoxitiem discs
ESBL
extended spectrum beta lactamase inhibitors
enzyme able to hydrolyse/inactivate most beta lactams (except carbapenemes), these strains are often resistant to other drug classes
MDR
multi drug resistant
resistance to 3 or more antimicrobial classes
CIA
critically important antimicrobials
reserved for use in humans
how does resistance occur
antibiotics kill most of the bacteria
some resistant ones survive
the resistant bacteria multiply and pass on their resistant gene
the new population are the more resistant to the drug
occurs in whole body (Gut) not just at treated site
causes of atb resistance
over prescribing
wrong dose/kind/duration
over use in farm animals
poor infection control in hospitals and clinics
antimicrobial stewardship
minimise development through
- rational use of antimicrobials
- infection control practices (biosafety) means less need
- education and surveillance
ways of classifying antimicrobials
chemical structure
origin
application
type or action
mechanisms
spectrum
efficacy dependent on
chemical structure of atb
b-lactams
aminoglycosides
macrolides
quinolones
fluroquinolones
origin fo atb
natural
synthetic
semi sythetci
mechanism of action atb
cell wall synthesis inhibitors
inhibitors of membrane function
inhibitors of protein synthesis
inhibitors of nucleic acid synthesis
type of action atb
bacteriostatic - tetracyclines, sulphonamides, macrolides
bacteriocidal - aminoglycosides, cephalosporins, penicillins, quinolones
often dose dependant - aminoglycosides, fluroquinones, metronidazole
efficacy dependent on
dose - quinolones, aminoglycosides
Time - penicillins, cephalosporins
dose and time - clindamycin
criteria for empirical antimicrobial choice
ants susceptibility of suspected pathogen
drug penetration and efficacy at infection site
route of admin
frequency of admin toxicity
cost
bacteriology testing and AST indicated in case of
complicated or serious infections
lack of response/inadequate response to therapy
recurrent infections
immunocompromised patients
suspicion of MDR bacteria
always preferable in skin and UTI when systemic treatment is planned
treating pyoderma
generalized pyoderma - always secondary
for localised and superficial infections - topical therapy
topical antiseptics - chlorhexidine
systemic therapy only if really deep/topical not working (check owner compliance)
first choice = clindamycin - mostly staphylococci infections
cytology v useful
treating otitis externa
almost always secondary - treat underlying cause
cytology first - so so important
most common = Malassezia pachydermatitis and bacteria (cocci, rods)
if Malassezia then no atb just antifungals
if cocci - often staph - topical therapy
if rods - bacteriology needed. gram neg rods eg Pseudomonas and proteus may need systemic therapy in which AST needed
treating urinary infections
always check sediment and do bacterial culture
bacteria in urine has to be quantified
atb based on AST and/or guidelines
some drugs concentrate in urine so even drugs that are intermediately sensitive on AST can be used (aminopenicillines) - they reach higher concs in urine than in serum
treating the oral cavity
systemic treatment if fever, lymphadenopathy, swelling or leukocytosis
clindamycin often first choice - ideally based on AST
for gingivitis or parodontitis - systemic therapy not indicated
often topical with chlorhexidien and removal of predisposing condition (tartar) needed
treating acute gastroenteritis
often just supportive therapy (often self limiting)
if general condition of animal unchanged, no atb
diagnosis related to bacteria important fo public health esp if immunocompromised or children in house
quantification important as GI pathogens can be found in gut of healthy animals
isolating Campylobacter
CCDA podloga
microaerophilic conditions
42 degrees
species identification important
isolating salmonella
several culture mediums
aerobic conditions
37 degrees
isolation of E.coli
aerobic
37 degrees
typisation
isolation of E.coli from faeces is irrelevant
isolation of clostridia
anaerobes
37 degrees
detection of toxins more important
treating resp infections
infection of upper resp tract often viral
suboptimal sampling conditions for bacteriology and therefore misguided therapy
If obligatory resp pathogen isolated from nasal/throat swab, it should be considered relevant
if lower airways unaffected and no fever - no atb
consult national or international guidelines
diagnosing tick borne diseases
snap test - for antibody detection
interpreted in relation to presenting signs - seropositivity is not necessarily related to manifesting disease, especially in endemic areas
if clinical signs are due to infection - first choice is doxycycline
treating sepsis
only clinical condition where immediate antimicrobial therapy, with as wide a spectrum as possible is indicated
hemoculture maybe but often not enough time to isolate causative bacteria and AST before death
treating MDR infections
whenever possible try local therapy
MRSA/MRSP often in skin and ear susceptible to fucidic acid
ESBL producing enterobacteria in urine - nitrofurantoin
