scholarly journals Comparison of Immunofluorescence Assays Results for Diagnosis of Rickettsial Diseases Using Direct Serum and Filter Paper Serum Spots

2021 ◽  
Vol 28 (2) ◽  
pp. 153-158
Author(s):  
Afroza Akbar Sweety ◽  
Saif Ullah Munshi ◽  
Mohammad Zaid Hossain ◽  
Baishakhi Islam ◽  
Shahina Tabassum ◽  
...  

Background: Rickettsial diseases are difficult to diagnose in Bangladesh due to low index of suspicion and lack of diagnostic facilities in most laboratories especially in rural areas. Immunofluorescence assay (IFA) is the gold standard serological test for diagnosis of Rickettsial diseases. For serological diagnosis of rickettsial diseases, use of filter paper is an inexpensive and convenient method for collecting, storing, and transporting of blood samples with little space without refrigeration. Current study shows that the rickettsial diseases were present in febrile patients in Bangladesh. The study also compared the results of direct serum by IFA and filter paper serum spot followed by IFA as an alternative way of testing frozen samples. Materials and Methods: This observational study for evaluation of rickettsial diseases from direct serum by IFA and sera dried on blotting paper followed by IFA at the department of Virology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh. A total of 152 patients’ sera were selected by systemic random sampling of every 3rd sera of 556 febrile patients who were tested negative for dengue and or Chikungunya virus infection. Forty cases were confirmed by IFA from direct sera. In addition, 60 samples were selected from 152 sera by systemic random sampling of every 3rd sera for blotting on filter paper for further IFA test. Out of 60 sera, 35 were confirmed by IFA from direct sera and of the 35 confirmed positive cases, 31(88.6%) were positive by IFA after blotting paper assay. Taking the IFA of direct sera as gold standard test, the sensitivity, specificity, positive predictive value and negative predictive value of IFA from blotting paper eluted sera were 88%, 100%, 100% and 86% respectively. Conclusion: The study showed the use of filter paper is an inexpensive and convenient method for storing and transporting samples for serological tests like IFA in diagnosis of rickettsial diseases. J Dhaka Medical College, Vol. 28, No.2, October, 2019, Page 153-158

Author(s):  
Hogir Mohammed Shukri Saadi ◽  
Ali Yahya Saeed

 It has been well recognized throughout the world that Helicobacter pylori is the main cause of gastric ulcer and stomach carcinoma. Laboratory diagnosis of H. pylori infection is made by invasive and non-invasive methods. Invasive methods require endoscopy which is uncomfortable an unacceptable by the most patients. Therefore, non-invasive methods particularly serological tests are easier and comfortable for patients.  A total of 86 patients with ages ranging from 18-77 years old (43 males and 43 females) who were referred to the Duhok Hepatology & Gastroenterology center/Azadi Teaching Hospital for endoscopic examination from June to October, 2013 were enrolled in the study. From each patient 5 ml of blood was collected under a septic condition and sera were separated for serology. Data from each participant were recorded in a special questionnaire form after consent agreed upon on ethical and scientific committee of the Azadi hospital. The efficacy of three different ELISA tests (IgG, IgM, IgA) was assessed taking culture as a gold standard method. pylori was found in 70.93%, 30.23% and 5.81% by ELISA IgG, IgA and IgM tests respectively. The highest percentage (70.93%) of H. pylori positive cases were found by ELISA IgG and the lowest percentage (5.81%) was recorded in ELISA IgM. The study found a significant relationship between age groups and H. pylori positive cases by ELISA IgG in which positive cases increased with the increase of ages. No statistical correlation was found between the sex, smoking status and residency of studied patients with H. pylori infection. A significant correlation was found between patients without endoscopic lesions and positive cases for H. pylori by ELISA IgG in which 75.67% of patients without endoscopic lesions were positive for anti-H. pylori antibodies compared to 41.66% in patients with endoscopic lesions. The efficacy of IgG, IgM and IgA tests was calculated compared with golden standard tests and ELISA IgG characterized by the highest values of sensitivity (75.75%), negative predictive value (36.00%) and accuracy (86.00%) but with lowest specificity (45.00%) and similar positive predictive value (81.96%) with IgM and IgA. The lowest sensitivity was 5.97% and accuracy 25.56% with ELISA Ig M. From the results of the present study we can conclude that among ELISA tests, anti-H. pylori IgG is a reliable serological test for the diagnosis of H. pylori infection.


Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1043
Author(s):  
Tove Hoffman ◽  
Linda Kolstad ◽  
Bengt Rönnberg ◽  
Åke Lundkvist

The potential of rapid point-of-care (POC) tests has been subject of doubt due to an eventual risk of production errors. The aim was therefore to evaluate the two separate production lots of a commercial POC lateral flow test, intended for the detection of IgM and IgG against the SARS-CoV-2 spike protein (S1). Control samples consisted of serum from individuals with confirmed SARS-CoV-2 infection and pre-COVID-19 negative sera gathered from a biobank. The presence of anti-S1 IgM/IgG in the sera was verified by an in-house Luminex-based serological assay (COVID-19 SIA). One hundred samples were verified as positive for anti-S1 IgG and 74 for anti-S1 IgM. Two hundred samples were verified as negative for anti-S1 IgM/IgG. For the two lots of the POC-test, the sensitivities were 93.2% and 87.8% for IgM and 93.0% and 100% for IgG. The specificities were 100% for IgM and 99.5% for IgG. The positive predictive value was 100% for IgM and 98.9% and 99.0% for IgG. The negative predictive value was 97.6% and 95.7% for IgM, and 96.6% and 100% for IgG. The evaluated POC-test is suitable to assess anti-SARS-CoV-2 S1 IgM and IgG, as a measure of previous virus exposure on an individual level. The external validation of separate lots of rapid POC-tests is encouraged to ensure high sensitivity before market introduction.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jairo Alfonso Mendoza-Roldan ◽  
Giovanni Benelli ◽  
Marcos Antonio Bezerra-Santos ◽  
Viet-Linh Nguyen ◽  
Giuseppe Conte ◽  
...  

Abstract Background Canine vector-borne diseases (CVBDs) associated to ticks are among the most important health issues affecting dogs. In Italy, Ehrlichia canis, Anaplasma spp., Rickettsia conorii and Borrelia burgdorferi (s.l.) have been studied in both healthy canine populations and those clinically ill with suspected CVBDs. However, little information is currently available on the overall prevalence and distribution of these pathogens in the country. The aim of this study was to assess the prevalence and distribution of tick-borne pathogens (TBPs) in clinically suspect dogs from three Italian macro areas during a 15-year period (2006–2020). Methods A large dataset (n = 21,992) of serological test results for selected TBPs in three macro areas in Italy was analysed using a Chi-square test to evaluate the associations between the categorical factors (i.e. macro area, region, year, sex and age) and a standard logistic regression model (significance set at P = 0.05). Serological data were presented as annual and cumulative prevalence, and distribution maps of cumulative positive cases for TBPs were generated. Results Of the tested serum samples, 86.9% originated from northern (43.9%) and central (43%) Italy. The majority of the tests was requested for the diagnosis of E. canis (47%; n = 10,334), followed by Rickettsia spp. (35.1%; n = 7725), B. burgdorferi (s.l.) (11.6%; n = 2560) and Anaplasma spp. (6.2%; n = 1373). The highest serological exposure was recorded for B. burgdorferi (s.l.) (83.5%), followed by Rickettsia spp. (64.9%), Anaplasma spp. (39.8%) and E. canis (28.7%). The highest number of cumulative cases of Borrelia burgdorferi (s.l.) was recorded in samples from Tuscany, central Italy. Rickettsia spp. was more prevalent in the south and on the islands, particularly in dogs on Sicily older than 6 years, whereas Anaplasma spp. was more prevalent in the north and E. canis more prevalent in the south and on the islands. Conclusions The results of this study highlight the high seroprevalence and wide distribution of the four TBPs in dogs with clinically suspected CVBDs from the studied regions of Italy. The very high seroprevalence of B. burgdorferi (s.l.) exemplifies a limitation of this study, given the use of clinically suspect dogs and the possibility of cross-reactions when using serological tests. The present research provides updated and illustrative information on the seroprevalence and distribution of four key TBPs, and advocates for integrative control strategies for their prevention. Grapic abstract


2020 ◽  
Vol 41 (S1) ◽  
pp. s188-s189
Author(s):  
Jeffrey Gerber ◽  
Robert Grundmeier ◽  
Keith Hamilton ◽  
Lauri Hicks ◽  
Melinda Neuhauser ◽  
...  

Background: Antibiotic overuse contributes to antibiotic resistance and unnecessary adverse drug effects. Antibiotic stewardship interventions have primarily focused on acute-care settings. Most antibiotic use, however, occurs in outpatients with acute respiratory tract infections such as pharyngitis. The electronic health record (EHR) might provide an effective and efficient tool for outpatient antibiotic stewardship. We aimed to develop and validate an electronic algorithm to identify inappropriate antibiotic use for pediatric outpatients with pharyngitis. Methods: This study was conducted within the Children’s Hospital of Philadelphia (CHOP) Care Network, including 31 pediatric primary care practices and 3 urgent care centers with a shared EHR serving >250,000 children. We used International Classification of Diseases, Tenth Revision (ICD-10) codes to identify encounters for pharyngitis at any CHOP practice from March 15, 2017, to March 14, 2018, excluding those with concurrent infections (eg, otitis media, sinusitis), immunocompromising conditions, or other comorbidities that might influence the need for antibiotics. We randomly selected 450 features for detailed chart abstraction assessing patient demographics as well as practice and prescriber characteristics. Appropriateness of antibiotic use based on chart review served as the gold standard for evaluating the electronic algorithm. Criteria for appropriate use included streptococcal testing, use of penicillin or amoxicillin (absent β-lactam allergy), and a 10-day duration of therapy. Results: In 450 patients, the median age was 8.4 years (IQR, 5.5–9.0) and 54% were women. On chart review, 149 patients (33%) received an antibiotic, of whom 126 had a positive rapid strep result. Thus, based on chart review, 23 subjects (5%) diagnosed with pharyngitis received antibiotics inappropriately. Amoxicillin or penicillin was prescribed for 100 of the 126 children (79%) with a positive rapid strep test. Of the 126 children with a positive test, 114 (90%) received the correct antibiotic: amoxicillin, penicillin, or an appropriate alternative antibiotic due to b-lactam allergy. Duration of treatment was correct for all 126 children. Using the electronic algorithm, the proportion of inappropriate prescribing was 28 of 450 (6%). The test characteristics of the electronic algorithm (compared to gold standard chart review) for identification of inappropriate antibiotic prescribing were sensitivity (99%, 422 of 427); specificity (100%, 23 of 23); positive predictive value (82%, 23 of 28); and negative predictive value (100%, 422 of 422). Conclusions: For children with pharyngitis, an electronic algorithm for identification of inappropriate antibiotic prescribing is highly accurate. Future work should validate this approach in other settings and develop and evaluate the impact of an audit and feedback intervention based on this tool.Funding: NoneDisclosures: None


2020 ◽  
Vol 41 (S1) ◽  
pp. s32-s32
Author(s):  
Ebbing Lautenbach ◽  
Keith Hamilton ◽  
Robert Grundmeier ◽  
Melinda Neuhauser ◽  
Lauri Hicks ◽  
...  

Background: Antibiotic resistance has increased at alarming rates, driven predominantly by antibiotic overuse. Although most antibiotic use occurs in outpatients, antimicrobial stewardship programs have primarily focused on inpatient settings. A major challenge for outpatient stewardship is the lack of accurate and accessible electronic data to target interventions. We sought to develop and validate an electronic algorithm to identify inappropriate antibiotic use for outpatients with acute bronchitis. Methods: This study was conducted within the University of Pennsylvania Health System (UPHS). We used ICD-10 diagnostic codes to identify encounters for acute bronchitis at any outpatient UPHS practice between March 15, 2017, and March 14, 2018. Exclusion criteria included underlying immunocompromising condition, other comorbidity influencing the need for antibiotics (eg, emphysema), or ICD-10 code at the same visit for a concurrent infection (eg, sinusitis). We randomly selected 300 (150 from academic practices and 150 from nonacademic practices) eligible subjects for detailed chart abstraction that assessed patient demographics and practice and prescriber characteristics. Appropriateness of antibiotic use based on chart review served as the gold standard for assessment of the electronic algorithm. Because antibiotic use is not indicated for this study population, appropriateness was assessed based upon whether an antibiotic was prescribed or not. Results: Of 300 subjects, median age was 61 years (interquartile range, 50–68), 62% were women, 74% were seen in internal medicine (vs family medicine) practices, and 75% were seen by a physician (vs an advanced practice provider). On chart review, 167 (56%) subjects received an antibiotic. Of these subjects, 1 had documented concern for pertussis and 4 had excluding conditions for which there were no ICD-10 codes. One received an antibiotic prescription for a planned dental procedure. Thus, based on chart review, 161 (54%) subjects received antibiotics inappropriately. Using the electronic algorithm based on diagnostic codes, underlying and concurrent conditions, and prescribing data, the number of subjects with inappropriate prescribing was 170 (56%) because 3 subjects had antibiotic prescribing not noted based on chart review. The test characteristics of the electronic algorithm (compared to gold standard chart review) for identification of inappropriate antibiotic prescribing were the following: sensitivity, 100% (161 of 161); specificity, 94% (130 of 139); positive predictive value, 95% (161 of 170); and negative predictive value, 100% (130 of 130). Conclusions: For outpatients with acute bronchitis, an electronic algorithm for identification of inappropriate antibiotic prescribing is highly accurate. This algorithm could be used to efficiently assess prescribing among practices and individual clinicians. The impact of interventions based on this algorithm should be tested in future studies.Funding: NoneDisclosures: None


2021 ◽  
Vol 15 (6) ◽  
pp. 1679-1681
Author(s):  
Afaque Ali ◽  
Majid Shaikh ◽  
Ahsanullah . ◽  
Adeel Ahmed ◽  
Abid Ali Sahito ◽  
...  

Objective: To determine the diagnostic accuracy of High-resolution computed tomography (HRCT) chest in detection of covid-19 infection taking PCR as gold standard. Study Design: Cross-sectional study Setting: Radiology department of Tabba Hospital, Karachi. Duration: From March 2019 to September 2020 Material and Methods: All the clinically suspected patients of covid-19, of any age, both genders and those referred to radiology for High-resolution computed tomography (HRCT) chest to detect the covid-19 infection were included. After two days, patients’ PCR reports were collected from the ward, after taking informed consent and permission from head of department. The diagnostic accuracy of HRCT was established with respect to sensitivity, PPV, NPV, and specificity by taking PCR as gold standard. All the information was collected via study proforma. Results: Total 70 patients suspected for COVID-19 were studied, and the patients’ mean age was 58.23±9.52 years. Males were in majority 54(77.1%). As per HRCT findings, COVID-19 infection was positive in 46 patients, however, 48 patients were detected positive for COVID-19 infection as per PCR findings. In the detection of COVID-19 infection, HRCT chest showed sensitivity of 91%, specificity of 90%, PPV of 83%, NPV of 84% and diagnostic accuracy of 94%; by taking PCR as gold standard. Conclusion: High-resolution computed tomography (HRCT) is a reliable diagnostic approach in promptly detecting the COVID-19; with 91% sensitivity, 90% specificity, 83% positive predictive value, 84% negative predictive value and 94% diagnostic accuracy. Keywords: Accuracy, HRCT, COVID-19


Author(s):  
Amanda Taylor ◽  
Susan Morpeth ◽  
Rachel Webb ◽  
Susan Taylor

Background: Group A Streptococcus (GAS) causes significant morbidity and mortality in New Zealand and is responsible for invasive disease and immune sequelae including acute Rheumatic Fever (ARF). Early treatment of GAS pharyngitis reduces the risk of ARF. In settings with a high-burden of GAS disease, a rapid GAS pharyngitis diagnostic test with a strong negative predictive value is needed to enable prompt and accurate treatment. Methods: This prospective study compares the Xpert® Xpress Strep A molecular test (Cepheid) to throat culture and a second molecular method, the BioGX Group A Streptococcus -OSR for BD MAX TM for the diagnosis of GAS pharyngitis. Throat swabs were collected from the emergency department and wards of Middlemore Hospital, New Zealand. The BioGX Group A Streptococcus - OSR for BD MAX TM , contributes to the composite gold-standard: throat culture or both molecular methods positive. Basic demographic, clinical and laboratory data was collected. Results: 205/214 swabs were suitable for analysis. 28/205 (13.7%) were GAS culture positive, 45/205 (22%) Xpert® Xpress Strep A positive and 38/205 (18.5%) BioGX positive. Compared to culture, the sensitivity, specificity, positive and negative predictive values of the Xpert® Xpress Strep A molecular test were 100%, 90.4%, 62.2% and 100%, respectively. Compared to the composite gold-standard, the sensitivity, specificity, PPV and NPV and were 100%, 95.8%, 84.4% and 100% respectively. 17 samples were Xpert® Xpress positive but culture-negative; 6 of these 17 swabs represent true positives with evidence of recent GAS infection. Ten samples were culture negative but both Xpert® Xpress and BioGX positive. Conclusion: The Xpert® Xpress Strep A molecular test is highly sensitive with a strong negative predictive value and rapid turnaround time. It can be safely introduced as a first line test for throat swabs in a high-incidence ARF population.


Author(s):  
Mohamed El-Diasty ◽  
◽  
Rana El-Said ◽  
Adel Abdelkhalek ◽  
◽  
...  

Brucellosis is an endemic disease among livestock and humans in Egypt. Sheep are the most common type of livestock ruminant in Egypt and considered the fundamental etiology for spreading and maintaining B. melitensis either in human being or animal populations. In the current study, we investigated the seroprevalence of brucellosis in sheep herds reared in Bilqase, one of the biggest cities at Dakahlia governorate in Egypt's Delta region. In total, 610 sheep from seven herds were investigated. Anti-Brucella antibodies were detected in 48 (7.8%) samples tested by Buffered Acidified Plate Antigen Test (BAPAT), in 44 (7.2%) samples tested by Rose Bengal Plate Test (RBPT) and in 41 (6.7%) samples tested by Milk Ring Test (MRT). The isolation rate was 29.6% (16 out of 54 examined samples). Brucella organism was isolated from three aborted fetuses, one tissue sample of slaughtered serologically positive ewe and 12 milk samples. The Abortus Melitensis Ovis Suis-PCR (AMOS-PCR) confirmed all Brucella strains as B. melitensis. More than three successive negative serological tests are required to declare that the infected herd is free from brucellosis. In conclusion, no single serological test could conclusively diagnose brucellosis in endemic areas. Confirmation of results with molecular diagnosis or culture is indispensable in diagnosis. B. melitensis was the prevalent serotype among sheep in Dakahlia governorate


2021 ◽  
Vol 15 (9) ◽  
pp. 2474-2476
Author(s):  
Maham Munir Awan ◽  
Afshan Noreen ◽  
Farah Kalsoom ◽  
Muhammad Tahir ◽  
Umaima Majeed ◽  
...  

Objective: To determine the accuracy of CT chest in diagnosis of COVID-19 taking RT-PCR-testing as gold standard. Materials and Methods: A total of 150 patients of suspicion of COVID-19 who were referred for CT Chest in Radiology Department of Nishtar Medical University Multan from June-2020 to May-2021 were included. In all patients, two RT-PCR test results were obtained with 7 days of admission in hospital. Presence of any of these positive was labelled as COVID-19 infection. CT chest was performed in all patients within 2 days of admission in hospital using 128 slices CT scan machine. The diagnosis of COVID-19 infection was made according to the recommendations by Radiological Society of North America (RSNA) protocol. Results: Mean age was 51.3±14.7 years. 78 (52%) patients were male and 72 (48%) patients were female. RTPCR test was positive in 89 (59.3%) patients. While the CT chest findings were suggestive of COVID-19 infection in 130 (86.7%) patients. The sensitivity of CT chest was 95.5%, specificity 26.2%, PPV wad 65.4% and NPV was 80.0%. Conclusion: CT chest has a very good sensitivity for detection of COVID-19, it can be used as a rapid diagnostic tool especially in areas of pandemic. However, the specificity of CT chest is low, that can limit its use in low COVID-19 affected areas. Keywords: COVID-19, Computed tomography, False Positive, True Positive, Positive Predictive Value, Negative Predictive Value.


2009 ◽  
Vol 25 (5) ◽  
pp. 1017-1024 ◽  
Author(s):  
Carolina Castro Martins ◽  
Loliza Chalub ◽  
Ynara Bosco Lima-Arsati ◽  
Isabela Almeida Pordeus ◽  
Saul Martins Paiva

The aim of this study was to assess agreement in the diagnosis of dental fluorosis performed by a standardized digital photographic method and a clinical examination (gold standard). 49 children (aged 7-9 years) were clinically evaluated by a trained examiner for the assessment of dental fluorosis. Central incisors were evaluated for the presence or absence of dental fluorosis and were photographed with a digital camera. Photographs were presented to three pediatric dentists, who examined the images. Data were analyzed using Cohen's kappa and validity values. Agreement in the diagnosis performed by the photographic method and clinical examination was good (0.67) and accuracy was 83.7%. The prevalence of dental fluorosis was reported to be higher in the clinical examination (49%) compared with the photographic method (36.7%). The photographic method presented higher specificity (96%) than sensitivity (70.8%), a positive predictive value (PPV) of 94.4% and a negative predictive value (NPV) of 77.4%. The diagnosis of dental fluorosis performed using the photographic method presented high specificity and PPV, which indicates that the method is reproducible and reliable for recording dental fluorosis.


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