Oral cavities of healthy infants harbour high proportions of Streptococcus salivarius strains with phenotypic and genotypic resistance to multiple classes of antibiotics

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Palma, Thais H. ; Harth-Chu, Erika N. ; Scott, Jodie ; Stipp, Rafael N. ; Boisvert, Heike ; Salomao, Mariana F. ; Theobaldo, Jessica D. ; Possobon, Rosana F. ; Nascimento, Leandro C. ; McCafferty, Jonathan W. ; Faller, Lina ; Duncan, Margaret J. ; Mattos-Graner, Renata O.

• Document type: Journal article
• Source: Journal of Medical Microbiology; v. 65, p. 9-pg., 2016-12-01.

Abstract

Emerging antibiotic resistance in the oropharyngeal microbiota, of which Streptococcus salivarius is a prominent species, represents a challenge for treating paediatric populations. In this study, we investigated the role of Streptococcus salivarius as a reservoir for antibiotic resistance genes (ARG) in the oral microbiota by analysing 95 Streptococcus salivarius isolates from 22 healthy infants (2-16 months of age). MICs of penicillin G, amoxicillin, erythromycin, tetracycline, doxycycline and streptomycin were determined. ARG profiles were assessed in a subset of 21 strains by next-generation sequencing of genomes, followed by searches of assembled reads against the Comprehensive Antibiotic Resistance Database. Strains resistant to erythromycin, penicillins and tetracyclines were isolated from 83.3, 33.3 and 16.6 %, respectively, of infants aged 2 to 8 months with no prior antibiotic treatment. These percentages were 100.0, 66.6 and 50.0 %, by 13 to 16 months of age. ARG or polymorphisms associated with antibiotic resistance were the most prevalent and involved genes for macrolide efflux (mel, mefA/E and macB), ribosomal protection [erm(B), tet(M) and tet(O)] and beta-lactamase-like proteins. Phylogenetically related strains showing multidrug-resistant phenotypes harboured multidrug efflux ARG. Polymorphic genes associated with antibiotic resistance to drugs affecting DNA replication, folate synthesis, RNA/protein synthesis and regulators of antibiotic stress responses were detected. These data imply that Streptococcus salivarius strains established during maturation of the oral microbiota harbour a diverse array of functional ARG, even in the absence of antibiotic selective pressures, highlighting a potential role for this species in shaping antibiotic susceptibility profiles of oropharyngeal communities. (AU)

• FAPESP's process: 13/06820-0 - Analysis of the patterns of antibiotic sensitivity in pioneer strains of streptococci from the oral cavity
• Grantee: Thaís Harder de Palma
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• FAPESP's process: 10/06785-1 - Phylogenetic analysis of Streptococcal strains of the groups Mitis and Sanguinis isolated from children during initial stages of oral colonization
• Grantee: Jessica Dias Theobaldo
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 09/50547-0 - Characterization of GbpB/PcsB homologues in commensal species of oral streptococci
• Grantee: Erika Nikitza Shiauha Harth Chu
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 10/06786-8 - Analysis of oral colonization by non-hemolytic species of the genus Streptococcus in children of 2 to 16 months of age
• Grantee: Mariana da Fonseca
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 15/12940-3 - Identification of surface proteins of Streptococcus mutans involved in evasion of opsonization by the complement system
• Grantee: Renata de Oliveira Mattos Graner
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/51832-3 - Analysis of a new Two Component System possibly involved in the adaptation of Streptococcus mutans and Streptococcus sanguinis to human saliva.
• Grantee: Renata de Oliveira Mattos Graner
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/09761-9 - Analysis of patterns of antibiotic sensitivity in pioneer strains of Streptococcus of the human oral cavity
• Grantee: Thaís Harder de Palma
• Support Opportunities: Scholarships in Brazil - Scientific Initiation