RESUMO
Introduction: EQAS program at New Delhi under IAMM was started in January 2014 across North and North east regions of India with 217 participants, which grew up to 540 by 2018. Materials and Methods: In 2014, 4 analytes per year were sent for 3 exercises, i.e. smear culture and serology. 2018 onwards PT analytes were increased from 4 to 12 and comparative performance of techniques analysed. Results: Out of the 22 smears sent for gram staining, ZN staining, Kinyoun staining and Albert staining, completely correct results ranged between 29.55% - 79.9%, 94.3% - 99.2%, 35.5% & 93.8%, respectively. Correct results for culture isolate identification & susceptibility testing and serology exercises varied between 70 & 92.4% and 73.1 & 98.59%, respectively. In the year 2018, 470 responses were received for bacterial culture identification & antibiotic susceptibility testing out of which manual and automated systems were used by 54% & 46% and 52.5% & 47.5% participants, respectively. Techniques used in BBV assays for HBsAg, HCV & HIV found all methods like ELISA, ELFA, CLIA and Card Test performing similarly. The major challenges in running the EQA program included requirement of large amount of specimens for PT item preparation, stability in hot and humid conditions and timely delivery of PT challenges in remote parts of the country. Conclusion: A large number of the participating laboratories (77%) had an overall score of >80% for all exercises, demonstrating acceptable baseline performance of EQAS registered laboratories. However, continued EQAS participation could further improve the quality of results.
RESUMO
Purpose: Enteric fever is a major public health problem in developing countries like India. An early and accurate diagnosis is necessary for a prompt and effective treatment. We have evaluated the diagnostic accuracy of two Rapid Salmonella‑IgM tests (Typhidot‑IgM and Enteroscreen‑IgM) as compared to blood culture in rapid and early diagnosis of enteric fever. Materials and Methods: A total of 2,699 patients’ serum samples were tested by Rapid Salmonella‑IgM tests and blood culture. Patients were divided into two groups. Test group—patients with enteric fever and blood culture positives for Salmonella Typhi; and three types of Controls, i.e. patients with non‑enteric fever illnesses, normal healthy controls and patients positive for S. Paratyphi‑ A. In addition to this we have also evaluated the significance of positive Salmonella‑IgM tests among blood culture‑negative cases. Results: The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the Typhidot‑IgM test and Enteroscreen‑IgM test considering blood culture as gold standard were 97.29% and 88.13%, 97.40% and 87.83%, 98.18% and 92.03%, 96.15% and 82.27%, respectively. Typhidot‑IgM test was found to be significantly more sensitive and specific as compared to Enteroscreen‑IgM. Among blood culture‑negative patients, Rapid Salmonella‑IgM tests detected 72.25% additional cases of enteric fever. Although the Rapid Salmonella‑IgM tests are meant to diagnose S. Typhi only, but these tests detect S. Paratyphi‑ A also. Thirty‑eight patients who were blood culture‑positive for S. Paratyphi‑ A were also positive by Rapid Salmonella‑IgM tests. Conclusion: Rapid Salmonella‑IgM tests offer an advantage of increased sensitivity, rapidity, early diagnosis and simplicity over blood culture.