Lana McCoy

The Effectiveness of Processed Grapefruit-Seed Extract as An Antibacterial Agent: II. Mechanism of Action and In Vitro Toxicity

OBJECTIVES Recent testimonials report grapefruit-seed extract, or GSE (Citricidal) to be effective against more than 800 bacterial and viral strains, 100 strains of fungus, and a large number of single and multicelled parasites. This study investigated GSE for antibacterial activity at varying time intervals and concentration levels and tissue toxicity at varying concentrations in an effort to determine if a concentration existed that was both microbicidal and nontoxic and in what period of time. DESIGN Gram-negative and gram-positive isolates were introduced into graduated dilutions of GSE (twofold concentrations ranging from 1:1, through 1:512) for determination of bacterial activity. In vitro assays with human skin fibroblast cells were also performed at the same dilutions to determine toxicity. RESULTS These tests indicated that from the 1:1 through the 1:128 concentrations, GSE remained toxic as well as bactericidal. However, test results indicated that at the 1:512 dilution, GSE remained bactericidal, but completely nontoxic. CONCLUSIONS The initial data shows GSE to have antimicrobial properties against a wide range of gram-negative and gram-positive organisms at dilutions found to be safe. With the aid of scanning transmission electron microscopy (STEM), the mechanism of GSEs antibacterial activity was revealed. It was evident that GSE disrupts the bacterial membrane and liberates the cytoplasmic contents within 15 minutes after contact even at more dilute concentrations.

The effectiveness of processed grapefruit-seed extract as an antibacterial agent: I. An in vitro agar assay.

OBJECTIVES 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. DESIGN 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.

Alternate antimicrobial therapy for vancomycin-resistant enterococci burn wound infections.

Survival after a major thermal burn is precarious and fraught with difficult complications associated with hypermetabolism, gut or respiratory dysfunction, and infection. Clinicians must be cognizant of a new threat to the patient with burn injuries--the emergence of vancomycin-resistant enterococci (VRE). In an analysis of 31 clinical isolates obtained during acute burn hospitalization, an optimal antimicrobial therapy for VRE has been identified. All VRE cultures were inoculated to the MicroScan Gram-Positive Breakpoint Combo Panel #8 (Dade Microscan, Inc, Sacramento, Calif), which speciates the enterococci, provides antimicrobial susceptibility patterns (including vancomycin) and a biotype, and examines streptomycin and gentamicin synergy. Eleven (35.5%) of the 31 isolates were identified as E faecium and 20 (64.5%) as E faecalis. All isolates were susceptible to chloramphenicol and tetracycline, whereas only half were sensitive to gentamicin synergy screen. All other antimicrobials screened against VRE were either ineffective or of limited effect. Our preliminary data supports the initiation of chloramphenicol therapy when a VRE burn wound infection is encountered or suspected.