The aim was to evaluate 16S rDNA sequencing in heart valves in patients with infective endocarditis undergoing surgery.
Fifty-seven patients with infective endocarditis were examined in this prospective study by analysing heart valves with 16S rDNA sequencing and culturing methods and comparing the results to blood cultures. As controls, heart valves from 61 patients without any signs of endocarditis were examined.
All together 77% of the endocarditis patients were positive for 16S rDNA, 84% had positive blood cultures and 23% had positive cultures from heart valves, whereas only 16% of the cultures from heart valves were concordant with results from blood cultures or 16S rDNA. Concordant results between 16S rDNA sequencing and blood cultures were found in 75% patients. All controls were negative for 16S rDNA. In 4 out of 9 patients with negative blood cultures, the aetiology was established by 16S rDNA alone, i.e. viridans group streptococci.
In this Swedish study, 16S rDNA sequencing of valve material was shown to be a valuable addition in blood culture-negative cases. The value of heart valve culture was low. Molecular diagnosis using 16S rDNA sequencing should be recommended in patients undergoing valve replacement for infective endocarditis.
Results of a comparative study of growth properties of elaborated nutrient medium VLACON and traditional Lovenshtein-Jensen medium are presented in the paper. It is established, that the rate of mycobacterium growth on VLACON medium is 10-20 times higher than on the traditional nutrient medium. Mycobacteria preserve their tinctorial, cultural and pathogenic properties during the cultivation on VLACON medium. Besides, the possibility of use of agglutination reaction with further coloring and microscopy of agglutinates for the accelerated differentiation of human and bull mycobacterium species from the bird species and atypical mycobacteria is shown.
National Mycobacterium Reference Laboratory, Institute of Cell and Molecular Sciences, Queen Mary College, Barts and the London School of Medicine, University of London, London, United Kingdom. email@example.com
To analyse the feasibility, cost and performance of rapid tuberculosis (TB) molecular and culture systems, in a high multidrug-resistant TB (MDR TB) middle-income region (Samara, Russia) and provide evidence for WHO policy change.
Performance and cost evaluation was conducted to compare the BACTEC MGIT 960 system for culture and drug susceptibility testing (DST) and molecular systems for TB diagnosis, resistance to isoniazid and rifampin, and MDR TB identification compared to conventional Lowenstein-Jensen culture assays.
698 consecutive patients (2487 sputum samples) with risk factors for drug-resistant tuberculosis were recruited. Overall M. tuberculosis complex culture positivity rates were 31.6% (787/2487) in MGIT and 27.1% (675/2487) in LJ (90.5% and 83.2% for smear-positive specimens). In total, 809 cultures of M. tuberculosis complex were isolated by any method. Median time to detection was 14 days for MGIT and 36 days for LJ (10 and 33 days for smear positive specimens) and indirect DST in MGIT took 9 days compared to 21 days on LJ. There was good concordance between DST on LJ and MGIT (96.8% for rifampin and 95.6% for isoniazid). Both molecular hybridization assay results correlated well with MGIT DST results, although molecular assays generally yielded higher rates of resistance (by approximately 3% for both isoniazid and rifampin).
With effective planning and logistics, the MGIT 960 and molecular based methodologies can be successfully introduced into a reference laboratory setting in a middle incidence country. High rates of MDR TB in the Russian Federation make the introduction of such assays particularly useful.
The placement of cadavers in shallow, clandestine graves may alter the microbial and geochemical composition of the underlying and adjacent soils. Using amplicon length heterogeneity-PCR (LH-PCR) the microbial community changes in these soils can be assessed. In this investigation, nine different grave sites were examined over a period of 16weeks. The results indicated that measurable changes occurred in the soil bacterial community during the decomposition process. In this study, amplicons corresponding to anaerobic bacteria, not indigenous to the soil, were shown to produce differences between grave sites and control soils. Among the bacteria linked to these amplicons are those that are most often part of the commensal flora of the intestines, mouth and skin. In addition, over the 16week sampling interval, the level of indicator organisms (i.e., nitrogen fixing bacteria) dropped as the body decomposed and after four weeks of environmental exposure they began to increase again; thus differences in the abundance of nitrogen fixing bacteria were also found to contribute to the variation between controls and grave soils. These results were verified using primers that specifically targeted the nifH gene coding for nitrogenase reductase. LH-PCR provides a fast, robust and reproducible method to measure microbial changes in soil and could be used to determine potential cadaveric contact in a given area. The results obtained with this method could ultimately provide leads to investigators in criminal or missing person scenarios and allow for further analysis using human specific DNA assays to establish the identity of the buried body.
Urinary tract infections (UTI) account for 2-5% of consultations in general practice, but only about half the patients with dysuria have significant bacteriuria (> 100,000 bacteria per ml). A microbiological diagnosis can be made by examination of a urine sample, and in Danish family practice the diagnosis of UTI is often reached by a microscopic analysis or a dip-slide culture test. These methods have a high validity when performed in hospital, but we need knowledge about the validity of microbiological urine examinations when performed in general practice. The aim of this study was to validate detection of bacteriuria by urine microscopy and dip-slide culture in general practice.
Urine specimens artificially produced by adding a known quantity of bacteria (Escherichia coli, Proteus mirabilis, Enterobacter cloacae, Staphylococcus epidermidis and Enterococcus faecalis) to sterile urine were sent to 25 general practices for microscopic examination and dip-slide culture. No prior instruction in testing procedure was given. As the gold standard, the results of a standardised culture method performed by skilled laboratory technicians at the Department of Microbiology, University of Southern Denmark, were used.
Significant bacteriuria was identified by microscopy with a sensitivity of 95% and a specificity of 83%. The corresponding figures for urine culture were 95% and 96%. The morphology of bacteria was interpreted correctly in 80% of microscopic examinations, and 60% of the bacteria strains were classified correctly in terms of their motility.
The results of urine microscopy and culture performed in general practice are to be relied on.
Comment In: Ugeskr Laeger. 2002 May 27;164(22):2930-112082826
Comment In: Ugeskr Laeger. 2002 May 27;164(22):2931-2; author reply 293212082827
The used methodology of the scientific substantiation of indicators is in the establishment of the conformity of laws of vital activity of indicator and pathogenic microorganisms in the real conditions of the action of the complex of factors, including disinfecting agents. In the one water sample simultaneously there were determined both the general indicator (GICB), thermotolerant (TTCB), glucose positive (GPCB) coliform bacteria, E.coli. On the base of long-term research in the various regions of the Russian Federation, as well with bearing in mind the analysis of domestic and foreign data, comparing the water quality and the incidence of intestinal infections in population it is recommended to use the index of determination of the total number glucose positive coliform bacteria (GPCB), which brings together a much broader range of bacteria of the Enterobacteriaceae family in comparison with total coliform bacteria (TCB) and thermotolerant coliform bacteria (TTCB) and warrants the absence in the test volume of water as an indicator lactose positive (E.coli, TCB, TTCB) and pathogens (salmonella) and potentially pathogenic bacteria which do not ferment lactose. Proposed index of GPCB is shown to allow to assess epidemiological risks not only more accurate, but also more efficiently without increasing the cost performance of bacteriological research.
An increasing number of non-O157 Shiga toxin-producing Escherichia coli (STEC) infections and outbreaks have been reported. In this study, we evaluated the performance of ImmunoCard STAT!(®) (Meridian Bioscience, Inc., Cincinnati, OH, USA) as a method to screen stool specimens for STEC (O157 and non-O157). An in-house real-time PCR method was used as the "gold standard". We also evaluated the prevalence and clinical characteristics of STEC infections in the Alberta South West Zone. From July to November 2011, 819 stool specimens submitted for routine stool culture were tested. With our in-house real-time PCR, 7 O157:H7 and 10 non-O157 STEC isolates were identified for a total of 17 STECs. In comparison, ImmunoCard STAT!(®) identified a total of 6, resulting in a sensitivity and specificity of 35% and 99%, respectively (P
The degree to which the results of valve culture depend on different laboratory procedures as well as other factors is unknown. The aim of this study was to compare the results of heart valve culture at 2 different endocarditis centres in order to clarify this.
The study included 223 patients with definitive endocarditis undergoing heart valve surgery at 2 Danish endocarditis centres (96 at the East centre and 127 at the West centre). The following data related to the samples were registered: transportation, time to inoculation, culture media used and duration of incubation, species distribution, and preoperative duration of appropriate antimicrobial treatment (DAAT). 16S polymerase chain reaction (PCR) of valve tissue was used to estimate the frequency of non-cultivable bacteria.
Valve culture was positive in 12.5% of cases at the East centre and 36.2% at the West centre (p
In an analytical-method comparison study of clinical samples, the Abbott RealTime CT new formulation assay (m2000 real-time PCR), consisting of a duplex PCR targeting different parts of the cryptic plasmid in Chlamydia trachomatis, was compared both with version 2 of the Roche Cobas TaqMan CT assay, comprising a duplex PCR for a target in the cryptic plasmid and the omp1 gene, and with the Gen-Probe Aptima Combo 2 assay (AC2) targeting the C. trachomatis 23S rRNA molecule. First-catch urine samples from Sweden were tested in Malmö, Sweden, for C. trachomatis with the m2000 real-time PCR assay and with an in-house PCR for the new variant C. trachomatis strain with a deletion in the cryptic plasmid. Aliquots of the urine samples were sent to Aarhus, Denmark, where they were further examined with the TaqMan CT and AC2 assays. A positive prevalence of 9.1% (148/1,632 urine samples examined) was detected according to the combined reference standard. The sensitivities and specificities of the three assays were as follows: for the Abbott m2000 assay, 95.3% (141/148) and 99.9% (1,483/1,485), respectively; for the Roche TaqMan assay, 82.4% (122/148) and 100.0% (1,485/1,485); and for the Gen-Probe AC2 assay, 99.3% (147/148) and 99.9% (1,484/1,485). The plasmid mutant strain was detected in 24% (36/148) of the C. trachomatis-positive samples. There is a difference in sensitivity between the new formulations of the Abbott and the Roche assays, but both assays detected the wild-type and new variant C. trachomatis strains equally well.
Cites: Euro Surveill. 2006;11(11):E061109.217213548
Cites: Euro Surveill. 2006;11(12):E061207.117213562
Cites: Sex Transm Infect. 2009 Jun;85(3):190-319060034
To establish the causes of bacterial excretion in complicated primary tuberculosis in children and adolescents, by comparing the data of computed tomography and the results of bacteriological studies.
The material of the study was data on 36 children and adolescents with complicated primary tuberculosis, including 14 and 22 children and adolescents with and without bacterial excretion, respectively. All the children and adolescents underwent computed tomography and bacteriological studies encompassing luminescence microscopy and sputum and bronchial and gastric wash cultures for Mycobacterium tuberculosis.
The bacterial excretion group showed a preponderance of a tuberculous process concurrent with the involvement of lung tissue and intrathoracic lymph nodes. Bacterial excretion was detected in the primary tuberculosis complex (50%), generalized tuberculosis process with the involvement of a few organs and systems (14.3%), and caseous pneumonia (7.1%). Bacterial excretion was accompanied by the tuberculous involvement of intrathoracic lymph nodes in 28.6%. In Group 1, sputum cultures and luminescence microscopy were carried out in all the children. At the same time, the most effective result was yielded by sputum culture that showed Mycobacterium tuberculosis in 78.6%; luminescence microscopy revealed mycobacteria in only 35.7% of cases. In 72.7% of the children and adolescents without bacterial excretion, the tuberculous process was located in the intrathoracic lymph nodes, without involving lung tissue in the pathological process. In the other 27.3%, the computed tomographic pattern of changes corresponded to that of the primary tuberculosis complex; in their presence, the tuberculous process ran with lymphogenic dissemination in 54.5% of cases and with bronchopulmonary involvement in 22.7%. In Group 2, a sputum culture was done in only 36.4% of the children and adolescents; microscopy was carried out in all.
When computed tomography reveals the disseminated forms of primary tuberculosis with the concomitant involvement of lung tissue and intrathoracic lymph nodes in the presence of lung destructive changes, with the involvement of a few organs and systems in the pathological process, it is necessary to use all bacteriological studies, including culnolecular genetic methods, in order to establish the etiology of existing changes.