Samuel Ponce de León

Contamination of intravenous fluids: A continuing cause of hospital bacteremia

BACKGROUND Nosocomial bacteremia caused by the contamination of intravenous (IV) infusates is considered rare. Unfortunately, this problem has been underestimated because its identification requires culturing infusates, a procedure not performed routinely. METHODS This study was conducted in a referral hospital where IV infusates are admixed in nursing areas. The aim was to determine the prevalence of infusate contamination in adult patients with gram-negative rod (GNR) bacteremia. Over a period of 32 months, a specimen of infusate was drawn for culture from each patient recruited after the laboratory reported a GNR in the blood. RESULTS A total of 384 infusates were cultured from 384 patients who had been diagnosed with GNR bacteremia. Seven infusates grew a GNR in culture, for a contamination rate of 2% (7/384; 95% confidence interval [CI] = 1% to 3%). In all cases, the infectious organism was the same as the organism isolated from the blood. Infusate contamination was responsible for 7% (7/108; 95% CI = 2% to 11%) of all primary bloodstream infections and 11% (7/62; 95% CI = 2% to 22%) of all primary bloodstream infections not associated with central venous catheter infection. CONCLUSIONS For patients in hospitals where IV drugs are admixed in nursing units, we recommend instituting infusate culture as routine practice following the diagnosis of a GNR in the blood.

Infecciones nosocomiales: tendencias seculares de un programa de control en México

OBJETIVO. Determinar la frecuencia de infecciones nosocomiales en el Instituto Nacional de la Nutricion Salvador Zubiran (INNSZ) desde la instauracion del programa de vigilancia hasta la actualidad y conocer su impacto en estancia hospitalaria y mortalidad. MATERIAL Y METODOS. Se realizo un estudio descriptivo, retrospectivo y retrolectivo en un hospital de referencia de tercer nivel de atencion. Se obtuvieron las frecuencias, el tipo y la distribucion de infecciones nosocomiales de la base de datos del Departamento de Epidemiologia Hospitalaria entre 1991 y 1996. Se determino en cada paciente el grado de gravedad de su enfermedad mediante la escala de McCabe-Jackson, asi como la edad promedio y el tiempo de estancia hospitaria. Se aplico la prueba de ji² para tendencias de los diferentes parametros evaluados. El estudio se dividio en tres etapas: prerremodelacion (1991-1993), remodelacion (1994-1995) y posremodelacion (1996). Se compararon los periodos prerremodelacion contra posremodelacion. RESULTADOS. Durante este periodo (1991-1996) la tasa de infecciones nosocomiales fue de 8.6 por 100 egresos en promedio, con una disminucion de 20% en su frecuencia a lo largo del mismo (p< 0.01), comparando las tasas que se observaron durante la prerremodelacion con las de la posrremodelacion. El area hospitalaria con mayor frecuencia de infecciones es la Unidad de Terapia Intensiva (26.9 infecciones por 100 egresos), seguida de areas de hospitalizacion con cuartos compartidos (9.47%) y con cuartos privados (7.5%). El sitio de infeccion mas frecuente fue el de vias urinarias (26.6% del total de episodios), seguido por infeccion de herida quirurgica (24.4%), neumonia nosocomial (12.1%) y bacteriemia primaria (9.5%). Se observo una disminucion estadisticamente significativa en la frecuencia de infecciones de vias urinarias y bacteriemias primarias (p< 0.05 y p< 0.00001, respectivamente), mientras que las infecciones de herida quirurgica y las neumonias aumentaron (p< 0.005 y p< 0.00001, respectivamente). La mortalidad asociada disminuyo 36% (p< 0.00001). La estancia hospitalaria disminuyo en 42.8%. No se encontraron diferencias significativas en la gravedad de los enfermos. CONCLUSIONES. Desde que comenzo a operar, en 1985, el programa de control de infecciones en el INNSZ, la frecuencia de infecciones nosocomiales ha disminuido en 56%, asi como la mortalidad asociada (36%). Estos cambios se deben tanto a dicho programa como a la reduccion de la estancia hospitalaria, y no parecen estar relacionados con la edad de los pacientes ni con la gravedad de su padecimiento.

Structural Analysis of Monomeric RNA-Dependent Polymerases: Evolutionary and Therapeutic Implications.

The crystal structures of monomeric RNA-dependent RNA polymerases and reverse transcriptases of more than 20 different viruses are available in the Protein Data Bank. They all share the characteristic right-hand shape of DNA- and RNA polymerases formed by the fingers, palm and thumb subdomains, and, in many cases, “fingertips” that extend from the fingers towards the thumb subdomain, giving the viral enzyme a closed right-hand appearance. Six conserved structural motifs that contain key residues for the proper functioning of the enzyme have been identified in all these RNA-dependent polymerases. These enzymes share a two divalent metal-ion mechanism of polymerization in which two conserved aspartate residues coordinate the interactions with the metal ions to catalyze the nucleotidyl transfer reaction. The recent availability of crystal structures of polymerases of the Orthomyxoviridae and Bunyaviridae families allowed us to make pairwise comparisons of the tertiary structures of polymerases belonging to the four main RNA viral groups, which has led to a phylogenetic tree in which single-stranded negative RNA viral polymerases have been included for the first time. This has also allowed us to use a homology-based structural prediction approach to develop a general three-dimensional model of the Ebola virus RNA-dependent RNA polymerase. Our model includes several of the conserved structural motifs and residues described in other viral RNA-dependent RNA polymerases that define the catalytic and highly conserved palm subdomain, as well as portions of the fingers and thumb subdomains. The results presented here help to understand the current use and apparent success of antivirals, i.e. Brincidofovir, Lamivudine and Favipiravir, originally aimed at other types of polymerases, to counteract the Ebola virus infection.

Genomic and proteomic analyses of Mycobacterium bovis BCG Mexico 1931 reveal a diverse immunogenic repertoire against tuberculosis infection

BackgroundStudies of Mycobacterium bovis BCG strains used in different countries and vaccination programs show clear variations in the genomes and immune protective properties of BCG strains. The aim of this study was to characterise the genomic and immune proteomic profile of the BCG 1931 strain used in Mexico.ResultsBCG Mexico 1931 has a circular chromosome of 4,350,386 bp with a G+C content and numbers of genes and pseudogenes similar to those of BCG Tokyo and BCG Pasteur. BCG Mexico 1931 lacks R egion of D ifference 1 (RD1), RD2 and N-RD18 and one copy of IS6110, indicating that BCG Mexico 1931 belongs to DU2 group IV within the BCG vaccine genealogy. In addition, this strain contains three new RDs, which are 53 (RDMex01), 655 (RDMex02) and 2,847 bp (REDMex03) long, and 55 single-nucleotide polymorphisms representing non-synonymous mutations compared to BCG Pasteur and BCG Tokyo. In a comparative proteomic analysis, the BCG Mexico 1931, Danish, Phipps and Tokyo strains showed 812, 794, 791 and 701 protein spots, respectively. The same analysis showed that BCG Mexico 1931 shares 62% of its protein spots with the BCG Danish strain, 61% with the BCG Phipps strain and only 48% with the BCG Tokyo strain. Thirty-nine reactive spots were detected in BCG Mexico 1931 using sera from subjects with active tuberculosis infections and positive tuberculin skin tests.ConclusionsBCG Mexico 1931 has a smaller genome than the BCG Pasteur and BCG Tokyo strains. Two specific deletions in BCG Mexico 1931 are described (RDMex02 and RDMex03). The loss of RDMex02 (fadD23) is associated with enhanced macrophage binding and RDMex03 contains genes that may be involved in regulatory pathways. We also describe new antigenic proteins for the first time.

Endemic infusate contamination and related bacteremia.

BACKGROUND Recent reports suggest that in-use contamination of intravenous infusates is uncommon in hospitals with good standards of care. METHODS We conducted a survey in a referral hospital in Mexico with good standards of care but no pharmacists to prepare intravenous infusates; we tested the a priori hypothesis that the contamination rate is zero. Using a sterile syringe, we took an initial infusate specimen at the time of recruitment, specimen 1, for culture. We took a second specimen, specimen 2, from administration sets that were maintained for 72 hours. Blood cultures were obtained at the discretion of the physicians caring for the patients. RESULTS We cultured 1093 infusate specimens from 621 administration sets comprising 421 patients. We obtained a specimen 1 from each of the enrolled sets and a specimen 2 from 472 sets (76%). We analyzed 10 significant cultures and obtained a global infusate contamination rate of 0.9% (10/1093; 95% CI: 0.5%-1.7%). Two cases of infusate-related bacteremia occurred, establishing a global rate of 0.003/72 infusion hours. CONCLUSIONS Even in institutions with good nursing standards, endemic in-use infusate contamination may be a present danger. We must avoid the use of intravenous therapy whenever possible.

Nosocomial pediatric bacteremia: the role of intravenous set contamination in developing countries.

OBJECTIVE To assess the rate of bacterial contamination of intravenous administration sets at their rubber injection ports and matching infusates. DESIGN Cultures of injection ports and infusate during 26 visits to 4 hospitals. SETTING Four public general pediatric hospitals in Mexico City with substandard care practices. PATIENTS Hospitalized pediatric patients receiving intravenous solutions. RESULTS Overall, 176 of 251 injection ports were contaminated (70.1%; 95% confidence interval [CI95], 64.5% to 75.8%), 35 (13.9%; CI95, 9.7% to 18.2%) with gram-negative rods, primarily of the tribe Klebsielleae. Cultures of infusates were positive in 17 cases (6.8%, CI95, 3.7% to 9.9%), 5 of which grew gram-negative rods (2%; CI95, 0.6% to 4.6%). In 3 cases (1.2%), the same species with gram-negative rods was found in the infusates and on the injection ports. During one visit, 8 clustered cases of injection port contamination with a clonal Enterobacter cloacae were found; this agent was also found in the blood culture, intravenous fluid, and parenteral nutrition of one patient. Inadequate chlorination of tap water, a potential risk factor, was recorded during 22 visits (84.6%). CONCLUSION These data suggest that external contamination of the intravenous administration set could play a role in infusate contamination.

Réquiem por el sindicalismo

Este ensayo describe los efectos que ha tenido la desincorporacion de las empresas y la politica de apertura comercial en el escenario laboral del pais, asi como la imposibilidad de instrumentar la reforma laboral. El Pacto establece las condiciones necesarias para que el modelo economico funcione. Las bases centrales para la viabilidad del proyecto economico son los actores tradicionales. Esta funcionalidad que brinda la burocracia obrera al proyecto gubernamental es lo que explica que no se haya pretendido buscar una salida organizativa que sustituya a la vieja maquinaria sindical-corporativa. Tal vez el mejor ejemplo para comprender por que nuestra modernidad no acaba de nacer es la preservacion del viejo liderazgo sindical y sus anejas practicas. El conjunto del sindicalismo mexicano no encuentra salidas alternativas en los usos y desusos que se hacen del corporativismo

Are RNA Viruses Candidate Agents for the Next Global Pandemic? A Review

Abstract Pathogenic RNA viruses are potentially the most important group involved in zoonotic disease transmission, and they represent a challenge for global disease control. Their biological diversity and rapid adaptive rates have proved to be difficult to overcome and to anticipate by modern medical technology. Also, the anthropogenic change of natural ecosystems and the continuous population growth are driving increased rates of interspecies contacts and the interchange of pathogens that can develop into global pandemics. The combination of molecular, epidemiological, and ecological knowledge of RNA viruses is therefore essential towards the proper control of these emergent pathogens. This review outlines, throughout different levels of complexity, the problems posed by RNA viral diseases, covering some of the molecular mechanisms allowing them to adapt to new host species—and to novel pharmaceutical developments—up to the known ecological processes involved in zoonotic transmission.

The Pope, condoms, and the evolution of HIV

This reflection focuses on HIV resistance to antiretroviral therapy and the importance of using condoms. It touches on the Pope’s statements on the use of condoms and their inefficiency to prevent HIV transmission and argues against it stating that condoms play a key role in limiting the HIV pandemic.

Encefalopatías espongiformes transmisibles

Las encefalopatias espongiformes transmisibles (EET) han cobrado gran importancia en los ultimos anos. Principalmente por el surgimiento de la encefalopatia espongiforme del bovino (EEB) y la nueva variante de la ermedad de Creutzfeldt-Jakob (nvECJ), esta ultima probablemente adquirida por la ingesta de carne de bovino contaminada. Hasta la fecha se ha informado de 109 casos de la nvECJ en el humano y la gran mayoria de los casos ha ocurrido en el Reino Unido. No se sabe la magnitud real que podran tener las EET en el humano, sin embargo algunos piensan que nos encontramos en el principio de una pandemia de la nvECJ. En el presente articulo se discuten varios aspectos de las EET y metodos para la prevencion de la transmision de estas enfermedades, tanto en rumiantes como en el humano.