Differential Sensitivity of Lactobacillus spp. to Inhibition by Candidate Topical Microbicides

Abstract

Preclinical evaluation of vaginal microbicides includes screening against lactobacilli. However, there is no consensus regarding the species to be tested. This study was carried out to determine if results with one species would apply to other species, and to evaluate the utility of turbidometry as a screening tool. One current (PPCM; previously designated sulfuric acid-modified mandelic acid, SAMMA) and two former (cellulose sulfate, CS; and polystyrene sulfonate, PSS) candidate microbicides were evaluated. Bacterial growth was measured turbidometrically and by direct cell count. No microbicide affected Lact. gasseri, measured by either method. Apparent inhibition of Lact. jensenii by CS, PSS, and PPCM, and of Lact. crispatus by CS, occurred with turbidometric measurement. This was not substantiated with direct cell count. PSS and PPCM inhibited Lact. crispatus and Lact. acidophilus with both methods. These findings agree with results from vaginal isolates, which included Lact. gasseri, jensenii, acidophillus, crispatus, rhamnosis, casei, and paracasei. We conclude that sensitivities of similar lactobacilli to at least three microbicides are different. A single species is inadequate for screening vaginal products. Turbidometric evaluation is a sensitive, but not specific, screening method. We recommend that this method be used to screen candidate microbicides against several species of prevalent Lactobacillus species as an initial measure of microbicide safety evaluation.

Polyethylene Glycol-Based Hydrogels for Controlled Release of the Antimicrobial Subtilosin for Prophylaxis of Bacterial Vaginosis

“…Anderson et al evaluated the inhibitory effect of the microbicides sulfuric acid-modified mandelic acid (SAMMA), polystyrene sulfonate (PSS), and cellulose sulfate (CS) on commercially available lactobacillus spp. and vaginal isolates (66). Their findings indicated selective inhibition of Lactobacillus crispatus and Lactobacillus acidophilus with SAMMA and CS, suggesting differential sensitivity of Lactobacillus spp.…”

“…Their findings indicated selective inhibition of Lactobacillus crispatus and Lactobacillus acidophilus with SAMMA and CS, suggesting differential sensitivity of Lactobacillus spp. to the microbicide candidates (66). More recently, a clinical study by Ravel et al indicated a shift in vaginal microbiota from predominantly Lactobacillus spp.…”

Doderlin: Isolation and Characterization of a Broad-Spectrum Antimicrobial Peptide from Lactobacillus acidophilus

“…He also noted that the bactericidal activity of vaginal secretions was associated with lactic acid production due to the fermentation process performed by the bacilli (15). L. acidophilus ais the most abundant bacteria in these environments, and a member of the normal gut and vagina microbiota (16,17). Its role in the human intestinal microbiota is to assist the level of harmful bacteria and fungi lowering and to produce lactase, which is an important enzyme in milk digestion (18).…”

Viability of Bifidobacterium bifidum and Escherichia coli in Versus Prebiotic Effects of Jerusalem Artichoke (Helianthus tuberosus)

“…It is also important for maintaining gastrointestinal health. As a naturally occurring probiotic, Bifidobacteria and Lactobacilli can modify the metabolic activities in the body by modulating immune system [1], producing antimicrobial agents such as hydrogen peroxide, antimicrobial peptides (bacteriocins), and organic acids such as acetic and lactic acids [2]. When used in adequate amounts in diet, they can synthesis vitamins (such as K and B), stabilize barrier functions and enhance the calcium and other mineral absorption on the gut.…”