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Pharmacology > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Definition of infection?

A

Infection means the entry of a microorganism into the body, where it multiplies & causes disease

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2
Q

What are the 2 prerequisites for infection?

A

1, The host must be susceptible

2. The organism must be pathogenic (disease causing)

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3
Q

Definition of Pathogenic bacteria

A

These are disease causing bacteria as opposed to commensals (e.g. flora in the gastro-intestinal tract) that do not cause disease, but instead serve a useful purpose in preventing overgrowth of pathogenic bacteria

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4
Q

Opportunistic infections?

A

Under certain circumstances like in immunodeficiency or when broad spectrum antibiotics are overused, normally non-pathogenic organisms cause disease & these infections are called opportunistic infections

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5
Q

Nosocomial infections?

A

Infections obtained in the hospital environment

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6
Q

Super infection?

A

Infection occurring after or on top of an earlier infection, especially following Rx with broad-spectrum antibiotics

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7
Q

Selective toxicity?

A

A compound must exhibit selective toxicity, i.e. interfere with the growth of the infectious agent while having little or no deleterious(causing harm or damage) effect on host cells

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8
Q

Resistance?

A

Resistance to an antibiotic has occurred when an organism is no longer affected by a drug that previously killed it

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9
Q

What are the causes of drug resistance?

A
  1. Unnecessary use of antibiotics
  2. Inappropriate choice of antibiotics
  3. Using lower than effective doses.
  4. Using inappropriately long dosing intervals.
  5. Inappropriate use of broad spectrum agents.
  6. Inappropriate use of antibiotic combinations.
  7. Using bacteriostatic agents in immunodeficiency states.
  8. Continuing an antibiotic in the presence of resistance.
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10
Q

Drug Sensitivity?

A

The organism is sensitive to the drug if it is killed by it, or if the organism’s growth is inhibited by it

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11
Q

Broad spectrum & narrow spectrum antibiotics?

A
  1. Broad spectrum antibiotics kill / inhibit the growth of bacteria belonging to two / more different groups
  2. Narrow spectrum antibiotics only kill / inhibit a single / limited group of bacteria
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12
Q

Bactericidal antibiotics?

A

Antibiotics that kill bacteria.

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13
Q

Bacteriostatic antibiotics?

A
  • Antibiotics that INHIBIT (stop) the growth of the bacterium & allow the body’s defense mechanisms to destroy the organism
  • Some bacteriostatic drugs are bactericidal in high doses
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14
Q

Structure of bacteria?

A
  • Bacteria are unicellular, living organisms with a cell wall, cytoplasm & a nucleus containing one chromosome
  • They function like independent living cells
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15
Q

Description according to oxygen needs?

AEROBIC and ANAEROBIC

A
  1. Aerobic
    These bacteria rely on oxygen from the environment to live; therefore they need an oxygenated environment to survive.
  2. Anaerobic
    These bacteria produce their own oxygen from other chemical compounds; therefore they do not need an oxygenated environment to survive
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16
Q

Description according to Gram staining. Gram-Positive

A
  • Take up the crystal violet stain used in the test, & then appear to be purple-coloured when seen through a microscope
  • This is because the thick peptidoglycan layer in the bacterial cell wall retains the stain after it is washed away from the rest of the sample, in the decolorization stage of the test
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17
Q

Description according to Gram staining. Gram-Negative

A

Cannot retain the violet stain after the decolorization step
•Their peptidoglycan layer is much thinner & sandwiched between an inner cell membrane & a bacterial outer membrane, causing them to take up the counterstain (safranin or fuchsine) & appear red or pink

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18
Q

Cell wall inhibitors

A

Beta-lactam antibiotics:

  1. Penicillin’s
  2. Cephalosporins
  3. Carbapenems
  4. Monobactams
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19
Q
  1. Penicillin’s
A
  • Narrow spectrum: Penicillin G; Penicillin V; Benzathine penicillin; Procaine penicillin
  • Penicillinase resistant: Flucloxacillin, Cloxacillin
  • Broad spectrum: Ampicillin; Amoxycillin; Amoxycillin/clavulanic acid combination
  • Antipseudomonal penicillins: Piperacillin
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20
Q

Mechanism of action for Penicillin’s; Cephalosporins; Carbapenemes; Vancomycin ?

A
  • Inhibit bacterial cell wall synthesis (then cell lysis occur)
  • Bactericidal
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21
Q

Mechanism of action for Clavulanic acid?

A

Clavulanic acid acts as a beta-lactamase inhibitor (the enzyme that is formed by bacteria to inactivate the drug)

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22
Q

Penicillin Indications Narrow spectrum?

A

•Gram-positive cocci:
→Staphylococcus,
→ Streptococcus
•Syphilis

  • Streptococcal infections e.g. pneumonia
  • Meningitis: good BBB penetration during infection

•Cloxacillin / Flucloxacillin:
→staphylococcal
infections of the
skin.

  • Gonorrhoea (at present considered resistant)
  • Cellulitis or systemic sepsis
23
Q

Penicillin Indications Broad spectrum?

A 
•Gram-negative organisms
→  Haemophilus 
    influenzae – 
     pneumonia.
→Salmonella – 
   typhoid fever.
→Shigella –diarrhoea
E. coli- urine tract infections.
→Gonococcus- gonorrhoea (resistance common).

•Gram-positive organisms
→ Streptococcus e.g.
pneumonia.

•Piperacillin
→Pseudomonas
infections.

24
Q

Pharmacokinetics penicillin?

A
  • Ampicillin is given IV because of the low oral bioavailability
  • Amoxicillin has good oral bioavailability & the absorption is not influenced by food.
  • Procaine penicillin & benzathine penicillin are in suspension & are only given IM.
  • Food reduces the absorption of oral penicillin’s – give 1 hour before or 2 hours after meals
25
Q

Penicillin Side effects?

A
  • Nausea, vomiting, diarrhoea
  • Allergic reactions (in less than 1% of patients)
  • Overgrowth of fungi & resistant organisms - superinfections
26
Q

Penicillin Contraindications?

A

Hypersensitivity to penicillins or cephalosporins

27
Q

Cephalosporins generations?

A
  • First generation: Cephalexin; Cephazolin, Cephalotin
  • Second generation: Cefuroxime, Cefachlor
  • Third generation: Ceftriaxone, Cefotaxime
  • Fourth generation: Cefepime
28
Q

Indications of 1st-generation of Cephalosporins?

A
  • Mainly Gram-positive bacteria, •Proteus,
  • E coli,
  • Klebsiella
29
Q

Indications of 2nd-generation of Cephalosporins?

A
  • Mainly Gram-negative bacteria: Haemophilis; Also Bacteroides
  • Less active against Gram-positive bacteria
30
Q

Indications of 3rd-generation of Cephalosporins?

A

Mainly Gram-negative bacteria

31
Q

Indications of 4th-generation of Cephalosporins?

A

Gram-negative- and Gram-positive bacteria, including Pseudomonas

32
Q

Ceph side effects

A

•Allergic reactions (5-16% cross reaction with penicillin),
•Nausea, vomiting, diarrhoea.
•Nephrotoxic (in very ill patients).
•Super infections
•High doses neurotoxic.
•Disulfiram reaction with cefuroxime & cefamandole.
Bleeding tendency with cefamandole

33
Q

Carbapenemes Indication Imipenem?

A
  • Activity against many Gram-positive & Gram-negative aerobic & anaerobic bacteria, also some Pseudomonas.
  • Use generally limited to severe nosocomial infections: septicemia, endocarditis, respiratory tract-, genitourinary-, intra-abdominal-, bone & joint-, skin & soft tissue infections.
  • Formulated with cilastatin: a specific enzyme inhibitor that blocks renal metabolism of imipenem & enhances its urinary concentration.
34
Q

Carbapenems side effects?

A
  1. Hypersensitivity
  2. Gastro-intestinal
  3. Haematological
  4. CNS
  5. Seizures
35
Q

Carbapenemes Indication Meropenem?

A
  1. Similar spectrum of activity as imipenem

2. In addition penetrates well into CSF – alternative for bacterial meningitis

36
Q

Vancomycin indications?

A
  1. Pseudomembranous enterocolitis – oral
  2. Resistant staphylococcal & enterococcal infections, methicillin-resistant
    Staphylococcus aureus
  3. Endocarditis in penicillin allergy
37
Q

Vancomycin pharmacokinetics?

A

Must be given parenteral because oral absorption is negligible

38
Q

Vancomycin Side effects?

A
  1. Nephrotoxic
  2. Ototoxic
  3. Red man syndrome due to histamine release (not true allergy)
  4. Monitor blood levels
39
Q

Protein synthesis inhibitors?

A
  1. Tetracyclines
  2. Glycylcyclines
  3. Aminoglycosides
  4. Macrolides/Ketolides
  5. Clindamycin
40
Q

Tetracyclines

A
  1. Doxycycline

2. Minocycline

41
Q

Aminoglycosides

A
  1. Streptomycin
  2. Gentamycin
  3. Amikacin
  4. Tobramycin
42
Q

Macrolides/ ketolides

A

•New generation: Azithromycin &
Clarithromycin : longer half-life
•Erythromycin

43
Q

Tetracyclines, Aminoglycosides, Macrolides, Chloramphenicol, Clindamycin, Mechanism of action?

A
  • Inhibit bacterial protein synthesis. Effective against atypical organisms
  • Bacteriostatic
44
Q

Tetracyclines indications?

A
  • Severe acne
  • Tick bite fever: Rickettsiae
  • Malaria prophylaxis: doxycycline
  • Atypical organisms: Chlamydia, Mycoplasma, Legionella
  • Sexual transmitted illnesses
  • Brucellosis, Chronic bronchitis
  • Cholera, Typhoid fever (resistance common)
45
Q

Tetracycline side effects?

A
  • Phototoxic reactions
  • Nausea, vomiting, diarrhoea
  • Teeth discolouration & inhibition of bone growth in children due to binding with calcium
  • Super infections e.g. Candida
46
Q

Tetracycline Contraindications

A
  1. Children <12 years

2. Pregnancy & lactation

47
Q

Tetracycline Drug interactions

A

•Food & cations like Ca, Mg, Al, Fe decreases oral absorption

48
Q

Aminoglycosides

A
  1. Gram-negative bacteria: Pseudomonas, Klebsiella, E coli
  2. Tuberculosis
  3. Topical in the eye
  4. Brucellosis
49
Q

Aminoglycosides

A
  1. Very polar & highly water soluble.
  2. Not absorbed orally – must be given IM or IV.
  3. Used in combination with penicillins because it can not cross cell membranes well
50
Q

Aminoglycosides Side effects

A
  1. Ototoxic (related to high blood level & duration)
  2. Nephrotoxic
  3. Neuromuscular paralysis: act as a blocking agent at neuromuscular junction.
  4. Monitor blood levels - TDM
51
Q

Aminoglycosides Contraindications

A
  1. Renal disease
  2. Pregnancy & lactation
  3. Myasthenia gravis
52
Q

Which medications can cause yellow sclera,& clay colored stools?

A
  1. Erythromycin
  2. Phenazopyridine

The thing is Liver Toxicity, key term JAUNDICE.

53
Q

A patient in sepsis is prescribed several antibiotics during their hospital stay. What patient teaching should be included?

A
  1. Levo_floxacin
    & Doxy_cycline; both no Sun exposure and not baby safe.
  2. Vanco_mycin & Azithro_mycin; they kill the kidney
    SO Creatinine>1.3 means bad kidney and Urine output=<30ml means kidney is in distress

3 Azithro_mycin: Throws QT intervals and liver out of work.

Therefore:

  1. Avoid direct sun exposure.
  2. Oral birth control ineffective
  3. Take until finished
  4. Monitor QT intervals
  5. Monitor creatinine and BUN
54
Q

Patient education when prescribing antibiotics?

A
  1. Finish Med: To prevent super infection.

Key words
•Take until all meds are finished
•DO NOT stop when feeling better.

  1. Accidental pregnancy
    •C-Child Care
    •C-“Cillins”: Penicillin, Amoxicillin
    •C-“Cycline”: Doxycycline, Tetracyline.

key words:
•Oral contraceptives are ineffective
•Use additional contraceptives like IUD

  1. NO Alcohol
4. NO FOOD
MTF "Move The Food"
M- Macrolides: Azy_thromycin
T-Tetra_cycline: Doxycycline
F-Fluoroquinolones: Levo_floxacin

key words
•Take on an empy stomach
•With a FULL glass of water

5. NO Sun
AVOID " Fun The Sun"
F-Fluoroquinolones: Levo_floxacin
T-Teracycline: Doxycycline
S-Sulfa drugs= Sun Burn
•Trimethoprim-sulfa methox azole (Brand: Bactrim).
  1. SUPER Toxic (Kidney + Ears)
    Vencomycin, Gentamycin, Neomycin

Pharmacology (5 decks)

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