81 terms

Antimicrobial Drugs

Chapter 10
Antimicrobial drug
a chemical substance that destroys disease-causing microorganisms with minimal damage to host tissues
Chemotherapeutic agents
are compounds that destroy pathogenic microorganisms or inhibit their growth and are used in the treatment of diseases
Who developed the concept of chemotherapy to treat microbial diseases
Paul Ehrlich
Selective toxicity
chemotherapeutic agents that could kill pathogens without harming the host
What did Ehrlich use on syphilis
arsenic chemical
Who discovered the first antibiotic
Alexander Fleming
Who developed the first antibiotic for human use
Florey and Chain
microbial products or their derivatives that can kill susceptible microorganisms or inhibit their growth
three targets antibacteria drugs affect in prokaryotic cells
cell wall, ribosomes and metabolism
What three organisms are more difficult to treat
helminthic infections, fungal, protozoan,
Why are fungus, protozoa and helminthic infections more difficult to treat?
because they have eukaryotic cells
What do fungal infections drugs target?
The plasma membrane differences
What single infection is the MOST difficult to treat
Viral infection
drug that interferes with critical stages in the virus life cycle is
2 drugs that inhibit the synthesis of virus specific nucleic acids
zidovudine, acyclovir
What inhibits virus replication
Interferon proteins
One thing an effective chemoterapeutic agent must have
selective toxicity
narrow spectrum drugs
affect only a select group of microbes
broad spectrum drugs
affect a large number of microbes
3 sources of bacteria
natural, semisynthetic or synthetic
2 general effects of antibiotics
static and cidal
When does superinfections occur
superinfections occur when a pathogen develops resistance to the drug being used or when normally resistant microbiota multiply excessively
3 places where drugs come from (italicized)
Streptomyces, Penicillum and Cephalosporium (mold)
killiing microorganisms
inhibiting their growth
All penicillins contain a _-____________ ____
B-Lactum Ring
Penicillins inhibit
peptidoglycan synthesis
natural penicillins are produced by
natural penicillins are effective against
gram-positive cocci and spirochetes
Penicillinases aka
bacterial enzymes that destroy natural penicillins
what produces penicillinases
staphylococcus species
MRSA are resistant to
oxacillin and methicillin
two types of semisynthetic penicillins
ampicillinn and methicillin
What does the monobactam aztreonam affect?
only gram-negative bacteria
Cephalosporins do two things
1) inhibit cell wall synthesis
2) are used against penicillin-resistant strains
Three examples of Polypeptide antibiotic
Bacitracin, Vancomycin, cycloserine
Bacitracin is used against
gram positive bacteria (Topical only)
Vancomycin and cycloserine are used for
killing drug resistant gram-positive staphylococci
What can be used against MRSA
Vancomycin and cycloserine
Three antimycobacterial antibiotics
Isoniazid (INH), Ethambutol, Streptomycil
4 antibacterial antibiotics
penicillin, penicillinase resistant penicillin, the monbactam aztreonam, polypeptide antibiotics
5 inhibitors of protein synthesis
chloramphenicol, aminoglycosides, tetracyclines, macrolides, oxamoldinones, antisense nucleic acids
2 types of aminoglycosides
streptomycin and gentamicin
3 things streptomycin is effective against
mycobacteria, plague and gram-negative bacteria
how are tetracyclines produced
by some species of the Actinomycete genus, Streptomyces
Erythromycin is a type of
what is the method of action of erythromycin
inhibit protein synthesis by binding to the bacterial ribosomes
what is erythromycin effective against (3)
gram positive bacteria, mycoplasma, few gram negative bacteria
what is oxamolidinones effective against
only gram positive bacteria
define antisense nucleic acids
designed to be complementary to specific RNA molecules of pathogens and thus block protein synthesis
Two things that cause damage to plasma membranes
polymyxin B and bacitracin
polymyxin is effective against
gram-negative bacteria
antimetabolites inhibit
metabolic pathways
How do antimetabolites work
they mimic a normal molecule
What ddo sulfonamides do
inhibit folic acid synthesis
another name for sulfonamides
sulfa drugs
Why are humans not effected by sulfonamides
they obtain the vitamin from food
3 things used as antiviral drugs
amantadine, rimantadine, weak organic bases
why are weak organic bases used as antiviral drugs
they can neutralize the acidic environment of phagolysosomes and thereby prevent viral uncoating
an enzyme needed by HIV during its replication cycle
What does Isoniazid (INH) do
inhibits mycolic acid synthesis in mycobacteria
INH is administered with what to treat tuberculosis
rifampin or ethambutol
3 inhibitors of nucleic acid
rifamycin and quinolones and fluoroquinolones
what does Rifamycin (rifampin) inhibit
mRNA synthesis
What do quinolones and fluoroquinolones inhibit
DNA synthesis for treatment of urinary tract infections
What is bacterial gyrase for
needed for correct coiling of replicating bacterial DNA
disadvantage of DNA RNA inhibiting antibiotics
may interfere with human DNA and RNA and be toxic and develops antibiotic resistace
What do antiviral drugs target
the different stages of viral reproduction
how do you block attaachment of viruses to host cells
by peptide and sugar analogs of either attachment or receptor proteins
most drugs affect the...
nucleic acid synthesis of the virus
Pathogens that are resistant to most antimicrobial agents
Cross resistance
typically occurs when drugs are similar in structure so the bacteria resists all of them
multiple resistance
resistance to more than one drug at a time
an example of synergism within drugs
penicillin and streptomycin are used for bacterial endocarditis. one damages the cell wall so the other can enter
an example of an antagonistic combination of drugs
penicillin (works on growing bacteria) and tetracycline (stops growth)
Three pathogens that have low-permeability membrane barriers
Pseudomonas aeruginosa, Mycobacterium tuberculosis, enterococcus
what kind of bacteria contain plasmids
gram negative
7 gram negative bacteria with R-factor plasmids
E. coli, Proteus, Serratia, Enterobacter, Salmonella, Shigella and pseudomonas
example of penicillinase bacteria
neisseria gonorrhoeae