School in Italy: a safe place for children and adolescents

Background: During the first SARS-CoV-2 pandemic phase, the sudden closure of schools was one of the main measures to minimize the spread of the virus. In the second phase, several safety procedures were implemented to avoid school closure. To evaluate if the school is a safe place, students and staff of two school complexes of Rome were monitored to evaluate the efficacy of prevention measures inside the school buildings. Methods: Oral secretions specimens were collected from 1262 subjects for a total of 3431 samples, collected over a 3 months period. Detection of Coronavirus SARS-CoV-2 was performed by real-time PCR. Target genes were represented by E gene, RdRP/S gene and N gene. Results: Among the 3431 samples analyzed, just 16 sample resulted as positive or low positive: 1 sample in the first month, 12 samples in the second month and 3 in the third month. In each period of evaluation, all positive children attended different classes. Conclusions: Even if the school has the potential for spreading viruses, our preliminary results show the efficacy of the implementations undertaken in this setting to minimize virus diffusion. Our evidence suggests that school does not act as an amplifier for transmission of SARS-CoV-2 and can be really considered a safe place for students

Induction of immune response after SARS-CoV-2 mRNA BNT162b2 vaccination in healthcare workers

[no abstract available

Highly specific memory B cells generation after the 2nd dose of BNT162b2 vaccine compensate for the decline of serum antibodies and absence of mucosal IgA

Specific memory B cells and antibodies are a reliable read-out of vaccine efficacy. We analysed these biomarkers after one and two doses of BNT162b2 vaccine. The second dose significantly increases the level of highly specific memory B cells and antibodies. Two months after the second dose, specific antibody levels decline, but highly specific memory B cells continue to increase, thus predicting a sustained protection from COVID-19. We show that although mucosal IgA is not induced by the vaccination, memory B cells migrate in response to inflammation and secrete IgA at mucosal sites. We show that the first vaccine dose may lead to an insufficient number of highly specific memory B cells and low concentration of serum antibodies, thus leaving vaccinees without the immune robustness needed to ensure viral elimination and herd immunity. We also clarify that the reduction of serum antibodies does not diminish the force and duration of the immune protection induced by vaccination. The vaccine does not induce sterilizing immunity. Infection after vaccination may be caused by the lack of local preventive immunity because of the absence of mucosal IgA

Molecular typing of C. difficile clinical isolates in an outbreak evaluation

Introduction: Clostridium difficile is a Gram-positive spore-forming anaerobic bacillus. C. difficile is one of the major responsible of hospital acquired infections, since its spores are highly resistant to heat and common detergents treatment.The aim of this study was to exclude a nosocomial infection in an Intensive Care Unit at Bambino Gesù Children Hospital by using a molecular typing method (rep-PCR). Methods: 9 C. difficile strains were collected within 2 weeks from 9 faecal samples, belonging to 4 patients hospitalized in the intensive care unit. Identification of C. difficile was obtained by phenotypic method and confirmed by genotypic methods. Susceptibility of isolates was evaluated by using E-test. Molecular typing of these strains was obtained by semi-automatic rep-PCR. Results: All antibiotic susceptibility tests resulted overlapping. Genotypic analysis by rep-PCR showed that isolates belonging to the same patient had a similarity index > 96%, whereas, by comparing strains from different patients, a similarity index < 87% was observed. Conclusions: Molecular fingerprinting of 9 C. difficile isolates arranged the strains in 4 different groups, corresponding to 4 patients.The rep- PCR with the semi-automated Diversilab platform was able to ruled out the presence of a C. difficile nosocomial outbreak in a paediatric Intensive Care Unit. Finally, this system can be used as a “first line” tool, nevertheless, confirmation by “gold standard” fingerprinting methods is necessary. However, even though the system may seem easy to use, it is still not reproducible and criteria for interpretation of analytical results must be fully assessed by trained personnel in the practice of microbial fingerprinting

Meningitis due to Fusobacterium necrophorum

Introduction: Fusobacterium necrophorum is an anaerobic Gram negative bacillus highly virulent, responsible, usually in children or adolescents, of localized abscesses and pharynx, as well as severe systemic infections, called Lemierre syndrome. Methods: A 15 year old child came to the emergency department (ED) of Bambino Gesù Children Hospital. Physicians prescribed chemicalphysical examination on blood and liquor, blood cultures for aerobic and anaerobic bacteria and for fungi (BD Ped Plus, lytic Ana, Micosis), microbiological culture on liquor (CSF) and on the swab from the right outer ear. Results: On chemical examination, liquor appears cloudy, with 309 mg/dl of total proteins, glucose undetectable,WBC 11,160 mmc, 92% of neutrophils. Hyperleukocytosis was detected also on the emocrome (WBC 21x103/μl, 92% neutrophils). No bacterial antigens were detected. CSF culture resulted negative for aerobic bacteria, even after 48 hours of incubation. After 24 hours of inoculation, the blood culture for anaerobic bacteria resulted positive and, Fusobacterium necrophorum was isolated and identified, by genomic sequencing, after 24 hours growth on Schaedler medium. Microbiological culture of the right outer ear swab, highlighted only Corynebacterium spp. After 6 days from admission, the patient died for meningitis. Conclusion:This event has shown the severity of infection by F. necrophorum and, at the same time, the underestimation of this germ in the spectrum of etiologic agents responsible for meningitis.The only microbiological indication was obtained from the anaerobes bacteria blood culture. Following this episode our working procedures for what concerns liquor samples management was modified, including routinely the investigation for anaerobic bacteria. Presumably this episode of meningitis has originated from a F. necrophorum otitis of the right ear, unfortunately not microbiologically confirmed.The anaerobic bacteria should always be considered as potentially responsible of meningitis, especially when ear infections or pharyngeal abscesses precede or accompany the onset of symptoms

BioTimer Assay, a new method for counting Staphylococcus spp. in biofilm without sample manipulation applied to evaluate antibiotic susceptibility of biofilm

The medical device-related infections are frequently a consequence of Staphylococcus biofilm, a lifestyle enhancing bacterial resistance to antibiotics. Antibiotic susceptibility tests are usually performed on planktonic forms of clinical isolates. Some methods have been developed to perform antibiotic susceptibility tests on biofilm. However, none of them counts bacterial inoculum. As antibiotic susceptibility is related to bacterial inoculum, the test results could be mistaken. Here, a new method, BidTimer Assay (BTA), able to count bacteria in biofilm without any manipulation of samples, is presented. Moreover, the BTA method is applied to analyze antibiotic susceptibility of six Staphylococcus strains in biofilm and to deter-mine the number of viable bacteria in the presence of sub-inhibitory doses of four different antibiotics. To validate BTA, the new method was compared to reference methods both for counting and antibiotic susceptibility tests. A high agreement between BTA and reference methods is found on planktonic forms. Therefore, BTA was employed to count bacteria in biofilm and to analyze biofilm antibiotic susceptibility. Results confirm the high resistance to antibiotics of Staphylococcus biofilm. Moreover, BTA counts the number of viable bacteria in the presence of sub-inhibitory doses of antibiotics. The results show that the number of viable bacteria depends on sub-inhibitory doses, age of biofilm and type of antibiotic. In particular, differently to gentamicin and ampicillin, sub-inhibitory doses of ofloxacin and azithromycin reduce the number of viable bacteria at lower extent in young than in old biofilm. In conclusion, BTA is a reliable, rapid, easy-to-perform, and versatile method, and it can be considered a useful tool to analyze antibiotic susceptibility of Staphylococcus spp. in biofilm. Published by Elsevier B.V

Individuazione di un nuovo marker da impiegare per una corretta stadiazione dell’infezione da EBV

Epstein Barr Virus (EBV), also classified as Human Herpes Virus 4, infects the vast majority of adults worldwide and establishes both non-productive (latent) and productive (lytic) infection. Classical EBV diagnosis includes quantitative determination of viral DNA and serological analysis, based on the determination of IgG and IgM responses against the viral capsid antigen (VCA) and the IgG response against the EBV nuclear antigen-1 (EBNA-1). EBV-serology can be misleading in some cases, such as acute infections with low or undetectable VCA IgM, convalescent patients with persistent or reactivated VCA IgM and negative anti- EBNA-1 IgG, due to a loss of this marker during immunosuppression. In all these cases avidity determination of IgG is helpful to prevent false diagnosis. Avidity represents the stability of the antigen-antibody interaction. Its value increases during the infection, so high avidity never associates with a primary acute infection. We studied the importance of avidity determination of p18 (VCA)-IgG to achieve unequivocal interpretation of serological results. The amount of IgG and IgM is determined by Chemiluminescent Immune Assay (CLIA), a rapid and highly sensitive method suitable for automation. The intensity of luminous signal produced by antibody-antigen recognition is expressed as Relative Light Unit (RLU). p-18 IgG is determined using a recombinant p18 antigen expressed in E. coli. Avidity index is determined in CLIA by the ratio between denaturated and not denaturated IgG specific antibodies expressed in RLU. These results demonstrate that avidity determination represents an important additional marker particularly in cases with aberrant serological profile

The Disappearance of Respiratory Viruses in Children during the COVID-19 Pandemic

Background: Social distancing measures are used to reduce the spreading of COVID-19. The aim of this study was to assess the impact of local restrictions on the transmission of respiratory virus infections. Methods: we retrospectively analyzed the nasopharyngeal samples of all patients (0–18 years old) admitted with respiratory symptoms in a large Italian tertiary hospital during the last three seasons from 2018 to 2021. Results: A strong reduction in all viral respiratory infections was observed in the last season (2020–2021) compared to the two previous seasons (−79.69% and −80.66%, respectively). In particular, we found that during the epidemic period 2018–2019 and 2019–2020, the total number of Respiratory Syncytial Virus (RSV) cases was, respectively 726 and 689, while in the last season a total of five cases was detected. In the first months of 2018–2019 and 2019–2020, the total flu infections were 240 and 354, respectively, while in the last season we did not detect any influenza virus. As other viruses, the presence of Rhinovirus declined, but to a lesser extent: a total of 488 cases were assessed compared to the 1030 and 1165 cases of the two previous respective epidemic seasons. Conclusions: Public health interventions and distancing (including continuous use of face masks) settled to counter the pandemic spread of COVID-19 had a macroscopic impact on all respiratory virus transmission and related diseases, with a partial exception of Rhinovirus. The absence of viruses’ circulation could result in a lack of immunity and increased susceptibility to serious infections in the next seasons