Abstract
Streptococcus pneumoniae infections are one of the major causes of morbility and mortality worldwide. Although vaccination and antibiotherapy constitute fundamental and complementary strategies against pneumococcal infections, they present some limitations including the increase in non-vaccine serotypes and the emergence of multidrug-resistances, respectively. Ribosomally-synthesized antimicrobial peptides (i.e. bacteriocins) produced by Lactic Acid Bacteria (LAB) may represent an alternative or complementary strategy to antibiotics for the control of pneumococal infections. We tested the antimicrobial activity of 37 bacteriocinogenic LAB, isolated from food and other sources, against clinical S. pneumoniae strains. Streptococcus infantarius subsp. infantarius LP90, isolated from Venezuelan water-buffalo milk, was selected because of its broad and strong anti-pneumococcal spectrum. The in vitro safety assessment of S. infantarius LP90 revealed that it may be considered avirulent. The analysis of a 19,539-bp cluster showed the presence of 29 putative open reading frames (ORFs), including the genes encoding 8 new class II-bacteriocins, as well as the proteins involved in their secretion, immunity and regulation. Transcriptional analyses evidenced that the induction factor (IF) structural gene, the bacteriocin/IF transporter genes, the bacteriocin structural genes and most of the bacteriocin immunity genes were transcribed. MALDI-TOF analyses of peptides purified using different multichromatographic procedures revealed that the dairy strain S. infantarius LP90 produces at least 6 bacteriocins, including infantaricin A1, a novel anti-pneumococcal two-peptide bacteriocin.
Highlights
Streptococcus pneumoniae, regarded as one of the most important human pathogens, is the etiological agent of diseases such as acute otitis media, sinusitis and pneumonia, as well as of potentially life-threatening invasive infections, such as bacteremia and meningitis, which constitute major causes of morbility and mortality worldwide [1]
The biochemical, genetic and transcriptional characterization of multibacteriocin production by the dairy strain S. infantarius LP90 revealed that it produces at least 6 bacteriocins, including infantaricin A1, a novel anti-pneumococcal twopeptide bacteriocin which could be used as an alternative or complementary strategy to antibiotics for the treatment of human infections caused by S. pneumoniae, for which vaccination and antibiotic programs may be non-fully effective
LP90 grown at 37 ̊C for 12 h displayed the strongest extracellular antimicrobial activity and the broadest anti-pneumococcal spectrum inhibiting the growth of the 7 S. pneumoniae strains used as indicators
Summary
Streptococcus pneumoniae, regarded as one of the most important human pathogens, is the etiological agent of diseases such as acute otitis media, sinusitis and pneumonia, as well as of potentially life-threatening invasive infections, such as bacteremia and meningitis, which constitute major causes of morbility and mortality worldwide [1]. Several studies have revealed some drawbacks including the parallel increase of non-vaccine serotypes [2]. Antibiotherapy constitutes a complementary strategy to vaccination, treatments with antibiotics may lead to dysbiosis and the spreading of antibiotic-resistant bacteria. Researchers are urged to discover and develop alternative or complementary strategies to antibiotherapy based on novel modes of action, such as bacteriocins produced by Lactic Acid Bacteria (LAB) [4]. The biochemical, genetic and transcriptional characterization of multibacteriocin production by the dairy strain S. infantarius LP90 revealed that it produces at least 6 bacteriocins, including infantaricin A1, a novel anti-pneumococcal twopeptide bacteriocin which could be used as an alternative or complementary strategy to antibiotics for the treatment of human infections caused by S. pneumoniae, for which vaccination and antibiotic programs may be non-fully effective
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