Irma Casas

Evaluation of interferon-gamma release assays in the diagnosis of recent tuberculosis infection in health care workers.

Background Health care workers (HCWs) are a group at risk of latent tuberculosis infection (LTBI). The aims of this study were to determine IFN-γ response by QuantiFERON-TB GOLD In Tube (QFN-G-IT) and T-SPOT.TB in HCWs, comparing the results with tuberculin skin test (TST); and to analyze the capacity of IFN-γ tests to detect recent versus remote LTBI with a prolonged stimulation test (PST). Methodology/Principal Findings A total of 147 HCWs were enrolled; 23 of whom were BCG vaccinated. 95 HCWs (64.6%) had a previous positive TST and were not retested; and 52 HCWs had a previous negative TST or were tested for the first time. When we analysed individuals without previous positive TST, the number of positive results for T-SPOT.TB was 12/52 (23.1%); and for QFN-G-IT, 9/52 (17.3%). The global concordance (κ) between T-SPOT.TB and QFN-G-IT with TST was 0.754 and 0.929 respectively. Of individuals with previous positive TST, T-SPOT.TB and QFN-G-IT were negative in 51.6% (49/95) and 62.1% (59/95) respectively, decreasing the concordance to 0.321 and 0.288, respectively. In non-BCG vaccinated HCWs with previous positive TST a positive IFN-γ test was associated with degree of exposure and diameter of TST. PST was performed in 24 HCW with previous positive TST and negative IFN-γ tests. PST was developed in 3 cell cultures stimulated with medium alone, ESAT-6 and CFP-10, respectively. In the third and sixth day of incubation period, part of the supernatants were replaced with complete medium supplemented with (rIL)-2. On day 9, ELISPOT assay was performed. In 14 samples PST was not valid due to not having enough cells. In 8 cases, the response was negative, and in 2 cases positive, suggesting that these patients were infected with Mycobacterium tuberculosis in some point in the past. Conclusions Both IFN-γ tests showed a similar number of positive results, and concordance between the tests was excellent. None of the tests was affected by prior BCG vaccination. IFN-γ tests are a useful tool for detecting recent infection in HCW population.

Immunogenicity of 60 novel latency-related antigens of Mycobacterium tuberculosis

The aim of our work here was to evaluate the immunogenicity of 60 mycobacterial antigens, some of which have not been previously assessed, notably a novel series of in vivo-expressed Mycobacterium tuberculosis (IVE-TB) antigens. We enrolled 505 subjects and separated them in individuals with and without latent tuberculosis infection (LTBI) vs. patients with active tuberculosis (TB). Following an overnight and 7 days stimulation of whole blood with purified recombinant M. tuberculosis antigens, interferon-γ (IFN-γ) levels were determined by ELISA. Several antigens could statistically significantly differentiate the groups of individuals. We obtained promising antigens from all studied antigen groups [dormancy survival regulon (DosR regulon) encoded antigens; resuscitation-promoting factors (Rpf) antigens; IVE-TB antigens; reactivation associated antigens]. Rv1733, which is a probable conserved transmembrane protein encoded in DosR regulon, turned out to be very immunogenic and able to discriminate between the three defined TB status, thus considered a candidate biomarker. Rv2389 and Rv2435n, belonging to Rpf family and IVE-TB group of antigens, respectively, also stood out as LTBI biomarkers. Although more studies are needed to support our findings, the combined use of these antigens would be an interesting approach to TB immunodiagnosis candidates.

Risk factors for hospital-acquired pneumonia outside the intensive care unit: a case-control study.

BACKGROUND Hospital-acquired pneumonia (HAP) is one of the leading nosocomial infections and is associated with high morbidity and mortality. Numerous studies on HAP have been performed in intensive care units (ICUs), whereas very few have focused on patients in general wards. This study examined the incidence of, risk factors for, and outcomes of HAP outside the ICU. METHODS An incident case-control study was conducted in a 600-bed hospital between January 2006 and April 2008. Each case of HAP was randomly matched with 2 paired controls. Data on risk factors, patient characteristics, and outcomes were collected. RESULTS The study group comprised 119 patients with HAP and 238 controls. The incidence of HAP outside the ICU was 2.45 cases per 1,000 discharges. Multivariate analysis identified malnutrition, chronic renal failure, anemia, depression of consciousness, Charlson comorbidity index ≥3, previous hospitalization, and thoracic surgery as significant risk factors for HAP. Complications occurred in 57.1% patients. The mortality attributed to HAP was 27.7%. CONCLUSIONS HAP outside the ICU prevailed in patients with malnutrition, chronic renal failure, anemia, depression of consciousness, comorbidity, recent hospitalization, and thoracic surgery. HAP in general wards carries an elevated morbidity and mortality and is associated with increased length of hospital stay and increased rate of discharge to a skilled nursing facility.

Tuberculosis en personal sanitario de un hospital general

BACKGROUND AND OBJECTIVE: Tuberculosis is an occupational disease in health care workers. The objective of our study was to review tuberculosis cases in health care professionals from a general hospital and to determine their incidence in relation to the general population. PATIENTS AND METHOD: This was a retrospective study of tuberculosis cases among health care workers in a university hospital from 1988 to 2002, evaluating the annual cumulative incidence. RESULTS: 21 tuberculosis cases were found in health care workers. Pulmonary disease was the most frequent type (62%) followed by pleural effusion (28%). The most affected professional category were medical residents (38%) with the emergency service (48%) being the work place with the highest risk. The cumulative incidence in our hospital was higher in relation to the general population although there was a variability between both populations. CONCLUSIONS: There is risk of tuberculosis transmission among health care workers, principally in the emergency service and the pathology and microbiological departments. A concerted effort is needed to maintain prevention measures in the work place where there is a high risk of infection.

Hospital-Acquired Legionnaires Disease in a University Hospital: Impact of the Copper-Silver Ionization System

We evaluated the impact of the copper-silver ionization system in a hospital where hyperendemic nosocomial legionellosis and was present and all previous disinfection measures had failed. After implementation of the copper-silver ionization system, environmental colonization with Legionella species decreased significantly, and the incidence of nosocomial legionellosis decreased dramatically, from 2.45 to 0.18 cases per 1000 patient discharges.

IP-10 is an accurate biomarker for the diagnosis of tuberculosis in children

OBJECTIVE Performance of IFN-γ assays in children is compromised. Therefore, we investigated the utility of IP-10 for the detection of active tuberculosis (TB) and latent tuberculosis infection (LTBI) diagnosis in children; comparing its positivity with QuantiFERON-TB Gold In-Tube (QFN-G-IT) and T-SPOT.TB. METHODS We studied 230 children from three groups: active TB, screening (healthy children without known exposure to active TB patient screened at school or by their paediatrician) and contact-tracing studies. IFN-γ release was determined by QFN-G-IT and T-SPOT.TB. IP-10 was detected in QFN-G-IT supernatants by ELISA. RESULTS When combining QFN-G-IT and IP-10 assays, positive results improved significantly from 38.3% in QFN-G-IT and 33.9% in IP-10 to 41.3%. Age and type of contact were significant risk factors associated with positive QFN-G-IT and IP-10 results. IP-10 levels after antigen-specific stimulation were significantly higher in comparison to IFN-γ levels. Correlation between the three assays was good (κ = 0.717-0.783). CONCLUSIONS IP-10 cytokine is expressed in response to TB specific-antigens used in QFN-G-IT. In conclusion, the use of IFN-γ T-cell based assays in combination with an additional IP-10 assay detection could be useful for diagnosing active TB and LTBI in children.

Hepatitis C virus transmission during colonoscopy evidenced by phylogenetic analysis

BACKGROUND Nosocomial transmission events still play an important role in hepatitis C virus (HCV) spreading. Among most reported medical procedures involved in nosocomial transmission, endoscopy procedures remain controversial and might be underestimated. OBJECTIVE The aim of the study was to investigate a case of nosocomial person-to-person transmission of HCV in an endoscopy unit. STUDY DESIGN An acute HCV infection was detected in a person that had undergone a colonoscopy after an HCV-infected patient. Serum samples from both persons were subjected to a molecular epidemiology study. The HCV NS5B genetic region was amplified and directly sequenced and the E1-E2 region was amplified, cloned and sequenced (20 clones per specimen). All sequences were subjected to phylogenetic analyses. A conventional epidemiological investigation was performed to determine the most likely cause of HCV transmission. RESULTS NS5B sequence analysis revealed that both persons were infected with closely related HCV-1b strains. Furthermore, phylogenetic analysis of E1-E2 sequences evidenced a direct transmission between patients. The epidemiological investigation pointed out to anesthetic procedures as the most likely source of HCV transmission. The index case, not having spontaneously cleared the infection 10 months after infection, required antiviral treatment, which resulted in a sustained virological response. CONCLUSIONS The molecular epidemiology study performed provided evidence of a person-to-person transmission of HCV during a colonoscopy procedure, and the anesthetic procedure was the most likely source of HCV transmission. This study highlights the importance of strictly following standard precautions by healthcare workers in order to prevent nosocomial HCV transmission.

A novel whole-blood miRNA signature for a rapid diagnosis of pulmonary tuberculosis.

One essential aspect for controlling the spread of tuberculosis (TB) is to diagnose it in an early stage. However, the commonly used test systems are still insufficient. Moreover, current assays perform poorly in discriminating between active TB and latent tuberculosis infection (LTBI). Due to limited knowledge of promising TB biomarkers, global “omics” approaches bear attractive options to follow [1]. MiRNAs are important post-transcriptional regulators shown to be involved in the modulation of immune responses against intracellular pathogens [2]. These findings open the possibility of using miRNAs as TB biomarkers for diagnosis. In the present study, we have investigated their role as blood biomarkers for detecting active TB. A novel, whole-blood miRNA signature enables to rapidly diagnose TB with 91.21% sensitivity and 87.95% specificity http://ow.ly/FVvHt

Prevalence of and Risk Factors for Methicillin-Resistant Staphylococcus aureus Carriage at Hospital Admission

To determine the prevalence of and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) carriage at the time of admission to our hospital, we screened the medical records of 1,128 patients for demographic and clinical data. The antimicrobial resistance pattern and genotype of MRSA isolates were studied. The prevalence of MRSA carriage at hospital admission was 1.4%. Older patients and patients previously admitted to healthcare centers were the most likely to have MRSA carriage at admission.

Incidencia y características del asma bronquial de inicio en la edad adulta

Objetivo Determinar la incidencia del asma del adulto, junto con las caracteristicas funcionales e inmunologicas de la enfermedad, sus causas y su evolucion. Pacientes y metodos Tras la identificacion de los habitantes de Barcelona Norte con un primer diagnostico de asma del adulto, se procedio a la caracterizacion de la enfermedad por cuestionario, funcion respiratoria y pruebas cutaneas de alergia. Los pacientes con una ocupacion causante de asma, sibilancias durante el trabajo y/o sensibilizacion a un alergeno laboral se consideraron afectados de asma relacionada con la ocupacion. Los factores de riesgo de cronificacion del asma se determinaron por medio de analisis multivariante. Resultados En 2 anos se identificaron 218 primeros diagnosticos de asma del adulto (poblacion: 68.067 adultos; incidencia anual: 160/100.000). Aceptaron participar en el estudio 152 pacientes (indice de respuesta: 70%), de los que se caracterizo a 140 que referian sibilancias y/o asma bronquial en el ultimo ano (92%). Las pruebas cutaneas mostraron atopia en 57 casos (41%). Se diagnostico asma relacionada con la ocupacion en 19 casos (14%), por mamiferos domesticos en 8 (6%), por farmacos en 7 (5%) y por alergenos ambientales en 44 (31%), siendo la limpieza domestica la ocupacion mas frecuentemente asociada a la enfermedad (26%). De los 102 pacientes examinados de nuevo a los 2 anos, 70 presentaban asma cronica (69%); la atopia ( odds ratio [OR] = 3,39; intervalo de confianza [IC] del 95%, 1,15-9,99) y una ocupacion de riesgo cuando se diagnostico la enfermedad (OR = 5,54; IC del 95%, 1,05-29,11) fueron los factores de cronificacion del asma. Conclusiones La ocupacion del paciente esta relacionada con el asma del adulto en algo mas de una decima parte de los casos y es un determinante principal de la cronicidad de sus sintomas.