Diagnostic accuracy of antigen detection in urine and molecular assays testing in different clinical samples for the diagnosis of progressive disseminated histoplasmosis in patients living with HIV/AIDS: A prospective multicenter study in Mexico.

BACKGROUND: The progressive disseminated histoplasmosis (PDH) has been associated with severe disease and high risk of death among people living with HIV (PLWHIV). Therefore, the purpose of this multicenter, prospective, double-blinded study done in ten Mexican hospitals was to determine the diagnostic accuracy of detecting Histoplasma capsulatum antigen in urine using the IMMY ALPHA Histoplasma EIA kit (IAHE), clarus Histoplasma GM Enzyme Immunoassay (cHGEI IMMY) and MiraVista Histoplasma Urine Antigen LFA (MVHUALFA); as well as the Hcp100 and 1281-1283220SCAR nested PCRs in blood, bone-marrow, tissue biopsies and urine. METHODOLOGY/PRINCIPAL FINDINGS: We included 415 PLWHIV older than 18 years of age with suspicion of PDH. Using as diagnostic standard recovery of H. capsulatum in blood, bone marrow or tissue cultures, or histopathological exam compatible, detected 108 patients (26%, [95%CI, 21.78-30.22]) with proven-PDH. We analyzed 391 urine samples by the IAHE, cHGEI IMMY and MVHUALFA; the sensitivity/specificity values obtained were 67.3% (95% CI, 57.4-76.2) / 96.2% (95% CI, 93.2-98.0) for IAHE, 91.3% (95% CI, 84.2-96.0) / 90.9% (95% CI, 87.0-94.0) for cHGEI IMMY and 90.4% (95% CI, 83.0-95.3) / 92.3% (95% CI, 88.6-95.1) for MVHUALFA. The Hcp100 nested PCR was performed on 393, 343, 75 and 297, blood, bone marrow, tissue and urine samples respectively; the sensitivity/specificity values obtained were 62.9% (95%CI, 53.3-72.5)/ 89.5% (95%CI, 86.0-93.0), 65.9% (95%CI, 56.0-75.8)/ 89.0% (95%CI, 85.2-92.9), 62.1% (95%CI, 44.4-79.7)/ 82.6% (95%CI, 71.7-93.6) and 34.9% (95%CI, 24.8-46.2)/ 67.3% (95%CI, 60.6-73.5) respectively; and 1281-1283220SCAR nested PCR was performed on 392, 344, 75 and 291, respectively; the sensitivity/specificity values obtained were 65.3% (95% CI, 55.9-74.7)/ 58.8% (95%CI, 53.2-64.5), 70.8% (95%CI, 61.3-80.2)/ 52.9% (95%CI, 46.8-59.1), 71.4% (95%CI, 54.7-88.2)/ 40.4% (95%CI, 26.4-54.5) and 18.1% (95%CI, 10.5-28.1)/ 90.4% (95%CI, 85.5-94.0), respectively. CONCLUSIONS/SIGNIFICANCE: The cHGEI IMMY and MVHUALFA tests showed excellent performance for the diagnosis of PDH in PLWHIV. The integration of these tests in clinical laboratories will certainly impact on early diagnosis and treatment.

Distribución de genes de adhesión y regulación de biofilm en Staphylococcus aureus / Distribution of adhesion and biofilm regulation genes in Staphylococcus aureus / Distribuição dos genes de adesão e regulação de biofilme em Staphylococcus aureus

La formación de biofilms es un importante factor de virulencia que contribuye en la cronicidad de los procesos infecciosos producidos por Staphylococcus aureus. Las proteínas presentes en su superficie pueden promover la formación de biofilm. En este estudio se comparó la distribución de genes que codifican para proteínas de adhesión asociadas con la formación de biofilm en cepas resistentes (MRSA) y sensibles a meticilina (MSSA). Al analizar un total de 106 aislados obtenidos de muestras sólidas y líquidas recuperados de un hospital de México, se determinó que la formación de biofilm está asociada de manera significativa a cepas MRSA (83%). Mediante la reacción en cadena de la polimerasa (PCR), se buscó la presencia de nueve genes de adhesinas (eno, ebps, fnbA, fnbB, fib, clfA, clfB, bbp, y cna) y dos de regulación del biofilm (icaA, icaD). Los resultados mostraron que los genes icaA, icaD, eno, ebps, clfA, clfB se amplificaron en todas las cepas mientras que los genes fnbA, fnbB, fib, y bbp tuvieron una distribución variable. Los datos obtenidos muestran por primera vez que la presencia del gen cna se encuentra asociada a cepas MSSA y no productoras de biofilm (p<0,05).

Biofilm formation is an important virulence factor that contributes to the chronicity of the infectious processes caused by Staphylococcus aureus. The proteins on the surface of this bacterium can promote the formation of a biofilm. The distribution of genes encoding adhesion proteins associated with biofilm formation in methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) strains was compared in this study. The analysis of a total of 106 isolates obtained from solid and liquid samples collected from a hospital in Mexico showed that biofilm formation was significantly associated with MRSA strains (83%). The presence of nine adhesine genes (eno, ebps, fnbA, fnbB, fib, clfA, clfB, bbp, cna) and two biofilm regulatory genes (icaA, icaD) was looked for by polymerase chain reaction (PCR). The results evidenced that icaA, icaD, eno, ebps, clfA, and clfB genes were amplified from all strains, while fnbA, fnbB, fib, and bbp genes were non-uniformly distributed among them. Notably, the results showed for the first time that the presence of the cna gene is associated with biofilm non-producing MSSA strains (p<0.05).

A formação de biofilmes é um fator de virulência importante que contribui para a cronicidade dos processos infecciosos produzidos por Staphylococcus aureus. As proteínas presentes em superfície podem promover a formação de biofilme. Neste estudo, comparou-se a distribuição de genes que codificam para proteínas de adesão associadas com a formação de biofilmes em cepas resistentes (MRSA) e sensíveis à meticilina (MSSA). A análise de um total de 106 isolados obtidos a partir de amostras sólidas e líquidas coletadas em um hospital no México mostrou que a formação de biofilme é associada significativamente a cepas MRSA (83%). A técnica de reação em cadeia da polimerase (PCR) foi utilizada para verificar a presença de nove genes de adesinas (eno, ebps, fnbA, fnbB, fib, clfA, clfB, bbp, cna) e dois genes reguladores do biofilme (icaA, icaD). Os resultados mostraram que os genes icaA, icaD, eno, ebps, clfA, clfB foram amplificados em todas as cepas, enquanto que os genes fnbA, fnbB, fib, e bbp tiveram uma distribuição variável. Os dados obtidos mostram pela primeira vez que a presença do gene cna está associada a cepas MSSA e não produtoras de biofilme (p<0,05).