Bioluminescence screening for bacteriuria

Comparation of the effectiveness of conventional needle irrigation and photon-induced photoacoustic streaming with sodium hypochorite in the treatment of teeth with apical periodontitis: a randomized clinical trial

Photon-initiated photoacoustic streaming (PIPS) with an Er: YAG laser has been introduced in root canal treatment to improve irrigation and facilitate the removal of bacteria in the root canal system. This study aimed to compare the antibacterial effectiveness of two different root canal irrigation techniques, conventional needle irrigation (CNI) and PIPS, using 1% sodium hypochlorite (NaOCl), in the treatment of teeth with apical periodontitis. Sixty patients with a total of sixty teeth affected by apical periodontitis were included in this study. The teeth underwent root canal therapy, and after mechanical instrumentation, they were randomly assigned to two groups (n = 30) based on the final irrigation protocol: CNI or PIPS with 1% NaOCl. Bacterial suspensions in the root canals were evaluated using Adenosine 5'-triphosphate (ATP) assay kit after mechanical instrumentation and after final irrigation. Then, a follow-up was conducted after 7 days. The results revealed that final irrigation significantly reduced ATP values in both the CNI and PIPS groups (P < 0.001). The ATP values after final irrigation was greater in the CNI group compared to the PIPS group (P < 0.001). After a 7-day follow-up, percussion tenderness and fistula were significantly resolved in both groups (P < 0.05). A multivariate linear regression model was used to identify the factors that influence post irrigation ATP values. The analysis demonstrated that pre-operative percussion tenderness (P = 0.006), the presence of a fistula (P < 0.001) and the method used in the final irrigation (P < 0.001) had a significant impact on the ATP value after final irrigation. These results indicate that employing PIPS with 1% NaOCl as the final irrigation protocol exhibited superior antibacterial effectiveness and has the potential to enhance clinical outcomes in the treatment of teeth afflicted with apical periodontitis.

An Intact Cell Bioluminescence-Based Assay for the Simple and Rapid Diagnosis of Urinary Tract Infection

Urinary tract infection (UTI) is one of the most common infections, accounting for a substantial portion of outpatient hospital and clinic visits. Standard diagnosis of UTI by culture and sensitivity can take at least 48 h, and improper diagnosis can lead to an increase in antibiotic resistance following therapy. To address these shortcomings, rapid bioluminescence assays were developed and evaluated for the detection of UTI using intact, viable cells of Photobacterium mandapamensis USTCMS 1132 or previously lyophilized cells of Photobacterium leiognathi ATCC 33981™. Two platform technologies-tube bioluminescence extinction technology urine (TuBETUr) and cellphone-based UTI bioluminescence extinction technology (CUBET)-were developed and standardized using artificial urine to detect four commonly isolated UTI pathogens-namely, Escherichia coli, Proteus mirabilis, Staphylococcus aureus, and Candida albicans. Besides detection, these assays could also provide information regarding pathogen concentration/level, helping guide treatment decisions. These technologies were able to detect microbes associated with UTI at less than 105 CFU/mL, which is usually the lower cut-off limit for a positive UTI diagnosis. Among the 29 positive UTI samples yielding 105-106 CFU/mL pathogen concentrations, a total of 29 urine specimens were correctly detected by TuBETUr as UTI-positive based on an 1119 s detection window. Similarly, the rapid CUBET method was able to discriminate UTIs from normal samples with high confidence (p ≤ 0.0001), using single-pot conditions and cell phone-based monitoring. These technologies could potentially address the need for point-of-care UTI detection while reducing the possibility of antibiotic resistance associated with misdiagnosed cases of urinary tract infections, especially in low-resource environments.

Detection of urinary tract infections on lab-on-chip device by measuring photons emitted from ATP bioluminescence

A microfluidic Lab-on-chip (LOC) platform for in vitro detecting Urinary Tract Infections (UTI) for clinical diagnostic applications has been built. Based on one commercial adenosine 5'-triphosphate (ATP) assay kit, one chip designed before was applied to detect UTI with the help of photomultiplier tube (PMT) and quantitative determination was made by measuring the photons of light emitted in the bioluminescent reaction of ATP with the enzyme luciferase. The chip had been tested and materials had been well prepared before testing the PMT detecting system. The data from PMT were visualized by the Labview™, appearing good linearity between voltage values and the concentration of the ATP ranging from 2×10(-12) M to 2×10(-8) M. Fresh urine sample with different amounts of Escherichia coli had been measured by the system, appearing good linearity trend between the voltage values and number of the E.coli. This study successfully expressed the concept of measuring ATP directly in the urine to quickly and accurately detect UTI on a microfluidic chip.

Rapid antimicrobial susceptibility determination of uropathogens in clinical urine specimens by use of ATP bioluminescence

We describe the first direct testing of the antimicrobial susceptibilities of bacterial pathogens in human clinical fluid samples by the use of ATP bioluminescence. We developed an ATP bioluminescence assay that eliminates somatic sources of ATP to selectively quantify the bacterial load in clinical urine specimens with a sensitivity of <1,000 CFU per milliliter. There was a log-log relationship between light emission and the numbers of CFU in clinical urine specimens. A clinical study was performed to evaluate the accuracy of the ATP bioluminescence assay for determination of the antimicrobial susceptibilities of uropathogens in clinical urine specimens tested in a blinded manner. ATP bioluminescent bacterial density quantitation was used to determine the inoculation volume in growth medium with and without antibiotics. After incubation at 37 degrees C for 120 min, the ATP bioluminescence assay was repeated to evaluate the uropathogen response to antibiotics. The ability of the ATP bioluminescence assay to discriminate between antimicrobial susceptibility and resistance was determined by comparison of the results obtained by the ATP bioluminescence assay with the results obtained by standard clinical microbiology methods. Receiver operator characteristic curves were used to determine the optimal threshold for discriminating between susceptibility and resistance. Susceptibility and resistance were correctly predicted in 87% and 95% of cases, respectively, for an overall unweighted accuracy of 91%, when the results were stratified by antibiotic. For samples in which the pathogen was susceptible, the accuracy improved to 95% when the results for samples with less than a 25-fold increase in the amount of bacterial ATP in the medium without antibiotics were excluded. These data indicate that a rapid bioluminescent antimicrobial susceptibility assay may be useful for the management of urinary tract infections.

Selective expression of carcinoembryonic antigen promoter in cancer cell lines: targeting strategy for gene therapy in colorectal cancer

PURPOSE

This study was designed to characterize the mechanisms regulating the expression of the human carcinoembryonic antigen promoter (pCEA), in terms of tissue-specific targeting for gene therapy. The promoter was subcloned to a luciferase reporter gene (pCEA/Luc) in our laboratory and compared with a virally controlled luciferase vector (pSV40/Luc).

METHODS

Four human cancer cell lines (HeLa, SW480, Caco2, and SW1116) were transfected with either pCEA/Luc or pSV40/Luc. Cells were treated with interferon-gamma and assayed at 72 hours after treatment. Carcinoembryonic antigen level was measured by enzyme immunoassay. Luciferase expression was measured at 48 hours and one week after transfection by luminometry.

RESULTS

Luciferase activity after transfection with pCEA/Luc was higher in CEA-positive cells than in CEA-negative cells (P < 0.0001). pCEA/Luc demonstrated higher activity than pSV40/Luc in CEA-positive cells (P < 0.0001), but not in CEA-negative cells. In Caco2 cells, which before confluence are CEA-negative, luciferase expression increased on reaching confluence (P < 0.0001). Well to moderately differentiated cells responded to the interferon-gamma treatment, but the increase in CEA secretion did not correspond to an increase in pCEA/Luc expression.

CONCLUSIONS

The expression of pCEA correlates well with the CEA production by the specific cell line offering a potential tissue-specific targeting strategy for colon cancer gene therapy. Furthermore, the tissue-specific CEA promoter has a higher and more persistent activity in CEA-positive human cancer cells than a viral promoter. The lack of response to interferon-gamma treatment suggests a different mechanism of action for interferon-gamma other than directly interacting with the promoter.

Simplified technique for detection of significant bacteriuria by microscopic examination of urine

A comparative study of microscopic examination of 10 microl (simplified loop technique) and 50 microl (traditional drop technique) of uncentrifuged Gram-stained urine specimens for detection of significant bacteriuria was carried out. The results demonstrated that the 10-microl loop technique can be used as an alternative to the 50-microl drop technique for presumptive diagnosis of urinary-tract infection in bacteriological practice, with the advantages of greater rapidity and ease of performance.

Treatment of urinary tract infection. Clinical and economic considerations

The epidemiology, clinical manifestations, natural history and management of urinary tract infection (UTI) are briefly reviewed as background to the economic considerations of diagnosis and treatment. Specific pharmacoeconomic analyses, such as cost-effectiveness and cost-benefit analyses, of UTI are not available. Analysis of the direct costs of diagnosis and treatment reveal that laboratory costs comprise the largest proportion, followed by physician consultation and pharmaceutical costs, respectively. Antimicrobial treatment has focused on acquisition cost without due regard to costs associated with method of delivery (especially with parenteral therapy), drug monitoring, complications, suboptimal therapy, drug wastage and waste disposal. These factors indicate a preference for ambulatory therapy using oral antimicrobials rather than institutional care using parenteral agents. Indirect costs, such as lost work time and quality-of-life factors, are not readily available. Evidence suggests that nosocomial UTIs add significantly to hospital costs. Studies citing the cost effectiveness of infection control programmes have often lacked detail and may have accrued benefits to the service without apportioning full costs. Future research directions include analysis of laboratory economics in relation to the clinical encounter, improved analysis of the utility and total costs of newer antimicrobials, quantifying home versus hospital treatment and improved costing of infection control programmes.

Reliability of a bioluminescence ATP assay for detection of bacteria

The reliability of bioluminescence assays which employ the luciferin-luciferase ATP-dependent reaction to evaluate bacterial counts was studied, both in vitro and on urine specimens. Bioluminescence and cultural results for the most common urinary tract pathogens were analyzed. Furthermore, the influence of the culture medium, of the assaying method, and of the phase of growth on bioluminescence readings was studied. Results show that Proteus, Providencia, and Morganella strains are not correctly detected, neither in vitro nor in urine samples, by the standard assaying method. The analysis of assaying parameters demonstrated that some modifications to the extraction procedure of bacterial ATP could improve the reliability of this technique.

Rapid screening for bacteriuria in pregnancy

We evaluated a bioluminescence assay as a screening test for the detection of bacteriuria in pregnancy. A total of 1,000 urine specimens from a randomly selected group of pregnant women undergoing prenatal surveillance was investigated. Sequential dilution of urine specimens on CLED agar plates served as a reference method. Set against the reference group, bioluminescence screening scored a 93% sensitivity, a 78% specificity and a 99% predictive accuracy for negative results. All urine specimens were also analysed chemically for the presence of nitrite and leucocyte esterase by dip sticks. Dip sticks proved to be insufficient because of poor sensitivities of 54% and 59%, respectively. The bioluminescence assay is an effective, time- as well as labor-saving but questionably cost-effective method for the detection of bacteriuria in pregnancy.

Laboratory in the diagnosis and management of urinary tract infections

The laboratory is essential in the diagnosis and management of UTIs. The presence of pyuria and bacteriuria, the two most important indicators of UTIs, are most accurately determined by standard techniques. In quantitating pyuria, the finding of greater than or equal to 10 leukocytes/mm3 of urine by either hemocytometry or direct microscopy correlates highly with symptomatic, culture-proven UTIs. The determination of bacteriuria by direct microscopy is inaccurate, particularly at lower levels of bacteriuria; thus, quantitative urine cultures remain the most accurate measure of bacteriuria. Significant bacteriuria, previously defined as greater than or equal to 10(5) CFU/ml of urine, has been redefined with the observation that as few as 10(2) CFU/ml can be associated with significant pyuria and symptoms suggestive of cystitis. The need for routine and posttreatment urine cultures in nonpregnant women with acute dysuria remains controversial, but current data suggest that they are usually unnecessary. Rapid diagnostic tests for detection of pyuria and bacteriuria are designed to increase efficiency and decrease cost in the diagnosis of UTI. Unfortunately, none of these techniques can quantitate pyuria or bacteriuria as accurately as the standard methods, but the level of accuracy offered by the standard methods is not always necessary in the care of patients with uncomplicated UTIs. These tests are particularly well suited for screening asymptomatic high-risk populations. Noninvasive localization techniques continue to be explored as possible alternatives to invasive localization procedures, but they remain largely research tools that are not readily available to the practicing clinician. Understanding the applicability and appropriate use of newer technologies in the evaluation of patients with UTIs and how these technologies complement the standard diagnostic techniques will lead to better, more efficient, and less costly patient care.

Urinary tract infection: economic considerations

Urinary tract infection results in significant morbidity and mortality while consuming large amounts of national resources. The prevention, diagnosis, and treatment of urinary tract infection produce both costs and benefits, and economic analysis provides a rational framework for looking at these effects. The goals and methods of economic analysis in medicine are summarized, and strategies to address uncomplicated cystitis, nosocomial urinary tract infection, and pyelonephritis are reviewed, with an emphasis on the economic trade-offs faced by decision makers.

Clinical relevance of culture versus screens for the detection of microbial pathogens in urine specimens

The use of screens to detect "significant levels" of pathogenic microorganisms in urine specimens offers the advantages of both rapidly reporting results and controlling costs. Many of these screens, however, are insensitive at microbial counts below 10(5) colony-forming units (CFU)/ml of urine. It is increasingly apparent that patients with almost any type of urinary tract infection (except for most patients who are asymptomatic or who have pyelonephritis) may have urine concentrations of pathogens as low as 10(2) to 10(3) CFU/ml. This review documents factors that can contribute to diminished concentrations of microorganisms in urine, lists patient populations in whose urine microorganisms in concentrations well below 10(5) CFU/ml have been associated with infection, and makes recommendations for selection of laboratory tests, including rapid screens, for the diagnosis and management of urinary tract infections.

Automated bacteriuria screening using the Berthold LB 950 luminescence analyser

The Berthold LB950 Automatic Luminescence Analyser was used to estimate bacterial adenosine triphosphate in urine. The system provided a rapid (15 min) and fully automated screening test for bacteriuria at the 10(5) CFU/ml level. Bioluminescence results for 1040 urines were compared with viable counts using two reference culture methods and frequency distributions of bacterial counts and adenosine triphosphate levels were calculated. With a specificity of 79% the automated method showed a sensitivity of 84% using a pour plate reference count and 91% using a standard loop reference count. When contaminated urines were excluded the sensitivity improved to 98%. The automated bioluminescence test, though expensive, was shown to work well with good quality specimens.

FiltraCheck-UTI, a rapid, disposable system for detection of bacteriuria

The initial evaluation of the FiltraCheck-UTI bacteriuria detection system is described. The colorimetric test, which utilizes a disposable filter disk and a stable reagent system, does not require instrumentation. The test procedure is simple and may be performed in less than 1 min. Results obtained with the FiltraCheck-UTI system were compared with those obtained by conventional semiquantitative culturing. Of 1,198 urine specimens evaluated, 202 (16.9%) were determined to be significant positives at greater than or equal to 10(5) CFU/ml by the culture method. The sensitivity and specificity of the FiltraCheck-UTI system were 96.5 and 79.7%, respectively, and the negative predictive value was 99.1%. The high sensitivity, rapidity, simplicity, and unique disposable format of the FiltraCheck-UTI system offer significant advantages over other commonly used screening methods.