Comparative study of Typhidot-M with Widal and blood culture in diagnosis of enteric fever

Objective: To evaluate the diagnostic utility of Typhidot-M and Widal test in the early diagnosis of enteric fever (EF) in terms ofsensitivity and specificity. Methods: The study included 270 children in the age group of 1-18 years admitted to the Department ofPediatrics from November 2012 to February 2014, with fever of 5 days or more and with clinical symptoms and signs suggestiveof typhoid fever. Detailed history and clinical examination findings were recorded on a standard pro forma. Complete hemogram(hemoglobin, platelet count, and total and differential leukocyte count), Typhidot-M test, Widal tube test, and blood culture weredone on day 1 of admission. For Widal test, a titer of 1 in 160 or more for “O” agglutinins and a titer of 1 in 320 or more for “H”agglutinins were considered as positive results. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value(NPV) were calculated. Results: Of 270 children included in the study, Salmonella typhi was isolated from 82 samples (30.4%)and the remaining 188 (69.6%) were blood culture negative. Widal test was positive in 107 children (39.6%) and Typhidot-M waspositive in 136 (50.4%). The sensitivity was 78%, specificity was 79.3%, PPV was 59.8%, and NPV was 91.4% for Widal test.Typhidot-M test had a sensitivity of 81.7%, specificity of 84.6%, PPV of 69.8%, and NPV of 91.4%. Conclusion: Prompt diagnosisof EF is essential for appropriate management and it is, therefore, important to have a satisfactory test to replace conventional testsused for diagnosis. The present study compares newer test (Typhidot-M) against conventional tests such as Widal test and bloodculture, and it appears to be a practical alternative to Widal test in the early detection of EF even in the resource-poor laboratoriesas it neither requires much laboratory equipment nor laboratory expertise to conduct the test. This test can be done within 7 daysof illness, but whenever feasible confirmation with blood culture is strongly recommended, especially with the well-documentedpresence of multidrug-resistant strains of salmonella typhi worldwide. However, both Widal and Typhidot-M appear to correlateless satisfactorily with blood culture, and thus, there is a need for developing a test which allows accurate and early diagnosis of EFto manage a child effectively and limit its morbidity and mortality

In Vitro Efficacy of Biocompatible Zinc Ion Chelating Molecules as Metallo-β-Lactamase Inhibitor among NDM Producing Escherichia coli

Objective This article assesses the effectiveness of captopril, tetracycline, and ciprofloxacin as metallo-β-lactamase (MBL) inhibitors against New Delhi metallo-β-lactamase (NDM)-producing Escherichia coli. Materials and Methods Twenty-four well-characterized carbapenem-resistant E. coli isolates which produced NDM (n = 21) and Oxa-48-like enzymes (n = 3) were used to assess the inhibitors. The positive control organism was designed by cloning the NDM gene into pET-24a plasmid and transforming it into expression vector E. coli BL21. All the proposed inhibitors were assessed for their interaction with MBLs using checkerboard minimum inhibitory concentration (MIC) assay with imipenem and meropenem. The fractional inhibitory concentration (FIC) index was calculated to assess the activity of molecules. Results The E. coli BL21 (DE3) pET-24a-bla NDM showed carbapenem resistance upon isopropyl β-D-1-thiogalactopyranoside induction and had MIC of 32 µg/mL for both imipenem and meropenem. For the test isolates, ∑FIC values of imipenem and meropenem with ethylenediaminetetraacetic acid (EDTA) ranged from 0.039 to 0.266 and 0.023 to 0.156, respectively. At a 256 µg/mL concentration, captopril had ∑FIC index value for imipenem and meropenem as 0.133 to 0.375 and 0.133 to 0.188, respectively. The tetracycline and ciprofloxacin in combination with meropenem/imipenem showed indifferent results. Conclusion Among the three molecules tested, captopril had MBL inhibitory activity, but the concentration required for inhibition was beyond the therapeutic safety levels. Ciprofloxacin and tetracycline had weak or no MBL inhibitory activity. Checkerboard MIC of EDTA with carbapenem antibiotic and control organism with NDM enzyme production helped us create a reference system for comparing and assessing the results of potential MBL inhibitors in future