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The aim of this study was to clinically validate a heminested polymerase chain reaction (PCR) method, based on the IS6110 insertion segment of Mycobacterium tuberculosis complex, for the diagnosis of tuberculosis. Samples of pulmonary, extrapulmonary and blood origin were collected prospectively from 331 patients. All samples were processed to detect acid-fast bacilli by direct stain, culture and PCR. The gold standard comparison was a clinically based final case definition of tuberculosis corresponding to group 3 of the American Thoracic Society's classification system. The sensitivities of stain, culture and PCR were 41%, 65% and 59%, respectively. Overall specificity exceeded 97% for all techniques. The combination of PCR and direct stain achieved a sensitivity similar to that of culture alone. The PCR method detected 74 of 95 (78%) culture-positive results. In a hospital setting, PCR could be a useful, reliable tool for diagnosis of tuberculosis and may be introduced as a complementary routine diagnostic laboratory method.

A prospective analysis of 43 episodes of Pseudomonas aeruginosa bacteremia in HIV-1-infected subjects was performed and the results compared with the incidence and outcome of Pseudomonas aeruginosa bacteremia in other high-risk patients, such as transplant recipients, leukemia patients, or patients hospitalized in the intensive care unit. The incidence of bacteremia/fungemia as a whole and of gram-negative and Pseudomonas aeruginosa bacteremia in particular was greater in HIV-1-infected subjects than in the unselected general population admitted. In contrast, the incidence of Pseudomonas aeruginosa bacteremia in HIV-1-infected patients did not differ from that in patients with other high-risk conditions. In patients with HIV-1 infection, independent risk factors for presenting Pseudomonas aeruginosa bacteremia were nosocomial origin (OR, 2.7; 95% CI, 1.3-5.7), neutropenia (OR, 2.7; 95% CI, 1.07-6.8), previous treatment with cephalosporins (OR, 3.6; 95% CI, 1.1-11.6), and a CD4+ cell count lower than 50 cells/mm3 (OR, 3.1; 95% CI, 1.7-8.6). Primary bacteremia and pneumonia were the most common forms of presentation. Fourteen (33%) patients died as a consequence of the bacteremia. The presence of severe sepsis (OR, 17.5; 95% CI, 3.2-68) and the institution of inappropriate definitive antibiotic therapy (OR, 2.7; 95% CI, 1.1-13) were independently associated with a poor outcome. One year after the development of bacteremia, only eight (19%) patients remained alive.

The aim of this study was to assess the feasibility of a method for presumptive identification of mycobacteria, based on the morphology in smears prepared from radiometric Bactec-positive cultures (Becton Dickinson, USA) and to select the appropriate DNA probe (AccuProbe; Gen Probe, USA). The smear morphology of acid-fast bacilli was evaluated in 468 positive cultures from clinical samples: 313 Mycobacterium tuberculosis complex, 67 Mycobacterium avium complex, 32 Mycobacterium kansasii, 49 Mycobacterium xenopi, and seven Mycobacterium gordonae. The sensitivity and specificity for various morphological patterns were as follows: cord formation for Mycobacterium tuberculosis complex 90% and 100%, respectively; striped bacilli for Mycobacterium kansasii, 66% and 99%; sea urchin for Mycobacterium xenopi, 96% and 99%; short bacilli for Mycobacterium avium complex, 61% and 99%; fine-striped bacilli associated with Mycobacterium avium complex from blood samples, 33% and 98%. This criterion was applied in the selection of a suitable DNA probe for the identification of 178 cultures. The correct probe was selected in 98%, 97%, and 72% of cultures, respectively, for Mycobacterium tuberculosis complex, Mycobacterium avium complex, and Mycobacterium kansasii. The observation of acid-fast bacilli morphology in radiometric cultures is a rapid and cost-efficient method for presumptive identification of common clinical isolates of mycobacteria.

The value of determining D-lactate concentrations in body fluids for the rapid diagnosis of bacterial infections was investigated. A total of 336 body fluid samples were analyzed: 208 ascitic fluids, 57 synovial fluids, 40 cerebrospinal fluids and 32 pleural fluids. Using a cut-off value of 0.05 mM, the overall sensitivity was 0.96 and the specificity was 0.88. Therefore, the measurement of D-lactate concentration in body fluids offers a rapid (2-hour) and useful method of differentiating between infectious and non-infectious body fluid diseases.

Beta-glucuronidase and phenylalanine deaminase tests for screening urine specimens to provide rapid reporting (2 hours) of Escherichia coli and Proteeae species were evaluated. A total of 2,318 urine specimens were processed for these two tests. For the detection of Escherichia coli in urine, the sensitivity and specificity of the beta-glucuronidase test were 0.96 and 0.99 respectively; predictive positive and negative values were 0.97 and 0.99. For the detection of Proteeae in urine, the sensitivity and specificity of the phenylalanine test were 0.92 and 0.99. Predictive values were 0.99 for a negative test and 0.95 for a positive test. The data suggest that beta-glucuronidase and phenylalanine deaminase tests performed directly in urine sediment have potential usefulness as rapid and reliable tests that are easy to perform and interpret for the diagnosis of urinary tract infections caused by Escherichia coli or Proteeae species.