超出生体重児に対する早期デキサメサゾン投与の有用性 : National Institute of Child Health and Human Development Neonatal research Network報告 (海外誌掲載論文の和文概要とそれに対するコメント)

Streptolysin S (SLS) is a potent cytolytic toxin and virulence factor that is produced by nearly all Streptococcus pyogenes strains. Despite a 100-year history of research on this toxin, it has only recently been established that SLS is just one of an extended family of post-translationally modified virulence factors (the SLS-like peptides) that are produced by some streptococci and other Gram-positive pathogens, such as Listeria monocytogenes and Clostridium botulinum. In this Review, we describe the identification, genetics, biochemistry and various functions of SLS. We also discuss the shared features of the virulence-associated SLS-like peptides, as well as their place within the rapidly expanding family of thiazole/oxazole-modified microcins (TOMMs).

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Streptolysin S-like virulence factors: the continuing sagA

Group A Streptococcus (Streptococcus pyogenes), group B Streptococcus (Streptococcus agalactiae) and Streptococcus pneumoniae (pneumococcus) are host-adapted bacterial pathogens among the leading infectious causes of human morbidity and mortality. These microbes and related members of the genus Streptococcus produce an array of toxins that act against human cells or tissues, resulting in impaired immune responses and subversion of host physiological processes to benefit the invading microorganism. This toxin repertoire includes haemolysins, proteases, superantigens and other agents that ultimately enhance colonization and survival within the host and promote dissemination of the pathogen.

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Streptococcal toxins: role in pathogenesis and disease.

Targeted treatment for bacterial infections: prospects for pathogen-specific antibiotics coupled with rapid diagnostics

Natural products as mediators of disease

Among nonhemolytic Streptococcus pyogenes (group A streptococcus) strains (n = 9) isolated from patients with pharyngitis or acute otitis media, we identified three deletions in the region from the epf gene, encoding the extracellular matrix binding protein, to the sag operon, mediating streptolysin S production.

Nonhemolytic Streptococcus pyogenes Isolates That Lack Large Regions of the sag Operon Mediating Streptolysin S Production

BACKGROUND Escherichia coli causes neonatal early-onset sepsis (EOS) that is associated with high mortality and increasing antibiotic resistance. Thus, we estimated the prevalence, antibiotic susceptibility and risk factors for colonization of E. coli in premature infants at birth and characterized the pathogenicity of the isolates. METHODS A prospective surveillance study was conducted at three Japanese perinatal centers between August 2014 and February 2017. Infants weighing <2 kg and/or at gestational age <35 weeks at birth were enrolled. We screened the mothers and neonates for E. coli colonization. Pulsed-field gel electrophoresis was used to analyze the relatedness between the maternal and neonatal isolates. Virulence factors for the isolates were determined using polymerase chain reaction. RESULTS We enrolled 421 premature infants born to 382 mothers. The rate of colonization in mothers was 47.6%, comprising 5.9% extended-spectrum beta-lactamase-producing E. coli (ESBL-E) and 20.0% ampicillin-resistant strains. Ten (2.4%) infants exhibited colonization; ESBL-E and ampicillin-resistant strains colonized three and four infants, respectively. Three antibiotic-resistant, strain-positive infants developed EOS. Pulsed-field gel electrophoresis revealed vertical transmission of bacteria in four infants. Multivariate logistic regression analysis revealed that ESBL-E-positive mothers [odds ratio (OR), 19.2; 95% confidence interval (CI), 2.5-145.7)] and vaginal delivery (OR, 9.4; 95% CI, 1.7-50.7) were risk factors for neonatal colonization. The infant isolates possessed numerous virulence factors. CONCLUSIONS Although the prevalence of E. coli-colonized premature infants at birth was low, the rate of antibiotic resistance and the attack rate for EOS were high. Infants with ESBL-E positive mothers should be closely monitored for EOS.

Miki Takahashi

Papers

Nonhemolytic Streptococcus pyogenes Isolates That Lack Large Regions of the sag Operon Mediating Streptolysin S Production

Prevalence and Risk Factor for Antibiotic-resistant Escherichia coli Colonization at Birth in Premature Infants: A Prospective Cohort Study