Portal cytokine response and metabolic markers in the early stages of abdominal sepsis in pigs.

BACKGROUND: The portal vein could play a major role in disseminating the local inflammation of acute bacterial peritonitis since it is responsible for the venous drainage of the gastrointestinal tract. We hypothesized that after peritoneal exposure to Escherichia coli, a gradient between the portal and systemic levels of cytokines would be expected. METHODS: Acute peritonitis was induced by depositing 200 ml of broth with live E. coli in the peritoneal cavity of the animals in the B-group (n = 7). They were then observed for 4 h and compared with a control group (C-group, n = 7). Tumour necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-10 and vascular endothelial growth factor were measured repeatedly in the portal vein and the femoral artery. Portal vein metabolic markers (microdialysis), haemodynamics, biochemistry, plasma volume (PV), fluid shifts and total tissue water content were recorded or calculated. RESULTS: The intervention led to PV contraction, increased fluid extravasation, increased pulmonary vascular resistance and reduced urinary output in the B-group as compared with the C-group. The levels of glucose in the portal vein were reduced in both study groups with no between-group differences. The levels of TNF-α and IL-6 increased markedly in the portal vein as well as in the systemic circulation of the B-group, but no gradient was seen between them. The corresponding levels of TNF-α and IL-6 remained low and stable in the C-group. CONCLUSION: The portal vein appears to play a minor role in supplying TNF-α and IL-6 to the systemic circulation after peritoneal exposure to a substantial dose of E. coli.

Direct detection of mycobacterial species in pulmonary specimens by two rapid amplification tests, the gen-probe amplified mycobacterium tuberculosis direct test and the genotype mycobacteria direct test.

Nucleic acid amplification tests have improved tuberculosis diagnostics considerably. This study evaluates a new amplification test, the GenoType Mycobacteria Direct (GTMD) test, for detection of the Mycobacterium tuberculosis complex, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium kansasii, and Mycobacterium malmoense directly in 61 sputum samples. Thirty (49.2%) samples were auramine smear positive, and 31 (50.8%) were smear negative. The GTMD results were compared to the Gen-Probe Amplified M. tuberculosis Direct (MTD) test results, using culturing and sequencing of the 16S rRNA gene as reference methods. The GTMD test could identify 28 of 29 samples containing the M. tuberculosis complex and was negative in a sputum sample containing M. intracellulare. The overall sensitivity and specificity results were 93.3% and 90.0% for the GTMD test, respectively, and 93.1% and 93.5% for the MTD test, respectively. The GTMD test is rapid and can be easily included in routine clinical laboratories for the direct detection of the M. tuberculosis complex in smear-positive sputum samples as an adjunct to microscopy and culture. Further studies are needed to evaluate the performance of the GTMD test for the detection of atypical mycobacteria.

Evaluation of the nitrate-based colorimetric method for testing the susceptibility of Mycobacterium tuberculosis to streptomycin and ethambutol in liquid cultures.

OBJECTIVES: To evaluate the inexpensive colorimetric nitrate reductase-based antibiotic susceptibility (CONRAS) assay for testing the susceptibility of Mycobacterium tuberculosis to streptomycin and ethambutol in liquid cultures, and to compare the CONRAS test with the manual mycobacteria growth indicator tube (MGIT) test, using the radiometric BACTEC 460TB method as reference. METHODS: A total of 89 M. tuberculosis isolates were tested for susceptibility to streptomycin and ethambutol using the CONRAS and manual MGIT methods and the results were compared with BACTEC 460TB. Isolates with discrepant results between the CONRAS test and BACTEC 460TB were analysed using the agar proportion method, Etest and mutation analysis of genes involved in resistance to streptomycin and ethambutol. RESULTS: The agreement between the CONRAS test and BACTEC 460TB was 88% for streptomycin and 84% for ethambutol. The corresponding agreement of the manual MGIT test with BACTEC 460TB was 89 and 80%, respectively. There was good agreement for streptomycin and moderate agreement for ethambutol between the CONRAS and manual MGIT tests on one hand and BACTEC 460TB on the other (CONRAS test, kappa(streptomycin) 0.74 and kappa(ethambutol) 0.59, P < 0.001; manual MGIT test, kappa(streptomycin) 0.77 and kappa(ethambutol) 0.50, P < 0.001). CONCLUSIONS: There is good agreement for the two non-radiometric liquid culture methods (CONRAS and manual MGIT) compared with BACTEC 460TB for the detection of streptomycin resistance. Further standardization is needed for testing of ethambutol resistance using the CONRAS and manual MGIT assays.

Rapid colorimetric method for testing susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin in liquid cultures.

We have developed a rapid colorimetric method for testing the susceptibility of M. tuberculosis to isoniazid (INH) and rifampin (RIF) based on incorporation of nitrate in broth cultures containing growth supplements. The performance of this colorimetric nitrate reductase-based antibiotic susceptibility (CONRAS) test was compared with that of the radiometric BACTEC 460TB system in determining the susceptibilities of 74 M. tuberculosis strains to INH and RIF. By using the BACTEC 460TB system as the "gold standard," the sensitivity (i.e., the ability to detect true drug resistance) and specificity (i.e., the ability to detect true drug susceptibility) of the CONRAS test were 100 and 95% for INH and 94 and 100% for RIF, respectively. The repeatability of the CONRAS test was excellent (for INH, kappa = 1 and P < 0.001; for RIF, kappa = 0.88 and P < 0.001). For the majority of strains, results were obtained within 5 days. The CONRAS test is rapid, accurate, and inexpensive and is an adequate alternative, particularly for resource-poor countries.