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PubMed1977

Rapid biochemical tests for characterization of the Mycoplasmatales.

Methods are described for the rapid detection of beta-D-glucosidase and phosphatase in mycoplasma cultures using fluorogenic 4-methylumbelliferone substrates. These methods were applied to a selection of mycoplasma cultures and were compared with the conventionally used tests for these enzymes. Results were similar by both methods, but the fluorogenic tests could be read after 1 h, whereas the conventional tests took several days.

Acholeplasma↗
PubMed1979

[Studies of bovine Mycoplasma mastitis. 3. Testing of biochemical properties of Mycoplasma strains isolated from 3 stocks].

Thirty-two isolates of altered milk samples taken from cows with mastitis on three industrialised dairy cattle units were biochemically tested following five passes through no-inhibitor media, assessment of filtratability through 450-nm-membrane filter, and clone assay. Something between five and ten clones of each of the strains involved were tested for their growth properties both at 22 degrees C and in no-serum media, sensitivity to digitonin and capability of aesculin hydrolysis. TTC reduction (triphenyltetrazolium-chloride), as well as for decomposition of glucose, arginine, and urea. The properties found were characteristic of M. bovis, A. laidlawii, and A. axanthum, and of the family of mycoplasmataceaea in the strains of one of the stocks.

Animals↗
PubMed1975

Reproducibility of the analytab (API 20E) system.

The reproducibility of the Analytab (API 20E) system for identification of Enterobacteriaceae was evaluated with 110 clinical isolates. Each isolate was identified by two technologists at different times. Genus-species identification was 97.3% reproducible; however, only 55.5% of the strains gave identical reactions in all 20 of the API 20E biochemical tests on repeat testing. Of those strains which varied, 56% possessed only one variable biochemical test. The reproducibility for each biochemical test was calculated and ranged from 89 to 100%. A subset of 20 of the most variable strains was tested further under conditions of varying incubation time (15 and 22 h) and inoculum concentration (10(7), 10(5), and 10(3) colony-forming units per ml), and by having four technologists interpret the test results. The reproducibility for each biochemical test for these 20 variable strains ranged from 86 to 99%. Less variation in interpretation by technologists was seen at an incubation time of 22 h and an inoculum concentration of 10(7) colony-forming units per ml. Consideration of the reproducibility for each biochemical test can aid in determining the probability that two isolates suspected of being the same strain, but with API profiles which differ by one or more biochemical test results, are in fact the same strain. Variables such as inoculum size, incubation time, technologist interpretation, and strip variability affect the API test results and should be standardized to minimize their effects.

Bacteriological Techniques↗
PubMed2026

Metagenomic next-generation sequencing of cerebrospinal fluid reveals pathogen spectrum and mortality predictors among patients with advanced HIV-1 disease at a tertiary hospital in China.

BACKGROUND: Central nervous system (CNS) infections remain the major causes of morbidity and mortality among people living with HIV-1 (PLWH), particularly in resource-limited settings. However, the clinical characteristics and prognostic indicators of PLWH with suspected CNS infections are not well defined. In this study, we aim to characterize the spectrum of CNS pathogens, clinical characteristics, in-hospital mortality, and factors associated with death among people with advanced HIV-1 disease (AHD) in Guangxi, China. METHODS: Metagenomic next-generation sequencing (mNGS) was performed to analyze types of infection in cerebrospinal fluid (CSF) from 61 treatment-naive PLWH with suspected CNS infections. Clinical data, routine laboratory tests, and biochemical tests were collected and analyzed. RESULTS: Among the 61 CSF samples, primarily with AHD, a total of 206 pathogens were identified. Viral pathogens predominated, with Epstein-Barr virus being the most frequently identified, followed by cytomegalovirus. Compared with patients with single-pathogen infection, those with multiple infections (viral, bacterial, and fungal) exhibited significantly lower CD4 T cell counts, higher C-reactive protein levels, and markedly reduced lipid metabolism parameters. However, infection types were not significantly associated with in-hospital death. Multivariate logistic regression analysis identified plasma low density lipoprotein (LDL) and CSF lactate dehydrogenase (LDH) as independent predictors of in-hospital death. CONCLUSION: In PLWH with AHD and suspected CNS infections, multiple pathogens frequently coexist in the CSF. Plasma LDL and CSF LDH levels were independent predictors of death, indicating their potential value as early risk stratification in AHD.

Humans↗
PubMed1977

Comparison of enteric identification systems.

An evaluation of methods for identification of Enterobacteriaceae was made employing the new commercial Micro-Media Enteric System (MMES) with that of the Analytab Products Incorporated (API) and the Conventional tube media schema as suggested by the Center for Disease Control (CDS). The MMES system employed 20 biochemical tests, the API 21, and the CDC procedure 25. Sixteen of these were identical biochemical tests. Two hundred clinical isolates of Enterobacteriaceae were tested employing procedures recommended by the manufacturers of MMES and API, and methods suggested by CDC. Among the sixteen identical biochemical tests the agreement was 98.0% (Conventional), 98.2% (API), and 97.98% (MMES). Bacteria misidentified by the API system totaled 5 (2.5%), 12 (6%) for the Conventional, and 13 (6.5%) for the MMES. Five of the bacteria misidentified with the MMES procedure were due to false positive citrate tests. This problem was subsequently eliminated. The results of this study indicated that the new MMES method for identification of Enterobacteriaceae compared favorably with both the API and Conventional procedures. However, significant advantages of the MMES method were evident in initial purchase price, utilization of technology time, and less tedium performing the test.

Bacteriological Techniques↗