Implementation of Whole Genome Sequencing of Tuberculosis Isolates in a Referral Center in Rome: Six Years' Experience in Characterizing Drug-Resistant TB and Disease Transmission

Over the past years, Tuberculosis (TB) control strategies have been effective in reducing drug-resistant (DR) TB globally; however, a wider implementation of new diagnostic strategies, such as Whole genome sequencing (WGS), would be critical for further improvement. The aim of this study, based on WGS of Mycobacterium tuberculosis (MTB) strains isolated in a TB referral center over 6 years, was to evaluate the efficacy of this methodology in improving therapy guidance for clinicians and in improving the understanding of the epidemiology of TB transmission. WGS was performed in addition to pDST on 1001 strains consecutively isolated between January 2016 and December 2021; the results allowed us to improve the quality of data on resistance and to identify possible clusters of transmission. Prediction of rifampicin-resistant (RR) or multi-drug-resistant TB strains (MDR-TB, defined as resistance to at least rifampicin and isoniazid) was obtained for 50 strains (5%). Mutations predictive of an MDR isolate were further characterized, and Ser450Leu and Ser315Thr were found to be the most frequent mutations in rpoB and katG genes, respectively. Discordances between WGS and phenotypic drug susceptibility testing (pDST) were found in few strains, and their impact on clinical decisions and outcome was addressed. The introduction of WGS in our Institute improved our diagnostic routine, allowing accurate patient management, and was a valid instrument for epidemiological investigations and infection control.

Epidemiological and Molecular Investigation of the Heater-Cooler Unit (HCU)-Related Outbreak of Invasive Mycobacterium chimaera Infection Occurred in Italy

BACKGROUND

From 2013 onwards, a large outbreak of Mycobacterium chimaera (MC) invasive infection, which was correlated with the use of contaminated heater-cooler units (HCUs) during open chest surgery, was reported from all over the world. Here, we report the results of the epidemiological and molecular investigations conducted in Italy after the alarm raised about this epidemic event.

METHODS

MC strains isolated from patients or from HCU devices were characterized by genomic sequencing and molecular epidemiological analysis.

RESULTS

Through retrospective epidemiological analysis conducted between January 2010 and December 2022, 40 possible cases of patients infected with MC were identified. Thirty-six strains isolated from these patients were analysed by whole genome sequencing (WGS) and were found to belong to the genotypes 1.1 or 1.8, which are the genotypes correlated with the outbreak. Most of the cases presented with prosthetic valve endocarditis, vascular graft infection or disseminated infection. Among the cases found, there were 21 deaths. The same analysis was carried out on HCU devices. A total of 251 HCUs were found to be contaminated by MC; genotypes 1.1 or 1.8 were identified in 28 of those HCUs.

CONCLUSIONS

To ensure patients' safety and adequate follow-up, clinicians and general practitioners were made aware of the results and public health measures, and recommendations were issued to prevent further cases in the healthcare settings. The Italian Society of Cardiac Surgery performed a national survey to assess the incidence of HCU-related MC prosthetic infections in cardiac surgery. No cases were reported after HCU replacement or structural modification and disinfection and possibly safe allocation outside surgical rooms.

A Cholera Case Imported from Bangladesh to Italy: Clinico-Epidemiological Management and Molecular Characterization in a Non-Endemic Country

Despite the number of cholera outbreaks reported worldwide, only a few cases are recorded among returning European travellers. We describe the case of a 41-year-old male, returning to Italy after a stay in Bangladesh, his origin country, who presented with watery diarrhoea. Vibrio cholerae and norovirus were detected in the patient's stools via multiplex PCR methods. Direct microscopy, Gram staining, culture and antibiotic susceptibility tests were performed. The isolates were tested using end-point PCR for the detection of potentially enteropathogenic V. cholera. Serotype and cholera toxins identification were carried out. Whole genome sequencing and bioinformatics analysis were performed, and antimicrobial resistance genes identified. A phylogenetic tree with the most similar genomes of databases previously described was built. Sample of the food brought back by the patient were also collected and analysed. The patient was diagnosed with V. cholerae O1, serotype Inaba, norovirus and SARS-CoV-2 concomitant infection. The isolated V. cholerae strain was found to belong to ST69, encoding for cholera toxin, ctxB7 type and was phylogenetically related to the 2018 outbreak in Dhaka, Bangladesh. Adopting a multidisciplinary approach in a cholera non-endemic country ensured rapid and accurate diagnosis, timely clinical management, and epidemiological investigation at national and international level.

Investigating the Origin of Mycobacterium chimaera Contamination in Heater-Cooler Units: Integrated Analysis with Fourier Transform Infrared Spectroscopy and Whole-Genome Sequencing

Mycobacterium chimaera is ubiquitously spread in the environment, including factory and hospital water systems. Invasive cases of M. chimaera infection have been associated with aerosols produced by the use of heater-cooler units (HCU) during cardiac surgery. The aim of this study was to evaluate for the first time the performance of IR-Biotyper system on a large number of M. chimaera isolates collected from longitudinal environmental HCUs samples and water sources from hospitals located in three Italian provinces. In addition, IR-Biotyper results were compared with whole-genome sequencing (WGS) analysis, the reference method for molecular epidemiology, to investigate the origin of M. chimaera contamination of HCUs. From November 2018 to May 2021, 417 water samples from 52 HCUs (Stockert 3T, n = 41 and HCU40, n = 11) and 23 hospital taps (used to fill the HCU tanks) were concentrated, decontaminated, and cultured for M. chimaera. Positive cultures (n = 53) were purified by agar plate subcultures and analyzed by IR-Biotyper platform and Ion Torrent sequencing system. IR-Biotyper spectra results were analyzed using a statistical approach of dimensionality reduction by linear discriminant analysis (LDA), generating three separate clusters of M. chimaera, ascribable to each hospital. Furthermore, the only M. chimaera-positive sample from tap water clustered with the isolates from the HCUs of the same hospital, confirming that the plumbing system could represent the source of HCU contamination and, potentially, of patient infection. According to the genome-based phylogenies and following the classification proposed by van Ingen and collaborators in 2017, three distinct M. chimaera groups appear to have contaminated the HCU water systems: subgroups 1.1, 2.1, and branch 2. Most of the strains isolated from HCUs at the same hospital share a highly similar genetic profile. The nonrandom distribution obtained with WGS and IR-Biotyper leads to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, in addition with the current hypothesis that contamination occurs at the HCU production site. This opens the possibility that other medical equipment, such as endoscope reprocessing device or hemodialysis systems, could be contaminated by M. chimaera. IMPORTANCE Our manuscript focuses on interventions to reduce waterborne disease transmission, improve sanitation, and control infection. Sanitary water can be contaminated by nontuberculous Mycobacteria, including M. chimaera, a causative agent of invasive infections in immunocompromised patients. We found highly similar genetic and phenotypic profiles of M. chimaera isolated from heater-cooler units (HCU) used during surgery to thermo-regulate patients' body temperature, and from the same hospital tap water. These results lead to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, adding to the current hypothesis that contamination occurs at the HCU production site. In addition, this opens the possibility that other medical equipment using sanitized water, such as endoscope reprocessing devices or hemodialysis systems, could be contaminated by nontuberculous Mycobacteria, suggesting the need for environmental surveillance and associated control measures.

Epidemiology of ventilator-associated pneumonia in ICU COVID-19 patients: an alarming high rate of multidrug-resistant bacteria

Background

COVID‑19 is a novel cause of acute respiratory distress syndrome (ARDS) that leads patients to intensive care unit (ICU) admission requiring invasive ventilation, who consequently are at risk of developing of ventilator‑associated pneumonia (VAP). The aim of this study was to assess the incidence, antimicrobial resistance, risk factors, and outcome of VAP in ICU COVID-19 patients in invasive mechanical ventilation (MV).

Methods

Observational prospective study including adult ICU admissions between January 1, 2021, and June 31, 2021, with confirmed COVID-19 diagnosis were recorded daily, including demographics, medical history, ICU clinical data, etiology of VAPs, and the outcome. The diagnosis of VAP was based on multi-criteria decision analysis which included a combination of radiological, clinical, and microbiological criteria in ICU patients in MV for at least 48 h.

Results

Two hundred eighty-four COVID-19 patients in MV were admitted in ICU. Ninety-four patients (33%) had VAP during the ICU stay, of which 85 had a single episode of VAP and 9 multiple episodes. The median time of onset of VAP from intubation were 8 days (IQR, 5–13). The overall incidence of VAP was of 13.48 episodes per 1000 days in MV. The main etiological agent was Pseudomonas aeruginosa (39.8% of all VAPs) followed by Klebsiella spp. (16.5%); of them, 41.4% and 17.6% were carbapenem resistant, respectively. Patients during the mechanical ventilation in orotracheal intubation (OTI) had a higher incidence than those in tracheostomy, 16.46 and 9.8 episodes per 1000-MV day, respectively. An increased risk of VAP was reported in patients receiving blood transfusion (OR 2.13, 95% CI 1.26–3.59, p = 0.005) or therapy with Tocilizumab/Sarilumab (OR 2.08, 95% CI 1.12–3.84, p = 0.02). The pronation and PaO₂/FiO₂ ratio at ICU admission were not significantly associated with the development of VAPs. Furthermore, VAP episodes did not increase the risk of death in ICU COVID-19 patients.

Conclusions

COVID-19 patients have a higher incidence of VAP compared to the general ICU population, but it is similar to that of ICU ARDS patients in the pre-COVID-19 period. Interleukin-6 inhibitors and blood transfusions may increase the risk of VAP. The widespread use of empirical antibiotics in these patients should be avoided to reduce the selecting pressure on the growth of multidrug-resistant bacteria by implementing infection control measures and antimicrobial stewardship programs even before ICU admission.

Supplementary Information

The online version contains supplementary material available at 10.1186/s44158-022-00065-4.

Increased Association of Pulmonary Thromboembolism and Tuberculosis during COVID-19 Pandemic: Data from an Italian Infectious Disease Referral Hospital

Pulmonary thromboembolism (PTE) has been associated with tuberculosis (TB), but the true incidence is unknown. The aim of our study was to retrospectively evaluate the PTE prevalence in TB patients hospitalized at the National Institute for Infectious Diseases L. Spallanzani during the January 2016–December 2021 period. Retrospective data collection and evaluation were conducted. Among 1801 TB patients, 29 (1.61%) exhibited PTE. Twenty (69%) had comorbidities; eleven (37.9%) had predisposing factors for PTE. Nineteen (65.5%) had extensive TB disease. The commonest respiratory symptoms were cough (37.9%), dyspnea (31%), chest pain (10.3%), and hemoptysis (6.9%). Twenty-five (86.2%) had elevated serum D-dimer levels. An increased prevalence of PTE from 0.6% in the pre-COVID-19 pandemic period to 4.6% in the pandemic period was found. Acute respiratory failure and extensive TB disease increased significantly in the pandemic period. The increase in PTE could be explained by the increased severity of TB in patients in the pandemic period and by increased clinical suspicion and, consequently, increased requests for D-dimer testing, including in patients with non-COVID-19 pneumonia. Patients with extensive pulmonary disease are at high risk of developing PTE. Clinicians should be aware of this potentially life-threatening complication of TB, and patients should receive a thromboembolism risk assessment.

Molecular analysis of clinical isolates of ceftazidime-avibactam-resistant Klebsiella pneumoniae

OBJECTIVES

To analyse the strains collected during a 1-year survey of ceftazidime-avibactam-resistant KPC-producing Klebsiella pneumoniae, in order to investigate the molecular mechanisms potentially responsible for their resistant phenotype.

METHODS

Clinical KPC-producing K. pneumoniae isolates were collected from 31 patients in six different hospitals in Rome. For eight of the patients, an additional strain grown before the start of treatment was also available, bringing the total of isolates studied to 39. Antimicrobial susceptibility was determined by automated system, broth microdiluition and E-test as appropriate. In silico analysis of acquired resistance genes was achieved by whole-genome sequencing, while multilocus sequence typing and core genome multilocus sequence typing were employed for molecular typing. Mutations associated with ceftazidime-avibactam resistance were identified by Sanger sequencing of the bla_KPC gene. Possible mutations in OmpK35 and OmpK36 outer membrane proteins were also investigated.

RESULTS

Molecular analyses highlighted the circulation of the ST512, 101 and 307 high-risk clones; 26 of the 31 patients carried a mutated KPC variant, five had a wild-type KPC-3. Among the KPC variants detected, 11 were different mutations within the bla_KPC-3 gene, four of which were novel mutational changes.

CONCLUSIONS

Different mutations including single amino-acid substitutions, insertions or deletions within the bla_KPC gene were found in 26/31 ceftazidime-avibactam-resistant KPC-producing K. pneumoniae strains belonging to high-risk clones circulating in Italy. Of note, in 14/31 cases the isolates displayed resistance to both ceftazidime-avibactam and carbapenems, raising concerns for the possible selection of a multidrug-resistant phenotype.

Laboratory management of Crimean-Congo haemorrhagic fever virus infections: perspectives from two European networks

Background

Crimean-Congo haemorrhagic fever virus (CCHFV) is considered an emerging infectious disease threat in the European Union. Since 2000, the incidence and geographic range of confirmed CCHF cases have markedly increased, following changes in the distribution of its main vector, Hyalomma ticks.

Aims

To review scientific literature and collect experts’ opinion to analyse relevant aspects of the laboratory management of human CCHF cases and any exposed contacts, as well as identify areas for advancement of international collaborative preparedness and laboratory response plans.

Methods

We conducted a literature review on CCHF molecular diagnostics through an online search. Further, we obtained expert opinions on the key laboratory aspects of CCHF diagnosis. Consulted experts were members of two European projects, EMERGE (Efficient response to highly dangerous and emerging pathogens at EU level) and EVD-LabNet (Emerging Viral Diseases-Expert Laboratory Network).

Results

Consensus was reached on relevant and controversial aspects of CCHF disease with implications for laboratory management of human CCHF cases, including biosafety, diagnostic algorithm and advice to improve lab capabilities. Knowledge on the diffusion of CCHF can be obtained by promoting syndromic approach to infectious diseases diagnosis and by including CCHFV infection in the diagnostic algorithm of severe fevers of unknown origin.

Conclusion

No effective vaccine and/or therapeutics are available at present so outbreak response relies on rapid identification and appropriate infection control measures. Frontline hospitals and reference laboratories have a crucial role in the response to a CCHF outbreak, which should integrate laboratory, clinical and public health responses.

Clinical evaluation of TRCReady M.TB for rapid automated detection of M. tuberculosis complex in respiratory samples

SETTING

Timely diagnosis of tuberculosis (TB) is essential for effectively controlling and managing the disease. Although international guidelines recommend acid-fast bacilli staining and culture as the 'gold standard', new molecular methods are available to safely and rapidly identify positive samples.

OBJECTIVE

To evaluate the performance of the newer and fully automated version of a molecular assay for rRNA amplification (TRCReady^® M.TB) on 1028 respiratory samples collected from 378 patients for its possible use as a reliable screening method. Results were evaluated using culture as the reference test.

RESULTS

Of four diagnostic protocols employed, best results were obtained when TRCReady M.TB was used together with microscopy on the first respiratory sample, followed by microscopy alone on a second one. The sensitivity and specificity were respectively 97% and 100%, with a turnaround time of 24 h. We propose a possible laboratory algorithm for rapid identification of patients with TB.

CONCLUSIONS

TRCReady offers the advantages of full automation and avoidance of cross-contamination. As such, it should be considered as a more economical option for TB screening than other commercial assays that are currently available.

Clinical management of imported malaria in Italy: results from a national cross-sectional survey in 2015

In Italy, malaria continues to be one of the most common imported parasitoses; therefore, continuous surveillance of epidemiological data and clinical management is needed. In 2016, the National Institute for Infectious Diseases 'Lazzaro Spallanzani' in Rome promoted a retrospective questionnaire-based survey to assess the clinical management of imported malaria cases in Italy in 2015. The questionnaire was sent to 104 Tropical and/or Infectious Diseases Units in the country, and 37 of them filled out and returned the questionnaires. A total of 399 malaria cases were reported in 2015, mostly caused by Plasmodium falciparum and imported from Africa. Malaria chemoprophylaxis was correctly used by a minority of patients. Most patients presented with uncomplicated malaria and were treated orally. In severe cases, intravenous artesunate or quinine alone or in combination were administered, although one third of these severe cases received oral treatment. This retrospective survey reveals a lack of homogeneity in management of malaria-imported cases in Italy. Improvement of malaria chemoprophylaxis, standardization of clinical management of malaria cases and harmonization of oral and intravenous drug availability are needed throughout the country.

A case of persistent bacteraemia by Ralstonia mannitolilytica and Ralstonia pickettii in an intensive care unit

The Ralstonia spp. genus is a group of non-fermentative, Gram-negative bacteria often resistant to many antibiotics, which are emerging as opportunistic pathogens frequently associated with infections in hospital settings. We present herein a case of combined R. pickettii and R. mannitolilytica persisting and relapsing bacteraemia, possibly caused by a septic arterial thrombosis secondary to the rupture of an internal carotid artery aneurysm. Microbiology studies showed that both Ralstonia isolates produced biofilm and carried class D oxacillinase genes. When confronted with infections caused by members of the Ralstonia genus, identification to the species level is crucial for correct clinical management, as the two species show different antibiotic susceptibility patterns.

Molecular and phenotypical characterization of two cases of antibiotic-driven ceftazidime-avibactam resistance in bla KPC-3-harboring Klebsiella pneumoniae

Background: For years, Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae have represented a serious health problem in hospitals worldwide. Since its approval in 2015, ceftazidime-avibactam (CAZ-AVI) had been successfully used for treating complicated KPC-K. pneumoniae infections, until increasing reports of resistance began to emerge.

Methods: Phenotypic tests and molecular analysis were performed in four multidrug-resistant K. pneumoniae isolates, collected from two patients following treatment with CAZ-AVI.

Results: In this study, we report two cases of emergence of CAZ-AVI resistance in KPC-3-producing K. pneumoniae isolates, collected from two patients following treatment with CAZ-AVI. Molecular analysis highlighted the D179Y mutation in the bla_KPC-3 gene, whose role in the loss of hydrolytic activity (resulting in decreased carpabenem minimum inhibitory concentrations and negative phenotypic tests) of the enzyme has already been shown.

Conclusion: Most surveillance schemes aimed at detecting carbapenem-resistant Enterobacteriaceae (CRE) rely on confirmatory phenotypic tests for detecting carbapenemase production. As reports of these treatment-induced, altered CRE phenotypes are increasing, the initial susceptibility testing should be followed by a combination of phenotypic and molecular methods, to make sure that no potential carbapenemase-producing bacteria are missed.

Serological evaluation for Chagas disease in migrants from Latin American countries resident in Rome, Italy

Background

Chagas disease (CD) is a systemic parasitic infection caused by the protozoan Trypanosoma cruzi, whose chronic phase may lead to cardiac and intestinal disorders. Endemic in Latin America where it is transmitted mainly by vectors, large-scale migrations to other countries have turned CD into a global health problem because of its alternative transmission routes through blood transfusion, tissue transplantation, or congenital. Aim of this study was to compare the performance of two commercially available tests for serological diagnosis of CD in a group of Latin American migrants living in a non-endemic setting (Rome, Italy). The study was based on a cross-sectional analysis of seroprevalence in this group. Epidemiological risk factors associated to CD were also evaluated in this study population.

Methods

The present study was conducted on 368 subjects from the Latin American community resident in Rome. Following WHO guidelines, we employed a diagnostic strategy based on two tests to detect IgG antibodies against T. cruzi in the blood (a lysate antigen-based ELISA and a chemiluminescent microparticle CMIA composed of multiple recombinant antigens), followed by a third test (an immunochromatographic assay) on discordant samples.

Results

Our diagnostic approach produced 319/368 (86.7%) concordant negative and 30/368 (8.1%) concordant positive results after the first screening. Discrepancies were obtained for 19/368 (5.2%) samples that were tested using the third assay, obtaining 2 more positive and 17 negative results. The final count of positive samples was 32/368 (8.7% of the tested population). Increasing age, birth in Bolivia, and previous residence in a mud house were independent factors associated with T. cruzi positive serology.

Conclusions

Serological diagnosis of CD is still challenging, because of the lack of a reference standard serological assay for diagnosis. Our results reaffirm the importance of performing CD screening in non-endemic countries; employing a fully automated and highly sensitive CMIA assay first could be a cost- and resource-effective strategy for mass screening of low-risk patients. However, our results also suggest that the WHO strategy of using two different serological assays, combined with epidemiological information, remains the best approach for patients coming from endemic countries.

Ceftaroline Plus Ampicillin Against Gram-Positive Organisms: Results from E-Test Synergy Assays

In an era of increasing drug resistance and limited numbers of antimicrobials in the drug production pipeline, healthcare-associated infections represent a growing public health threat. When therapeutic options are limited, clinicians often resort to using antimicrobial combinations that produce a synergistic effect on the target pathogen. Novel antibiotics are therefore welcome in the daily practice of medicine. For example, ceftaroline is a broad-spectrum cephalosporin active against a variety of bacteria, including methicillin-resistant Staphylococcus aureus, but with limited activity against enterococci, particularly Enterococcus faecium. In this study, we tested the efficacy of ceftaroline against clinical isolates of gram-positive bacteria (S. aureus, Enterococcus faecalis, and E. faecium) by the broth microdilution and E-test assays, and then evaluated the synergistic effect of ceftaroline and ampicillin using the E-test method. The time-kill assay was used to confirm the data on selected strains. This drug combination has been recently shown to be effective against E. faecalis and could offer the advantage of cost-effectiveness (compared to other synergistic associations) as well as good tolerability. The E-test was chosen because of its relative simplicity of use that makes it suitable for routine clinical laboratories as a quick tool to guide clinicians when confronted with difficult-to-treat infections that may require an empirical approach. Our results indicate the presence of a synergistic effect of ceftaroline and ampicillin on most of the strains used, especially E. faecium and E. faecalis. The fact that two of those Enterococcus strains were vancomycin resistant suggests that the possible use of this combination for combating the spread of vancomycin-resistant enterococci should be explored.

Isolation of KPC 3-producing Enterobacter aerogenes in a patient colonized by MDR Klebsiella pneumoniae

We describe the interspecies transmission of the plasmid-mediated blaKPC-3 gene, which confers carbapenem resistance, between clinically relevant gram-negative bacteria in a single patient. A KPC-3 producing Enterobacter aerogenes was isolated from a hospitalized patient previously colonized and then infected by a Klebsiella pneumoniae ST101 carrying the blaKPC-3 gene. The strains showed identical plasmids. Since intense horizontal exchanges among bacteria can occur in the gut, clinicians should be aware that patients colonized by carbapenem-resistant K. pneumoniae could become carriers of other carbapenem-resistant Enterobacteriaceae.

Healthcare-Associated Infection in Italy Annual Point-Prevalence Surveys, 2002–2004

Objective.

Healthcare-associated infections (HAIs) are an important cause of morbidity and mortality worldwide. During the period from 2002 through 2004, a group of Italian hospitals was recruited to conduct HAI point-prevalence surveys.

Design.

Three point-prevalence surveys.

Methods.

A total of 9,609 patients were surveyed.

Results.

The overall frequency of HAI was 6.7% (645 infections among the 9,609 surveyed patients). The most frequent HAIs were lower respiratory tract infections, which accounted for 35.8% (231 of 645 HAIs) of all HAIs, followed by urinary tract infections (152 [23.6%] of 645 HAIs), bloodstream infections (90 [14.0%] of 645 HAIs), and surgical site infections (79 [12.2%] of 645 HAIs). In both multivariate and univariate analysis, invasive procedures, duration of stay, chemotherapy, trauma, coma, and the location of the hospital were all factors statistically significantly associated with the occurrence of an HAL Enterobacteriaceae were the most common isolates recovered in medical and surgical wards, whereas gram-negative aerobic bacilli were the most common isolates recovered in intensive care units. Approximately one-half of all of the patients surveyed were receiving antibiotics at the time of our study; the most used antibiotic classes were fluoroquinolones in medical wards, cephalosporins in surgical wards, and penicillins and glycopeptides in intensive care units.

Conclusion.

Our study emphasizes the need for implementing further HAI surveillance to provide the National Health System with proper tools to prevent and manage infection in hospitalized patients.

Cellular and humoral immune responses to pandemic influenza vaccine in healthy and in highly active antiretroviral therapy-treated HIV patients

Influenza vaccination is recommended for HAART-treated HIV patients to prevent influenza illness and complications. Due to the known ability of T cells to mediate a broadly cross-reactive response, vaccination effectiveness in cell-mediated immune (CMI) response induction is a main objective in new influenza vaccination strategies. Nevertheless, data on CMI responses after pandemic vaccination in HIV subjects are still missing. In the present study, the ability of a single dose of adjuvanted pandemic influenza vaccine to induce humoral and CMI responses was compared in HAART-treated HIV patients and in healthcare workers. Healthcare workers (HCW, n=65) and HAART-treated HIV patients (HIV, n=67) receiving pandemic vaccination were enrolled and analyzed before (t0) and after (t1) vaccination. The analysis of strain-specific humoral response was performed by HAI assay; CMI against pandemic (A/H1N1/Cal/09) and seasonal (A/H1N1/Brisb/07 and A/H3N2/Brisb/07) strains was analyzed by ELISpot and intracellular staining followed by flow cytometry. Pandemic vaccination was effective in inducing both humoral and cell-mediated responses in HAART-treated HIV patients as well as in HCWs. A large fraction of both HCWs and HIV-infected patients showed a T cell response to the pandemic strain before vaccination, suggesting possible previous exposure to A/H1N1/pdm/09 and/or cross-reactive T cells. Notably, pandemic vaccine was also able to boost cross-reactive immune responses to seasonal strains. Finally, a weaker boost of both strain-specific and cross-reactive T cell immunity was found in individuals showing a higher baseline response. These data show the effectiveness of adjuvanted pandemic vaccine to induce both humoral and cellular (strain-specific and cross-reactive) immune responses in HIV patients similar to HCWs.

A case of dengue type 3 virus infection imported from Africa to Italy, October 2009

In October 2009, a traveller returning from Africa to Italy was hospitalised with symptoms suggestive of a haemorrhagic fever of unknown origin. The patient was immediately placed in a special biocontainment unit until laboratory investigations confirmed the infection to be caused by a dengue serotype 3 virus. This case reasserts the importance of returning travellers as sentinels of unknown outbreaks occurring in other countries, and highlights how the initial symptoms of dengue fever resemble those of other haemorrhagic fevers, hence the importance of prompt isolation of patients until a final diagnosis is reached.

A case of dengue type 3 virus infection imported from Africa to Italy, October 2009

In October 2009, a traveller returning from Africa to Italy was hospitalised with symptoms suggestive of a haemorrhagic fever of unknown origin. The patient was immediately placed in a special biocontainment unit until laboratory investigations confirmed the infection to be caused by a dengue serotype 3 virus. This case reasserts the importance of returning travellers as sentinels of unknown outbreaks occurring in other countries, and highlights how the initial symptoms of dengue fever resemble those of other haemorrhagic fevers, hence the importance of prompt isolation of patients until a final diagnosis is reached.

The European network of Biosafety-Level-4 laboratories: enhancing European preparedness for new health threats

Emerging and re-emerging infections and possible bioterrorism acts will continue to challenge both the medical community and civilian populations worldwide, urging health authorities to respond rapidly and effectively. Established in 2005, the European Community (EC)-funded European Network of Biosafety-Level-4 laboratories (Euronet-P4), which brings together the laboratories in Porton Down, London, Hamburg, Marburg, Solna, Lyon and Rome, seeks to increase international collaboration in the areas of high containment laboratory biosafety and viral diagnostic capability, to strengthen Europe's capacity to respond to an infectious disease emergency, and to offer assistance to countries not equipped with such costly facilities. Network partners have agreed on a common strategy to fill the gaps identified in the field of risk group-4 agents’ laboratory diagnosis, namely the lack of standardization and of reference samples. The network has received a further 3-year funding, to offer assistance to external laboratories, and to start the planning of field activities.

Case definition for Ebola and Marburg haemorrhagic fevers: a complex challenge for epidemiologists and clinicians

Viral haemorrhagic fevers (VHFs) represent a challenge for public health because of their epidemic potential, and their possible use as bioterrorism agents poses particular concern. In 1999 the World Health Organization (WHO) proposed a case definition for VHFs, subsequently adopted by other international institutions with the aim of early detection of initial cases/outbreaks in western countries. We applied this case definition to reports of Ebola and Marburg virus infections to estimate its sensitivity to detect cases of the disease. We analyzed clinical descriptions of 795 reported cases of Ebola haemorrhagic fever: only 58.5% of patients met the proposed case definition. A similar figure was obtained reviewing 169 cases of Marburg diseases, of which only 64.5% were in accordance with the case definition. In conclusion, the WHO case definition for hemorrhagic fevers is too specific and has poor sensitivity both for case finding during Ebola or Marburg outbreaks, and for early detection of suspected cases in western countries. It can lead to a hazardous number of false negatives and its use should be discouraged for early detection of cases.

Facing the threat of highly infectious diseases in Europe: the need for a networking approach

In recent years emerging and re-emerging infections, as well as the risk of bioterrorist events, have attracted increasing attention from health authorities because of the epidemic potential that renders some of them a real public health challenge. These highly infectious diseases (HIDs) are occurring more and more frequently in Europe, and despite the many initiatives in place to face them, many unsolved problems remain, and coordinated efforts for dealing with HIDs appear mandatory. Whereas uncoordinated measures would lead to only partial and poor responses to these emerging threats, networking represents a valuable approach to these diseases, in order to: (i) ensure a rapid and effective response; (ii) stimulate complementarity and prevent duplication; (iii) promote international cooperation, exchange of experience, good practice and protocols; and (iv) support the less prepared countries in the European Community.

Patient to patient transmission of hepatitis B virus: a systematic review of reports on outbreaks between 1992 and 2007

BACKGROUND

Hepatitis B outbreaks in healthcare settings are still a serious public health concern in high-income countries. To elucidate the most frequent infection pathways and clinical settings involved, we performed a systematic review of hepatitis B virus outbreaks published between 1992 and 2007 within the EU and USA.

METHODS

The research was performed using two different databases: the PubMed Database and the Outbreak Database, the worldwide database for nosocomial outbreaks. Selection of papers was carried out using the Quorom algorithm, and to avoid selection biases, the inclusion criteria were established before the articles were identified.

RESULTS

Overall, 30 papers were analyzed, reporting on 33 hepatitis B virus outbreaks that involved 471 patients, with 16 fatal cases. Dialysis units accounted for 30.3% of outbreaks followed by medical wards (21.2%), nursing homes (21.2%), surgery wards (15.2), and outpatient clinics (12.1%). The transmission pathways were: multi-vial drugs (30.3%), non-disposable multi-patient capillary blood sampling devices (27.2%), transvenous endomyocardial biopsy procedures (9.1%), and multiple deficiencies in applying standard precautions (9.1%).

CONCLUSION

The analysis of transmission pathways showed that some breaches in infection control measures, such as administration of drugs using multi-vial compounds and capillary blood sampling, are the most frequent routes for patient-to-patient transmission of hepatitis B virus. Moreover some outbreak reports underlined that heart-transplant recipients are at risk of contracting hepatitis B virus infection during the transvenous endomyocardial biopsy procedure through indirect contact with infected blood as a result of environmental contamination. To prevent transmission, healthcare workers must adhere to standard precautions and follow fundamental infection control principles, such as the use of sterile, single-use, disposable needles and avoiding the use of multi-vial compounds in all healthcare settings including outpatient settings.

Risk management of febrile respiratory illness in emergency departments

Febrile Respiratory Illness (FRI) is defined as a new or worsening episode of either cough or shortness of breath, presenting with fever (temperature 38 degrees C or higher) or chills in the previous 24 hours. Some FRI could cause large outbreaks of potentially life-threatening diseases (multi- or extensively drug resistant MTB, SARS, pandemic influenza) if not adequately controlled. Emergency Departments (EDs) are preferential sites of disease transmission because of the presence of both infectious and susceptible patients in the same space, the lack of rapid isolation of infectious patients, and the frequent and close contacts among patients and HCWs often not protected by PPE. The management of risk of FRI transmission is thus extremely important in EDs, where all procedures of infection control should be in place and continually monitored and assessed. In this article the main procedures for the management of risk of FRI transmission in EDs are described and discussed.

A curriculum for training healthcare workers in the management of highly infectious diseases

The SARS epidemic, the threat of bioterrorism, and recent examples of imported highly infectious diseases (HID) in Europe have all highlighted the importance of competent clinical and public health management of infectious disease emergencies. Although the European Union of Medical Specialists in Europe and the Infectious Diseases Society of America have developed curricula for training in infectious disease medicine, neither of those mentions training in the management of HIDs. The European Network for Infectious Diseases (EUNID, http://www.eunid.com) is a European Commission co-funded network of experts in HID management, created to help improve the preparedness for HID emergencies within Europe. One of EUNID's agreed tasks is the development of a curriculum for such a training. Between April 2005 and September 2006, EUNID developed a curriculum and accompanying training course on the basis of a questionnaire that was sent to all country representatives and discussion, followed by amendment of drafts shared through the project website, and a final consensus meeting. The resulting curriculum consists of a two-module course covering the core knowledge and skills that healthcare workers need to safely treat a patient who has, or who may have, an HID. The first module introduces theoretical aspects of HID management, including disease-specific knowledge, infection control, and the public health response, through didactic teaching and class-based discussion. The second module involves a "skill station" and a clinical scenario, and equips trainees with relevant practical skills, including the use of specialised equipment and teamwork practice in patient management. Together, the curriculum and course contribute to the creation of a common framework for training healthcare professionals in Europe, and although they are designed primarily for clinicians that are directly involved in patient care, they are relevant also to public health professionals and others who may be involved in HID management and emergency response.

Isoniazid prophylaxis differently modulates T-cell responses to RD1-epitopes in contacts recently exposed to Mycobacterium tuberculosis: a pilot study

RATIONALE

Existing data on the effect of treatment of latent tuberculosis infection (LTBI) on T-cell responses to Mycobacterium tuberculosis (MTB)-specific antigens are contradictory. Differences in technical aspects of the assays used to detect this response and populations studied might explain some of these discrepancies. In an attempt to find surrogate markers of the effect of LTBI treatment, it would be important to determine whether, among contacts of patients with contagious tuberculosis, therapy for LTBI could cause changes in MTB-specific immune responses to a variety of RD1-antigens.

METHODS AND RESULTS

In a longitudinal study, 44 tuberculin skin test+ recent contacts were followed over a 6-month period and divided according to previous exposure to MTB and LTBI treatment. The following tests which evaluate IFN-gamma responses to RD1 antigens were performed: QuantiFERON TB Gold, RD1 intact protein- and selected peptide-based assays. Among the 24 contacts without previous exposure that completed therapy, we showed a significant decrease of IFN-gamma response in all tests employed. The response to RD1 selected peptides was found to be more markedly decreased compared to that to other RD1 antigens. Conversely, no significant changes in the response to RD1 reagents were found in 9 treated subjects with a known previous exposure to MTB and in 11 untreated controls.

CONCLUSION

These data suggest that the effect of INH prophylaxis on RD1-specific T-cell responses may be different based on the population of subjects enrolled (recent infection versus re-infection) and, to a minor extent, on the reagents used.

Accumulation of dysfunctional effector CD8+ T cells in the liver of patients with chronic HCV infection

BACKGROUND/AIMS

Hepatitis C virus (HCV) causes a chronic infection that can lead to fibrosis and carcinoma. Immune responses mediated by cytotoxic T lymphocytes (CTLs) could be involved in viral clearance or persistence, and therefore in determining the course of the disease.

METHODS

Intrahepatic and peripheral blood CD8+T cells were obtained from 32 HCV-chronically infected patients and analysed by flow-cytometry for surface markers of differentiation, IFNgamma and TNFalpha production, degranulation capacity and perforin content, after CD3 triggering. Results were compared with those obtained from 13 patients with a non-viral liver disease.

RESULTS

Intrahepatic CD8+T cells of HCV-infected patients, despite their phenotype of pre-terminally and terminally differentiated effectors (CCR7-CD45RA-/+), are poorly responsive to T cell receptor (TCR)-mediated stimulation compared with those obtained from uninfected subjects. This defect correlates with the severity of fibrosis, is more pronounced in patients with ALT<1.5xN than with ALT>1.5xNU/ml, and is not evident after mitogen stimulation.

CONCLUSIONS

The present study describes the accumulation of hypo-responsive CD8+T cells in the liver of patients with chronic HCV infection. Understanding the mechanisms underlying this impairment may be helpful in the design of innovative strategies for HCV treatment.

CD1d expression by hepatocytes is a main restriction element for intrahepatic T-cell recognition

The liver has specific mechanisms to protect itself from infectious agents and to avoid autoimmunity, indicating an important role of the hepatic tissues in antigen presentation and tolerance induction. Since intrahepatic lymphocytes may contribute to the innate immunity and to the liver pathology, it is of interest to analyze the expression of antigen presenting molecules and of the related T cell recognition in liver, and how these change in relation to different diseases. We analyzed the expression of MHC class I, and of CD1-a, -b, -c, and -d proteins on liver tissues from patients with different hepatic diseases. Moreover, in the same patients we studied the intrahepatic and peripheral NKT cell recognition of alpha-galactosyl ceramide antigen in the context of CD1d. Unlike in other tissues, classical MHC class I molecules were poorly expressed in the hepatic compartment, suggesting that inflamed hepatocytes may trigger weak MHC-restricted T cell responses. Nevertheless, we observed a prevalent expression of HLA class I-like CD1d isoform on the hepatocyte surface, indicating that CD1d is the main restriction element in the liver. In patients with viral hepatitis, the intrahepatic CD1d expression parallels the recruitment of CD56+Valpha24Vbeta11+ NKT cells in the liver which recognize CD1d presenting glycolipids such as alpha-galactosyl ceramide, suggesting that the intrahepatic T cell immunity may focus on glycolipid antigens.

Lymphocyte distribution and intrahepatic compartmentalization during HCV infection: a main role for MHC-unrestricted T cells

Hepatitis C virus (HCV) infection induces an acute and chronic liver inflammation through an immune-mediated pathway that may lead to cirrhosis and liver failure. Indeed, HCV-related hepatitis is characterized by a dramatic lymphocyte infiltrate into the liver which is mainly composed by HCV non-specific cells. Several data indicated that interferon (IFN)-gamma secretion by intrahepatic lymphocytes (IHL) may drive non-specific cell homing to the liver, inducing interferon inducible protein-10 (IP-10) production. An interesting hallmark of these IHL is the recruitment of lymphocytes associated with mechanisms of innate immunity, such as natural killer (NK), natural killer T (NKT) and gamma delta T lymphocytes. CD81 triggering on NK cell surface by the HCV envelope glycoprotein E2 was recently shown to inhibit NK cell function in the liver of HCV-infected persons, resulting in a possible mechanism contributing to the lack of virus clearance and to the establishment of chronic infection. In contrast, intrahepatic NKT cells restricted to CD1d molecules expressed on the hepatocyte surface may contribute to a large extent to liver damage. Finally, an increased frequency of T cells expressing the gamma delta T cell receptor (TCR) was observed in HCV-infected liver and recent observations indicate that intrahepatic gamma delta T cell activation could be directly induced by the HCV/E2 particle through CD81 triggering. These cells are not HCV specific, are able to kill target cells including primary hepatocytes and their ability to produce T helper (Th)1 cytokines is associated with a higher degree of liver disease. Together, CD1d/NKT and/or E2/CD81 interactions may play a major role in the establishment of HCV immunopathogenesis. In the absence of virus clearance, the chemokine-driven recruitment of lymphocytes with an innate cytotoxic behavior in the liver of HCV-infected patients may boost itself, leading to necroinflammatory and fibrotic liver disease.

Reciprocal activating interaction between natural killer cells and dendritic cells

We analyzed the interaction between human peripheral blood natural killer (NK) cells and monocyte-derived immature dendritic cells (DC). Fresh NK cells were activated, as indicated by the induced expression of the CD69 antigen, and their cytolytic activity was strongly augmented by contact with lipopolysaccharide (LPS)-treated mature DC, or with immature DC in the presence of the maturation stimuli LPS, Mycobacterium tuberculosis or interferon (IFN)-alpha. Reciprocally, fresh NK cells cultured with immature DC in the presence of the maturation stimuli strongly enhanced DC maturation and interleukin (IL)-12 production. IL-2--activated NK cells directly induced maturation of DC and enhanced their ability to stimulate allogeneic naive CD4(+) T cells. The effects of NK cells were cell contact dependent, although the secretion of IFN-gamma and TNF also contributed to DC maturation. Within peripheral blood lymphocytes the reciprocal activating interaction with DC was restricted to NK cells, because the other lymphocyte subsets were neither induced to express CD69, nor induced to mature in contact with DC. These data demonstrated for the first time a bidirectional cross talk between NK cells and DC, in which NK cells activated by IL-2 or by mature DC induce DC maturation.

CD4(+) T cell clones producing both interferon-gamma and interleukin-10 predominate in bronchoalveolar lavages of active pulmonary tuberculosis patients

The pattern of cytokine production in T cell clones derived from bronchoalveolar lavages (BAL) of active pulmonary tuberculosis (TB) patients was analyzed in clones obtained by limiting dilution procedures which expand with high efficiency either total T lymphocytes, independently of their antigen-recognition specificity, or Mycobacterium tuberculosis-specific T cells. BAL-derived clones, representative of CD4(+) cells from five patients with active TB, produced significantly higher amounts of IFN-gamma than BAL-derived CD4(+) clones from three inactive TB donors or four controls (with unrelated, noninfectious pathology). Average IL-4 and IL-10 production did not differ significantly in the three groups. Although these data suggest a predominant Th1 response to M. tuberculosis infection in the lungs, the majority of BAL-derived CD4(+) clones produced both IFN-gamma and IL-10 and the percentage of clones with this pattern of cytokine production was significantly higher in clones derived from BAL of active TB patients than from controls. Only rare clones derived from peripheral blood (PB)-derived CD45RO(+) CD4(+) T cells of both patients (nine cases) and controls (four cases) produced both IFN-gamma and IL-10; instead, the IL-10-producing clones derived from PB T cells most often also produced IL-4, displaying a typical Th2 phenotype. Higher average amounts of IFN-gamma and IL-10 were produced by BAL-derived CD8(+) clones of four active TB patients than of four controls, although the frequency of CD8(+) clones producing both IFN-gamma and IL-10 was lower than that of CD4(+) clones. The M. tuberculosis-specific BAL-derived T cell clones from three active TB patients were almost exclusively CD4(+) and produced consistently high levels of IFN-gamma often in association with IL-10, but very rarely with IL-4. Unlike the BAL-derived clones, the M. tuberculosis-specific clones derived from PB CD45RO(+) CD4(+) T cells of three different active TB patients and two healthy donors showed large individual variability in cytokine production as well as in the proportion of CD4(+), CD8(+), or TCR gamma/delta(+) clones. These results indicate the predominance of CD4(+) T cells producing both the proinflammatory cytokine IFN-gamma and the anti-inflammatory cytokine IL-10 in BAL of patients with active TB.

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) in rat testis nuclei is bound to chromatin

In rat testis nuclei the activity of the selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPx, EC 1.11.1.12) is much higher than in other tissues and subcellular compartments, with the sole exception of mitochondria. In nuclei, the bound enzyme is solubilized by DNase I treatment, thus suggesting a binding to chromatin. Treatment with ionic strength releases about 70% of bound PHGPx, suggesting that electrostatic bonds are involved. Immunogold electron microscopy indicates the association of PHGPx with chromatin structures in isolated nuclei. A possible interpretation of these data is a PHGPx protective role against DNA peroxidative damage. Furthermore, in agreement with kinetic and structural information, PHGPx-chromatin binding could suggest an hypothetical thiol oxidase activity toward specific thiol bearing proteins which could substitute for GSH as alternative donor substrates. Such activity could give to the enzyme a new important function which is not only protective but also has a specific regulatory function in chromatin condensation.

Purification and characterization of phospholipid hydroperoxide glutathione peroxidase from rat testis mitochondrial membranes

The selenoenzyme phospholipid hydroperoxide glutathione peroxidase (PHGPx) is highly expressed in rat testis, where it is under gonadotropin control. In this organ a relevant PHGPx activity is strongly linked to mitochondria of cells undergoing differentiation to spermatozoa. This prompted a study on the possible difference between the soluble and the mitochondrial enzyme and the nature of the binding. The mitochondrial PHGPx activity could be solubilized by detergents or by the combined action of mild detergent treatment and ionic strength, thus suggesting an electrostatic binding of the protein to the inner surfaces of the organelle. The same chromatographic purification procedures were applied to cytosolic and membrane bound PHGPx, without revealing any significant difference between the two forms. Moreover, the electrophoretic mobility, the reactivity to antibodies and the fragmentation patterns also suggested the identity of the two forms of testis PHGPx. Eventually, testis cytosolic and membrane bound PHGPx showed the same substrate specificity for both peroxidic and thiol substrates. On the other hand, a complex behaviour on hydrophobic interaction chromatography, compatible with multiple forms of the enzyme, and with a different tertiary structure of the major peaks was observed for soluble and mitochondrial PHGPx. Accordingly, two-dimensional electrophoresis followed by immunostaining with monoclonal antibodies, showed the presence of multiple isoforms with a different pattern between the soluble and the mitochondrial enzyme. These differences are not accounted for by glycosylation or a different degree of phosphorylation of tyrosines. In both enzymes, indeed, no glycosylation was detected and no more than 10% of PHGPx molecules were shown to contain a phosphotyrosine residue.