Antimicrobial Chemotherapy Flashcards
An antimicrobial that kills bacteria
Bactericidal (e.g.Penicillin)
An antimicrobial that inhibits growth of bacteria
Bacteriostatic (e.g. erythromycin)
An organism is considered this is it is inhibited or killed by levels of antimicrobial that are available at the site of infection
Sensitive
An organism is considered this if it is not killed or inhibited by levels of antimicrobial that are available at the site of infection
Resistant
Minimum concentration of antimicrobial needed to inhibit visible growth of a given organism
Minimum Inhibitory Concentration (MIC)
Minimum concentration of antimicrobial needed to kill a given organism
Minimum Bacterialcidal Concentration (MBC)
Applied to a surface, usually skin or mucous membranes
Topical e.g. conjunctiva
Taken internally, either orally or parenterally
Systemic
Administered either intra-venously (IV) or intra-muscular (IM), occaisonally subcutaneously
Parental
Sites of antibiotic action
Inhibition of cell wall
Inhibition of protein synthesis
Inhibition of nucleic acid synthesis
Antibiotics that inhibit cell wall synthesis
B lactams
Glycopeptides
B lactam antibiotics
Penicillin and Cephalosporin
Mode of action of Penicillin and Cephalosporin
Disrupt peptidoglycan synthesis by inhibiting enzymes responsible for crosslinking
Original naturally occurring B-lactam discovered by Fleming
Benzyl Penicillin (Penicillin G)
Glycopeptide Antibiotics
Vancomycin
Teicoplanin
Mode of action of Vancomycin and Teicoplanin
Inhibit assembly of a peptidoglycan precursor.
Only act on Gram positive- cannot penetrate gram negative cell wall
Route of administration for Glycopeptide
Parentally
Toxic Glycopeptide
Vancomycin
Antibiotics that inhibit protein synthesis
Aminoglycosides
Macrolides and Tetracyclines
Oxazolidinones
Cyclic Lipopeptide
Aminoglycosides antibiotic
Gentamicin
Aminoglycosides mechanism
Inhibit protein synthesis
Toxic Aminoglycosides
Gentamicin
Macrolides and Tetracyclines
Erythromycin, Clarythromycin and Tetracyclines
Glycopeptides act on _________ organism
Gram positive
Aminoglycosides used for treatment of Gram ______ organism
Negative
Macroslides and Tetracyclines are useful for treatment in Gram ____ infection and for people allergic to
Positive and Penicillin
Oxazolidinones antibiotic
Linezolid
Linezolid is useful for ____ infection and given ____
MRSA and orally
Cyclic Lipopeptide
Daptomycin
Antibiotics that inhibit nucleic acid synthesis
Trimethoprim & sulphamethoxazole
Fluoroquinolones
Mechanism of Trimethoprim & sulphamethoxazole
Inhibit different steps in purine synthesis and combined form in the drug co-trimoxazole
Mechanism of Fluoroquinolones
Inhibit DNA synthesis directly in gram negative organism
Fluoroquinolones Antibiotics
Ciprofloxacin (orally) and Levofloxacin
Types of Resistance
Inherent or intrinsic
Acquired resistance
All strains of a given species are naturally resistance
Inherent or intrinsic
Resistance present in some strains of the species but not in others
Acquired
Acquired resistance can be acquired through_____ and _____
A spontaneous mutation during DNA multiplication and genes that code for resistance are spread via plasmids or on transposons due to selective pressure
Two mechanisms for B-lactam resistance
B-lactamase production and alteration of penicillin binding protein (PBP) target site
Co-amoxixlav (Penicillin)
Amoxicillin +Clavulanic acid
Clavulanic acid
B-lactamase inhibitor
Flucloxacillin (Penicillin)
Modification of antibiotc side chain to produce an antibiotic which is resistant to B-lactamase
Microbial that can break down third generation cephalosporin and penicillins
ESBL (Extended spectrum B-lactamases)
A group of extremely resistant Gram negative organism resistant to carbapenems
Carbapenemase Producing Enetrobacteriaceae
Organism that alters PBP
MRSA
Vancomycin resistance is unusual in ________
Gram positive organism
Two mechanisms of antibiotic resistance
Inactivation of antibiotic and alteration of target site of antibiotic
Penicillins
Penicillin G Amoxicillin Ampicillin Co-amoxiclav Flucloxacillin Piperacillin Imipenem Meropenum
IV treatment for pneumococcal, meningococcal and strep pyogenes (Group A) infection
Benzyl penicillin (Penicillin G) oral
Amoxicillin and Ampicillin
Streptococci and coliforms infection
Flucloxacillin
Staphylococcal infection
Has extended spectrum and is active against Pseudomonas species
Piperacillin (used with tazobactam)
Carbapenems with widest spectrum
Imipenem, meropenem
Encourage Clostridium difficile
Cephalosporins
Only third generation that has action against a pseudomonas species
Ceftriaxone (cephalosporins)
Used against gram negative organisms such as pseudomonas
Gentamicin
Used against gram positive, both aerobic and anaerobic
Vancomycin and Teicoplanin
Mainly against gram positive organism and used as an alternative to penicillin
Clarithromycin and Erythromycin
Used against atypical pneumonia (chlamydia psittacci, coxiella burnetti, mycoplasma pneumonia and legionella pneumophilia)
Clarithromycin and Erythromycin
Chlamydia treatment
Azithroymycin
Pseudomonas infection (ciprofloxacin) and pneumococci (levofloxacin)
Quinolones
Metronidazole
effective against anaerobes
Fusidic acid
anti-staphylococcal drug
Trimethoprim
Urinary infection and chest infections
Tetracyclines
Genital tract (chlamydia) and respiratory tract infection. Not given to pregnant women and children under 12 as it is deposited in teeth and bone
Clindamycin
Good at tissue penetration, taken orally and used against gram positive organism (staph and strept)
Linezolid
MRSA
Daptomycin
Gram positive orgamism (serious MRSA)
Fidaxomicin
bactericidal against C.difficle
Urinary tract agents (gram negative aerobes)
Nalidixic acid
Urinary tract agents with exception of proteus and psuedomonas
Nitrofurantoin
Allergic Reaction
Immediate
Delayed
Gastrointestinal
Immediate Hypersensitivity allergic reaction
IgE mediated within minutes of administration
Delayed Hypersensitivity allergic reaction
Can take hours or days e.g. Steven’s-Johnson syndrome
Gastrointestinal Side effects
C. difficile:
Diarrhoea
Pseudomonas colitis
CDI treatment from overuse of broad spectrum antibiotics
oral metranidazole or oral vancomycin
Therapy with broad spectrum penicillins and cephalosporins lead to overgrowth of the yeast Candida albicans
Thrush
Tetracycline and anti-tuberculosis drugs isoniazid and rifampicin
Liver toxicity
Aminoglycoside (gentamicin) or vancomycin side effect
Renal Toxicity
Ototoxicity (side effect)
Aminoglycoside or vancomycin use
Optic Neuropathy (side effect)
Ethambutol (anti-tuberculosis drug)
Encephalopathy and convulsions (side effect)
High dose of penicillin and cephalosporin
Peripheral Neuropathy (side effect)
Metronidazole and nitrofurantoin
Haematological toxicity (side effect)
Co-trimoxazole Anti-virals: Zidovudine (HIV) Ganciclovir (CMV) Linezoilid
Prevention of Adverse Reactions
Used only when indicated and in the minimum dose to achieve efficacy
Patient characteristics
Age, Renal, Liver function and pregnancy
Indications for Antimicrobials
Prophylaxis and Therapy
Combination Therapy
Cover mixed infection
Synergy
Minimise the development of resistance strains
Outcomes of combination therapy
Additive
Antagonistic
Synergistic
Combination of two cidal drugs
additive or synergistic
Combination of two static drugs
additive or synergistic
Combination of one static and one cidal
anatagonism
Macolides are Bacterio______
static
Standard course of treatment
7 days
Course for IV therapy for staph.aureus infection
14 days
Two main reasons for monitoring serum levels
Ensure therapeutic levels are being achieved
Ensure levels are not so high to be toxic
Antibiotics most commonly measured
Gentamicin and Vancomycin
How is Vancomycin measured
Measure trough level
Types of susceptibility testing
Automated methods
E test
Automated susceptibility methods
MIC that determine whether an organism is sensitive or resistant
Simplest way to measure MIC using a paper test strip with gradient of antibiotic concentration
E test
Anti-Fungal Drugs
Polyenes
Azoles
Allylamines
Echinocandins
Antifungal drugs that bind to ergosterol in fungal cell wall and increase permeability
Polyenes
Polyenes
Amphotericin B (IV) Nyastatin
Fungal skin infections, pessaries for vaginal thrush and oesophageal candidiasis
Nyastatin
Inhibit ergosterol synthesis
Azoles
Azoles
Fluconazole
Voriconazole
Itraconazole
Used to treat yeast (not filamentous) infection
Fluconazole
Not all yeast are sensitive to ______
Fluconazole
Aspergillosis
Voriconazole and itraconazole
Supress ergosterol synthesis, but act at a different stage of the synthetic pathway of azoles
Allylamines
Allylamines
Terbinafine
Fungal infection of skin and nails
Terbinafine
Inhibit synthesis of glucan polysaccharide in several types of fungi
Echinocandins
Used for seriious candida and Aspergillus infections
Echinocandins
Echinocandins
Caspofungin, myafungin and Anidulafungin
Types of Anti-Viral Drugs
Anti-Herpes
Anti-HIV
Drugs for Chronic Hep B and C
Active against Herepes Simplex and Varicella zoster virus
Aciclovir
Nucleoside analogue
Aciclovir
used for HSV and shingles with better bioavailability than Aciclovir
Famciclovir
Nucloside analogue used to treat CMV
Ganciclovir
Highly nephrotoxic, given IV and is used to treat HSV, VZV and CMV
Foscarnet
Types of anti-HIV drugs
Zidovudine (AZT, ZDV)
Nevirapine, Efavirenz
Saquinavir, Darunavir
Nucleoside analogue that interferes with the action of reverse transcriptase
Zidovudine (AZT, ZDV)
Non-nucleoside reverse transcriptase inhibitors
Nevirapine, Efavirenz
Protease Inhibitor that inhibits viral protease enzymes
Saquinavir, Darunavir
Used to treat selected chronic Hep B and C infection
IFN-alpha
Subcutaneous injection of IFN-alpha and _____ is a common treatment for
Ribavarin and Hep C
Mainly used for HIV treatment but can be used for Hep B. Given orally
Lamivudine
Treatment for influenza A and B within 48 hours of symptoms of post exposure prophylaxis
Zanamavir and Oseltamivir
Nucleoside analogue Used for treatment of Respiratory Synctial Virus infections
Ribavarin (inhaled in fine spray)
Pseudomembranous colitis usually results from Vancomycin (True/False)
False - caused by antibiotic therapy and treated with oral vancomycin or metronidazole
Thrush is due to overgrowth of anaerobic bacteria during broad spectrum antibiotic therapy (True/False)
False- broad spectrum antibiotic causes the overgrowth of the yeast Candida albicans
Vancomycin and Tecoplanin are Glycopeptides suitable to treat gram positive organisms such as _____
MRSA
Penicillin allergic patients may also be allergic to cephalosporins (True or False)
True
What type and names are the drugs combines to make co-trimaxazole
Trimethoprim and Sulphamethoxazole
Inhibition of DNA synthesis