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Effect of Oral Probiotic Streptococcus salivarius K12 on Group A Streptococcus Pharyngitis: A Pragmatic Trial in Schools

Doyle, Hélène, MD*; Pierse, Nevil, MSc, PhD; Tiatia, Ramona, MA, PhD; Williamson, Deborah, BSc, MB ChB, MRCP, FRCPA, PhD; Baker, Michael, MB ChB, FAFPHM; Crane, Julian, MBBS, FRCP*

The Pediatric Infectious Disease Journal: July 2018 - Volume 37 - Issue 7 - p 619–623
doi: 10.1097/INF.0000000000001847
Original Studies

Background: The aim of this study was to examine effectiveness of oral probiotic Streptococcus salivarius K12 in preventing group A streptococcus pharyngitis in 5- to 14-year-old children at high risk of acute rheumatic fever. New Zealand has high rates of acute rheumatic fever among Māori and Pacific children. Children were already enrolled in a school-based Ministry of Health throat swabbing and treatment program. Children self-identified and reported sore throats daily and were swabbed twice weekly.

Methods: A total of 1314 children were quasirandomized (based on odd or even birthdates) to receive either K12 (2.5 × 109 cfu per lozenge) or placebo lozenges and continued observed daily treatment (in the school week, during school time) for one school year.

Results: A total of 801 children (61.0%) reported a sore throat on one or more occasions resulting in 2927 pharyngeal swabs. Of these swabs, 1525 (52.1%) were taken from 411 children receiving K12 and 119 (7.8%) of these were positive for group A streptococcus on routine culture. In addition, 1402 (47.8%) swabs were taken from 390 children receiving placebo and 124 (8.8%) were positive. Overall there was a nonsignificant 11.2% relative reduction in positive swabs among children receiving K12. This relative reduction was greater for older children, 7–9 years of age, 15.6%, and for children 10 years and older, 30.2%.

Conclusions: S. salivarius K12 had modest nonsignificant effects on culture-positive sore throats when given at school, during the school day. Based on our pragmatic trial, the routine use of this probiotic in the prevention of pharyngitis associated with GAS detection is not supported.

From the *Department of Medicine

Department of Public Health, University of Otago, Wellington, New Zealand

Department of Microbiology and Immunology, The University of Melbourne, Melbourne, Victoria, Australia.

Accepted for publication November 10, 2017.

This study was funded by a partnership consortium of the Health Research Council of New Zealand, Cure Kids, The New Zealand Heart Foundation and the Ministry of Health. BLIS technologies supplied the active probiotic and placebo gratis. The authors have no other funding or conflicts of interest to disclose.

Address for correspondence: Julian Crane, MBBS, FRCP, Department of Medicine, University of Otago, PO Box 7343, Wellington, New Zealand. E-mail:

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