Chemical Methods of Microbial Control

Chemotherapy

Treatment of a disease with chemical agents

Paul Ehrlich

He came up with chemotherapy?

Antimicrobial

Chemical that causes antibiosis in some microbes. May be topical or ingested

Antibiotic

Inhibits growth of bacteria

Antifungal

Inhibits the growth of fungi

Antiprotozoals

Inhibits the growth of protozoa

Antiviral

Inhibits the growth of viruses

Antibiotics, antifungal, antiprotozoals, antiviral

Four types of antimicrobials

Number of microbes, environment, time of exposure, microbial characteristics

Effectiveness of Treatment depends on_______

Use-Dilution Test

Metal rings dipped in test bacteria are dried and places in disinfectant for 10 mins before transferred to a culture media

Disk-Diffusion Method

Antimicrobial disks are placed on a culture media with bacteria

Alexander Fleming (1928)

Discovered penicillin

Florey and Chain (1940)

Performed the first clinical trials of penicillin

1942

What year did mass production of penicillin start?

Natural, Semisynthetic, synthetic

Three sources of antibiotics

Streptomycin

Changes shape of 30S portion, causing code on mRNA to be read incorrectly

Tetracyclines

Interfere with attachment of tRNA to mRNA- ribosome complex

Chloramphenicol

Binds to 50S portion and inhibits formation of peptide bond

Natural Beta-Lactams

• Penicillium

• Narrow but useful spectrum (only typically affect G + without beta lactamases

Semisynthetic Beta-Lactams

• Natural plus synthetic components

• Penicillinase-resistant

• Extended spectrum (adds effect against G-)

Chemotherapeutic agent

Chemical that inhibits the growth or kills microbes

Antibiotic

Natural antimicrobial agent produced by microbes

Kirby-Bauer Method (Disc Diffusion Method)

Technique used to measure susceptibility and resistance of a specific microorganisms to a chemotherapeutic agent on a Mueller-Hinton agar