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| − | ==Introduction==
| + | {{review}} |
| − | [[Image:Donkey Europe 2.JPG|thumb|right|200px|<small><center>Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary]</center></small>]]
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| − | Antimicrobial agents should '''only be used in situations where the diagnosis
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| − | warrants this'''. The use of antimicrobial agents for relatively trivial infections
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| − | encourages the selection of resistant organisms. Irrational use may expose
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| − | treated animals to unnecessary risks.
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| − | ==Dosing==
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| − | Successful antimicrobial therapy relies on administering sufficient doses
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| − | to effectively suppress ('''bacteriostatic''') or kill ('''bactericidal''') pathogens at
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| − | the site of infection so that the host’s defences can eliminate them. For
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| − | diseases of unknown cause or attributable to organisms with '''unpredictable
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| − | susceptibility''', e.g. [[:Category:Enterobacteriaceae|Gram-negative enteric bacteria]], there is no substitute for
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| − | '''bacterial culture and identification of the causative agent'''. A '''Gram stain''' can
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| − | be performed immediately on a direct smear and will direct initial therapy
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| − | until the laboratory results are obtained.
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| − | In the laboratory, the relationship between an antimicrobial drug
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| − | and a pathogen is described by the '''minimum inhibitory concentration (MIC)''', the lowest drug concentration that inhibits bacterial growth. The information listed in a culture and susceptibility report is intended to guide
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| − | antimicrobial selection but must be interpreted carefully since the testing
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| − | does not take into account a number of important factors, such as '''host defences, drug distribution, the infection site environment and the route of drug administration'''.
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| − | ===Local factors may influence an agent’s activity at the infection site===
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| − | * [[Potentiated-Sulphonamides|'''Potentiated sulphonamides''']] achieve adequate concentrations in abscesses but are ineffective in purulent material and necrotic tissue
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| − | * '''Rifampin, the [[Tetracyclines|tetracyclines]] and [[Nitroimidazoles|metronidazole]]''' all achieve high concentrations in abscesses and retain their antimicrobial activity in purulent environments
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| − | For many drugs, the distinction between bactericidal and bacteriostatic is
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| − | not exact and depends on the pathogen involved and the drug concentration attained in the target tissues. A '''bactericidal drug''' ([[Aminoglycosides|aminoglycoside]], [[Penicillins|penicillin]], [[Cephalosporins|cephalosporin]], [[Potentiated-Sulphonamides|potentiated sulphonamide]]) is '''preferable to a bacteriostatic drug''' ([[Tetracyclines|tetracycline]], [[Sulphonamides|sulphonamide]]) for '''neonatal septicaemia, life-threatening conditions and surgical prophylaxis'''.
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| − | [[Penicillins]] and [[Cephalosporins|cephalosporins]] are bactericidal but exhibit so-called
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| − | '''time-dependent''' (concentration-independent) bacterial killing. <u>Plasma
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| − | concentrations of these agents should exceed the MIC of the pathogen
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| − | for 50-80% of the inter-dosing interval</u>, and further increases in dose
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| − | rate will not increase the bactericidal activity.
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| − | [[Aminoglycosides]] exhibit '''concentration-dependent''' bacterial killing and often also produce a
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| − | '''prolonged post-antibiotic effect''' (a period after drug concentration falls
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| − | below MIC when the bacterial growth remains suppressed), thereby
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| − | allowing <u>long interdosing intervals that maximize clinical efficacy and
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| − | minimize side effects</u>.
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| − | ===Combinations of agents are appropriate in only a few situations===
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| − | * '''Known synergy''', e.g. a [[Penicillins|penicillin]] or [[Cephalosporins|cephalosporin]] with an [[Aminoglycosides|aminoglycoside]]
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| − | * '''Preventing rapid development of bacterial resistance''', e.g. [[Macrolides and Lincosamides|erythromycin]] plus rifampin to treat ''[[Rhodococcus equi]]'' infections
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| − | * Extending the spectrum of activity in the initial therapy of '''life-threatening infections'''
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| − | * Treatment of '''true mixed''' bacterial infections
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| − | ===Avoid non-synergistic or antagonistic combinations===
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| − | * A bactericidal agent with a bacteriostatic agent. The former require actively dividing bacteria for their activity and the latter stop bacterial growth
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| − | * A [[Penicillins|penicillin]] plus a [[Potentiated-Sulphonamides|potentiated sulphonamide]] has minimally additive effects against pathogens but additive effects against the commensal gastrointestinal microflora
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| − | ==Literature Search==
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| − | [[File:CABI logo.jpg|left|90px]]
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| − | Use these links to find recent scientific publications via CAB Abstracts (log in required unless accessing from a subscribing organisation).
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| − | <br><br><br>
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| − | [http://www.cabdirect.org/search.html?q=(title:(antimicrobial)+OR+title:(antibiotic)+OR+subject:(antimicrobials)+OR+subject:(antibiotics))+AND+(ab:(donkey)+OR+title:(donkey))&fq=sc:%22ve%22 Antimicrobials in donkeys publications]
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| − | ==References==
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| − | * Horspool, L. (2008) Clinical pharmacology In Svendsen, E.D., Duncan, J. and Hadrill, D. (2008) ''The Professional Handbook of the Donkey'', 4th edition, Whittet Books, Chapter 12
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| | |linkpage =Pharmacology - Donkey | | |linkpage =Pharmacology - Donkey |
| | |linktext =Pharmacology - Donkey | | |linktext =Pharmacology - Donkey |
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| | |pagetype=Donkey | | |pagetype=Donkey |
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| − | {{infotable
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| − | |Maintitle = [[Sponsors#The Donkey Sanctuary|This page was sponsored and content provided by '''THE DONKEY SANCTUARY''']]
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| − | |Maintitlebackcolour = B4CDCD
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| − | }}[[Category:Donkey]]
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| − | [[Category:Pharmacology_-_Donkey]]
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