Background Pleural infection is common, and has a >30% major morbidity and mortalitydparticularly when infection is caused by Gram-negative, Staphylococcus aureus or mixed aerobic pathogens. Standard pleural fluid culture is negative in w40% of cases. Culturing pleural fluid in blood culture bottles may increase microbial yield, and is cheap and easy to perform. Objectives To determine whether inoculating pleural fluid into blood culture bottles increases the culture positivity of pleural infection over standard laboratory culture, and to assess the optimum volume of inoculum to introduce. Methods 62 patients with pleural infection were enrolled. Pairs of aerobic and anaerobic blood culture bottles were inoculated at the bedside with 2, 5 or 10 ml of pleural fluid, and two pleural fluid specimens were sent for standard culture. Pleural fluid from nine control patients was cultured to test for 'false-positive' results. Results The addition of blood culture bottle culture to standard culture increased the proportion of patients with identifiable pathogens by 20.8% (20/53 (37.7%) to 31/53 (58.5%) (difference 20.8%, 95% CI difference 8.9% to 20.8%, p<0.001)). The second standard culture did not similarly improve the culture positivity (19/49 (38.8%) to 22/49 (44.9%) (difference 6.1%, 95% CI difference À2.5% to 6.1%, p¼0.08)). The culture inoculum volume did not influence bacterial isolation frequency. The control fluids were culture negative. Conclusions Blood culture bottle culture of infected pleural fluid increases microbial yield when used in addition to standard culture. This technique should be part of routine care.

Identification as a study of diagnostic accuracy using at least one measure of accuracy (such as sensitivity, specificity, predictive values, or AUC) 1, 5

SummaryPersons with latent Mycobacterium tuberculosis infection (LTBI) vary by their risk of progression to tuberculosis but are clinically indistinguishable. We identified a cellular immune signature that correlates strongly with time since exposure, providing a rationale for immunological risk stratification to improve targeting of LTBI treatment.

Testicular tuberculosis (TB) is rare, and, because of this, the lack of pathognomonic clinical features and its tendency to mimic other commoner conditions, the diagnosis is frequently delayed or may be missed. In this case, the initial clinical presentation was typical for bacterial epididymo-orchitis in a 38-year-old man. When the patient failed to improve with standard treatment including broadening of antibiotics, the diagnosis was re-considered because some unusual signs suggested testicular malignancy or lymphoma. Further, history-taking and subsequent cross-sectional imaging with CT/MRI identified co-existent pulmonary nodularity, thoracic and abdominal lymphadenopathy and bony changes that, together, raised the suspicion of TB. Mycobacterium tuberculosis was confirmed on DNA-based testing of the hydrocele fluid, although standard acid-fast bacilli culture was negative. This case prompted a review of the literature to explore the optimal steps in the investigation and diagnosis of this rare disease.

A fingerprint offers a convenient, noninvasive sampling matrix for monitoring therapeutic drug use. However, a barrier to widespread adoption of fingerprint sampling is the fact that the sample volume is uncontrolled. Fingerprint samples ( n = 140) were collected from patients receiving the antibiotic isoniazid as part of their treatment, as well as from a drug-naive control group ( n = 50). The fingerprint samples were analyzed for isoniazid (INH) and acetylisoniazid (AcINH), using liquid chromatography high-resolution mass spectrometry. The data set was analyzed retrospectively for metabolites known to be present in eccrine sweat. INH or AcINH was detected in 89% of the fingerprints collected from patients and in 0% of the fingerprints collected from the control group. Metabolites lysine, ornithine, pyroglutamic acid, and taurine were concurrently detected alongside INH/AcINH and were used to determine whether the fingerprint sample was sufficient for testing. Given a sufficient sample volume, the fingerprint test for INH use has sensitivity, specificity, and accuracy of 100%. Normalization to taurine was found to reduce intradonor variability. Fingerprints are a novel and noninvasive approach to monitor INH therapy. Metabolites can be used as internal markers to demonstrate a sufficient sample volume for testing and reduce intradonor variability.

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