Transcript The Growing Problem of Antibiotic Resistance

The Growing Problem
of Antibiotic Resistance
张驰
王昳楠
Have we conquered bacteria yet?
Why the pharmaceutical industry
has cut resources devoted to the
development of new antibiotics
Lack of financial incentives
 Short lifetime in the marketplace
 The most effective antibiotics being held
back from widespread use

Enzymes involved in the
synthesis of the bacterial
cell wall
Penicillin
 Vancomycin

Components of the system by which
bacteria duplicate, transcribe, and
translate their genetic information
 Linezolid
 Daptomycin
3. Enzymes
that catalyze metabolic reactions
specifically in bacteria.
Take sulfa drugs for example
Sulfa drugs, are effective antibiotics
because they closely resemble the
compound p-aminobenzoic acid (PABA)
p-aminobenzoic acid
Sulfa
Function of PABA

PABA is an intermediate in the bacterial
synthesis of folate(folic acid).

However, humans lack the enzymes to
convert PABA to folate,and therefore require a
dietary supply of folate anyway,so PABA is
considered nonessential and is not
recognized as a vitamin for humans.

Thus, bacterial growth is limited through folate
deficiency without effect on human cells.
Function of Sulfa drugs

Sulfa drugs are structurally similar to PABA,
and their antibacterial activity is due to their
ability to interfere with the conversion of PABA
to folate by the enzyme dihydropteroate
synthetase.
Why bacteria become resistant
to antibiotics?
Take Penicillin for example
Penicillin is a β-lactam; that is, it contains a fourmembered β-lactam ring (shown in color).
Background

By the 1940s, researchers had discovered that
certain bacteria possess an enzyme calledβlactamase(or penicillinase).

During World War II, none of the major diseasecausing bacteria possessed a gene for β-lactamase.

Today, the production of β–lactamase by wide
variety of infectious cells is the primary cause of
penicillin resistance.
How did
these species acquire the gene?
—— not only among the cells of a given
species, but also between species
Accessions

Conjugation

Transduction

Transformation
Conjugation
DNA is passed from one bacterial cell to another
Transduction
a bacterial gene is carried from cell to cell by a virus
Transformation
a bacterial cell is able to pick up naked DNA
from its surrounding medium
Other reasons of bacteria’s resistant
Not all penicillin-resistant bacteria have acquired aβ–lactamase gene.

possess modifications in their cell walls that block
entry of the antibiotic

selectively export the antibiotic once it has entered the
cell

possess modified transpeptidases that fail to bind the
antibiotic
About AIDS

high rate of virus production

reverse transcriptase lead to high rate of
mutation
This problem is being combatted by

Taking several different drugs targeted at
different viral enzymes

designing drugs that interact with the most highly
conserved portions of each targeted enzyme
Antibiotic abuse

Antibiotic resistant bacteria is a growing threat
and becoming increasingly common.

Antibiotic abuse also places the patient at
unnecessary risk of adverse effects of antibiotics.
Thank you ~