Risk assessment of tuberculosis in immunocompromised patients. A TBNET study.

RATIONALE: In the absence of active tuberculosis, a positive tuberculin skin test (TST) or interferon-γ release assay (IGRA) result defines latent infection with Mycobacterium tuberculosis, although test results may vary depending on immunodeficiency. OBJECTIVES: This study compared the performance of TST and IGRAs in five different groups of immunocompromised patients, and evaluated their ability to identify those at risk for development of tuberculosis. METHODS: Immunocompromised patients with HIV infection, chronic renal failure, rheumatoid arthritis, solid-organ or stem-cell transplantation, and healthy control subjects were evaluated head-to-head by the TST, QuantiFERON-TB-Gold in-tube test (ELISA), and T-SPOT.TB test (enzyme-linked immunospot) at 17 centers in 11 European countries. Development of tuberculosis was assessed during follow-up. MEASUREMENTS AND MAIN RESULTS: Frequencies of positive test results varied from 8.7 to 15.9% in HIV infection (n = 768), 25.3 to 30.6% in chronic renal failure (n = 270), 25.0% to 37.2% in rheumatoid arthritis (n = 199), 9.0 to 20.0% in solid-organ transplant recipients (n = 197), 0% to 5.8% in stem-cell transplant recipients (n = 103), and 11.2 to 15.2% in immunocompetent control subjects (n = 211). Eleven patients (10 with HIV infection and one solid-organ transplant recipient) developed tuberculosis during a median follow-up of 1.8 (interquartile range, 0.2-3.0) years. Six of the 11 patients had a negative or indeterminate test result in all three tests at the time of screening. Tuberculosis incidence was generally low, but higher in HIV-infected individuals with a positive TST (3.25 cases per 100 person-years) than with a positive ELISA (1.31 cases per 100 person-years) or enzyme-linked immunospot result (1.78 cases per 100 person-years). No cases of tuberculosis occurred in patients who received preventive chemotherapy. CONCLUSIONS: Among immunocompromised patients evaluated in this study, progression toward tuberculosis was highest in HIV-infected individuals and was poorly predicted by TST or IGRAs. Clinical trial registered with www.clinicaltrials.gov (NCT 00707317).

Viridans group streptococci in blood culture isolates in a Swedish university hospital: antibiotic susceptibility and identification of erythromycin resistance genes.

One hundred and twenty-nine isolates of viridans group streptococci in blood cultures from patients with septicaemia or endocarditis isolated between 1998 and 2003 were tested for antibiotic susceptibility to penicillin, ciprofloxacin, clindamycin, dalbavancin, daptomycin, erythromycin, linezolid, tigecycline, trimethoprim/sulphamethoxazole and vancomycin. Reduced susceptibility to penicillin (minimum inhibitory concentration (MIC) > or =0.25 microg/mL) was found in 18% of the isolates, and 4% of the strains were resistant to penicillin (MIC> or =4.0 microg/mL). Nineteen percent of the isolates had reduced susceptibility to erythromycin (MIC> or =0.5 microg/mL), among which ermB and mefA were found in 40% and 80%, respectively. Strains sequenced as Streptococcus mitis by rnpB had a high degree of non-susceptibility to erythromycin (32%) and penicillin (21%). The level of penicillin resistance in this Swedish study was lower compared with studies from other countries where the antibiotic pressure might be higher than in Sweden. Susceptibility to newer antibiotics was high; all strains were susceptible to dalbavancin, daptomycin, linezolid and vancomycin.

Immune responses to ESAT-6 and CFP-10 by FASCIA and multiplex technology for diagnosis of M. tuberculosis infection; IP-10 is a promising marker.

BACKGROUND: There is a need for reliable markers to diagnose active and latent tuberculosis (TB). The interferon gamma release assays (IGRAs) are compared to the tuberculin skin test (TST) more specific, but cannot discriminate between recent or remote TB infection. Here the Flow-cytometric Assay for Specific Cell-mediated Immune-response in Activated whole blood (FASCIA), which quantifies expanded T-lymphoblasts by flow-cytometric analysis after long-term antigen stimulation of whole blood, is combined with cytokine/chemokine analysis in the supernatant by multiplex technology for diagnosis of Mycobacterium tuberculosis (Mtb) infection. METHODS AND FINDINGS: Consecutive patients with suspected TB (n = 85), with microbiologically verified active pulmonary TB (n = 33), extra pulmonary TB (n = 21), clinical TB (n = 11), presumed latent TB infection (LTBI) (n = 23), patients negative for TB (n = 8) and 21 healthy controls were studied. Blood samples were analyzed with FASCIA and multiplex technology to determine and correlate proliferative responses and the value of 14 cytokines for diagnosis of Mtb infection: IFN- γ, IL-2, TNF-α, IP-10, IL-12, IL-6, IL-4, IL-5, IL-13, IL-17, MIP-1ß, GM-CSF, IFN-α2 and IL-10. Cytokine levels for IFN-γ, IP-10, MIP-1ß, IL-2, TNF-α, IL-6, IL-10, IL-13 and GM-CSF were significantly higher after stimulation with the Mtb specific antigens ESAT-6 and CFP-10 in patients with active TB compared to healthy controls (p<0.05) and correlated with proliferative responses. IP-10 was positive in all patients with verified TB, if using a combination of ESAT-6 and CFP-10 and was the only marker significantly more sensitive in detecting active TB then IFN-γ (p = 0.012). Cytokine responses in patients with active TB were more frequent and detected at higher levels than in patients with LTBI. CONCLUSIONS: IP-10 seems to be an important marker for diagnosis of active and latent TB. Patients with active TB and LTBI responded with similar cytokine profiles against TB antigens but proliferative and cytokine responses were generally higher in patients with active TB.

16S rDNA sequencing of valve tissue improves microbiological diagnosis in surgically treated patients with infective endocarditis.

OBJECTIVES: The aim was to evaluate 16S rDNA sequencing in heart valves in patients with infective endocarditis undergoing surgery. METHODS: Fifty-seven patients with infective endocarditis were examined in this prospective study by analysing heart valves with 16S rDNA sequencing and culturing methods and comparing the results to blood cultures. As controls, heart valves from 61 patients without any signs of endocarditis were examined. RESULTS: All together 77% of the endocarditis patients were positive for 16S rDNA, 84% had positive blood cultures and 23% had positive cultures from heart valves, whereas only 16% of the cultures from heart valves were concordant with results from blood cultures or 16S rDNA. Concordant results between 16S rDNA sequencing and blood cultures were found in 75% patients. All controls were negative for 16S rDNA. In 4 out of 9 patients with negative blood cultures, the aetiology was established by 16S rDNA alone, i.e. viridans group streptococci. CONCLUSION: In this Swedish study, 16S rDNA sequencing of valve material was shown to be a valuable addition in blood culture-negative cases. The value of heart valve culture was low. Molecular diagnosis using 16S rDNA sequencing should be recommended in patients undergoing valve replacement for infective endocarditis.

Detection of proliferative responses to ESAT-6 and CFP-10 by FASCIA assay for diagnosis of Mycobacterium tuberculosis infection.

There is a large and growing worldwide need for reliable tests to diagnose active and latent tuberculosis (TB). Improved methodology for identifying individuals with true latent TB (LTBI), particularly those with a recent infection, would pave the way for targeted prophylactic treatment. The traditionally used tuberculin skin test (TST) is unspecific and impractical. Interferon gamma release assays (IGRA) are more specific than the TST but, like that test, cannot discriminate either between recent and remote TB infection, or between these and a mere immunological memory of previous TB infection. The Flow-cytometric Assay for Specific Cell-mediated Immune-response in Activated whole blood (FASCIA) combines long-term antigen stimulation of whole blood and flow-cytometric analysis with quantification of the expanded T-lymphoblasts and can also be employed for measurement of cytokine responses.

Identification of species of viridans group streptococci in clinical blood culture isolates by sequence analysis of the RNase P RNA gene, rnpB.

OBJECTIVES: Viridans group streptococci (VGS) cause severe diseases such as infective endocarditis and septicaemia. Genetically, VGS species are very close to each other and it is difficult to identify them to species level with conventional methods. The aims of the present study were to use sequence analysis of the RNase P RNA gene (rnpB) to identify VGS species in clinical blood culture isolates, and to compare the results with the API 20 Strep system that is based on phenotypical characteristics. METHODS: Strains from patients with septicaemia or endocarditis were analysed with PCR amplification and sequence analysis of the rnpB gene. Clinical data were registered as well. RESULTS: One hundred and thirty two VGS clinical blood culture isolates from patients with septicaemia (n=95) or infective endocarditis (n=36) were analysed; all but one were identified by rnpB. Streptococcus oralis, Streptococcus sanguinis and Streptococcus gordonii strains were most common in the patients with infective endocarditis. In the isolates from patients with haematological diseases, Streptococcus mitis and S. oralis dominated. In addition in 76 of the isolates it was possible to compare the results from rnpB analysis and the API 20 Strep system. In 39/76 (51%) of the isolates the results were concordant to species level; in 55 isolates there were no results from API 20 Strep. CONCLUSION: Sequence analysis of the RNase P RNA gene (rnpB) showed that almost all isolates could be identified. This could be of importance for evaluation of the portal of entry in patients with septicaemia or infective endocarditis.

In-hospital and long-term mortality in infective endocarditis in injecting drug users compared to non-drug users: a retrospective study of 192 episodes.

In a retrospective study, in-hospital and long-term mortality for patients with infective endocarditis (IE) was analysed. The study was conducted at a department of infectious diseases in Stockholm, Sweden. Mortality was compared between injecting drug users (IDUs) and patients without drug abuse (non-IDUs). 192 episodes of IE from 1995 to 2000 were analysed, 60 in IDUs and 135 in non-IDUs, median follow-up 4.4 y. Episodes were classified using the Duke criteria: 145 definite and 47 possible. Of 53 definite episodes in IDUs, 55% were right-sided IE and 43% left-sided IE (including combined left- and right-sided). Surgical treatment was used in 34/145 definite episodes, all being left-sided IE. The in-hospital mortality was 14/145 (9.6%). There was no difference in in-hospital mortality between patient groups with left-sided IE. The IDU patients with left-sided IE had a higher long-term mortality with the increased mortality rate explained by late deaths in the surgically treated IDUs. Treatment results for IDUs with right-sided IE were good with no in-hospital mortality, no relapses and no increase in long-term mortality. This difference in prognosis between left-sided and right-sided IE in IDUs makes high quality echocardiography important to identify patients with left-sided IE and worse prognosis.

Swedish guidelines for diagnosis and treatment of infective endocarditis.

Swedish guidelines for diagnosis and treatment of infective endocarditis (IE) by consensus of experts are based on clinical experience and reports from the literature. Recommendations are evidence based. For diagnosis 3 blood cultures should be drawn; chest X-ray, electrocardiogram, and echocardiography preferably transoesophageal should be carried out. Blood cultures should be kept for 5 d and precede intravenous antibiotic therapy. In patients with native valves and suspicion of staphylococcal aetiology, cloxacillin and gentamicin should be given as empirical treatment. If non-staphylococcal etiology is most probable, penicillin G and gentamicin treatment should be started. In patients with prosthetic valves treatment with vancomycin, gentamicin and rifampicin is recommended. Patients with blood culture negative IE are recommended penicillin G (changed to cefuroxime in treatment failure) and gentamicin for native valve IE and vancomycin, gentamicin and rifampicin for prosthetic valve IE, respectively. Isolates of viridans group streptococci and enterococci should be subtyped and MIC should be determined for penicillin G and aminoglycosides. Antibiotic treatment should be chosen according to sensitivity pattern given 2-6 weeks intravenously. Cardiac valve surgery should be considered early, especially in patients with left-sided IE and/or prosthetic heart valves. Absolute indications for surgery are severe heart failure, paravalvular abscess, lack of response to antibiotic therapy, unstable prosthesis and multiple embolies. Follow-up echocardiography should be performed on clinical indications.

Candida albicans tricuspid valve endocarditis in an intravenous drug addict: successful treatment with fluconazole.

An addicted, intravenous drug user was treated for Candida albicans tricuspid valve endocarditis with high dose fluconazole for 8 months, without relapse after 30 months.

Streptococcus viridans septicaemia: a comparison study in patients admitted to the departments of infectious diseases and haematology in a university hospital.

Infective endocarditis caused by viridans streptococci is a well-described disease. Streptococcus viridans is also an important etiologic agent causing septicaemia in neutropenic patients with haematological diseases. In this study we retrospectively reviewed charts from 111 patients with 121 episodes of viridans streptococci septicaemia during the period 1992-97 for clinical data, presence of endocarditis, subtype and outcome. Forty-seven episodes of S. viridans septicaemia were documented in 45 non-neutropenic patients treated at the Department of Infectious Diseases (Group A). Thirty of these episodes were defined as definite and 9 as possible infective endocarditis, using Duke's critera. Seventy-four episodes of S. viridans septicaemia were identified in 66 patients treated at the Department of Haematology (Group B), only 1 of which fulfilled the criteria for possible infective endocarditis. S. sanguis was the most common subtype (18/47; 38%) in Group A and S. mitis was the major subtype (51/74; 69%) in Group B.

Prospective 7-year monitoring of MAC bacteremia in HIV-positive Swedish patients.

OBJECTIVE: To record the cumulative incidence of Mycobacterium avium complex (MAC) bacteremia among HIV-infected patients and to study colonization in relation to symptoms of infection. METHODS: In a prospective study, 61 patients with a CD4 count less-than-or-eq, slant200x106/L were followed by cultures from sputum, feces and blood every 3--6 months and for development of MAC bacteremia and clinical symptoms. The main end-points were MAC bacteremia and death. RESULTS: From the start in November 1989 to January 1997 about 34% had developed MAC bacteremia with a median follow-up of 22 months. At the time of positive blood cultures, all but one patient had symptoms consistent with disseminated MAC infection. Positive cultures from respiratory and gastrointestinal tract were recorded before MAC bacteremia in only four patients. All but one had symptoms at the time of positive blood culture. CONCLUSIONS: The incidence of MAC bacteremia was similar to figures in other studies. The presence of symptoms in close relation to positive blood cultures supports late colonization and late infection in HIV disease. Screening patients with samples from the respiratory and gastrointestinal tracts is not useful