Validation of a PCR for diagnosis of typhoid fever and salmonellosis by amplification of the hilA gene in clinical samples from Colombian patients.
Validation of a PCR test to detect hilA gene sequences of Salmonella spp. was performed in blood and faeces samples from typhoid fever and salmonellosis patients. Sensitivity (S), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV) of the PCR in blood samples were performed by testing: 37 patients with clinical diagnosis of typhoid fever, 34 of them confirmed by isolation of S. Typhi from blood cultures; 35 patients infected with other pathogens corroborated by blood culture (Klebsiella pneumoniae, 9; Serratia marcescens, 5; Escherichia coli, 4; Pseudomonas aeruginosa, 9; Providencia alcalifaciens, 4 and Enterobacter cloacae, 4) and blood samples from 150 healthy volunteers. To evaluate S, SP, PPV and NPV of the PCR in faeces samples we studied: 34 patients with enteritis due Salmonella spp. (S. Typhimurium, 21; S. Enteritidis, 9; S. Choleraesuis, 3 and S. Agona, 1); faeces samples from 35 patients with enteric infection due to Shigella sonnei (8), Shigella flexneri (10), enteropathogenic E. coli (12), Aeromonas hydrophila (5) and faeces samples from 150 healthy volunteers. The S, SP, PPV and NPV of the PCR in blood samples were all 100 %. PCR detected three patients with clinical diagnosis of typhoid fever and negative blood cultures. In faeces samples, S was 97 %, SP 100 %, PPV 100 % and NPV 99 %. The lowest number of c.f.u. ml(-1) detected by PCR in blood samples was 1 x 10(1) and in faeces samples 4 x 10(2).
Sánchez-Jiménez
M M
MM
Laboratorio de Microbiología, Instituto Colombiano de Medicina Tropical, Cra 43a No. 52 Sur 99, Sabaneta, Colombia 2Facultad de Medicina Universidad de Antioquia Programa de Maestría Ciencias Básicas Biomédicas, Colombia 3Instituto de Ciencias de la Salud CES, Medellín, Colombia.
Cardona-Castro
Nora
N
Laboratorio de Microbiología, Instituto Colombiano de Medicina Tropical, Cra 43a No. 52 Sur 99, Sabaneta, Colombia 2Facultad de Medicina Universidad de Antioquia Programa de Maestría Ciencias Básicas Biomédicas, Colombia 3Instituto de Ciencias de la Salud CES, Medellín, Colombia.
D001426:Bacterial Proteins; D001769:Blood / Q000382:microbiology; D003105:Colombia; D005243:Feces / Q000382:microbiology; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011237:Predictive Value of Tests; D012480:Salmonella Infections / Q000175:diagnosis* / Q000382:microbiology; D019779:Salmonella enterica / Q000235:genetics / Q000302:isolation & purification*; D012485:Salmonella typhi / Q000235:genetics / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D015534:Trans-Activators / Q000235:genetics; D014435:Typhoid Fever / Q000175:diagnosis* / Q000382:microbiology
D001426:Bacterial Proteins; C102236:HilA protein, Salmonella; D015534:Trans-Activators