Infection Session 2- Infection Model And Antibiotics Flashcards
Describe the basic model of infection
Pathogen and patient -> infection -> management -> outcome
What aspects of the patient will affect their infection?
Age Gender Physiological state Pathological state Social factors Calendar time Relative time Places they've been
Name the mechanisms of infection
Contiguous spread Inoculation Haematogenous Ingestion Inhalation Vector Vertical transmission
What is the difference between specific and supportive treatment?
Specific treats the infection and supportive make the patient more comfortable- both can be used simultaneously
What can be described as supportive treatment?
Symptom relief and physiological restoration
What are the examples of specific treatment?
Antimicrobials and surgery
What are the 4 different categories of antimicrobials?
Antibacterial
Antifungal
Antiviral
Antiprotozoal
What are the different ways tat antibacterial can be classified?
Bactericidal or bacteriostatic Spectrum- broad/narrow Target site (mechanism of action) Chemical structure (antibacterial class)
List the ideal features of antimicrobial agents
Selectively toxic Few adverse effects Reach site of infection Oral/IV formulation Long half life (infrequent dosing) No interference with other drugs
What are the targets for different classes of antibacterials?
Cell was synthesis
Protein synthesis
Cell membrane function
Nucleic acid synthesis
How can some microbes become resistant? (Mechanisms)
Drug inactivating enzymes
Altered target- target enzyme has lowered affinity for antibacterial
Altered uptake- decreased permeability or increased efflux
How can antibiotic resistance occur genetically?
Chromosome gene mutation
Horizontal gene transfer
Name the different penicillins and what they are active against
Penicillin- mainly active against streptococci
Amoxicillin- active against all gram +ve and some gram -ve
Flucloxacillin- active against staphylococci and streptococci
B-lactamase inhibitor combinations:
Co-amoxiclav- all of above and anaerobes and gram -ve
Piperacillin/tazobactam- as above and more gram -ve including pseudomonas
What are the properties of cephalosporins?
Broad spectrum but no anaerobe activity- better at treating gram -ve than penicillin (can cause C. Diff)
Name a cephalosporin and where is has good activity
Cetriaxone has good activity in the CSF
What is an example of a carbapenem and what are its properties?
Meropenem- very broad spectrum, active against most gram -ve
Can generally be used in penicillin allergy
What is an example of a glycopeptide and what are its properties?
Vancomycin- active against most gram +ve, some enterococci are resistant, not absorbed, narrow therapeutic margin
What are the important clinical points about tetracycline and doxycycline?
Oral only
Broad spectrum- used in penicillin allergy for gram +ve
Active in atypical pathogens in pneumonia
Active against chlamydia and some protozoa
Don’t give to anyone under the age of 12
What is the most common aminoglycoside and its clinical relevance?
Gentamicin- profound activity against gram -ve Good activity in blood/urine Can be nephrotoxic/ototoxic Therapeutic drug monitoring required Reserved for severe gram -ve sepsis
Give an example of a macrolide and its properties
Erythromycin- well distributed including intracellular penetration
Alternative to penicillin for mild gram +ve infections
Active against atypical respiratory pathogens
Give an example of quinolone and its properties
Ciprofloxacin- inhibit DNA gyrase
Very active against gram -ve and atypical pathogens
Risk of C. Diff
How does trimethoprim and sulphonamides work?
Inhibitors of folic acid synthesis
What are trimethoprim and sulphonamides used for?
Trimethoprim used alone in uk for UTI
When combined with sulphamethoxazole- used to treat PCP and has activity against MRSA
What are the 2 types of antifungals?
Azores- active against yeasts +/- molds
Polyenes
How do Azores work and what are they used for?
Inhibit cell membrane synthesis
Fluconazole used to treat candida
How do polyenes work and what are they used for?
Inhibit cell membrane function
Nystatin used for topical treatment of candida
Amphotericin for IV treatment of systemic fungal infections
Give 2 examples of antivirals and what they are used for
Aciclovir- when phosphorylated inhibits viral DNA polymerase, used for herpes simplex and varicella zoster
Tamiflu- inhibits viral neuraminidase, used for influenza A and B
What is metronidazole used for?
Anaerobic bacteria
Protozoa- amoebae, giardiasis and trichomonas
