Fabio Rumpianesi

Use in routine clinical practice of two commercial blood tests for diagnosis of infection with Mycobacterium tuberculosis: a prospective study

BACKGROUND Two commercial blood assays for the diagnosis of latent tuberculosis infection--T-SPOT.TB and QuantiFERON-TB Gold--have been separately compared with the tuberculin skin test. Our aim was to compare the efficacy of all three tests in the same population sample. METHODS We did a prospective study in 393 consecutively enrolled patients who were tested simultaneously with T-SPOT.TB and QuantiFERON-TB Gold because of suspected latent or active tuberculosis. 318 patients also had results available for a tuberculin skin test. FINDINGS Overall agreement with the skin test was similar (T-SPOT.TB kappa=0.508, QuantiFERON-TB Gold kappa=0.460), but fewer BCG-vaccinated individuals were identified as positive by the two blood assays than by the tuberculin skin test (p=0.003 for T-SPOT.TB and p<0.0001 for QuantiFERON-TB Gold). Indeterminate results were significantly more frequent with QuantiFERON-TB Gold (11%, 43 of 383) than with T-SPOT.TB (3%, 12 of 383; p<0.0001) and were associated with immunosuppressive treatments for both tests. Age younger than 5 years was significantly associated with indeterminate results with QuantiFERON-TB Gold (p=0.003), but not with T-SPOT.TB. Overall, T-SPOT.TB produced significantly more positive results (38%, n=144, vs 26%, n=100, with QuantiFERON-TB Gold; p<0.0001), and close contacts of patients with active tuberculosis were more likely to be positive with T-SPOT.TB than with QuantiFERON-TB Gold (p=0.0010). INTERPRETATION T-SPOT.TB and QuantiFERON-TB Gold have higher specificity than the tuberculin skin test. Rates of indeterminate and positive results, however, differ between the blood tests, suggesting that they might provide different results in routine clinical practice.

Performance of tests for latent tuberculosis in different groups of immunocompromised patients.

BACKGROUND Immunocompromised persons infected with Mycobacterium tuberculosis (MTB) have increased risk of tuberculosis (TB) reactivation, but their management is hampered by the occurrence of false-negative results of the tuberculin skin test (TST). The T-cell interferon (IFN)-gamma release blood assays T-SPOT.TB (TS.TB) [Oxford Immunotec; Abingdon, UK] and QuantiFERON-TB Gold In-Tube (QFT-IT) [Cellestis Ltd; Carnegie, VIC, Australia] might improve diagnostic accuracy for latent TB infection (LTBI) in high-risk persons, although their performance in different groups of immunocompromised patients is largely unknown. METHODS AND RESULTS Over a 1-year period, we prospectively enrolled patients in three different immunosuppressed groups, as follows: 120 liver transplantation candidates (LTCs); 116 chronically HIV-infected persons; and 95 patients with hematologic malignancies (HMs). TST, TS.TB, and QFT-IT were simultaneously performed, their results were compared, and intertest agreement was evaluated. Overall, TST provided fewer positive results (10.9%) than TS.TB (18.4%; p < 0.001) and QFT-IT (15.1%; p = 0.033). Significantly fewer HIV-infected individuals had at least one positive test (9.5%) compared with LTCs (35.8%; p < 0.001) and patients with HMs (29.5%; p < 0.001). Diagnostic agreement between tests was moderate (kappa = 0.40 to 0.65) and decreased in the HIV-infected group when the results of the TS.TB were compared with either TST (kappa = 0.16) or QFT-IT (kappa = 0.19). Indeterminate blood test results due to low positive control values were significantly more frequent with QFT-IT (7.2%) than with TS.TB (0.6%; p < 0.001). CONCLUSIONS Blood tests identified significantly more patients as being infected with MTB than TST, although diagnostic agreement varied across groups. Based on these results, we recommend tailoring application of the new blood IFN-gamma assays for LTBI in different high-risk groups and advise caution in their current use in immunosuppressed patients.

Performance of commercial blood tests for the diagnosis of latent tuberculosis infection in children and adolescents

BACKGROUND. The accurate diagnosis of latent tuberculosis infection reduces the risk of progression to severe disseminated disease. However, in young children, a major limitation of the standard tuberculin skin test is that false-negative results cannot be detected. The new interferon-γ release assays QuantiFERON-TB Gold (Cellestis Carnegie Victoria, Australia), QuantiFERON-TB In-Tube (Cellestis), and T-SPOT.TB (Oxford Immunotec, Abingdon, United Kingdom) show promise of greater accuracy, but they may also be affected by impaired cellular immunity, resulting in indeterminate results (ie, insufficient response in positive-control wells). OBJECTIVE. To evaluate the impact of age on the performance of interferon-γ release assays when used in a routine hospital setting among children tested for suspected active or latent TB infection. METHODS. We retrospectively studied 496 children 0 to 19 years of age who had been tested with the tuberculin skin test and at least 1 interferon-γ release assay: 181 with QuantiFERON-TB Gold and 315 with QuantiFERON-TB In-Tube. In 154 of the children, paired interferon-γ release assay testing was available: 87 with QuantiFERON-TB Gold/T-SPOT.TB and 67 with QuantiFERON-TB In-Tube/T-SPOT.TB. RESULTS. Compared with T-SPOT.TB, the rates of indeterminate results were significantly higher for both QuantiFERON-TB Gold and QuantiFERON-TB In-Tube. QuantiFERON-TB Gold and QuantiFERON-TB In-Tube also gave indeterminate results more frequently in children <4 years of age than in those ≥4 years of age. Indeterminate results were associated with younger age for both QuantiFERON-TB Gold and QuantiFERON-TB In-Tube but not for T-SPOT.TB. Considering age as a binary variable (<4 and ≥4 years of age), a significantly higher concentration of phytohaemagglutinin-produced interferon-γ was observed in older children with both QuantiFERON-TB Gold and QuantiFERON-TB In-Tube. CONCLUSIONS. Different blood tests for the diagnosis of latent tuberculosis infection in children seem to perform differently, because both QuantiFERON-TB tests were more likely than T-SPOT.TB to give indeterminate results in children <4 years of age.

Persistent Carriage and Infection by Multidrug-Resistant Escherichia coli ST405 Producing NDM-1 Carbapenemase: Report on the First Italian Cases

ABSTRACT We report on the first detection of the NDM-1 carbapenemase in Italy, in Escherichia coli isolated in October 2009. Prolonged colonization and relapsing infection by NDM-1-positive E. coli were observed in a patient (index case) with an indirect epidemiological link with areas of endemicity. Transient colonization was apparently observed in another patient linked with the index case.

Mucorales -specific T cells emerge in the course of invasive mucormycosis and may be used as a surrogate diagnostic marker in high-risk patients

Mucorales-specific T cells were investigated in 28 hematologic patients during the course of their treatment. Three developed proven invasive mucormycosis (IM), 17 had infections of known origin but other than IM, and 8 never had fever during the period of observation. Mucorales-specific T cells could be detected only in patients with IM, both at diagnosis and throughout the entire course of the IM, but neither before nor for long after resolution of the infection. Such T cells predominantly produced IL-4, IFN-γ, IL-10, and to a lesser extent IL-17 and belonged to either CD4(+) or CD8(+) subsets. The specific T cells that produced IFN-γ were able to directly induce damage to Mucorales hyphae. None of the 25 patients without IM had Mucorales-specific T cells. Specific T cells contribute to human immune responses against fungi of the order Mucorales and could be evaluated as a surrogate diagnostic marker of IM.

Group B streptococcal colonization in 160 mother-baby pairs: a prospective cohort study.

OBJECTIVES To identify the source of postnatal colonization with group B Streptococcus (GBS) and to evaluate the impact of intrapartum antibiotic prophylaxis (IAP) administration in newborn infant transmission. STUDY DESIGN A prospective, longitudinal study evaluated GBS colonization in 160 mother-baby pairs. Specimens were collected from the time of delivery to 8 weeks post-partum, from rectum, vagina, and milk of mothers, and from throat and rectum of neonates. Women were grouped according to their GBS status at discharge from the hospital: culture-positive carriers (n = 83), culture-negative carriers (n = 26), and noncarriers (n = 51). Newborns were considered colonized if GBS was yielded from at least 1 site. RESULTS A total of 35 (21.9%) neonates were colonized; 30 were born to culture-positive carriers, 2 to culture-negative carriers, and 3 to noncarriers. Infants of culture-positive carriers exposed to IAP were less likely to be colonized (15/57 vs 15/26, P = .01), or heavily colonized, (7/57 vs 9/26, P = .04). Of all newborns, those exposed to IAP and discharged GBS-free from hospital, often became colonized subsequently (12/57 vs 1/26, P = .09). Molecular typing analysis (available for 30 of 32 carrier mothers and their infants) confirmed an identical strain of GBS in all mother-baby pairs. Six of 83 culture-positive carrier mothers had a positive milk culture. Their respective neonates all were heavily colonized. CONCLUSIONS Newborns exposed to IAP and GBS-free at hospital discharge subsequently acquire GBS from their mothers. Culture-positive milk is associated with heavy neonatal colonization.

Genomic characterization of Nontuberculous Mycobacteria

Mycobacterium tuberculosis and Mycobacterium leprae have remained, for many years, the primary species of the genus Mycobacterium of clinical and microbiological interest. The other members of the genus, referred to as nontuberculous mycobacteria (NTM), have long been underinvestigated. In the last decades, however, the number of reports linking various NTM species with human diseases has steadily increased and treatment difficulties have emerged. Despite the availability of whole genome sequencing technologies, limited effort has been devoted to the genetic characterization of NTM species. As a consequence, the taxonomic and phylogenetic structure of the genus remains unsettled and genomic information is lacking to support the identification of these organisms in a clinical setting. In this work, we widen the knowledge of NTMs by reconstructing and analyzing the genomes of 41 previously uncharacterized NTM species. We provide the first comprehensive characterization of the genomic diversity of NTMs and open new venues for the clinical identification of opportunistic pathogens from this genus.

Characterization of 17 strains belonging to the Mycobacterium simiae complex and description of Mycobacterium paraense sp. nov.

Fourteen mycobacterial strains isolated from pulmonary samples of independent patients in the state of Pará (Brazil), and three strains isolated in Italy, were characterized using a polyphasic approach. Thorough genetic investigation, including whole-genome sequencing, demonstrated that the strains belong to the M. simiae complex, being most closely related to Mycobacterium interjectum. For 14 of the strains, evidence emerged supporting their inclusion in a previously unreported species of the genus Mycobacterium, for which the name Mycobacterium paraense sp. nov. is proposed (type strain, IEC26(T) = DSM 46749(T) = CCUG 66121(T)). The novel species is characterized by slow growth, unpigmented or pale yellow scotochromogenic colonies, and a HPLC mycolic acid profile different from other known mycobacteria. In different genetic regions, high sequence microheterogeneity was detected.

A rare case of localized mucosal leishmaniasis due to Leishmania infantum in an immunocompetent Italian host.

The case of authoctonous isolated laryngeal leishmaniasis due to L. infantum in an italian immunocompetent host is reported. It is highlighed the need to consider mucosal leishmaniasis in the differential diagnosis of laryngeal tumors. Rapid nested-PCR technique and enzyme restriction analysis were useful for diagnosis and species identification directly from bioptic samples.

Fusarium verticillioides fungemia in a liver transplantation patient: successful treatment with voriconazole ☆

Fusarium is an opportunistic fungal pathogen which is emerging as a significant cause of morbidity and mortality in immunocompromised hosts. We present a rare case of F. verticillioides fungemia that occurred in a patient who underwent a second orthotopic liver transplantation for chronic rejection and completely responded to treatment with voriconazole.