Evaluation of Different Techniques for Nodal Tuberculosis Diagnosis Among Immigrants and Natives in a Low TB Burden and High Immigrant Receiving Italian City. An Eight Year Retrospective Analysis

Introduction: Node represents one of the most common Conclusions: Nodal TB was the most common extra-pulmonary TB site of reactivation, occurring mostly among Asians. NAAT is a rapid and sensitive tool contributing to nodal TB diagnosis, especially among certain ethnicities (e.g. Asians). TB culture is the reference standard for nodal TB diagnosis and histology presents typical diagnostic features with or without acid fast bacilli within the specimen. The diagnostic role of nucleic acid amplification tests (NAATs) is controversial, and NAATs are recommended in conjunction with TB culture and histology. The present study describes nodal TB epidemiology and antibiotic (ATB) resistance, and compares the sensitivity of culture, NAAT and histology among natives and foreign-born nodal TB cases in a low TB burden and high immigrant receiving city (Ferrara) of Northern Italy, between 2009 and 2017. Methods: We retrospectively identified all TB cases admitted to Ferrara University-Hospital from 2009 to 2017. We recorded gender, age, country of birth, site of disease, smear positivity and ATB sensitivity. We also recorded the results of smear microscopy, TB culture and NAAT, and the histological results of all nodal TB cases. Granulomatous inflammation, caseous necrosis, Langhans’ giant cells, epithelioid cell, the presence of acid fast bacilli, were considered histological features supporting TB diagnosis. Results: We identified 229 TB cases over the study period. 30 out of the 72 extra-pulmonary cases (41.7%) presented nodal TB. Six were natives, 24 foreigners, 19 females and 11 males (p>0.05). (POCO CHIARO) Foreign-born nodal TB cases were significantly younger than native cases (34.8 vs 76.3 years, p <0.05). 2/17 cases were drug-resistant; no multidrug-resistant (MDR) or extensively-drug (XDR) resistant cases were recorded.Asians (93.3% were from Pakistan) presented a higher risk of developing nodal TB compared with not Asian cases (p>0.01; OR 7.3; CI: 3.17-16.78). TB culture, smear microscopy, NAAT and histology results are depicted in Table 1. 12/13 positive NAAT tests were confirmed by culture and/or histology. No statistical difference was found comparing TB culture, NAAT, and histological techniques.Conclusions: Nodal TB was the most common extra-pulmonary TB site of reactivation, occurring mostly among Asians. NAAT is a rapid and sensitive tool contributing to nodal TB diagnosis