scholarly journals Evaluation of loop-mediated isothermal amplification assay for detection of scrub typhus in patients with acute febrile illness presenting to a Tertiary Care Center in Puducherry, India

2019 ◽  
Vol 11 (01) ◽  
pp. 082-086 ◽  
Author(s):  
Patricia Anitha Karthikeyan ◽  
Sugeerappa Laxmanappa Hoti ◽  
Reba Kanungo
Keyword(s):  
Diagnostic Test ◽  
Scrub Typhus ◽  
Tertiary Care ◽  
Lamp Assay ◽  
Febrile Illness ◽  
Isothermal Amplification ◽  
Acute Febrile Illness ◽  
Loop Mediated Isothermal Amplification ◽  
Igm Antibodies ◽  
Two Samples

Abstract PURPOSE: Scrub typhus an acute febrile illness has diverse clinical manifestations, which overlap with other febrile illnesses. Due to this reason, it is misdiagnosed, leading to inappropriate treatment, sometimes resulting in fatality. Thus, accurate diagnosis of scrub typhus is important for appropriate treatment. This study evaluated the loop-mediated isothermal amplification (LAMP) assay as a diagnostic test for scrub typhus among patients with fever. MATERIALS AND METHODS: A total of 50 cases of acute febrile illness clinically resembling scrub typhus, with or without an eschar, or cases of pyrexia of unknown origin were included in the study. Blood samples collected from these cases were subjected to detection of IgM antibodies to Orientia tsutsugamushi by ELISA, conventional groEL polymerase chain reaction (PCR), and the LAMP assay. RESULTS: Twelve cases had fever for less than a week, and two had fever for more than 3 weeks. IgM antibodies to O. tsutsugamushi were detected in 37 out of 50 samples (74%). LAMP assay was positive in 33 samples (66%). groEL gene-based PCR detected 35 (70%) samples as positive. Two samples negative by LAMP assay were positive by this PCR. Twenty samples collected from patients with dengue, typhoid, and malaria tested by the LAMP assay were negative, indicating its good specificity. LAMP assay and the conventional groEL-based PCR could detect 72.7% and 74.3% of the samples, respectively before the 10th day after onset of fever, whereas IgM ELISA could detect only 40.5% of the 37 samples. CONCLUSION: This study suggests that LAMP assay could be a useful diagnostic test for detecting scrub typhus in the acute phase of the illness and a cheaper alternative to other molecular methods in resource poor settings.

scholarly journals 1655. Performance of Molecular and Serologic Tests for the Diagnosis of Scrub Typhus

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S605-S605
Author(s):  
George M Varghese ◽  
Kavitha Kannan ◽  
Kundavaram Abhilash ◽  
Alice Nithyananth ◽  
Thambu David ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Predictive Value ◽  
Scrub Typhus ◽  
Spotted Fever ◽  
Lamp Assay ◽  
Febrile Illness ◽  
Geographic Region ◽  
Enzyme Linked Immunosorbent Assay ◽  
Acute Febrile Illness ◽  
Igm Antibodies

Abstract Background Diagnosis of scrub typhus, caused by the bacterium Orientia tsutsugamushi, is challenging because of the overlap of its nonspecific symptoms with other infections coupled with the lack of sufficient data on the performance of diagnostic tests. Early diagnosis of scrub typhus is crucial to improve outcomes and this study evaluated the diagnostic performance of various tests. Methods Adult patients with acute febrile illness and manifestations suggestive of scrub typhus confirmed by positive PCR in the blood or eschar were characterized as cases. Patients with acute febrile illness and a confirmed alternate etiology such as culture-confirmed typhoid, smear/PCR positive for malaria, PCR/NS1 antigen positive for dengue, PCR positive for influenza, PCR/MAT positive for leptospirosis, PCR positive for spotted fever were characterized as controls with other infections. The healthy controls consisted of subjects from the same geographic region. We performed the following tests on blood samples for scrub typhus and calculated the sensitivity, specificity, positive predictive value, and negative predictive value: (1) Quantitative PCR using 47 kDa gene (qPCR); (2) Conventional PCR using 56kDa gene (cPCR); (3) Loop-mediated isothermal amplification assay (LAMP assay); (4) Immunofluorescence assay (IFA); (5) Enzyme-linked immunosorbent assay (ELISA); (6) Weil–Felix test (WF test); and (7) Immunochromatographic Rapid Diagnostic Test (RDT). Results Among the 302 participants, 152 had confirmed scrub typhus (cases) and 150 were controls. ELISA and RDT detecting IgM antibodies had excellent discriminative potential with sensitivities and specificities of 94%, 93% and 92%, 93%, respectively. False-positive IgM serology was observed with spotted fever and leptospirosis. The sensitivity and specificity of IFA were found to be 80% and 85%, respectively. qPCR exhibited excellent sensitivity (96%) and perfect specificity. Conclusion ELISA and RDT detecting IgM antibodies have excellent sensitivity and specificity while the sensitivity of IFA is suboptimal for the diagnosis of scrub typhus. Given its perfect specificity and superior sensitivity, qPCR is preferred for diagnostic confirmation in reference laboratories. Disclosures All authors: No reported disclosures.

scholarly journals Performance of molecular and serologic tests for the diagnosis of scrub typhus

2020 ◽  
Vol 14 (11) ◽  
pp. e0008747
Author(s):  
Kavitha Kannan ◽  
Rebecca John ◽  
Debasree Kundu ◽  
Divya Dayanand ◽  
Kundavaram P. P. Abhilash ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Predictive Value ◽  
Diagnostic Tests ◽  
Scrub Typhus ◽  
Spotted Fever ◽  
Lamp Assay ◽  
Febrile Illness ◽  
Acute Febrile Illness ◽  
Orientia Tsutsugamushi ◽  
Igm Antibodies

Diagnosis of scrub typhus, caused by the bacterium Orientia tsutsugamushi, is challenging because of the overlap of its non-specific symptoms with other infections coupled with the lack of sufficient data on the performance of diagnostic tests. Early diagnosis of scrub typhus is crucial to improve outcomes and this study evaluates the diagnostic performance of various tests. The present study aims at assessing the accuracy of various rapid diagnostic tests, serologic tests, and nucleic acid amplification methods on well-characterized patient samples. Adult patients with acute febrile illness and manifestations suggestive of scrub typhus confirmed by positive PCR in the blood, eschar or tissue were characterized as cases. Patients with acute febrile illness and a confirmed alternate etiology such as culture-confirmed typhoid, smear/PCR positive for malaria, PCR/NS1 antigen positive for dengue, PCR positive for influenza, PCR/MAT positive for leptospirosis, PCR positive for spotted fever were characterized as controls with other infections. The healthy controls consisted of subjects from the same geographic region. We performed the following tests on blood samples for scrub typhus and calculated the sensitivity, specificity, positive predictive value, and negative predictive value: (1) Quantitative real time PCR using 47kDa gene (qPCR); (2) Conventional PCR using 56kDa gene (cPCR); (3) Loop-mediated isothermal amplification assay (LAMP assay); (4) Immunofluorescence assay (IFA); (5) Enzyme-linked immunosorbent assay (ELISA); (6) Weil-Felix test(WF test); and (7) Immunochromatographic Rapid Diagnostic Test (RDT).Among the 316 participants, 158 had confirmed scrub typhus (cases) and 158 were controls. ELISA and RDT detecting Orientia tsutsugamushi specific IgM antibodies had excellent discriminative potential with sensitivities and specificities of 92%, 94% and 92%, 92% respectively. The sensitivity and specificity of IFA were found to be 95% and 74% respectively. IgM serology had a false positivity rate of 8% with other acute febrile illnesses such as dengue, leptospirosis and spotted fever due to the nonspecific binding of the pentavalent IgM. LAMP assay had 91.7% sensitivity and 77.2% specificity while qPCR provided excellent sensitivity (97%) and perfect specificity. In conclusion, ELISA and RDT detecting Orientia tsutsugamushi specific IgM antibodies have excellent sensitivity and specificity while the accuracy of IFA is suboptimal for the diagnosis of scrub typhus. Given its perfect specificity and superior sensitivity, qPCR is preferred for diagnostic confirmation in reference laboratories particularly for diagnosis of early disease with less than 7 days duration. This study provides a comprehensive evaluation of all currently available diagnostic tests for scrub typhus.

scholarly journals Differentiating Scrub Typhus, Dengue Fever and Typhoid Fever in Indian Children Presenting with Acute Febrile Illness

2020 ◽  
Vol 40 (2) ◽  
pp. 93-99
Author(s):  
Saheli Misra Chatterjee ◽  
Suman Mondal ◽  
Kaushik Mukhopadhyay ◽  
Niloy Kumar Das
Keyword(s):  
Dengue Fever ◽  
Scrub Typhus ◽  
Tertiary Care ◽  
Febrile Illness ◽  
Acute Febrile Illness ◽  
Indian Children ◽  
Diagnostic Dilemma ◽  
Female Ratio ◽  
Neutrophil Lymphocyte Ratio ◽  
Lymphocyte Ratio

Introduction: The disease spectrum of dengue, scrub typhus and typhoid presenting as acute febrile illness is often a diagnostic dilemma to the clinician. The purpose of this study is to compare the clinical features and laboratory parameters of children suffering from typhoid, dengue and scrub typhus and use these parameters in early identification of scrub typhus before conclusion is made from serological diagnosis. Methods: A retrospective observational analytical study was conducted among children presenting with acute febrile illness in a tertiary care level hospital. Over the period of one year 113 cases were identified of which 39 were dengue, 44 were typhoid and 30 were scrub typhus. Results: The mean age of the children was 7.45 ± 2.98 years, median was eight with an interquartile range of six to ten years. The male to female ratio was 1.3:1. Symptoms of vomiting (61.54%), headache (46.15%) and hepatomegaly (47.37%) were significantly higher among children with dengue fever. A significantly higher number of children with scrub typhus fever had temperature above 40°C. The incidence of low haemoglobin, raised C reactive protein, raised ALT and low albumin levels were significantly higher in them. Children with acute febrile illness having temperature > 40°C, absolute neutrophil/lymphocyte ratio > 2 early in the illness were more likely to suffer from scrub typhus with relative probability ratio (RPR) of 25.68 and 10.57 respectively (p < 0.001). Children with WBC < 5000/mm3 were more likely to be suffering from dengue with RPR of 10.60 (p < 0.001). Conclusion: Children with acute febrile illness with temperature > 40°C and absolute neutrophil/lymphocyte ratio > 2 early in the illness were more likely to be suffering from scrub typhus.

scholarly journals Evaluation of Loop-Mediated Isothermal Amplification Assay for the Detection of Pneumocystis jirovecii in Immunocompromised Patients

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Preeti Singh ◽  
Sundeep Singh ◽  
Bijay Ranjan Mirdha ◽  
Randeep Guleria ◽  
Sanjay Kumar Agarwal ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Nested Pcr ◽  
Lamp Assay ◽  
High Sensitivity ◽  
Single Step ◽  
Isothermal Amplification ◽  
Pneumocystis Jirovecii ◽  
Immunocompromised Patients ◽  
Loop Mediated Isothermal Amplification ◽  
Common Opportunistic Infection

Pneumocystis pneumonia (PCP) is one of the common opportunistic infection among HIV and non-HIV immunocompromised patients. The lack of a rapid and specific diagnostic test necessitates a more reliable laboratory diagnostic test for PCP. In the present study, the loop-mediated isothermal amplification (LAMP) assay was evaluated for the detection of Pneumocystis jirovecii. 185 clinical respiratory samples, including both BALF and IS, were subjected to GMS staining, nested PCR, and LAMP assay. Of 185 respiratory samples, 12/185 (6.5%), 41/185 (22.2%), and 49/185 (26.5%) samples were positive by GMS staining, nested PCR, and LAMP assay, respectively. As compared to nested PCR, additional 8 samples were positive by LAMP assay and found to be statistically significant (p<0.05) with the detection limit of 1 pg. Thus, the LAMP assay may serve as a better diagnostic tool for the detection of P. jirovecii with high sensitivity and specificity, less turn-around time, operational simplicity, single-step amplification, and immediate visual detection.

scholarly journals Diagnostic tools used in the evaluation of acute febrile illness in South India: a scoping review

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Divyalakshmi Bhaskaran ◽  
Sarabjit Singh Chadha ◽  
Sanjay Sarin ◽  
Rajashree Sen ◽  
Sonia Arafah ◽  
...  
Keyword(s):  
Scoping Review ◽  
Low Income ◽  
South India ◽  
Scrub Typhus ◽  
Tertiary Care ◽  
Febrile Illness ◽  
Low Income Countries ◽  
Diagnostic Tools ◽  
Original Research ◽  
Acute Febrile Illness

Abstract Background Acute febrile illness (AFI) is characterized by malaise, myalgia and a raised temperature that is a nonspecific manifestation of infectious diseases in the tropics. The lack of appropriate diagnostics for the evaluation of AFI leads to increased morbidity and mortality in resource-limited settings, specifically low-income countries like India. The review aimed to identify the number, type and quality of diagnostics used for AFI evaluation during passive case detection at health care centres in South India. Methods A scoping review of peer-reviewed English language original research articles published between 1946-July 2018 from four databases was undertaken to assess the type and number of diagnostics used in AFI evaluation in South India. Results were stratified according to types of pathogen-specific tests used in AFI management. Results The review included a total of 40 studies, all conducted in tertiary care centres (80% in private settings). The studies demonstrated the use of 5–22 tests per patient for the evaluation of AFI. Among 25 studies evaluating possible causes of AFI, 96% tested for malaria followed by 80% for dengue, 72% for scrub typhus, 68% for typhoid and 60% for leptospirosis identifying these as commonly suspected causes of AFI. 54% studies diagnosed malaria with smear microscopy while others diagnosed dengue, scrub typhus, typhoid and leptospirosis using antibody or antigen detection assays. 39% studies used the Weil-Felix test (WFT) for scrub typhus diagnosis and 82% studies used the Widal test for diagnosing typhoid. Conclusions The review demonstrated the use of five or more pathogen-specific tests in evaluating AFI as well as described the widespread use of suboptimal tests like the WFT and Widal in fever evaluation. It identified the need for the development of better-quality tests for aetiological diagnosis and improved standardised testing guidelines for AFI.

scholarly journals Rapid detection of a novel B1-β-lactamase gene, blaAFM-1 using a loop-mediated isothermal amplification (LAMP) assay

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Yingcheng Qin ◽  
Xiaonv Duan ◽  
Yuan Peng ◽  
Yongyu Rui
Keyword(s):  
Recombinant Plasmid ◽  
Sanger Sequencing ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
Conventional Pcr ◽  
Predictive Values ◽  
Clinical Strains ◽  
Loop Mediated Isothermal Amplification ◽  
Two Samples ◽  
Lactamase Gene

Abstract Background BlaAFM-1 (GenBank Accession No. 143105.1) is a new B1 subclass metallo-β-lactamase gene discovered by our group, and isolated from an Alcaligenes faecalis plasmid that renders carbapenem antibiotics ineffective. In this study, we generated a fast and reliable assay for blaAFM-1 detection. Methods We designed optimum loop-mediated isothermal amplification (LAMP) primers and constructed a recombinant plasmid AFM-1 to specifically detect blaAFM-1. Optimal LAMP primers were used to assess sensitivity of the recombinant plasmid AFM-1 and blaAFM-1-supplemented samples (simulated sputum and simulated feces). Fifty two samples, without blaAFM-1, were used to assess LAMP real-time assay specificity; these samples were verified by conventional PCR and sequencing for the absence of blaAFM-1. Three hundred clinical Gram-negative carbapenem-resistant strains were tested by LAMP assay for strains carrying blaAFM-1, which were confirmed by conventional PCR and Sanger sequencing. We calculated the sensitivity and its 95% confidence interval (95% CI), specificity and its 95% CI, and predictive values of the LAMP assay and conventional PCR/sequencing by investigating positive and negative clinical strains. Results The lowest limit of detection for the recombinant plasmid AFM-1 and blaAFM-1-supplemented samples (in both simulated sputum and simulated feces) was 101 copies/reaction. All amplification curves of the 52 blaAFM-1-free bacteria strains were negative, suggesting the LAMP assay had excellent specificity for detecting blaAFM-1. Among the 300 clinical strains, eight were positive for blaAFM-1 using LAMP. These LAMP results were consistent with conventional PCR and Sanger sequencing data. As with conventional PCR/sequencing, the LAMP method exhibits 100% sensitivity (95% CI 59.8–100%) and 100% specificity (95% CI 98.4–100%) for blaAFM-1 detection. The LAMP assay is also time-efficient (1 h) for blaAFM-1 detection. Conclusions We established a new LAMP assay with high sensitivity and specificity to detect the novel B1-β-lactamase gene, blaAFM-1.

scholarly journals Scrub typhus infection, not a benign disease: an experience from a tertiary care center in Northern India

2019 ◽  
Vol 92 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Deepak Jain ◽  
Nitya Nand ◽  
Kajaree Giri ◽  
Jaikrit Bhutani
Keyword(s):  
Scrub Typhus ◽  
Care Center ◽  
Invasive Mechanical Ventilation ◽  
Tertiary Care ◽  
Febrile Illness ◽  
North India ◽  
Acute Febrile Illness ◽  
Orientia Tsutsugamushi ◽  
Tertiary Care Centre ◽  
Function Tests

Introduction. Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi. It is characterised by fever, rash, myalgia and diffuse lymphadenopathy. Most common complications are sepsis, shock, acute respiratory distress syndrome (ARDS), hepatitis, pre renal azotemia and multi organ dysfunction syndrome (MODS). Mortality rates range from 7-30% in untreated cases. Scrub typhus is endemic to a part of the world known as ‘the tsutsugamushi triangle’. River banks, grassy areas generally harbour scrub typhus infection; however, recently there has been an increase in prevalence of infection from dry regions like Haryana. Objective. To assess the clinical spectrum and complications of scrub typhus infection at a tertiary care centre in North India. Material and methods. An observational study was conducted on patients >14 years old with acute febrile illness >7 days duration, admitted indoor from emergency department, from July to November 2017. Suspected cases were tested for specific IgM antibodies against Orientia tsutsugamushi by ELISA. Results. Among the 230 patients, screened for scrub typhus infection, 39 (16.95%) came out to be positive. Most common patient complaints were fever followed by cough and breathlessness, myalgia, nausea, vomiting and behavioral abnormality. 15% of patients required inotropic support initially and 48% had oxygen saturation of less than 90% at the time of presentation. Pleural effusion and crepitations were present in 41% of patients. Most common biochemical alterations were: abnormal liver function tests (95%), followed by thrombocytopenia, anemia, abnormal renal function tests, and hyponatremia. 12 patients (30.7%) were shifted to intensive care unit, 8 of which (20.5%) needed invasive mechanical ventilation and 4 patients (10.3%) underwent hemodialysis. Various complications were noted in 89.7% of cases, the most common being ARDS followed by sepsis, acute kidney injury (AKI) and meningitis. The mortality rate in this study was 18%. Conclusions. This study emphasizes that scrub typhus infection is on a rampant resurgence and it is associated with significant complications. High degree of suspicion as well as development of effective measures to treat, control and prevent is critical to lower the disease burden.

scholarly journals Burden of scrub typhus among patients with acute febrile illness attending tertiary care hospital in Chitwan, Nepal

BMJ Open ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. e034727
Author(s):  
Sangita Thapa ◽  
Pradip Hamal ◽  
Navin Kumar Chaudhary ◽  
Lokendra Bahadur Sapkota ◽  
Jaya Prasad Singh
Keyword(s):  
Scrub Typhus ◽  
Tertiary Care ◽  
College Teaching ◽  
Febrile Illness ◽  
Care Hospital ◽  
Acute Febrile Illness ◽  
Medical College ◽  
Igm Elisa ◽  
High Prevalence ◽  
And Control

ObjectivesScrub typhus is an emerging neglected tropical disease, reported from many parts of Asia including Nepal. This study aims to determine the seroepidemiology of scrub typhus among febrile patients attending Chitwan Medical College Teaching Hospital (CMC-TH), Bharatpur, Nepal.Study design and settingThis was a hospital laboratory-based prospective study conducted in CMC-TH (a 750-bed hospital) located in Bharatpur, Chitwan district of Nepal.ParticipantsA total of 1797 patients visiting CMC-TH with acute febrile illness (temperature more than 38°C) were enrolled in this study.MethodsA total of 1797 blood samples were collected from patients presenting with acute febrile illness. The samples were processed for detection of antibody for scrub typhus by ELISA for specific IgM antibody and Weil-Felix test.ResultsOut of 1797 serum sample of febrile patients, 524 (29.2%) were scrub typhus positive. Maximum seropositive cases were from Chitwan district, 271 (51.7%) with predominance among women, 314 (35.9%). Scrub typhus was common among age group 51–60 years (37.2%) and farmers, 182 (37.8%). Highest seropositivity was found in July, 60 (57.7%). Fever was common clinical symptom. Thrombocytopenia was seen in 386 (73.7%) and raised transaminase aspartate aminotransferase, 399 (76.1%) among seropositive cases. Weil-Felix test positive were 397 (22.1%) and IgM ELISA positive were 524 (29.2%). The correlation between IgM ELISA and Weil-Felix test showed statistically significant association (r=0.319, p<0.001).ConclusionHigh prevalence of scrub typhus implies that patients with acute febrile illness should be investigated for scrub typhus with high priority. There is utmost need of reliable diagnostic facilities at all levels of healthcare system in Nepal. Infection with scrub typhus was found high and this calls for an urgent need to introduce vaccine against scrub typhus. More sustain and vigorous awareness programmes need to be promoted for early diagnosis, treatment and control.

scholarly journals A study on clinical profile of acute undifferentiated febrile illness in a tertiary care hospital

2020 ◽  
Vol 7 (3) ◽  
pp. 404
Author(s):  
Mariraj I. ◽  
Mohammed Adil ◽  
Ramkumar M. ◽  
Jagadeesan M. ◽  
Prasanna Karthik S. ◽  
...  
Keyword(s):  
Enteric Fever ◽  
Scrub Typhus ◽  
Tertiary Care Hospital ◽  
Tertiary Care ◽  
Febrile Illness ◽  
Clinical Profile ◽  
Malarial Parasite ◽  
Care Hospital ◽  
Acute Febrile Illness ◽  
Function Test

Background: Acute febrile illness is very common among patients seeking hospital care in tropical country like India. This study was conducted to evaluate etiology and clinical profile of Acute Undifferentiated Febrile Illness (AUFI) in a tertiary care hospital.Methods: This study was conducted in 175 patients with acute febrile illness who were admitted in the medical wards and ICU from January 2018 to June 2019 in a tertiary care hospital. Clinical examination and investigations like complete hemogram, liver function test, renal function test, smear for malarial parasite, widal test, urine analysis blood and urine culture, antibody titters for dengue, Leptospirosis and imaging were done.Results: Out of 175, 94 (54%) were males and 81 (46%) were females. The commonest etiology was dengue (19%) followed by enteric fever (18%), scrub typhus (16%), malaria (14%), tuberculosis (6%) and leptospirosis (5%). 138 (79%) patients had less than 14 days of fever of which dengue was the most common and 37 (21%) patients had more than 14 days of fever with tuberculosis being predominate. Other common symptoms were chills/rigors, headache and myalgia seen in 77%, 71% and 42% respectively. Icterus was seen in malaria (42%) and leptospirosis (38%). Elevated transaminases levels were observed with dengue, leptospirosis, scrub typhus, enteric fever and malaria. ARDS was most common in scrub typhus.Conclusions: Among acute febrile illness, dengue and enteric fever were the most common in this study. A thorough and probing search for an eschar is very important in scrub typhus. The treating physician has to keep in mind the comprehensive list of differential diagnosis for patients with febrile illness and anticipating the complications.

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