The human immune system and the microbiota co-evolve, and their balanced relationship is based on crosstalk between the two systems through the course of life. This tight association and the overall composition and richness of the microbiota play an important role in the modulation of host immunity and may impact the immune response to vaccination. The availability of innovative technologies, such as next-generation sequencing (NGS) and correlated bioinformatics tools, allows a deeper investigation of the crosstalk between the microbiota and human immune responses. This review discusses the current knowledge on the influence of the microbiota on the immune response to vaccination and novel tools to deeply analyze the impact of the microbiome on vaccine responses.

In order to estimate the antibody prevalence rates for Toscana virus (TOSV) among children and adults, we evaluated the seroprevalence of TOSV in a population (n ‫؍‬ 2,737) living in Tuscany during the period of 1999 to 2006. The seroprevalence rate was 19.8% in adults and 5.8% in children, showing an age-dependent increase in TOSV-specific immunity. Meningitis due to TOSV infection was more frequent in adults than in children.

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We evaluated temporal fluctuations in macrolide resistance rates, analysing genetic determinants of resistance and clonal evolution in a population of 2744 S. pyogenes isolates collected in the period 2000-2013. The total resistance rate to erythromycin of the isolates was 17.9 %. A maximum of erythromycin resistance emerged in 2000 (38.6 %), followed by a significant decrease to 5.2 % in 2012 (P,0.0001). Molecular analysis revealed the presence and co-presence of known genetic resistance determinants mefA, mefE, ermTR and ermB, in line with phenotypes. PFGE analysis identified genetically related groups in 2000 and 2007-2008, mainly the MLS and M phenotypes, respectively. The most prevalent emm types among a representative subset of resistant isolates were emm2, emm75 and emm77. All emm2 and 88.2 % of the strains harbouring the emm75 gene were only recorded in M-phenotype strains, whilst all emm77-positive strains had the inducible MLS phenotype. The analysed susceptible isolates showed several emm types partially shared with resistant ones. Our results suggest that changes in bacterial population clonality, rather than horizontal transfer of resistance determinants, plays a major epidemiological role in S. pyogenes. Continuous monitoring of microbiological epidemiology seems to be crucial for correct and effective management of streptococcal infections.

BackgroundHealthcare workers (HCWs) represent a tuberculosis (TB) risk group for a wide range of tasks in healthcare, even in countries with low TB incidence, like Italy. Latent Tuberculosis Infection (LTBI) screening programs are an important tool for TB prevention in these setting.MethodsA retrospective study under a LTBI screening program among HCWs at the Siena University Hospital (Italy), was conducted between September 2011 and July 2015. Tuberculin Skin Test (TST) was used as a first level examination; all TST-positive cases were tested with QuantiFERON-TB Gold In-Tube (QFT-GIT) test, together with a group of TST-negative subjects.ResultsAmong the 2136 HCWs screened, 144 (6.7 %) were TST-positive and therefore tested with QFT-GIT, confirming a positive result in 36 cases (25 %). Agreement between two tests was poor (k = 0.092; 95 %, Confidence Interval [CI]- 0.048–0.136, p = 0.002). Among TST-positive cases, discordant results occurred more frequently in BCG vaccinated than unvaccinated HCWs (86.3 %, p < 0.001). The probability of a QFT-GIT-positive result increased according to the TST diameter (p = 0.001). No putative risk factor was associated with LTBI occurrence.ConclusionsThe use of QFT-GIT test as a second step in TST-positive cases offers an appropriate tool for LTBI detection, especially among BCG-vaccinated HCWs.