Silvia Contini

Design of immunogenic peptides from Mycobacterium tuberculosis genes expressed during macrophage infection

In vitro diagnosis of MTB-infection uses MTB-proteins coded for by genes of the region of differentiation 1 (RD1) of the MTB genome. This study wants to test if proteins preferentially expressed during MTB-intracellular growth might provide new targets for the diagnosis of MTB-infection. To this end seventy-five multiepitopic HLA-promiscuous MTB-peptides were designed by quantitative implemented peptide-binding motif analysis from 3 MTB-protein genes expressed in activated human macrophages (MA), 4 genes expressed during growth in non-activated human macrophages (MN-A), 12 housekeeping genes (HKG) and 6 genes of the RD1 region (RD1) as control. ELISpot for IFN-was performed to measure the responses of PBMCs deriving from 45 patients affected by active tuberculosis and 34 controls. In active-TB patients, the mean response to RD1-derived peptides was higher than that to either MA (p<0.01), MN-A (p<0.008) or HKG (p<0.01) derived peptides. In TST-positive subjects all selected peptides elicited significant IFN-T-cell responses (p<0.02 compared to TST-negatives), but without differences between the subgroups. Further, T-cell responses to RD1 peptides were lower in the 23 active-TB treated patients than in the untreated ones (p<0.01). The response to MA peptides in treated active-TB was higher than when untreated (p<0.01). These results demonstrate that the use of in vitro models of MTB-intracellular infection to select MTB gene products for further in silico and in vitro assessment of their immunogenicity have the potential to identify novel antigens amenable to the design of new tools for diagnosis and monitoring of tuberculosis.

Molecular Diagnosis of Fatal Nocardia farcinica Pneumonia in an HIV-Negative Patient

Nocardiosis is a rare and potentially life-threatening infection caused by several species of the Nocardia genus. Most cases occur in immunocompromised patients, and a delay in establishing the diagnosis is common due to the non-specific clinical presentations and the difficulty in cultivating Nocardia. Although the majority of pulmonary nocardiosis cases are caused by Nocardia asteroides, cases of human infection due to N. farcinica are increasingly diagnosed due to recent developments in taxonomy and diagnostic methods. N. farcinica is a separate species from N. asteroides and appears to be more virulent and resistant to antibiotics. Herein, we describe the case of a 65-year-old HIV-negative immunocompromised patient with a fulminant bilateral pulmonary nocardiosis while on empirical treatment with trimethoprim/sulfamethoxazole and imipenem. Post-mortem diagnosis of N. farcinica infection was performed by means of DNA amplification and sequencing of the 65-kDa bacterial heat shock protein.

Socioeconomic status and biomedical risk factors in migrants and native tuberculosis patients in Italy.

Action on social determinants is a main component of the World Health Organization End Tuberculosis (TB) Strategy. The aim of the study was to collect information on socioeconomic characteristics and biomedical risk factors in migrant TB patients in Italy and compare it with data collected among Italian TB patients. A cross-sectional study was conducted among TB patients aged ≥18 years over a 12-months enrolment period in 12 major Italian hospitals. Information on education, employment, housing and income was collected, and European Union Statistics on Income and Living Conditions index was used to assess material deprivation. Among migrants, we also analyzed factors associated with severe material deprivation. Migrants were compared with younger (18–64 years) and older (65+ years) Italians patients. Out of 755 patients enrolled (with a median age of 42 years, interquartile range: 31–53), 65% were migrants. Pulmonary, microbiologically confirmed, and new cases were 80%, 73%, and 87% respectively. Prevalence of co-morbidities (i.e. diabetes, chronic kidney disease, neoplastic diseases and use of immunosuppressive drugs) was lower among migrants compared to Italian TB patients, while indicators of socioeconomic status, income and housing conditions were worst in migrants. Forty-six percent of migrants were severely deprived vs. 9% of Italians (p<0.0001, 11.3% and 5.5% among younger and older Italians, respectively). Among migrants, being male, older, irregular, unemployed, with a shorter time spent in Italy, a lower education level, and without a co-morbidity diagnosis were factors associated with severe material deprivation at multi-variable logistic regression. Moreover, socioeconomic indicators for Italian patients did not differ from those reported for the general Italian population, while migrant TB patients seem to have a higher prevalence of severe material deprivation than other migrants residing in Italy. Intervention to address the needs of this population are urgent.