Microbiology Finals (Part 2 of 3)

“magic bullet’
chemotherapy

Staphylococcus aureus was
inhibited in the area surrounding the colony of a mold that
had contaminated a Petri plate →Pellicillillm notatum later
on named Penicllin

Mechanism of inhibition → antibiotic:
substance produced by microorganisms that in small
amounts inhibits another microorganism

1927:

More than half of our antibiotics are produced by species
of

Active against a selected group of
bacterial types. They can act on either gram +ve or gram –ve but not both

Antibiotics that affect a broad range ofgram-positive or gram-negative
bacteria.

which is not sensitive to bacterial antibiotics

Overgrowth of microorganism or growth of a target pathogen that
has developed resistance to the antibiotic

they kill microbes directly

they prevent microbes from growing

MOA of Antibiotics and other
Antimicrobials

Inhibiting Cell Wall synthetis

Inhibiting protein synthesis

Injuringthe plasma membrane

Inhibiting synthesis of essential metabolites

Inhibiting Nucleic acid synthesis

Antibiotics Inhibiting Cell Wall
Synthesis: Beta Lactams

have a common core structure containing a B-lactam ring called the nucleus.

which is the first member of a new class of
antibiotics. It is a synthetic antibiotic that has only a single
ring rather than the conventional B -lactam double ring

resemble those of penicillin

is a polypeptide antibiotic effective primarily against gram-positive bacteria, such as staphylococci and streptococci.

the name is derived from its source, a Bacillus isolated from a wound on a girl named

is one of a small group of glycopeptide antibiotics derived from a species of Streptomyces found in the jungles of Borneo
➢ Vancomycin has been considered the last line of antibiotic defense for t reatment of Staphylococcus aureus infections that are resistant to
other antibiotics.

The widespread use of vancomycin to treat MRSA has led to the appearance of

is a very effective synthetic antimicrobial drug against
Mycobacterium tuberculosis.

is effective only against mycobacteria. The drug apparently
inhibits incorporation of mycolic acid into the cell wall It is a
comparatively weak antitubercular drug; its principal use is as the
secondary drug to avoid resistance problems

inhibits the formation of peptide bonds in the growing polypeptide
chain by reacting with the 50S portion of the 70S prokaryotic ribosome.

are a group of antibiotics in which amino sugars are linked by glycoside bonds

interfere with the initial steps of protein synthesis by changing the shape of the 30S portion

group of closely related broad-spectrum antibiotics produced by Streptomyces spp. Valuable against the intracellular rickettsias and chlamydias.

are a group of antibiotics named for the presence of a macrocyclic lactone ring

are another new class of antibiotics developed in response to
vancomycin resistance.

bactericidal antibiotic effective against gram-negative bacteria. drugs used against infections by gram-negative Pseudomonas.

The best-known derivative of the rifamycin family of antibiotics is

Rifampin is against mycobacteria in the treatment of

First quinolone drug developed
➢ It exerted a unique bactericidal effect by selectively inhibiting an
enzyme (DNA gyrase) needed for the replication of DNA.

Fluoroquinolones 1st Gen

first synthetic antimicrobial drugs used to treat microbial diseases

combination is an excellent example of drug

When the biosynthesis of ergosterol in a fungal membrane is interrupted, the membrane becomes excessively permeable, killing the cell.

antifungals, which include members of the

Polyenes

Azole-Imidazole

Allylamines