Presence of black and red colored test lines.

<p>Samples applied to both tests (<i>Salmonella</i> Ag Rapid Test, Creative diagnostics) contained <i>Salmonella</i> Enteritidis and both were scored as a positive test result. The test above shows a red colored control line and a black colored test line. The picture below shows a red colored control and test line.</p

Diagnostic accuracy of antigen-based immunochromatographic rapid diagnostic tests for the detection of <i>Salmonella</i> in blood culture broth

<div><p>Background</p><p>In low resource settings, <i>Salmonella</i> serovars frequently cause bloodstream infections. This study investigated the diagnostic performance of immunochromatographic rapid diagnostic tests (RDTs), which detect <i>Salmonella</i> antigens, when applied to stored grown blood culture broth.</p><p>Material/Methods</p><p>The SD Bioline One Step <i>Salmonella</i> Typhi Ag Rapid Detection Kit (Standard Diagnostics, Republic of Korea), marketed for the detection of <i>Salmonella enterica</i> serovar Typhi (<i>Salmonella</i> Typhi) in stool and the <i>Salmonella</i> Ag Rapid Test (Creative Diagnostics, USA), marketed for the detection of all <i>Salmonella</i> serotypes in stool, were selected for evaluation based on a pre-test evaluation of six RDT products. The limits of detection (LOD) for culture suspensions were established and the selected RDT products were assessed on 19 freshly grown spiked blood culture broth samples and 413 stored clinical blood culture broth samples, collected in Cambodia and the Democratic Republic of the Congo.</p><p>Results</p><p>The LOD of both products was established as 10⁷−10⁸ CFU/ml. When applied to clinical blood culture broth samples, the diagnostic sensitivity and specificity of the SD Bioline RDT were respectively 100% and 79.7% for the detection of <i>Salmonella</i> Typhi; 94.4% (65/69) of false-positive results were caused by <i>Salmonella</i> Enteritidis. When considering the combined detection of <i>Salmonella</i> Typhi and Enteritidis (both group D <i>Salmonella</i>), sensitivity and specificity were 97.9% and 98.5% respectively. For Creative Diagnostics, diagnostic sensitivity was 78.3% and specificity 91.0% for all <i>Salmonella</i> serotypes combined; 88.3% (53/60) of false negative results were caused by <i>Salmonella</i> Paratyphi A.</p><p>Conclusions</p><p>When applied to grown blood culture broths, the SD Bioline RDT had a good sensitivity and specificity for the detection of <i>Salmonella</i> Typhi and <i>Salmonella</i> Enteritidis. The Creative Diagnostics product had a moderate sensitivity and acceptable specificity for the detection of all <i>Salmonella</i> serovars combined and needs further optimization. A RDT that reliably detects <i>Salmonella</i> Paratyphi A is needed.</p></div

Demographic, clinical and laboratory results of MDR suspects (n = 9).

<p><b>A1</b>: First contact of case A; <b>A2</b>: Second contact of case A; <b>B1</b>: First contact of case B; <b>C1</b>: First contact of case C; <b>D1</b>: First contact of case D. <b>M</b>: male; <b>F</b>: female. <b>F1</b>: Failure in WHO standard first line treatment regimen for category 1 for new cases; <b>F2</b>: Failure in WHO standard first line treatment regimen for category 2 retreatment cases; <b>R2</b>: Relapse in WHO standard first line treatment regimen for category 2 retreatment cases. <b>NA</b>: Not applicable. <b>N° of FLD</b>: Number of first-line drugs. <b>SM</b>: smear microscopy results. <b>NG</b>: no growth. <b>ID</b>: identification. <b>MTBC</b>: <i>Mycobacterium tuberculosis</i> complex. <b>NT</b>: not tested. <b>R</b>: Resistant; <b>S</b>: sensitive; <b>C</b>: contaminated. <b>SLD</b>: second-line drugs.</p

Bacterial strains used for spiking blood culture bottles and corresponding rapid diagnostic test results.

<p>Bacterial strains used for spiking blood culture bottles and corresponding rapid diagnostic test results.</p

Determination of limit of detection and corresponding test line intensity for each rapid diagnostic test.

<p>Determination of limit of detection and corresponding test line intensity for each rapid diagnostic test.</p

Variable background clearance.

<p>Both tests shown (Standard Diagnostics Bioline One Step <i>Salmonella</i> Typhi Ag Rapid Detection Kit) with the presence of a control line and absence of a test line, show a negative test result. Background clearance is scored poor for the test above (more reddish) and good for the test below.</p

Phage type distribution among the S. Enteritidis population over the 6-year period (n- = 1,498; other: all phage types with less than 3% occurrence in the same combined population.

<p>Phage type distribution among the S. Enteritidis population over the 6-year period (n- = 1,498; other: all phage types with less than 3% occurrence in the same combined population.</p

Characteristics of the <i>Salmonella</i> antigen-based immunochromatographic rapid diagnostic tests evaluated.

<p>Characteristics of the <i>Salmonella</i> antigen-based immunochromatographic rapid diagnostic tests evaluated.</p

Minimal inhibitory concentrations and antimicrobial resistance in 233 non-typhoidal <i>Salmonella</i> from DR Congo.

<p>MIC: Minimal Inhibitory Concentration (mg/l); TMP-SMX: trimethoprim/sulphamethoxazole; MDR: multidrug resistant (Co-resistance against ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole), DCS: decreased ciprofloxacin susceptibility; na not applicable.</p>a<p>intermediate susceptible isolates were considered together with the resistant isolates;</p>b<p><a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002103#pntd.0002103-EUCAST1" target="_blank">[24]</a>.</p

Origin of blood cultures and NTS in DR Congo (number of NTS grown/number of blood cultures received at INRB).

<p>Approximate positions of Kinshasa (4°23′S 15°26′E), Bambesa (3°27′N 25°43′E) and the equator are indicated.</p