A Retrospective Analysis of Joint Cultures: Only Time Will Tell (Or Will It?)

2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S138-S138
Author(s):  
D Altenburger ◽  
S Strayer ◽  
S Carroll
Keyword(s):  
Retrospective Analysis ◽  
Propionibacterium Acnes ◽  
Culture Media ◽  
False Negative ◽  
Positive Culture ◽  
Growth Time ◽  
Average Growth ◽  
Negative Results ◽  
False Negative Results ◽  
Actinomyces Species

Abstract Introduction/Objective Multiple textbooks and guidelines, including CLSI, recommend holding joint cultures for 14 days. This prevents false negative results from “slower growers” which include Actinomyces species and Propionibacterium acnes. Holding of these cultures can be a burden for small microbiology labs. Methods A retrospective analysis of three years of joint cultures held for 14 days was reviewed. The length of time for the culture to turn positive and the organism that grew was noted. Results A total of 67 positive joint cultures were evaluated, which covered a period of 3 years at our institution. Of these, only 1 culture turned positive following day 5 (Propionibacterium acnes grew on day 6). The average time to positive for Propionibacterium acnes was 4 days. In comparison, the average growth time for Staphylococcus aureus and Proteus was 1 day, Pseudomonas aeruginosa was 1.2 days, all Streptococcus species was 2.4 days and Staphylococcus epidermidis was 2.7 days. No cultures grew Actinomyces during our study. Conclusion The consequences of missing a positive culture can be grave. In general, culture media has improved and provided increased growth rates. With resources becoming more limited, it may be time to revisit guidelines. This study is too small to be conclusive; a larger study may provide confirmation of the findings.

scholarly journals The frequency and character of community-acquired pneumonia comparison before and during the COVID-19 epidemic in the multi-specialty hospital

2020 ◽  
Vol 1 (1) ◽  
pp. 37-47
Author(s):  
Stepan A. Yaremenko ◽  
Natalia A. Rucheva ◽  
Kirill N. Zhuravlev ◽  
Valentin E. Sinitsyn
Keyword(s):  
Retrospective Analysis ◽  
False Negative ◽  
Community Acquired Pneumonia ◽  
Chest Ct ◽  
Viral Pneumonia ◽  
Negative Results ◽  
False Negative Results ◽  
Polymerase Chain ◽  
Ct Data ◽  
Suspected Pneumonia

BACKGROUND:The 2019 coronavirus disease outbreak (COVID-19) quickly swept the world in just a month. Polymerase chain reaction (PCR) is used in the diagnosis of this disease, but this test has limitations related to false negative results, as well as PCR is a time-consuming procedure. Under these conditions, chest computed tomography (CT) can become one of the main methods in the Clinicians Arsenal used for early detection of COVID-19 in patients who first seek medical help. AIMS:comparison of the frequency of community-acquired pneumonia and its characteristics according to CT data before and during the COVID-19 epidemic and study of the possibilities of their timely detection and differential diagnosis. MATERIALS AND METHODS:A retrospective analysis of chest CT scans results was performed in Davydovsky hospital (Moscow) from April 1 to April 17, 2020. It included all patients diagnosed with viral pneumonia at the CT. All patients with suspected diagnosis of viral pneumonia underwent PCR testing. Retrospective analysis of chest CT data from patients admitted to the hospital with suspected pneumonia for the same period in 2019 was taken as a comparison group. RESULTS:For the period from April 1 to April 17, 2020 according to chest CT, pneumonia was diagnosed in 140 cases, of which 65 (46.4%) were described as viral, compared with the same period in 2019 7 diagnoses of viral pneumonia (10.3%) were described a significant increase in cases of viral pneumonia (5.723;p0.01). Results of PCR test in patients with viral pneumonia according to CT data was: positive in 34 (52.3%), negative in 22 (33.8%), 9 (13.9%) patients were not tested. When comparing the frequency of detection on CT of viral pneumonia patterns in patients for the same period of time in 2019 and 2020, no significant differences were found. The probability of COVID-19 due to results of chest CT was: average 13.8%, high 75.4%. The severity of viral pneumonia according to CT data was: light 38.5%, medium 46.2%, severe 12.3%, extremely severe 3.1%. CONCLUSIONS:Rapid CT diagnostics of COVID-19, even with false negative results of PCR tests, can help to isolate a patient with suspected COVID-19, start treatment on time and prevent the further spread of viral infection in a pandemic. Nevertheless, due to the non-specificity of the revealed picture, the possibilities of CT to identify lung lesions by specific viral agents are limited.

scholarly journals Impedimetric screening for bacteriuria

1978 ◽  
Vol 7 (3) ◽  
pp. 273-278
Author(s):  
P Cady ◽  
S W Dufour ◽  
P Lawless ◽  
B Nunke ◽  
S J Kraeger
Keyword(s):  
False Negative ◽  
Positive Culture ◽  
Impedance Change ◽  
Initial Concentration ◽  
Negative Results ◽  
False Negative Results ◽  
Time Required ◽  
The Cost ◽  
Positive Results ◽  
Selection Of

A rapid, automated instrumental procedure for distinguishing urine cultures containing greater than 10(5) organism per ml is described. The method is based upon the measurement of changes in impedance that take place as microorganisms alter the chemical composition of the medium. The time required to detect impedance change is inversely related to the initial concentration of microorganisms in the sample. By defining an impedance-positive culture as one that gives detectable impedance change within 2.6 h, 95.8% of 1,133 urine cultures tested were correctly classified as containing more than or fewer than 10(5) organisms per ml. Selection of a longer detection time decreases false negative results at the cost of increased false positive results. Impedance screening is compared with screening data reported in the literature using adenosine-5'-triphosphate detection, microcalorimetry, electrochemical measurements, and optical microscopy.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Scoring System for the Diagnosis of COVID-19

2020 ◽  
Vol 13 (1) ◽  
pp. 413-414 ◽  
Author(s):  
Mohamed Farouk Allam
Keyword(s):  
Scoring System ◽  
Clinical Symptoms ◽  
False Negative ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Negative Results ◽  
False Negative Results ◽  
Symptoms And Signs

Due to the international spread of COVID-19, the difficulty of collecting nasopharyngeal swab specimen from all suspected patients, the costs of RT-PCR and CT, and the false negative results of RT-PCR assay in 41% of COVID-19 patients, a scoring system is needed to classify the suspected patients in order to determine the need for follow-up, home isolation, quarantine or the conduction of further investigations. A scoring system is proposed as a diagnostic tool for suspected patients. It includes Epidemiological Evidence of Exposure, Clinical Symptoms and Signs, and Investigations (if available). This scoring system is simple, could be calculated in a few minutes, and incorporates the main possible data/findings of any patient.

Detection of Streptococcus pneumoniae in Sputum Samples by Real- Time PCR.

2020 ◽  
Vol 18 ◽  
Author(s):  
Pegah Shakib ◽  
Mohammad Reza Zolfaghari
Keyword(s):  
Streptococcus Pneumoniae ◽  
Real Time ◽  
Real Time Pcr ◽  
False Negative ◽  
Cross Sectional Study ◽  
Laboratory Culture ◽  
Cross Sectional ◽  
Negative Results ◽  
False Negative Results ◽  
Pcr Method

Background: Conventional laboratory culture-based methods for diagnosis of Streptococcus pneumoniae are time-consuming and yield false negative results. Molecular methods including real-time (RT)-PCR rapid methods and conventional PCR due to higher sensitivity and accuracy have been replaced instead traditional culture assay. The aim of the current study was to evaluate lytA gene for detection of Streptococcus pneumoniae in the cerebrospinal fluid of human patients with meningitis using real-time PCR assay. Material and Methods: In this cross-sectional study, a total of 30 clinical specimens were collected from patients in a period from September to December 2018. In order to evaluate the presence of lytA gene, conventional and real-time PCR methods were used without culture. Results: From 30 sputum samples five (16.66%) isolates were identified as S. pneumoniae by lytA PCR and sequencing. Discussion: In this research, an accurate and rapid real-time PCR method was used, which is based on lytA gene for diagnosis of bacteria so that it can be diagnosed. Based on the sequencing results, the sensitivity for detection of lytA gene was 100% (5/5).

COVID-19: how nuclear medicine can provide a differential diagnosis in very dubious case

Coronaviruses ◽  
2020 ◽  
Vol 01 ◽  
Author(s):  
Maria Silvia De Feo ◽  
Viviana Frantellizzi ◽  
Giuseppe De Vincentis
Keyword(s):  
Infectious Disease ◽  
Differential Diagnosis ◽  
Ct Scan ◽  
Imaging Technique ◽  
False Negative ◽  
Clinical Signs ◽  
Negative Results ◽  
Infectious Disease Department ◽  
False Negative Results ◽  
99Mtc Hmpao

Background: We present the case of a 55-year-old woman, admitted to the Infectious Disease Department of Policlinico Umberto I, Rome, in mid-March 2020, with suspicion of COVID-19 infection. Objective: The rRT-PCR was negative and the following CT scan, performed to exclude false-negative results and help diagnosis, was inconclusive. Methods: It was decided to submit the patient to 99mTc-HMPAO-labelled leukocyte scan. Results: This exam led to the diagnosis of infective endocarditis. Conclusion: In the present pandemic scenario, 99mTc-HMPAO-labelled leukocyte scan represents a reliable imaging technique for differential diagnosis with COVID-19 in patients with confusing clinical signs, possible false-negative rRT-PCR results and inconclusive CT scan.

Aspiration Revisited: Prospective Evaluation of a Physiologically Pressurized Model With Animal Correlation and Broader Applicability to Filler Complications

2021 ◽  
Author(s):  
Hyoung-Jin Moon ◽  
Won Lee ◽  
Ji-Soo Kim ◽  
Eun-Jung Yang ◽  
Hema Sundaram
Keyword(s):  
Normal Saline ◽  
False Negative ◽  
Vascular Complications ◽  
Filler Injection ◽  
Negative Results ◽  
Needle Position ◽  
False Negative Results ◽  
In Vivo Testing

Abstract Background Aspiration testing before filler injection is controversial. Some believe that aspiration can help prevent inadvertent intravascular injection, while others cite false-negative results and question its value given that the needle position always changes somewhat during injection procedures. Objectives To test the relation of false-negative results to the viscosity of the material within the needle lumen and determine whether a less viscous material within the needle lumen could decrease the incidence of false-negative results. Methods In vitro aspiration tests were performed using 30-G and 27-G needle gauges, two cross-linked hyaluronic acid fillers, normal saline bags pressurized at 140 and 10 mmHg to mimic human arterial and venous pressures, and three needle lumen conditions (normal saline, air, and filler). Testing was repeated three times under each study condition (72 tests in total). For in vivo correlation, aspiration tests were performed on femoral arteries and central auricular veins in three rabbits (4–5 aspirations per site, 48 tests in total). Results In vitro and in vivo testing using 30-G needles containing filler both showed false-negative results on aspiration testing. In vitro and in vivo testing using needles containing saline or air showed positive findings. Conclusions False-negative results from aspiration testing may be reduced by pre-filling the needle lumen with saline rather than a filler. The pressurized system may help overcome challenges of animal models with intravascular pressures significantly different from those of humans. The adaptability of this system to mimic various vessel pressures may facilitate physiologically relevant studies of vascular complications.

scholarly journals Superiority of MALDI-TOF Mass Spectrometry over Real-Time PCR for SARS-CoV-2 RNA Detection

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 730
Author(s):  
Magda Rybicka ◽  
Ewa Miłosz ◽  
Krzysztof Piotr Bielawski
Keyword(s):  
Mass Spectrometry ◽  
Gold Standard ◽  
Viral Genome ◽  
False Negative ◽  
Rt Pcr ◽  
Rna Detection ◽  
Maldi Tof ◽  
Negative Results ◽  
False Negative Results ◽  
Pcr Test

At present, the RT-PCR test remains the gold standard for early diagnosis of SARS-CoV-2. Nevertheless, there is growing evidence demonstrating that this technique may generate false-negative results. Here, we aimed to compare the new mass spectrometry-based assay MassARRAY® SARS-CoV-2 Panel with the RT-PCR diagnostic test approved for clinical use. The study group consisted of 168 suspected patients with symptoms of a respiratory infection. After simultaneous analysis by RT-PCR and mass spectrometry methods, we obtained discordant results for 17 samples (10.12%). Within fifteen samples officially reported as presumptive positive, 13 were positive according to the MS-based assay. Moreover, four samples reported by the officially approved RT-PCR as negative were positive in at least one MS assay. We have successfully demonstrated superior sensitivity of the MS-based assay in SARS-CoV-2 detection, showing that MALDI-TOF MS seems to be ideal for the detection as well as discrimination of mutations within the viral genome.

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