Antimicrobials

Question 1

Name the 3 categories of beta lactam antibiotics

Answer 1

Penicillins, cephalosporins, carapenems

Question 2

Cephalexin, cefazolin, cefovecin, cefpodoxime and ceftazidime are all _____

Answer 2

cephalosporins

Question 3

Beta lactam antibiotics inhibit _____ by binding the ______ enzyme, inhibiting ______ cross-linking activity.

Answer 3

Beta lactam antibiotics inhibit cell wall synthesis by binding the PBP (penicillin binding protein) enzyme, inhibiting peptidoglycan cross-linking activity.

Question 4

Clavulanic acid and sublactam are examples of ______ inhibitors. If bacteria develop further resistance by altering their ____, this is called _____ resistance.

Answer 4

Clavulanic acid and sublactam are examples of beta lactamase inhibitors. If bacteria develop further resistance by altering their PBP (iei PBP2a), this is called methicillin resistance.

Question 5

_____ are resistant to beta lactams because they lack a _____

Answer 5

Mycoplasma are resistant to beta lactams because they lack a cell wall

Question 6

Vancomycin is a type of ____ inhibitor, but it is not a beta lactam, it is a _____. It is used to treat serious gram ______ infections.

Answer 6

Vancomycin is a type of cell wall synthesis inhibitor, but it is not a beta lactam, it is a glycopeptide. It is used to treat serious gram positive infections.

Question 7

_____ is a mixture of several closely related cyclic polypeptide antibiotics that has both bacteriostatic and bactericidal properties depending on the concentration of the drug and the susceptibility of the microorganism. They target primarily gram ____ bacteria.

Answer 7

Bacitracin, gram positive

Question 8

____ are bactericidal drugs and act on the outer membrane of gram-______ bacteria by destabilizing the phospholipids and lipopolysaccharides (LPS) present.

Answer 8

Polymyxins, gram-negative

Question 9

_______ are folic acid metabolism inhibitors; this means they impair production of _____ by impairing the conversion of ______ to ______ which ultimately gives rise to ______. This means they are bacterio-_____

Answer 9

Sulfonamides are folic acid metabolism inhibitors; this means they impair production of DNA nucleotides by impairing the conversion of para-aminobenzoic acid (PABA) to dihydrofolic acid (DHFA) which ultimately gives rise to thymidine, purines, and methionine. This means they are bacteriostatic.

Question 10

_______-sulfonamides are bacterio-_____ because the addition of _______ also blocks of the conversion of _______ to _____.

Answer 10

Potentiated sulfonamides are bacteriocidal because the addition of diaminopyrimidines (trimethoprim, methoprim, ormetoprim, aditoprim, and pyrimethamine) also blocks the conversion of dihydrofolic acid (DHFA) to tetrahydrofolic acid (THFA).

Question 11

Sulfonamides are considered ____ spectrum and also inhibit ______, _____, and some _____.

Answer 11

The spectrum of all sulfonamides is generally the same. Sulfonamides inhibit both gram-positive and gram-negative bacteria, Nocardia, Actinomyces spp, and some protozoa (eg, coccidia and Toxoplasma spp). More active or potentiated sulfonamides may have activity against several species of Streptococcus, Staphylococcus, Salmonella, Pasteurella, Corynebacterium, and even Escherichia coli in their spectra. Strains of Enterobacter, Klebsiella, Proteus, Clostridium, and Leptospira spp are susceptible but may become resistant. Rickettsiae, protozoa, coccidia, mycoplasmas, Pseudomonas, Bacteroides, and most Chlamydia are highly resistant.

Question 12

The ribosomal protein synthesis inhibitor classes are:

Answer 12

Aminoglycosides, tetracyclines, lincosamides, macrolides and phenicols

Question 13

“G-TANKS”: Gentamicin, Tobramycin, amikacin, neomycin, kanamycin and streptomycin are all _____

Answer 13

aminoglycosides

Question 14

Aminoglycosides are bacterio-____ and are most effective against gram-_____ ___-obes. This is because ___

Answer 14

Aminoglycosides are bacteriocidal and are most effective against gram negative aerobes. This is because they diffuse through the outer membrane of gram negative cells through porins, and further transport into the bacteria requires a proton pump and oxygen.

Question 15

The two main adverse effects of aminoglycosides are

Answer 15

nephrotoxicity and ototoxicity

Question 16

Chlotetracycline, tetracycline, oxytetracycline, doxycycline and minocycline are all ______

Answer 16

Tetracyclines

Question 17

Tetracyclines have ____ acitivity

Answer 17

gram positive and gram negative

Question 18

Lincomycin and clindamycin are the two _____. They are called ______ antibiotics because they contain a ____. They target gram-____ ____-obes and can also be used for ________. Since they inibit ____, they are typically bacterio-_____ but can be ____ at high concentrations.

Answer 18

Lincomycin and clindamycin are the two lincosamides. They are called monoglycoside antibiotics because they contain a single glycoside. They target gram-positive anaer-obes and can also be used for toxoplasmosis. Since they inhibit ribosomal protein synthesis they are typically bacteriostatic but can be cidal at high concentrations.

Question 19

Erythromycin, tylosin, tulathromycin and azythromycin are ______. This means they all have a ____ ring with one or more deoxy-sugars or amino-sugars attached.

Answer 19

Macrolides. They have a large macrocyclic lactone ring with one or more deoxy-sugars or amino-sugars are attached .

Question 20

Erythromycin, tylosin, tulathromycin and azythromycin are ____ whereas clindamycin and lincomycin are ________

Answer 20

Erythromycin, tylosin and azythromycin are macrolides whereas clindamycin and lincomycin are lincosamides

Question 21

____ are ____ spectrum and include chloramphenicol and florfenicol (nuflor). You cannot use them _____ in _____

Answer 21

Phenicols are broad spectrum and include chloramphenicol and florfenicol. You cannot use them extra label in food animals.

Question 22

_____ can cause aplastic anemia in humans, so gloves should be worn when handling the drug.

Answer 22

Chloramphenicol

Question 23

The direct DNA synthesis inhibitors are: (3)

Answer 23

flouroquinolones, rifamycin and metronidazole

Question 24

Enrofloxacin (baytril), orbifloxacin, marbofloxacin, pradofloxacin (cats) and ciprofloxacin are all ______

Answer 24

Flouroquinolones

Question 25

Flouroquinolones inhibit _____ and ______, therefore they are bacteri-_____. Their spectrum is primarily ______.

Answer 25

Flouroquinolones inhibit DNA gyrase and topoisomerase 4, therefore they are bactericidal. Their spectrum is primarily gram positive.

Question 26

Rifamycins include _____ and they are active againist _____, _____, and ______. They can also be an ____ at high doses.

Answer 26

Rifamycins include rifampin and they are active against gram positive, mycobacteria, and some gram negatives. They can also be an antiviral at high doses.

Question 27

Metronidazole is a type of _______ and is bacteri-_____. It is able to diffuse across the cell membrane of ____ bacteria and causes _____.

Answer 27

Metronidazole is a type of nitroimidazole and is bactericidal. Metronidazole is able to diffuse across the cell membranes of anaerobic bacteria where it cause DNA strand breaks, resulting in inhibition of protein synthesis and cell death. Metronidazole has activity against most obligate anaerobes, including Bacteroides spp (including Bacteroides fragilis), Eubacterium spp, Fusobacterium spp, Veillonella spp, Clostridium spp, Peptococcus spp, Peptostreptococcus spp, and Prevotella spp. Resistance to metronidazole appears to be rare, although Actinomyces spp are frequently resistant; resistance in clostridia, including Clostridioides difficile, has been reported.
Metronidazole is also trichomonacidal and amoebicidal. The mechanism of action for its antiprotozoal activity is not understood. It has therapeutic activity against Entamoeba histolytica, Trichomonas spp, Giardia spp, and Balantidium coli; however, its efficacy against Tritrichomonas spp is poor. It acts primarily against the trophozoite forms of Entamoeba spp rather than encysted forms.

Question 28

Which 4 antibiotics or antibiotic classes can cross the blood-prostate barrier?

Answer 28

Flouroquinolones (erythromycin), trimethoprim-sulfa, chloramphenicol and erythromycin

Question 29

_____ are contraindicated for administration in the caudal half of a reptile

Answer 29

Aminoglycosides; this is because blood from the back half of reptiles passes through the renal portal system before going forward so nephrotoxic drugs would be contraindicated

Question 30

Which antimicrobials are contraindicated in guinea pigs and why?

Answer 30

due to anibiotic associated enterotoxemia, antibiotics that destroy gram-positives and allow overgrowth of clostridium difficle should be avoided: Aminogycosides (streptomycin), bacitracin, oral penicillins, cefazolin, clindamycin and lincomycin, chlotetracycline and oxytetracycline, tylosin.

Question 31

One of the main potential side effects of sulfa drugs like TMS is

Answer 31

KCS

Question 32

Cephalosporins treated primarily gram-____ infections and they are ____ type of antibiotic. Examples include:

Answer 32

gram-positive, beta lactam , cefazolin, cephalexin (1st gen), cefpodoxime, ceftiofur, cefovecin, ceftazidine (3rd gen)

Question 33

Name the antibiotics or antibiotic classes that are cell wall synthesis inhibitors

Answer 33

Beta lactams (penicillins, cephalosporins and carbapenems)
Vancomycin