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Chapter 28: Clinical Microbiology and Immunology (HAI (Acquired from:…
Chapter 28: Clinical Microbiology and Immunology
HAI
Healthcare-associated infections
Acquired from:
Other patients
Hospital personnel
Frequently resistant to antibiotics
Nosocomial infection
Clinical lab workflow
Grow
General purpose media
Most aerobic
Facultatively aerobic organisms
Enriched media
Enhance growth of specific fastidious pathogens
Isolate
Selective media
Allows some organisms to grow
Identify
Differential media
Allows identification of organisms based on growth and appearance
Treatment
Min Inhibitory Concentration (MIC)
Wells containing serial dilutions of antibiotics
Wells inoculated with std amt of test organism
Min. amount of antibiotic needed to treat
Disc diffusion test
Assess antimicrobial activity
Agar spread evenly with bacteria
Inhibition zones
Areas treated with antimicrobial agent
More effective antimicrobials have larger zones
Antimicrobial Drugs
Anti-bacterial drugs
Toxic selectivity
Mechanism of action
Cell wall synthesis
Penicillins
Beta-lactam antibiotics
Protein synthesis
Ribosomes
50S inhibitors
30S inhibitors
Different than Eukaryotic cells
Aminoglycosides
Tetracyclines
Macrolide
Nucleic acid synthesis
Quinolones
Interfere with DNA gyrase
Susceptibility
Produced by Bacteria or fungi
Antiviral drugs
Target host structures as well
Toxicity
Nucleoside analogs
Block RT
Blocks production of viral DNA
Nucleoside reverse transcriptase inhibitors (NRTIs)
Nonnucleoside reverse transcriptase inhibitors (NNRTIs)
Bind directly to reverse transcriptase (RT)
Protease inhibitors
Inhibit processing of large viral proteins
Fusion inhibitors
Prevent virus fusing
Interferons
Small proteins
Stimulate antiviral proteins in uninfected cells
Anti-fungi drugs
Challenging b/c eukaryotic
Generally topical
Drug Resistance
Acquired ability to resist
5 Reasons: Organism...
is impermeable
inactivates
modifies the target
Develops resistant biochemical pathway
Pump out (efflux)
Overuse accelerates resistance