This document discusses superbugs and their mechanisms of antibiotic resistance. It describes how bacteria can acquire innate or acquired resistance. Acquired resistance occurs through chromosomal mutations or gene transfer between strains. Common resistance mechanisms include modification or inactivation of antibiotics, target site modification, and efflux pumps. The document also discusses potential ways to combat superbugs, such as using nanoshuttles or antimicrobial peptides, as well as potential applications of superbugs in bioremediation and fuel cells.

1. SUPERBUGS: MECHANISMS,
CONTROL & UTILIZATION
Presented by:
Noor-ul-Ain

2. WHAT ARE SUPERBUGS?
• Bacteria which have acquired increased resistance towards
the antibiotic class used for their treatment
• Multi-drug resistance acquired by bacteria through various
mutations which enhance its morbidity and mortality levels

3. Two type of resistance offered by bacteria:
• Innate Resistance
• Acquired Resistance
Acquired resistance may be through:
• Chromosomal mutations
• Gene Transfer among strains
Resistance Mechanisms Adopted by
Superbugs

4. • Modification/ Inactivation of
Antibiotics
• Target Site Modification
• Membrane Permeability &
Efflux Pumps
Resistance Mechanisms Adopted by
Superbugs

5. 1. Modification/ Inactivation of Antibiotics
• Three enzymes involved are
β-lactamases, Chloramphenicol acetyltransferases and Aminoglycoside-
modifying enzymes
• Transferases work by binding phosphoryl, adenylyl or acetyl groups to
the antibiotic molecule
• Aminoglycoside modifying enzymes reduce affinity of a modified
molecule and hinder binding to the 30S ribosomal subunit
• β-lactamases break open β-lactam ring through hydrolysis containing
ester and amide linkages
Resistance Mechanisms Adopted by
Superbugs

6. 2. Target Site Modification
• Fluoroquinolone resistance linked to the mutation among genes responsible for
encoding the target sites
• Genes undergo mutation at Quinolone Resistance-Determining Region
• Mutations in genes amino acid substitutions modify the target
protein structure fluoroquinolone-binding affinity of the enzyme decreases
• For instance, Amino acid substitution may include:
 substitution at serine 83 with Leucine in GyrA for P. stuarti
 substitution at serine 80 with Arginine in ParC for K. pneumoniae
Resistance Mechanisms Adopted by
Superbugs

7. 2. Membrane Permeability & Efflux Pumps
• Double membrane structure of gram negative bacteria resists the uptake and
transfer of drug
• Certain strains acquire such genes which produces altered bacterial cell walls
• Efflux pumps pump the antibacterial agent out of the cell
• Bacteria which are resistant towards tetracycline secrete membranous
proteins which act as efflux system of antibiotics
Resistance Mechanisms Adopted by
Superbugs

9. Resistance Mechanism in Clostridium difficile
C. difficile produces actin-ADP–ribosylating toxin (C. difficile transferase)
CDT adds ADP ribose to the actin protein, causes actin depolymerization
CDT also produces Microtubule-based protrusions
Actin depolymerization increases secretion of fibronectin (ECM Protein)
Changes in intracellular calcium level occurs
Increased concentration of ECM protein & microtubule based protrusions
forms a meshwork at host cell surface
C. difficile is adhered tightly to the host cell surface

11. Salmonella enterica confers resistance by the emergence of qnrS genotype with
increased mobility
Resistance Mechanism in Salmonella enterica
Qnr proteins provide resistance to the strain by protecting DNA-gyrase from
quinolones
Strains carrying qnr alleles can withstand elevated concentrations of fluoroquinolones
Plasmid-mediated Quinolone Resistance, increased possibility of transfer to other
strains

12. MRSA CM05 strain confers resistance against linezolid
Resistance Mechanism in MRSA
Resistance caused by qnr gene which releases Cfr methyltransferase
Enzyme leads to the modification in adenosine located at position 2503 in 23S
rRNA
Cfr adds extra methyl group to A2503
Leads to changes in molecular conformation

13. Ways to Combat
Superbugs

14. Ways to Combat Superbugs
1. Use of Nanoshuttles
• Nanoparticles used for efficient delivery
of drug into the cell
• Increase potential of therapeutic
treatment
• Reduce the concentration of antibiotic
into the surrounding serum
• For example, ciprofloxacin loaded zinc
doped hydroxyapatite increased
antimicrobial activity against
Staphylococcus aureus

15. 2. Use of Filamentous Phage
Ways to Combat Superbugs
• Combination of certain drug resistant strains with
filamentous phage resulted in resensitization of previously
resistant strains
• Filamentous phage is secreted through aqueous channels
in outer membrane
• Phage protein pIV creates channels with high conductivity
• Opening of pIV channels results in increased susceptibility
of host bacteria

16. 2. Use of Filamentous Phage
Ways to Combat Superbugs

17. 3. Antimicrobial peptides as Anti-MRSA agents
Ways to Combat Superbugs
• Antimicrobial assays of natural antimicrobial peptides isolated
demonstrated the inhibition of Staphylococcal growth
• Novel peptides can also be designed which have significant
antibacterial activity against bacterial strains
• A unique peptide sequence was designed i.e. DFTamP1 (1K, 2G,
2S, and 8 L) through database filtering technology
• DFTamP1 inhibited MRSA USA300 because of its high
hydrophobicity and low cationicity

18. Ways to Combat Superbugs
Database Filter Technology

19. Ways to Combat Superbugs
Anti-MRSA strategy of designed peptide sequence

20. POTENTIAL USE OF SUPERBUGS

21. Superbugs for Bioremediation
• Research today is focused on
 Design of superbugs with modified degradative genes through genetic
engineering
OR
 Discovery of naturally tolerant bacteria found in contaminated sites and
their utilization for bioremediation
• Hybrid strain of Pseudomonas putida was engineered by replacing gene
encoding for bphA1 with the gene encoding for toluene dioxygenase
(todC1)
• Hybrid strains were found to have enhanced ability to grow on wide
variety of hydrocarbons, also had the ability to degrade xenobiotic
compounds

22. • Genetically modified superbugs can play a
significant role in improving the power output
efficiency of fuel cells
• Superbugs are designed to over-express genes
can increase the prospect of electron flow to
an electrode
• Certain bacteria secrete redox-active
mediators which can transfer electrons to
conductive surfaces
• High flow rates require large biofilm surface
area and increased biofilm metabolic rate
Superbugs for Bioremediation

23. Superbugs for Bioremediation
Convective-flow membrane-less MFC with dual anodes and dual
cathodes for wastewater treatment