Section 10: Infections and Antimicrobials

Question 1

Iatrogenic infection

Answer 1

“brought forth by a healer”

illness caused by or resulting from medical treatment

Question 2

Nosocomial infection

Answer 2

infection from hospital or hospital like setting, secondary to patients original condition

Question 3

Sources of iatrogenic/nosocomial infection

Answer 3

• direct contact via touching
• contaminating fomites - instruments and fomites
• contact with contaminated fluids - blood and blood products
• airbone transmission

Question 4

Prevention and control of iatrogenic and nosocomial infection

Answer 4

• disinfection and treatment with antiseptics (joseph lister - remember!?)
• handwashing
• monitoring patient population

Question 5

Sterilization

Answer 5

absence from all life

Question 6

Disinfection

Answer 6

killing/removing pathogens

Question 7

Antiseptic

Answer 7

disinfectant applied to tissue

Question 8

Bactericide

Answer 8

substance that kills/removes ONLY bacteria

Question 9

Sepsis

Answer 9

severe infection leading to systemic immune response

Question 10

Asepsis

Answer 10

using septic technique

Question 11

Microbiostasis

Answer 11

inhibition of microbe growth

Question 12

Spectrum

Answer 12

range of activity against microbes

Question 13

Microbe-Inhibitory concentration (MIC)

Answer 13

Activity - drug tested to determine lowest concentration that inhibits MIC

Question 14

Combination Therapy

Answer 14

use of 1+ antibiotic to increase spectrum or killing effect

Question 15

Synergism

Answer 15

increased killing effect by using multiple antibiotics

Question 16

Antagonism

Answer 16

1 antibiotic interferes with action of another

Question 17

Methods of sterilization

Answer 17

• moist heat (steam, boiling water)
• autoclave (steam with pressure)
• dry heat (flame, oven)

Question 18

Inhibitors of cell wall synthesis (antibiotics)

Answer 18

• 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)

Question 19

Inhibitors of cell membrane (antibiotics)

Answer 19

Polymyxin B and E:

• replace Mg2+ and Ca2+ from membrane lipids, disrupting structure of bacterial cell membrane
• toxic! only topical use

Question 20

Inhibitors of protein synthesis (antibiotics)

Answer 20

• 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

Question 21

Inhibitors of nucleic acid synthesis

Answer 21

• rifampin: not toxic; used to treat TB

- (fluro)quinolones: inhibit DNA replication, bacteriocidal; eg. Ciprofloxacin (cipro)

Question 22

Antimetabolites

Answer 22

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)

Question 23

Clinical problems associated with antibiotic use

Answer 23

• infections continue even if symptoms subside
• affects normal flora
• microbes become resistant
• toxicity, not seen often, but possible
• sensitization - develop rashes, fever, anaphylaxis

Question 24

bacteriostatic

Answer 24

biochemical agents that stops bacteria from reproducing but doesn’t necessarily kill the bacteria

Question 25

bacteriocidal

Answer 25

substance that kills bacteria