Journal Article

<i>In vitro</i> antimicrobial activity of benzalkonium chloride against clinical isolates of <i>Streptococcus agalactiae</i>

A. Mosca, F. Russo and G. Miragliotta

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 57, issue 3, pages 566-568
Published in print March 2006 | ISSN: 0305-7453
Published online January 2006 | e-ISSN: 1460-2091 | DOI:
In vitro antimicrobial activity of benzalkonium chloride against clinical isolates of Streptococcus agalactiae

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  • Medical Oncology
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Objectives: Despite antibiotic prophylaxis for at-risk mothers during labour and delivery, Streptococcus agalactiae (group B Streptococcus; GBS) still causes substantial morbidity and mortality among newborns. In addition to the well-known side effects of the administration of antibiotics, resistance to drugs recommended for penicillin-allergic pregnant women, such as erythromycin and clindamycin, has increased, thus raising concern about the possibility of inadequate prophylaxis. On this basis we evaluated the antimicrobial activity of benzalkonium chloride against GBS, which has been described as an antimicrobial agent for the topical treatment of vaginal infections.

Methods: A total of 52 GBS from pregnant women have been studied. The capacity of benzalkonium chloride as well as of penicillin, erythromycin, clindamycin, vancomycin, chloramphenicol and tetracycline to inhibit GBS was evaluated using broth macrodilution and microdilution methods, respectively.

Results: While all the strains were penicillin- and vancomycin-susceptible, 19.2% were resistant to both erythromycin and clindamycin. In contrast, all GBS isolates were either inhibited or killed by benzalkonium chloride at not only low but also very similar concentrations (MIC90 = 3.12 mg/L).

Conclusions: Benzalkonium chloride might represent an alternative strategy that is useful in reducing vaginal GBS colonization in pregnant women before delivery by topical treatment.

Keywords: S. agalactiae; GBS; MICs; prophylaxis

Journal Article.  1336 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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