Evaluation of an adenosine 5'-triphosphate assay as a screening method to detect significant bacteriuria

The bioluminescent reaction of adenosine 5'-triphosphate (ATP) with luciferin and luciferase has been used in conjunction with a sensitive photometer (Lab-Line's ATP photometer) to detect significant bacteriuria in urine. This rapid method of screening urine specimens for bacteriuria was evaluated by using 348 urine specimens submitted to the clinical microbiology laboratory at the University of Minnesota Hospitals for routine culture using the calibrated loop-streak plate method. There was 89.4% agreement between the culture method and the ATP assay, with 7.0% false positive and 27.0% false negative results from the ATP assay using 10(5) organisms/ml of urine or greater as positive for significant bacteriuria and less than 10(5) organisms/ml as negative for significant bacteriuria.

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Improved Hydrophobic Grid Membrane Filter Method, Using EF-18 Agar, for Detection of Salmonella in Foods: Collaborative Study

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/73.5.734 ◽

1990 ◽

Vol 73 (5) ◽

pp. 734-742

Author(s):

Phyllis Entis

Keyword(s):

Membrane Filter ◽

Collaborative Study ◽

False Negative ◽

Screening Method ◽

Culture Method ◽

Soy Flour ◽

Poultry Meat ◽

Filter Method ◽

Negative Results ◽

False Negative Results

Abstract A collaborative study was carried out in 30 laboratories to validate Improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were Included In the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each Inoculated In advance with low levels of Individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the Improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved Interim official first action for all foods to replace the HGMF official final action method, 985.42.

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Comparison between VIDAS Automatic Enzyme-Linked Fluorescent Immunoassay and Culture Method for Salmonella Recovery from Pork Carcass Sponge Samples

Journal of Food Protection ◽

10.4315/0362-028x-65.10.1656 ◽

2002 ◽

Vol 65 (10) ◽

pp. 1656-1659 ◽

Cited By ~ 16

Author(s):

KUANG-SHENG YEH ◽

CHIN-EN TSAI ◽

SHIH-PING CHEN ◽

CHAO-WEI LIAO

Keyword(s):

False Negative ◽

Screening Method ◽

Culture Method ◽

Automated System ◽

Rapid Screening ◽

Assay Method ◽

Intensive Culture ◽

Negative Results ◽

False Negative Results ◽

Potential Alternative

VIDAS Salmonella (VIDAS-SLM) is an automated system that uses the enzyme-linked fluorescent assay method to detect Salmonella species. This study evaluated the efficacy of the VIDAS-SLM method in detecting Salmonella species in pork carcass sponge samples gathered from 10 slaughter plants in Taiwan. Two hundred fifty-seven pork carcass sponge samples were screened by the VIDAS-SLM method and by the culture method in parallel. While 18 sponge samples were found to test positive by both methods, the VIDAS-SLM method detected four additional positive samples for which the culture method failed to recover Salmonella. The specificity of the VIDAS-SLM method was found to be 0.98, and its sensitivity was 1.0, since no false-negative results occurred. Artificially inoculated Salmonella at concentrations as low as 5.0 × 100 CFU/ml was detected in the heat-inactivated sponge sample in the presence or absence of 5.0 × 104 CFU of Citrobacter freundii per ml. Thus, the VIDAS-SLM method is a rapid screening method and a potential alternative to the time- and labor-intensive culture method.

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Simplified microscopy for rapid detection of significant bacteriuria in random urine specimens

Journal of Clinical Microbiology ◽

10.1128/jcm.7.3.286-289.1978 ◽

1978 ◽

Vol 7 (3) ◽

pp. 286-289

Author(s):

G K Barbin ◽

J D Thorley ◽

J A Reinarz

Keyword(s):

False Negative ◽

Rapid Screening ◽

Negative Results ◽

Microscopy Technique ◽

Gram Staining ◽

False Negative Results ◽

Significant Bacteriuria ◽

Urine Microscopy ◽

Positive Results ◽

Urine Specimens

Simplified urine microscopy, nitrite testing, and dipstick culture were compared with urine loop streak culture colony counts in 219 random voided specimens to determine the accuracy of the three rapid screening techniques. Nitrite testing resulted in 65% false negative results, which could not be significantly improved by incubation at 37 degrees C but which could be improved by adding nitrate substrate before incubation. Dipstick culture could not be quantitated until after 18 h of incubation. A new, simplified microscopy technique, using unspun, unstained urine, resulted in 4% false negative results and 4% false positive results in specimens containing over 10(5) organisms per ml and was the best method Centrifuges, Gram staining reagents, and counting chambers are not necessary for accurate microscopic screening of random urine specimens for the presence of bacteriuria by this technique, and the results are immediately available.

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Non-chlamydial non-gonococcal urethritis or undiagnosed chlamydial urethritis?

International Journal of STD & AIDS ◽

10.1258/095646206776790178 ◽

2006 ◽

Vol 17 (5) ◽

pp. 296-298 ◽

Cited By ~ 8

Author(s):

K Manavi ◽

A McMillan ◽

H Young

Keyword(s):

Chlamydial Infection ◽

False Negative ◽

Culture Method ◽

Sexual Partners ◽

Chain Reaction ◽

Sexually Transmitted ◽

Female Partners ◽

Gonococcal Urethritis ◽

Negative Results ◽

False Negative Results

The aim of this study is to investigate the prevalence of sexually transmitted infections (STI) in the partners of men with non-chlamydial, non-gonococcal urethritis (NCNGU). Observational study of the sexual partners of men with NCNGU diagnosed in the Department of Genitourinary Medicine, Edinburgh between 1 June 2002 and 31 December 2003. The diagnosis of chlamydial infection was based on ligase chain reaction (LCx) between June 2002 and March 2003, and on polymerase chain reaction (PCR) thereafter. Gonococcal infection was diagnosed with culture method. Sexual partners of 99 (25%) of the 403 heterosexual men diagnosed with NCNGU were screened. Chlamydial infection was detected in 19 (19%) of the female sexual partners. Higher proportion of female partners of symptomatic men (15/51) had chlamydial infection compared with that of partners of asymptomatic men (4/48) ( P < 0.005). NCNGU may be related to false-negative results of chlamydial diagnostic tests. Screening and treatment of sexual partners of men with NCNGU is therefore necessary.

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False-Negative Results in Point-of-Care Qualitative Human Chorionic Gonadotropin (hCG) Devices Due to Excess hCGβ Core Fragment

Clinical Chemistry ◽

10.1373/clinchem.2008.121210 ◽

2009 ◽

Vol 55 (7) ◽

pp. 1389-1394 ◽

Cited By ~ 46

Author(s):

Ann M Gronowski ◽

Mark Cervinski ◽

Ulf-Håkan Stenman ◽

Alison Woodworth ◽

Lori Ashby ◽

...

Keyword(s):

Chorionic Gonadotropin ◽

Human Chorionic Gonadotropin ◽

Point Of Care ◽

False Negative ◽

The Core ◽

Core Fragment ◽

Negative Results ◽

False Negative Results ◽

Positive Results ◽

Urine Specimens

Abstract Background: During pregnancy, human chorionic gonadotropin (hCG) immunoreactivity in urine consists of intact hCG as well as a number of hCG variants including the core fragment of hCGβ (hCGβcf). We identified 3 urine specimens with apparent false-negative results using the OSOM® hCG Combo Test (Genzyme Diagnostics) qualitative hCG device and sought to determine whether an excess of 1 of the fragments or variants might be the cause of the interference. Methods: We measured concentrations of hCG variants in the urine from 3 patients with apparent false-negative hCG results. Purified hCG variants were added to urines positive for hCG and tested using the OSOM, ICON® 25 hCG (Beckman Coulter), and hCG Combo SP® Brand (Cardinal Health) devices. Results: Dilution of these 3 urine samples resulted in positive results on the OSOM device. Quantification of hCG variants in each of the 3 patient urine specimens demonstrated that hCGβcf occurred in molar excess of intact hCG. Addition of purified hCGβcf to hCG-positive urines caused false-negative hCG results using the OSOM and ICON qualitative urine hCG devices. Conclusions: Increased concentrations of hCGβcf can cause false-negative results on the OSOM and ICON qualitative urine hCG devices. .

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Ratio of urinary free immunoglobulin light chain κ to λ in the diagnosis of Bence Jones proteinuria

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm.2004.075 ◽

2004 ◽

Vol 42 (4) ◽

Cited By ~ 8

Author(s):

Takanari Nakano ◽

Atsuo Nagata ◽

Hidenori Takahashi

Keyword(s):

Light Chain ◽

False Negative ◽

Combination Method ◽

Immunoglobulin Light Chain ◽

Bence Jones Protein ◽

Diagnostic Efficacy ◽

Complementary Method ◽

Negative Results ◽

False Negative Results ◽

Urine Specimens

AbstractThe aim of this study was to evaluate the diagnostic efficacy of the ratio of urinary free light chain (FLC) kappa to lambda (κ/λ ratio) for the detection of Bence Jones protein (BJP). Urine specimens were collected from 243 patients suspected of having BJP. Immunofixation identified 59 BJP-positive specimens among them. The κ/λ ratios of all specimens were determined by FLC immunoassays and then the cutoffs for the κ/λ ratio were defined as 5.5 for BJP κ and 0.1 for BJP λ by ROC curve analyses. Using the cutoffs, we detected abnormal κ/λ ratios in 51 (86%) of the 59 BJP-positives and 11 (6%) of the 184 BJP-negatives identified by the results of immunofixation. High-resolution urinary protein electrophoresis (UPE), a sensitive method for BJP screening, showed almost equal sensitivity to the κ/λ ratio, detecting monoclonal band(s) in 52 (88%) of the 59 BJP-positives. However, in UPE analysis these positive specimens should be followed by redundant immunofixation analysis to determine the isotypes. We further evaluated the combination method of FLC assays with UPE that correctly diagnosed 82% of the specimens as positive or negative for BJP, with only two false-negative results. These results suggest that quantitative FLC immunoassays provide an alternative or complementary method for the detection of BJP.

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HIGH RATE OF FALSE-NEGATIVE RESULTS OF THE RECTAL SWAB CULTURE METHOD IN DETECTION OF GASTROINTESTINAL COLONIZATION WITH VANCOMYCIN-RESISTANT ENTEROCOCCI

The Pediatric Infectious Disease Journal ◽

10.1097/00006454-200206000-00028 ◽

2002 ◽

Vol 21 (6) ◽

pp. 578-579

Author(s):

&NA;

Keyword(s):

Rectal Swab ◽

False Negative ◽

Culture Method ◽

High Rate ◽

Negative Results ◽

Vancomycin Resistant Enterococci ◽

False Negative Results ◽

Vancomycin Resistant ◽

Gastrointestinal Colonization

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Phenothiazine Derivatives in Urine: "False Nagative Results" With the Forrest Color Test (FPN), and a Method for Their Elimination

Clinical Chemistry ◽

10.1093/clinchem/11.10.914 ◽

1965 ◽

Vol 11 (10) ◽

pp. 914-919

Author(s):

K N Campbell

Keyword(s):

False Negative ◽

False Positives ◽

Phenothiazine Derivatives ◽

Color Test ◽

False Negatives ◽

Delayed Reaction ◽

Negative Results ◽

False Negative Results ◽

Phenothiazine Drugs ◽

Urine Specimens

Abstract More than 100 Forrest color tests (FPN) were performed on urine specimens from patients taking phenothiazine drugs. The results obtained showed > 20% "false negatives" and 6% "false positives." A delayed reaction due to possible individual patient variation seems to have been the cause for false-negative results. These false negatives were shown to disappear when test readings were delayed for 1-5 min. Some false positives were due to liver dysfunction.

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Decreased signal in Emit assays of drugs of abuse in urine after ingestion of aspirin: potential for false-negative results

Clinical Chemistry ◽

10.1093/clinchem/40.4.608 ◽

1994 ◽

Vol 40 (4) ◽

pp. 608-612 ◽

Cited By ~ 19

Author(s):

R E Wagener ◽

M W Linder ◽

R Valdes

Keyword(s):

High Frequency ◽

Drugs Of Abuse ◽

False Negative ◽

Drug Analysis ◽

Negative Bias ◽

Negative Results ◽

False Negative Results ◽

Therapeutic Doses ◽

Drug Free ◽

Urine Specimens

Abstract During routine drug analysis with the Syva d.a.u. Emit immunoassays we observed a high frequency of urines with lower rates of changes in absorbance (delta A R) than the rate for a drug-free urine calibrator. Many of these urines contained salicylates. Among 40 urines with apparent salicylate concentrations between 15 and 420 mg/dL tested for benzoylecgonine (BE), 20 had delta A R < -4 (range +2 to -28 mA/min). The rates decreased with increasing salicylate: delta A R = -0.057 x (salicylate, mg/dL) -0.22 mA/min (r = 0.85, n = 40, P < 0.01). Urines from 100 control subjects (no salicylate) had mean +/- SD delta A R values of -1.05 +/- 2.2 mA/min (range +3 to -7; only two were < -4 mA/min). Although direct addition of salicylic acid (200 mg/dL) to urine specimens did not reproduce the negative bias, ingestion of aspirin (acetylsalicylic acid) did by -0.09 mA/min per 1 mg/dL (72.4 mumol/L) salicylate. Negative biases observed for other Emit d.a.u. assays after salicylate ingestion lead us to conclude that ingestion of therapeutic doses of aspirin may cause false-negative results for drug screens in urines by this technology.

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