JAC Advance Access originally published online on January 5, 2006
Journal of Antimicrobial Chemotherapy 2006 57(3):566-568; doi:10.1093/jac/dki474
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In vitro antimicrobial activity of benzalkonium chloride against clinical isolates of Streptococcus agalactiae
Section of Microbiology, Department of Clinical Medicine, Immunology and Infectious Diseases, University of Bari, Bari, Italy
Received 23 June 2005; returned 5 October 2005; revised 20 October 2005;
* Corresponding author. Tel: +390805478486; E-mail: miragliotta{at}midim.uniba.it
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