Notes in 5- Antimicrobial Chemotherapy

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Published	02/10/2024	It was micro-organisms themselves which first invented {{c1::antibiotics}} to combat other organisms and maintain their ecological niches.
Published	02/10/2024	An organism is {{c1::sensitive}} to an antibiotic if it is inhibited or killed by the antimicrobe available at the site of infection.An orga…
Published	02/10/2024	{{c1::Bactericidal}} is an antimicrobial that kills bacteria.{{c1::Minimal bactericidal concentration (M.B.C.)}} is the minim…
Published	02/10/2024	Routes of administration of antibiotics:1- {{c1::Topical}} → Applied to a surface (skin or to mucous membranes)2- {{c1::Systemic}} → Taken internally …
Published	02/10/2024	Classification of Bacteria:A- Morphology/Shape of bacteria:[1] {{c1::Cocci (spheres)}}[2] {{c1::Bacilli (rods)}}[3] {{c1::Spirals}}----…
Published	02/10/2024	Summary of Bacteria Classification (open up)
Published	02/10/2024	Antibiotics may inhibit or kill bacteria by acting at three different areas of metabolic activity.Mechanisms of action1- Inhibition of …
Published	02/10/2024	Mechanisms of action: Inhibition of cell wall synthesis[1] {{c1::Penicillins}} and {{c1::Cephalosporins}} → beta-lactams (contain beta-lactam rin…
Published	02/10/2024	Why are gram negative organisms resistant to Benzyl penicillin?
Published	02/10/2024	How do beta-lactams (Penicillins & Cephalosporins) inhibit cell wall synthesis?
Published	02/10/2024	{{c1::Beta lactams}} are bactericidal antibiotics that disrupt peptidoglycan synthesis by binding to the enzymes (penicillin-binding protein…
Published	02/10/2024	{{c1::Glycopeptides}} are bactericidal antibiotics that disrupt peptidoglycan synthesis by inhibiting the assembly of peptidoglyca…
Published	02/10/2024	How do glycopeptides (Vancomycin & Teicoplanin) inhibit cell wall synthesis?
Published	02/10/2024	Mechanisms of action: Inhibition of Protein Synthesis[1]{{c1::Gentamicin}} → AminoglycosidesThey are Concentration-dependent bactericidal an…
Published	02/10/2024	Why are antibiotics that inhibit protein synthesis not affecting both the bacterial and mammalian ribosome?e.g. Aminoglycosides → Gentamicin
Published	02/10/2024	How do aminoglycosides (Gentamicin) inhibit protein synthesis?
Published	02/10/2024	{{c1::Aminoglycosides}} are concentration-dependent bactericidal antibiotics that bind to 70S prokaryotic ribosome which impairs t…
Published	02/10/2024	{{c1::Macrolides}} are bactericidal or bacteriostatic antibiotics that stop the elongation of the peptide by interfering with…
Published	02/10/2024	How do Macrolides (Erythromycin) inhibit protein synthesis?
Published	02/10/2024	{{c1::Tetracyclines}} are bacteriostatic antibiotics that prevent the attachment of tRNA to the A site on the ribosome.They bind t…
Published	02/10/2024	How do Tetracyclines inhibit protein synthesis?
Published	02/10/2024	{{c1::Oxazolidinones}} are bacteriostatic or bactericidal antibiotics that prevent the formation of 70S subunit complex by inhibiting the ri…
Published	02/10/2024	How do Oxazolidinones (Linezolid) inhibit protein synthesis?
Published	02/10/2024	{{c1::Cylic Lipopeptides}} are strong bactericidal antibiotics that creates holes on the membrane which leads to the leakage of ions, causin…
Published	02/10/2024	How do Cyclic Lipopeptides (Daptomycin) inhibit protein synthesis?
Published	02/10/2024	Mechanisms of action: Inhibition of nucleic acid synthesis[1] {{c1::Trimethoprim}} and {{c1::Sulphamethoxazole}} → Inhibition in purine synt…
Published	02/10/2024	{{c1::Purine synthesis inhibitors}} are bacteriostatic, when combined they become Bactericidal antibiotics that Inhibit DNA synthesis e…
Published	02/10/2024	How do Purine synthesis inhibitors (Trimethoprim and Sulphamethoxazole) inhibit nucleic acid synthesis?
Published	02/10/2024	{{c1::Fluoroquinolones}} are bactericidal antibiotics that directly inhibit DNA synthesis by inhibiting an enzyme called DNA gyrase which prevent…
Published	02/10/2024	How do Fluoroquinolones (Ciprofloxacin & Levofloxacin) inhibit nucleic acid synthesis?
Published	02/10/2024	Most of the antibiotics become useless over time because bacteria develop {{c1::resistance}}i.e. they are unlikely to respond to attainable levels of …
Published	02/10/2024	Types of resistance:[1] {{c1::Intrinsic}} resistance - all strains of a given species are naturally resistant to an antibiotice.g.Streptococci → resis…
Published	02/10/2024	How is antibiotic resistance a good example of Darwinian evolution in action?
Published	02/10/2024	Two ways in which resistance is acquired:[1] {{c1::Spontaneous mutation}} → if positive, it will be retained throughout the generations.Change in stru…
Published	02/10/2024	{{c1::Horizontal gene transfer}} is when genetic material is moved between organisms using a method other than the Vertical transmission of DNA t…
Published	02/10/2024	What are the three ways through which horizontal gene transfer is done?
Published	02/10/2024	{{c1::β-lactamase production}} is a method of resistance where bacterial enzymes cleave the β–lactam ring of the antibiotic and thus render it in…
Published	02/10/2024	Ways to combat β-lactamase:1- {{c1::Modification}} of antibiotic side chain by combination producing new antibiotic resistant to β-lactamasee.g.c…
Published	02/10/2024	{{c1::Extended spectrum β–lactamases (ESBLs)}} are enzymes that mediate resistance to extended-spectrum (third generation) cephalosporins.Antibio…
Published	02/10/2024	{{c1::Carbapenemase-Producing Enterobacteriaceae (CPE)}} → acquired resistance (a bacterium that is a member of the Enterobacteriaceae family res…
Published	02/10/2024	Similar to penicillins and cephalosporins, {{c1::carbapenems}} are members of the β-lactam class of antibiotics.They were highly …
Published	02/10/2024	{{c1::B-lactamase}}, e.g. carbapenemase, are enzymes that cleave beta-lactam rings, so they don't allow them to bind to the enzyme (PBP) and…
Published	02/10/2024	Alteration of penicillin binding protein (PBP) target siteMicro-organisms develop resistance to β–lactams by changing the structure of their PBPs.&nbs…
Published	02/10/2024	{{c1::Alteration of penicillin binding protein (PBP) target site}} is an antibiotic resistance mechanism, developed through horizontal gene trans…
Published	02/10/2024	{{c1::MRSA}} is any strain of S. aureus that has developed, through horizontal gene transfer and natural selection, mult…
Published	02/10/2024	Vancomycin (glycopeptide) resistanceGlycopeptides could be relied on for the treatment of serious {{c1::Gram-positive infection}}.  Recently…
Published	02/10/2024	{{c1::Vancomycin Resistant Enterococci (VRE)}} are Enterococci that have an altered structure peptidoglycan precursor to which vancomycin normally bin…
Published	02/10/2024	Spectrum of Commonly Used Agents β-lactams: Penicillins
Published	02/10/2024	Spectrum of Commonly Used Agentsβ-lactams: CephalosporinsThird gen → {{c1::gram negative}}First gen → {{c1::gram positive}}
Published	02/10/2024	Spectrum of Commonly Used AgentsAminoglycosides → {{c1::gram-negative organisms}}
Published	02/10/2024	Spectrum of Commonly Used AgentsGlycopeptides → {{c1::gram-positive organisms}}
Published	02/10/2024	Spectrum of Commonly Used AgentsMacrolides → {{c1::gram-positive organisms}}
Published	02/10/2024	Spectrum of Commonly Used AgentsQuinolones → against nearly all {{c1::Gram-negative}}
Published	02/10/2024	Spectrum of Commonly Used Agents: Miscellaneous
Published	02/10/2024	Spectrum of Commonly Used Agents:Newer agents
Published	02/10/2024	Spectrum of Commonly Used Agents:Urinary tract agentsThe following agents are used only in the treatment of lower urinary tract infection (cystitis).
Published	02/10/2024	Most antimicrobials have adverse reactions. The incidence is dependent upon {{c1::dose}} and {{c1::duration}} of therapy. Approx. 5% o…
Published	02/10/2024	Side effects and Toxicity of antibiotics:[1] Allergic reactions----------------------[2] Immediate hypersensitivity → within …
Published	02/10/2024	The {{c1::Stevens-Johnson syndrome}} is a severe and sometimes fatal form of delayed hypersensitivity associated with the sulphonamides&nbsp…
Published	02/10/2024	Side effects and Toxicity of antibiotics:[1] {{c1::Allergic reactions}}- Any antimicrobial: commonly associated with the β-lactam.…
Published	02/10/2024	Side effects and Toxicity of antibiotics:[4] {{c1::Gastrointestinal side effects}}Nausea and vomiting are common. Diarrhoea associated with toxin…
Published	02/10/2024	{{c1::Pseudomembranous colitis}} refers to swelling or inflammation of the large intestine (colon) due to an overgrowth of Clostridioides diffici…
Published	02/10/2024	Side effects and Toxicity of antibiotics: (overgrowth of resistant organisms)[5] {{c1::Thrush}} → overgrowth of the yeast Candida albicans, resul…
Published	02/10/2024	Side effects and Toxicity of antibiotics:[6] {{c1::Liver toxicity}} → check patient history and liver healthThe liver is susceptible to a va…
Published	02/10/2024	Side Effects and Toxicity[8] Neurological toxicity -----------------------------A- {{c1::Ototoxicity}}This is most often seen following…
Published	02/10/2024	Side Effects and Toxicity:[9] {{c1::Haematological Toxicity}}--------------Toxic effect on the bone marrow resulting in: - Selective depress…
Published	02/10/2024	How do you minimise adverse reactions when using antibiotics?
Published	02/10/2024	Many factors have to be taken into consideration when choosing an antimicrobial agent for prophylaxis or treatment.Balance to be struck between the n…
Published	02/10/2024	Why should antibiotics not be prescribed unless absolutely necessary?
Published	02/10/2024	Patient Characteristics to consider when prescribing antibiotics:[1] {{c1::Age}}Certain drugs contraindicated in children (e.g., Ciprofloxacin, …
Published	02/10/2024	Why are mutagenic and teratogenic antimicrobials or both contraindicated in pregnancy?
Published	02/10/2024	Indication for Antimicrobials[1] {{c1::Prophylaxis}} - Administration of antimicrobials to prevent the future occurrence of infect…
Published	02/10/2024	Drug Related Considerations[1] Spectrum of antimicrobial agentThe antibiotic chosen should normally be effective against the known or l…
Published	02/10/2024	Why is it sometimes necessary to use antimicrobials in combination instead of monotherapy?
Published	02/10/2024	When antimicrobials are used in combination, there are three possible outcomes:- Their effects are {{c1::additive}}.-They are {{c1::antagonistic}…
Published	02/10/2024	When antimicrobials are used in combination, there are three possible outcomes:And give an example of combination:
Published	02/10/2024	General rules:Combination of two {{c1::cidal}} drugs or two {{c1::static}} drugs is {{c2::additive}} or {{c2::…
Published	02/10/2024	Why do we have to take Penetration to site of infection of antibiotics into consideration in clinical practice?
Published	02/10/2024	Why must Gentamicin and Vancomycin be constantly monitored when administered to a patient?
Published	02/10/2024	Gentamicin and Vancomycin have a {{c1::low therapeutic index}}.This means that the difference between a therapeutic&nbsp…
Published	02/10/2024	Patients with serious infections often require much {{c1::higher}} doses, the use of drug combinations may further influence dosage. In some…
Published	02/10/2024	What should be considered when urgent treatment of infection is needed before the organism is identified and its antibiotic sensitivity tested?
Published	02/10/2024	Why must we monitor serum levels of an antimicrobial when administering it to a patient?
Published	02/10/2024	Susceptibility TestingThe simplest way to measure the {{c1::Minimum Inhibitory Concentration (M.I.C.)}} of one antibiotic against one organi…
Published	02/10/2024	Susceptibility Testing- Automated methods:Most diagnostic labs use automated methodology.   The growth of individual isolates is measured in…
Published	02/10/2024	In vitro laboratory test gives only a {{c1::prediction}} whether the infection is likely to be cured by the antibiotic in question.Factors influencing…
Published	02/10/2024	The majority of antibiotics have no action on fungi and fungal infections.Fungi may be subdivided into {{c1::yeasts}} and {{c1::filamentous fungi…
Published	02/10/2024	Anti-Fungal Drugs[1] {{c1::Polyenes}}Bind to ergosterol this results in an increase in the permeability of the cell wall by making pores. Active …
Published	02/10/2024	{{c1::Polyenes}} are antifungal drugs that bind to ergosterol this results in an increase in the permeability of the cell wall by makin…
Published	02/10/2024	{{c1::Azoles}} are antifungal drugs that inhibit ergosterol synthesis e.g.[A] Imidazoles → miconazole & ketoconazole (irrelevant)[B…
Published	02/10/2024	{{c1::Allyamines}} are antifungal drugs that suppress ergosterol synthesis, but act at a different stage of the synthetic pathway from azoles.&nb…
Published	02/10/2024	{{c1::Echinocandins}} are antifungal drugs that inhibit the synthesis of glucan polysaccharide in several types of fungi.These agents are used fo…
Published	02/10/2024	Antibiotics have no action against viral infectionsThere are no virucidal agents (i.e. those that will kill the virus) but that they are all virustat…
Published	02/10/2024	Herpes viruses are not all equally sensitive to anti-viral agents, treatment is best if started early but it does not eradicate them because the agent…
Published	02/10/2024	{{c1::Aciclovir}} is an anti-herpes virus drug that is a nucleoside analogue, It must first be converted into its active form by an enzyme (thymidine …
Published	02/10/2024	Anti-Herpes Virus Drugs
Published	02/10/2024	{{c1::Zidovudine}} is the first anti-HIV drug, it is a nucleoside analogue interfering with the action of reverse transcriptase. (It slows the replica…
Published	02/10/2024	How are clinicians treating HIV in modern times?
Published	02/10/2024	{{c1::nucleoside analogue reverse transcriptase inhibitor}} → zidovudine{{c1::a non-nucleoside reverse transcriptase inhibitor}} → nevirapin…
Published	02/10/2024	Drugs for Chronic Hepatitis B and C[1] {{c1::Interferon-α}}Protein that forms part of the host immune response. Produced by genetic engineer…
Published	02/10/2024	{{c1::Interferon-α}} is a protein that forms part of the host immune response. Produced by genetic engineering and is used to trea…
Published	02/10/2024	What's the importance of pegylation of Interferon-alpha?
Published	02/10/2024	Drugs for Viral Respiratory Infections
Published	02/10/2024	Testing Anti-viral resistanceTesting viruses for resistance is only available for a few drugs in specialist centres. {{c1::Genotypic analysi…
Published	02/10/2024	Why is drug monitoring done to some anti-HIV drugs and aciclovir?
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