The effectiveness of processed grapefruit-seed extract as an antibacterial agent: I. An in vitro agar assay.
OBJECTIVE
Grapefruit-seed extract (GSE) Citricidal has, in recent reports, been reported to be successful in combating a variety of common infectious agents. In our study, drops of concentrated grapefruit-seed extract were tested for antibacterial properties against a number of gram-positive and gram-negative organisms.


METHODS
Sixty-seven (67) distinct biotypes were tested for their susceptibilities to the GSE as well as to 5 other topical antibacterials (Silvadene, Sulfamylon, Bactroban, Nitrofurazone, and Silvadene, Nystatin). Wells were punched into Mueller-Hinton agar plates, which were then inoculated with the organism to be tested; each well was then inoculated with one of the antibacterial agents. After an overnight incubation period, the plates were checked for zones of bacterial susceptibility around the individual wells, with a measured susceptibility zone diameter of 10 mm or more considered a positive result.


RESULTS
The GSE was consistently antibacterial against all of the biotypes tested, with susceptibility zone diameters equal to or greater than 15 mm in each case.


CONCLUSIONS
Our preliminary data thus suggest an antibacterial characteristic to GSE that is comparable to that of proven topical antibacterials. Although the GSE appeared to have a somewhat greater inhibitory effect on gram-positive organisms than on gram-negative organisms, its comparative effectiveness against a wide range of bacterial biotypes is significant.
Reagor
Lee
L
School of Medicine, University of Texas, Medical Branch, Galveston, USA.
Gusman
Jean
J
McCoy
Lana
L
Carino
Edith
E
Heggers
John P
JP
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002957:Citrus; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology; D012639:Seeds
D000900:Anti-Bacterial Agents; D010936:Plant Extracts