BI-121 Microbiology


Completing the following table.

All information you provide should be cited.

Table: The mode and spectrum of antibiotics as well as the organisms it affects are listed in the table.


Chemical class


Spectrum of Activity (gram +, broad, or -)

Mechanism of Action

Referred to


Polymyxin A




Table: The mode and spectrum of action of antibiotics, as well as the organisms it affects.


Chemical class


Bandwidth of activity (gram +/-, or wide)

Mechanism of Action

Referred to

Gram positive and Gram negative

By inhibiting the bacterial DNA Gyrase (topoisomerase Ii), it inhibits bacterial genome synthesis.

DNA gyrase is responsible for the uncoiling and replication of the bacterial double helix DNA.

Mechanism of quinolone activity and resistance.


Antibiotic Lipopolypeptide

Interacts to the anionic lipopolysaccharide outer membrane layers of gram-negative bacteria, increasing cell permeability. This promotes cell suicide.

Emergence of the colistin resistance mechanism MCR-1 mediated by plasmids in animals and humans in China: A molecular and microbiological study.

The Lancet infectious disease, vol.

Oxa-beta lactam antibiotic

Broad spectrum activity against gram-positive and gram-negative aerobic and anaerobic bacteria

It belongs to the group of bacteria called cephalosporins.

It blocks the bacterial cell-wall biosynthesis and interferes with the bactericidal action.

It reduces the cross-linking in the peptidoglycan layered.

It also activates autolysins that cause bacterial cell lysis.

Studies on b-lactam compounds.

Current Trends In Organic Synthesis, pp.

The majority of gram positives are found in the body, while a few gram of gram is negative.

Binds to the bacterial wall and inhibits transpeptidoglycan biosynthesis.

It prevents cross-linking of peptidoglycan layer

Chemistry of Penicillin.

Princeton University Press.

Polymyxin A

Lipopolypeptide antibiotic

Interacts directly with the anionic lipsopolysaccharide outer membrane layers of gram-negative bacteria.

This increases cell permeability by removing magnesium and calcium ions. Cell death can be promoted through leakage of cell contents.

Population pharmacokinetics intravenous Polymyxin B in Critically Ill Patients: Implications for selecting dosage regimens.

Clinical infectious diseases vol.

Therapeutic: Antiinfectives and glycopeptide

Gram positive

Inhibits the formation of bacterial cells wall in the second stage.

It also alters permeability of the bacteria cell wall and selectively inhibits the process of ribonucleic Acid biosynthesis

The rise of Enterococcus: Beyond vancomycin resistance


Antiinfectives and Therapeutics

Pharmacologic: Tertacyclins

Gram positive

By binding with the 30S of the bacterial ribosome, it inhibits bacterial protein production

Resistance mechanisms and antibiotics for Tetracycline.

Biological chemistry vol.


Gram positive

Interferes in the dyhydropteroate synthesise, inhibits metabolism pathway to folic acid

Design, synthesis, antimicrobial assessment and molecular docking studies for some new 2, 3-dihydrothiazoles as well as 4-thiazolidinones containing Sulfisoxazole.

Journal of enzyme inhibitor and medicinal chemistry vol.

Gram positive and gram neo aerobic bacteria

It blocks folic acid metabolism and leads to a decrease in the rate of hamatopoiesis.

It is a pyrimidine inhibiter of dihydrofolate reducetase.

Trimethoprim – Kinetic and mechanistic considerations for photochemical environmental fate and AOP treatments.