Diagnosis of active and latent tuberculosis (TB) remains a challenge; however, over the last few years, a new approach based on detecting Mycobacterium tuberculosis-specific T cells has shown much promise. In particular, there is substantial published evidence showing that the detection of ESAT-6- and CFP-10-specific T cells using the ex vivo enzyme-linked immunospot technique is a marked improvement over the existing tuberculin skin test. This technique, which detects gamma interferon-producing T cells, is now available as the commercial assay T SPOT-TB (Oxford Immunotec, Oxford, UK). In the present study, the usefulness of the T SPOT-TB test for diagnosis of TB in "real-world" clinical practice was investigated. Ninety patients of a southern German referral centre for TB with confirmed or suspected TB were randomly selected for this study. The results of the T SPOT-TB test were compared with the results of conventional diagnostic tools. The T SPOT-TB test detected 70 of 72 patients with pulmonary or extrapulmonary TB, indicating a sensitivity of 97.2% (95% confidence interval, 90.3-99.7). For 45 of these patients, tuberculin skin test (TST) results were also available. Only 40 (89%) of these 45 patients were positive in the TST compared to all 45 (100%) in the T SPOT-TB test (p=0.056). Among 12 of 90 patients for whom active TB disease was ruled out, the T SPOT-TB test was negative for 11 (92%), allowing the rapid exclusion of TB in patients suspected to have active TB disease. The T SPOT-TB test is a sensitive assay for detection of TB and represents a useful addition to the diagnostic algorithm available for detecting TB in low-incidence settings.

The considerable antibiotic resistance of H. pylori isolates argues for standard antibiotic susceptibility testing of H. pylori in pediatric patients prior to the initiation of antibiotic therapy.

Background Giardia duodenalis is a leading cause of gastroenteritis worldwide. Humans are mainly infected by two different subtypes, i.e., assemblage A and B. Genotyping is hampered by allelic sequence heterozygosity (ASH) mainly in assemblage B, and by occurrence of mixed infections. Here we assessed the suitability of current genotyping protocols of G. duodenalis for epidemiological applications such as molecular tracing of transmission chains. Methodology/Principal findings Two G. duodenalis isolate collections, from an outpatient tropical medicine clinic and from several primary care laboratories, were characterized by assemblage-specific qPCR (TIF, CATH gene loci) and a common multi locus sequence typing (MLST; TPI, BG, GDH gene loci). Assemblage A isolates were further typed at additional loci (HCMP22547, CID1, RHP26, HCMP6372, DIS3, NEK15411). Of 175/202 (86.6%) patients the G. duodenalis assemblage could be identified: Assemblages A 25/175 (14.3%), B 115/175 (65.7%) and A+B mixed 35/175 (20.0%). By incorporating allelic sequence heterozygosity in the analysis, the three marker MLST correctly identified 6/ 9 (66,7%) and 4/5 (80.0%) consecutive samples from chronic assemblage B infections in the two collections, respectively, and identified a cluster of five independent patients carrying assemblage B parasites of identical MLST type. Extended MLST for assemblage A altogether identified 5/6 (83,3%) consecutive samples from chronic assemblage A infections and 15 novel genotypes. Based on the observed A+B mixed infections it is estimated that only 75% and 50% of assemblage A or B only cases represent single strain infections, respectively. We demonstrate that typing results are consistent with this prediction. Conclusions/Significance Typing of assemblage A and B isolates with resolution for epidemiological applications is possible but requires separate genotyping protocols. The high frequency of multiple infections and their impact on typing results are findings with immediate consequences for result interpretation in this field.

Immune responses of the immunocompetent host to Bartonella henselae infection were investigated in the murine infection model using C57BL/6 mice. Following intraperitoneal infection with human-derived B. henselae strain Berlin-1, viable bacteria could be recovered from livers and spleens during the first week postinfection, while Bartonella DNA remained detectable by PCR in the liver for up to 12 weeks after infection. are at highest risk for developing BAP and suggested than BAP be considered an AIDS-defining opportunistic infection. Also, B. henselae has been shown to induce granuloma formation in experimentally infected animals (9, 22) and in lymph nodes, spleens, and livers of human patients suffering from CSD (8,12,13,27), indicating the induction of CMI in immunocompetent hosts. In addition, in the era prior to detection of B. henselae and its recognition as the main causative agent of CSD, the induction of a delayed-type hypersensitivity reaction, a hallmark of CMI, was used to diagnose CSD clinically (14). Cats are considered the natural host of B. henselae and source of infection for humans. There are few reports on experimental infection of cats with B. henselae; however, the course of disease in cats differs from that in humans, and the results for clinical manifestations and histopathological findings are conflicting (7,9,11,21,23), possibly as a result of using different B. henselae strains and/or different mechanisms of inoculation. In addition, characterization of the induced immune responses has been difficult because of limitations of immunological tools in feline models. In contrast, murine infection models have been shown to be often advantageous for immunological studies (16). In the present study, we used a murine model of B. henselae infection established in our laboratory (22) to investigate the immune responses induced in the immunocompetent host. Following intraperitoneal (i.p.) infection of C57BL/6 mice with B. henselae, the cellular and humoral immune responses were analyzed at multiple time points until 20 weeks postinfection (p.i.). Proliferative responses were studied in vitro by means of a splenocyte proliferation assay. The roles of different T-cell subsets were investigated by administration of monoclonal antibodies (MAbs) to CD4 and CD8 T cells in proliferation assays. In cytokine release studies, Th cells involved in CMI against B. henselae were further characterized. Humoral immune responses were studied by enzyme-linked immunoassay (ELISA) for Bartonellaspecific immunoglobulin G (IgG) antibodies, and the IgG isotypes were determined. In addition, development and alter-* Corresponding author. Present address: Hygiene-Institut, University of Heidelberg, Im Neuenheimer Feld 324,

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