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Knowledge of epidemiology is essential for guiding correct antibiotic prescription, reducing bacteremia-associated mortality, and implementing targeted infection control programs. However, only a few studies have reported on the epidemiology of bloodstream infections (BSIs) in pediatrics. We performed a retrospective analysis of all BSIs (excluding those caused by common skin contaminants) diagnosed from 2006 to 2022 in patients younger than 18 years who were treated at an Italian pediatric tertiary care hospital. Overall, 2395 BSIs were recorded, including 2207 (92.15%) due to bacteria and 188 (7.85%) due to fungi. The incidence rate (BSIs/10,000 hospital discharges, IR) of bacterial BSIs significantly increased during the study period. In particular, BSIs caused by S. aureus (including MRSA), Enterobacterales (including ESBL and AmpC producers), Enterococcus spp., and P. aeruginosa became more common. The frequency of carbapenem-resistant strains was <1% and stable over time. Conversely, there was a significant reduction in the incidence of BSIs due to S. pneumoniae. The BSIs were stratified by patient age, and S. aureus was the most frequent cause of BSIs in all age groups, while E. coli was the most frequent in the Enterobacterales family. S. agalactiae was the third most frequent cause of neonatal early-onset BSIs. The prevalence of Enterococcus spp. increased in the subgroups from 8 days to 5 years of age, while P. aeruginosa became more prevalent in children over 5 years of age. S. aureus was also the most frequent isolate in both community- and hospital-onset BSIs, followed by E. coli. The prevalence of multidrug-resistant (MDR) pathogens was very low. It was <5% for both Gram-positive (i.e., MRSA and VRE) and Gram-negative (ESBL, AmpC, and carbapenem-resistant) pathogens, and MDR pathogens were almost exclusively detected in hospital-onset BSIs. Fungi accounted for just under 8% of BSIs. C. albicans was the most frequently isolated strain, followed by C. parapsilosis. Notably, the IR of fungemia did not change significantly during the study period, in spite of an increase in the absolute number of events. The continuous monitoring of local epidemiology is essential to identify changes in the IRs of pathogens and antibiotic susceptibility and to guide antibiotic treatments, especially in the phase when antibiograms are not yet available. [ABSTRACT FROM AUTHOR]

Erythromycin resistance in Streptococcus pyogenes has been studied using a prospective study of acute pharyngitis in children in Italy. S. pyogenes was eradicated in 12 of 19 of patients who had erythromycin-resistant S. pyogenes who were treated with clarithromycin. It was also eradicated in 22 of 25 with erythromycin-susceptible strains. The constitutive-resistant phenotype was in correlation with failure of macrolide treatment., In a prospective study of acute pharyngitis in Italian children, 69 (38.3%) of 180 isolates of Streptococcus pyogenes were resistant to macrolides. S. pyogenes was eradicated in 12 (63.1%) of [...]

It is not yet clear whether immature NK (i NK) cells are bystanders to or rather participate in immune responses to pathogens that may colocalize in areas of NK-cell maturation such as bone marrow or lymph nodes. Mycobacteria, including Bacillus Calmette- Guerin ( BCG), have been shown to interact with peripheral NK cells and in vivo may colocalize in areas of i NK-cell development. We studied infection with BCG of human cord blood CD34+ Lin−-derived cultures containing myelomonocytes and i NK cells in vitro. Increased i NK-cell DNAM-1 expression, transient natural cytotoxicity receptor modulation, and production of IFN-γ were observed. Transcriptional receptor modulation was associated to BCG challenge, which determined increased i NK-cell cytotoxic activity against tumor cell lines and also increased killing of immature dendritic cells (i DCs). No requirement for cell contact was recorded for BCG-induced i NK-cell activation, while cytokine production including IL-18, IL-10, GM- CSF, and TGF-β contributed to the observed effects. Thus, i NK cells are affected by mycobacteria in vitro and may contribute to shaping of adaptive mature innate responses through i DC-i NK cross-talk. In addition, i NK-cell activation by BCG may represent a novel additional mechanism contributing to the effects observed upon BCG administration in vivo. [ABSTRACT FROM AUTHOR]

Abstract: Specific combinations of killer immunoglobulin-like receptors (KIR) and human leukocyte antigen (HLA) class I molecules characterized by a particular residue 80 are significantly associated with outcomes in different pathologic conditions, such as autoimmunity, pathogenic infection, cancer, and reproductive failure. Thus, a simplified method for HLA typing used in association with the analysis of KIR genotype (Kirotype) is of particular interest to extend the analysis of larger series. Here, we describe a quick and inexpensive method that allows use of pyrosequencing, a helpful subtyping of HLA class I molecules, into HLA-Bw6, -Bw4 I80 or -Bw4 T80, HLA-C1, or -C2 groups and HLA-A allotypes sharing Bw4+ epitope or the rare HLA-B allotypes displaying the C1 motif. In particular, this analysis is focused on the amino acids around residue 80, known to be relevant in defining the affinity of KIR/HLA interaction and in the functional effects. This method was demonstrated to have good sensitivity, specificity, and reproducibility of detection and it was validated using a panel of HLA-typed International Histocompatibility Workshop (IHW) cell lines and clinical isolates. Using an allele quantitative acquisition mode, the method permitted us to obtain an accurate sequencing as required in heterozygous and/or homozygous sample definition. [Copyright &y& Elsevier]

HIV-1 infection in humans results in an early and progressive NK cell dysfunction and an accumulation of an 'anergic' CD56 CD16 NK subset, which is characterised by low natural cytotoxicity receptor expression and low cytokine producing capacity. In contrast to humans, chimpanzee NK cells do not display a distinguishable CD56 and CD56 subset but, as shown here, could be subdivided into functionally different CD8 and CD8 subsets. The CD8 NK cells expressed significantly higher levels of triggering receptors including NKp46 and, upon in vitro activation, produced more IFN-γ, TNF-α and CD107 than their CD8 counterparts. In addition, chimpanzee CD8 NK cells had relatively high levels of HLA-DR expression, suggestive of an activated state. Killing inhibitory receptors were expressed only at low levels; however, upon in vitro stimulation, they were up-regulated in CD8 but not in CD8 NK cells and were functionally capable of inhibiting NKp30-triggered killing. In contrast to HIV-1-infected humans, infected chimpanzees maintained their dominant CD8 NK cell population, with high expression of natural cytotoxicity receptors. [ABSTRACT FROM AUTHOR]

Gut microbiota plays a role in human health and autoimmunity. Among environmental factor linked to type 1 diabetes (T1DM) pathogenesis, gut microbiota impairment seems to be involved. We evaluated gut microbial fingerprinting in 31 pediatric patients with new-onset T1DM and 25 healthy children using multiple polymorphic region of the 16S rRNA. We performed machine learning and metagenome functional analyses to identify significant taxa and metabolic pathways and correlate with clinical and metabolic parameters. Inclusion criteria were living in Northern Italy, born from Caucasian parents, singleton birth, personal history negative for acute/chronic gastrointestinal diseases and/or antibiotic or probiotics administration. Different Bacteroidetes species i.e., B.stercoris (q=1,473E-4), B.intestinalis (q=0.010), B.fragilis (q=0.0452) were significantly more frequent in patients as well as B.bifidum, Gammaproteobacteria, Holdemania, Synergistetes and their descendants. Abundance of the Synergistetes (q=0.001), Synergistia (q=4.798E-5), Synergistales (q=2.64E-4) and Synergistaceae (q=0.0017) was reported. Among Deltaproteobacteria descendants, the Desulfovibrionales (q=0.0016), Desulfovibrionaceae (q=0.016) and the Bilophila genus (q=0.036) were significantly lower in patients as well as B.vulgatus, Deltaproteobacteria, Parasutterella and Lactobacillus, Turicibacter genera. BMI-SDS, insulin autoantibodies, glycemia, HbA1c, Tanner and age were the most significant positively or negatively parameters related to specific clusters of taxa. The supervised analyses confirmed the importance of B. stercoris in T1DM patients and a relevant role of Synergistetes and its descendants. The robustness and coherence of our results underline the relevance of studying microbioma using multiple polymorphic regions, different types of analysis and approaches within each analysis. Disclosure: G. d'Annunzio: Consultant; Self; Sandoz. R. Biassoni: None. M. Squillario: None. E. Ugolotti: None. A. Barla: None. G. Piccolo: None. N. Minuto: None. M. Maghnie: None. [ABSTRACT FROM AUTHOR]

Antibiotic susceptibility of S. aureus was retrospectively assessed in 1833 strains isolated from skin lesions observed in an Italian tertiary care hospital. Methicillin resistance was more frequent in outpatients than in inpatients (18% vs. 14%, p  = 0.04) as well as resistance to cotrimoxazole (8% vs. 4.1%, p  < 0.001). Resistance to ampicillin was 99% in both groups, while for clindamycin it was 11% and 14%, respectively. Among topical antibiotics fusidic acid showed the better resistance profile (3%). Antibiotic resistance in pediatric skin infection in outpatients could represent a therapeutic problem in Italy.

HLA-C expression is associated with a differential ability to control HIV-1 infection. Higher HLA-C levels may lead to better control of HIV-1 infection through both a higher efficiency of antigen presentation to cytotoxic T lymphocytes and the triggering of activating killer immunoglobulin-like receptors on NK cells, whereas lower levels may provide poor HIV-1 control and rapid progression to AIDS. We characterized the relative amounts of HLA-C heterotrimers (heavy chain/β 2 microglobulin [β 2 m]/peptide) and HLA-C free heavy chains on peripheral blood mononuclear cells (PBMCs) from healthy blood donors harboring both alleles with stable or unstable binding to β 2 m/peptide. We analyzed the stability of HLA-C heterotrimers of different allotypes and the infectivity of HIV-1 virions produced by PBMCs with various allotypes. We observed significant differences in HLA-C heterotrimer stability and in expression levels. We found that R5 HIV-1 virions produced by PBMCs harboring unstable HLA-C alleles were more infectious than those produced by PBMCs carrying the stable variants. We propose that HIV-1 infectivity might depend both on the amounts of HLA-C molecules and on their stability as trimeric complex. According to this model, individuals with low-expression HLA-C alleles and unstable binding to β 2 m/peptide might have worse control of HIV-1 infection and an intrinsically higher capacity to support viral replication. IMPORTANCE Following HIV-1 infection, some people advance rapidly to AIDS while others have slow disease progression. HLA-C, a molecule involved in immunity, is a key determinant of HIV-1 control. Here we reveal how HLA-C variants contribute to the modulation of viral infectivity. HLA-C is present on the cell surface in two different conformations. The immunologically active conformation is part of a complex that includes β 2 microglobulin/peptide; the other conformation is not bound to β 2 microglobulin/peptide and can associate with HIV-1, increasing its infectivity. Individuals with HLA-C variants with a predominance of immunologically active conformations would display stronger immunity to HIV-1, reduced viral infectivity and effective control of HIV-1 infection, while subjects with HLA-C variants that easily dissociate from β 2 microglobulin/peptide would have a reduced immunological response to HIV-1 and produce more infectious virions. This study provides new information that could be useful in the design of novel vaccine strategies and therapeutic approaches to HIV-1., (Copyright © 2017 Parolini et al.)

Usually, HLA typing has been performed either by serology-based typing incubating a panel of known anti-HLA antibodies with viable lymphocytes of unknown HLA type or by molecular typing including medium-resolution HLA typing by Sequence Specific Oligonucleotide Probes (SSOP) or high-resolution HLA typing by Sequence Based Typing (SBT). Traditionally, HLA antigens have been defined using serological techniques, but these methods have several disadvantages, such as low resolution, the requirement for viable cells, and cell surface expression of HLA molecules. HLA type screening methods are categorized as low, medium, and high resolution, and only sequencing-based typing methods provide the highest resolution and are considered the gold standard for HLA typing.Among the HLA SBT based-methods, the Pyrosequencing(®) technique is an extremely versatile and accurate real-time sequencing technique with some advantages compared to classic Sanger method.Here, we describe a quick and inexpensive method that allows through the use of Pyrosequencing subtyping of HLA class I molecules, into HLA-Bw6, -Bw4 I80, or -Bw4 T80 and HLA-C1, or -C2 groups. In particular, this analysis is focused on the amino acids around residue 80. This method demonstrated good sensitivity, specificity, and reproducibility. Using a quantitative allele acquisition mode, the method provides accurate sequence information required for the definition of heterozygous and/or homozygous samples.