Intestinal Microbiota as a Host Defense Mechanism to Infectious Threats

The intestinal microbiota is a complex microbial community, with diverse and stable populations hosted by the gastrointestinal tract since birth. This ecosystem holds multiple anti-infectious, anti-inflammatory, and immune modulating roles decisive for intestinal homeostasis. Among these, colonization resistance refers to the dynamic antagonistic interactions between commensals and pathogenic flora. Hence, gut bacteria compete for the same intestinal niches and substrates, while also releasing antimicrobial substances such as bacteriocines and changing the environmental conditions. Short chain fatty acids (SCFAs) generated in anaerobic conditions prompt epigenetic regulatory mechanisms that favor a tolerogenic immune response. In addition, the commensal flora is involved in the synthesis of bactericidal products, namely secondary biliary acids or antimicrobial peptides (AMPs) such as cathellicidin-LL37, an immunomodulatory, antimicrobial, and wound healing peptide. Gut microbiota is protected through symbiotic relations with the hosting organism and by quorum sensing, a specific cell-to-cell communication system. Any alterations of these relationships favor the uncontrollable multiplication of the resident pathobionts or external entero-pathogens, prompting systemic translocations, inflammatory reactions, or exacerbations of bacterial virulence mechanisms (T6SS, T3SS) and ultimately lead to gastrointestinal or systemic infections. The article describes the metabolic and immunological mechanisms through which the intestinal microbiota is both an ally of the organism against enteric pathogens and an enemy that favors the development of infections

Liver fibrosis progression in a cohort of young HIV and HIV/ HBV co-infected patients: A longitudinal study using non-invasive APRI and Fib-4 scores

BackgroundThe risk of liver fibrosis increases over time in HIV and HIV-HBV individuals even under antiretroviral treatment (ART), warranting a rigorous and periodic monitorization. Given the lower availability of transient elastography, we aimed to assess the longitudinal variation of two non-invasive liver fibrosis scores, APRI and Fib-4, in cases with HIV monoinfection, HIV-HBV co-infection and individuals with HBsAg-seroclearance.MethodsWe performed an observational retrospective study between 2013 and 2019 on 212 HIV patients including 111 individuals with HIV mono-infection, 62 individuals with HIV-HBV co-infection and positive HBsAg and 39 cases with HIV-HBV infection and HBsAg-loss. The groups were followed at 36, 48, and 60 months. Liver fibrosis was indicated by an APRI >0.5 or Fib-4≥1.45 score and advanced fibrosis by an APRI score >1.5 or Fib-4 >3.25. Logistic regression with generalized estimating equations (GEE) was used to assess the predictors for the presence of liver fibrosis over time.ResultsDuring a median follow-up of 58.5 months the prevalence of liver fibrosis in all patients increased with 0.5% reaching 11.3% using an APRI score and with 0.9% reaching 10.8% using the Fib-4 score. At the visit corresponding to 60 months the prevalence of liver fibrosis was higher in all HIV-HBV patients compared with individuals with HIV mono-infection, namely: 16.1% on APRI and 12.9% on the Fib-4 score in HIV-HBV/HBsAg-positive individuals, 12.8% on both APRI and Fib-4 scores in HIV-HBV/HBsAg-negative individuals vs. 8.1 and 9%, respectively in HIV mono-infection. The presence of liver fibrosis over the study period was independently associated with plasma HIV RNA, CD4+T cell counts, HIV-HBV co-infection (for APRI >0.5) and ART non-adherence (for Fib-4 >1.45). At the final visit, non-adherence to ART and CD4+T cell counts remained associated with liver fibrosis.ConclusionsThe study found a slow progression of APRI and Fib-4 scores over time in young PLWH with extensive ART. Liver fibrosis scores continued to increase in patients with HIV mono-infection yet remained lower than in HIV-HBV patients irrespective on the presence of HBsAg. The periodic follow-up using non-invasive scores on the long-term could help improve the surveillance in low-income settings and high scores should be followed by additional diagnostic methods

Clinico-etiological and epidemiological particularities of respiratory virus diseases in children in the 2022-2023 season

In the period 2020-2022 as a result of epidemiological measures specific to the COVID-19 pandemic (protective mask, online teaching activity, social distancing) we witnessed a considerable decrease in the number of cases of respiratory viroids in children. With the lifting of prophylactic measures that coincided with the start of physical teaching activities and the onset of the cold season, we have been confronted in pediatric wards with an increase in the incidence of virological infections in the pediatric population. In this article we aim to analyze the particularities of respiratory virological diseases in children in the season 2022 - 2023 both from the etiological and epidemiological point of view and the characteristic clinical forms of the disease. We conducted a retrospective clinical study of cases admitted to the Clinical Departments of Infectious Diseases Pediatrics of the National Institute of Infectious Diseases “Prof. Dr. Matei Bals” in the period October 2022 - March 2023. During this period, we recorded 3.012 cases of respiratory virology in children, which represents the majority of pediatric pathology admitted (72,9 %). The peak incidence of respiratory virology occurred in December (688 cases). From the etiological point of view, most cases were SARS-CoV-2 infections, followed by influenza (predominantly type A), then a smaller number of infections with respiratory syncytial virus (RSV), rhinovirus, adenovirus, metapneumovirus. The most common clinical form of the disease was moderate (66.9%), with severe forms accounting for 10.5%. All pediatric cases of respiratory virology admitted to our wards have evolved favorably, with no deaths

Nasopharyngeal carriage of Streptococcus pneumoniae in Romanian children before the introduction of the pneumococcal conjugated vaccination into the national immunization programme: a national, multi-centre, cross-sectional observational study

Objectives: We analysed the distribution of vaccine and non-vaccine Streptococcus pneumoniae serotypes and the antimicrobial susceptibility of pneumococcal strains isolated from healthy Romanian children. Methods: A multi-centre cross-sectional study was performed in four counties to evaluate carried strains of S. pneumoniae isolated from 2000 children aged 0–5 years. Results: S. pneumoniae carriage was detected in 25.25% of the tested children. Carriage increased from 16.7% among infants to 29.4% in 3–5-year-old children (p 0.064 mg/l were recorded in 71.6%, but the penicillin MIC was >2 mg/l for only 8.4% of tested isolates. Conclusions: In Romanian children, the majority of carried S. pneumoniae isolates are vaccine serotypes. The isolates with MICs defining macrolide resistance were very frequent, as well as the isolates with MICs defining penicillin resistance in the case of meningitis or penicillin dose-dependent susceptibility for other infections, mainly for the strains belonging to PCV13 serotypes. The implementation of PCV13 within the Romanian national immunization programme could reduce the circulation of these strains with higher macrolide and/or penicillin MICs