Section 10: Infections and Antimicrobials Flashcards
Iatrogenic infection
“brought forth by a healer”
illness caused by or resulting from medical treatment
Nosocomial infection
infection from hospital or hospital like setting, secondary to patients original condition
Sources of iatrogenic/nosocomial infection
- direct contact via touching
- contaminating fomites - instruments and fomites
- contact with contaminated fluids - blood and blood products
- airbone transmission
Prevention and control of iatrogenic and nosocomial infection
- disinfection and treatment with antiseptics (joseph lister - remember!?)
- handwashing
- monitoring patient population
Sterilization
absence from all life
Disinfection
killing/removing pathogens
Antiseptic
disinfectant applied to tissue
Bactericide
substance that kills/removes ONLY bacteria
Sepsis
severe infection leading to systemic immune response
Asepsis
using septic technique
Microbiostasis
inhibition of microbe growth
Spectrum
range of activity against microbes
Microbe-Inhibitory concentration (MIC)
Activity - drug tested to determine lowest concentration that inhibits MIC
Combination Therapy
use of 1+ antibiotic to increase spectrum or killing effect
Synergism
increased killing effect by using multiple antibiotics
Antagonism
1 antibiotic interferes with action of another
Methods of sterilization
- moist heat (steam, boiling water)
- autoclave (steam with pressure)
- dry heat (flame, oven)
Inhibitors of cell wall synthesis (antibiotics)
- prevent cross linking of peptidoglycan by binding enzyme-receptor sites
- penicillin and derivatives (ampicillin, amoxicillin): beta lactam chemical structure; bacteria that produce enzyme beta lactamase are resistant
- cephalosporins: beta lactam chemical structure, derivatives grouped into generations by antimicrobial properties; bacteria that produce enzyme beta lactamase are resistant
- Bacitracin: toxic to kidneys, only used topically
- Vancomycin: fight staph aureus; treat systemic infections; toxic to kidneys, nerve deafness, skin rashes, thrombophlebitis
- Isoniazid: stops synthesis of mycocolic acids of cell walls of mycobacteria (ONLY mycobacteria)
Inhibitors of cell membrane (antibiotics)
Polymyxin B and E:
- replace Mg2+ and Ca2+ from membrane lipids, disrupting structure of bacterial cell membrane
- toxic! only topical use
Inhibitors of protein synthesis (antibiotics)
- streptomyocin: broad spectrum, used with penicillin-related antibiotics in streptococcal infections for their synergistic effects; derivatives: kanamycin and gentamycin
- tetramycin: broad spectrum, bacteriostatic; can cause photosensitivity, renal toxicity, stains teeth in young children
- chloramphenicol: broad spectrum, bacteriostatic; toxic: can cause aplastic anemia
- erythromycin: broad spectrum, bacteriostatic; USED INSTEAD OF PENICILLIN FOR THOSE ALLERGIC; mild toxicity
Inhibitors of nucleic acid synthesis
- rifampin: not toxic; used to treat TB
- (fluro)quinolones: inhibit DNA replication, bacteriocidal; eg. Ciprofloxacin (cipro)
Antimetabolites
Sulfonamides (sulfa drugs)
- PRECURSOR to antibiotics, antimicrobial agents derived from sulfonic acid
- inhibit folic acid synthesis
- wide spectrum, bacteriostatic
- can fight protozoa infections
- eg. dapsone: mycobacterium leprae (leprosy)
Clinical problems associated with antibiotic use
- infections continue even if symptoms subside
- affects normal flora
- microbes become resistant
- toxicity, not seen often, but possible
- sensitization - develop rashes, fever, anaphylaxis
bacteriostatic
biochemical agents that stops bacteria from reproducing but doesn’t necessarily kill the bacteria
bacteriocidal
substance that kills bacteria
