Tetracycline hydrochloride microbiology

Tetracycline hydrochloride
TETRACYCLINE HYDROCHLORIDE® FDA Package Insert
Description
Clinical Pharmacology
Microbiology
Indications and Usage
Contraindications
Warnings and Precautions
Adverse Reactions
Overdosage
Dosage and Administration
How Supplied
Labels and Packages

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohamed Moubarak, M.D. [2]

Microbiology

Tetracyclines are primarily bacteriostatic and exert their antimicrobial effect by the inhibition of protein synthesis. Tetracycline is active against a wide range of gram-negative and gram-positive organisms. The drugs in the tetracycline class have closely similar antimicrobial spectra, and cross-resistance among them is common. While in vitro studies have demonstrated the susceptibility of most strains of the following microorganisms, clinical efficacy for infections other than those included in the INDICATIONS AND USAGE section has not been documented.

Gram-negative Bacteria

Neisseria gonorrhea

Haemophilus ducreyi

Haemophilus influenzae

Yersinia pestis (formerly Pasteurella pestis)

Francisella tularensis (formerly Pasterurella tularensis)

Vibrio cholera (formerly Vibrio comma)

Bartonella bacilliformis

Brucella species

Because many strains of the following groups of gram-negative microorganisms have been shown to be resistant to tetracyclines, culture and susceptibility testing are recommended:

Escherichia coli

Klebsiella species

Enterobacter aerogenes

Shigella species

Acinetobacter species (formerly Mima species and Herellea species)

Bacteroides species

Gram-positive Bacteria

Because many strains of the following groups of gram-positive microorganisms have been shown to be resistant to tetracycline, culture and susceptibility testing are recommended. Up to 44 percent of strains of Streptococcus pyogenes and 74 percent of Streptococcusfaecalis have been found to be resistant to tetracycline drugs. Therefore, tetracyclines should not be used for streptococcal disease unless the organisms have been demonstrated to be susceptible.

Streptococcus pyogenes

Streptococcus pneumoniae

Enterococcus group (Streptococcus faecalis and Streptococcus faecium)

Alpha-hemolytic Streptococci (viridans group)

Other Microorganisms

Chlamydia psittaci

Chlamydia trachomatis

Ureaplasma urealyticum

Borrelia recurrentis

Treponema pallidum

Treponema pertenue

Clostridia species

Fusobacterium fusiforme

Actinomyces species

Bacillus anthraxis

Propionibacterium acnes

Entamoeba species

Balantidium coli

Susceptibility Testing

A tetracycline disk may be used to determine microbial susceptibility to drugs in the tetracycline class. If the Kirby-Bauer method of disk susceptibility testing is used, a 30 mcg tetracycline disk should give a zone of at least 19 mm when tested against a tetracycline susceptible bacterial strain. Microorganisms may be considered susceptible if the MIC (minimum inhibitory concentration) is not more than 4 mcg/mL and intermediate if the MIC is 4 to 12.5 mcg/mL.

References

Adapted from the FDA Package Insert.