Search

Infectious diseases are still a cause of high mortality and morbidity rates. Current microbiological diagnostic methods are based on culture and phenotypic identification of isolated microorganisms, which can be obtained in about 24-48 h. Given that the microbiological identification is of major importance for patient management, new diagnostic methods are needed in order to detect and identify microorganisms in a timely and accurate manner. Over the last few years, several molecular techniques based on the amplification of microbial nucleic acids have been developed with the aim of reducing the time needed for the identification of the microorganisms involved in different infectious processes. On the other hand, mass spectrometry has emerged as a rapid and consistent alternative to conventional methods for microorganism identification. This review describes the most widely used mass spectrometry technologies -matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and electrospray ionization time-of-flight (ESI-TOF)-, both for protein and nucleic acid analysis, as well as the commercial platforms available. Related publications of most interest in clinical microbiology are also reviewed.

Only about 50% of patients chronically infected with hepatitis C virus genotype 1 achieve a successful response to standard treatment with pegylated interferon-alfa and ribavirin. Moreover, the recently approved protease inhibitors will have to be administered together with these drugs. Consequently, predicting response to standard treatment, ideally before starting it, remains an important challenge. Although several baseline predictors of treatment failure have been described, including clinical and virological factors, none of them is able to provide reliable predictions at the individual level. In addition, the development of multivariate models combining several predictive factors has not yet yielded predictions with the requisite reliability for use in clinical practice. Therefore, further research is needed to improve predictive models and to describe new factors that would enable us to predict treatment outcome with greater reliability and reproducibility. The development of candidate selection algorithms that help clinicians to identify which patients could benefit from the new therapies on the basis of their chances of responding to standard therapy is of major interest for both patient well-being and healthcare expense. This review attempts to provide a view of the current options for predicting the response to pegylated interferon-alfa plus ribavirin therapy in patients chronically infected with hepatitis C virus genotype 1.

Mycoplasma pneumoniae is a human pathogen with worldwide distribution. This microorganism is a common cause (10-30%) of community-acquired pneumonia, also called primary atypical pneumonia because of the spectrum of clinical and radiological findings. The immune response is mainly based on rapid antibody production against peptide and glycolipid antigens derived from this microorganism. During the primary infection, IgM levels generally rise within the first week, and are then followed by an IgG response. Titers of IgG and IgA increase in reinfections. Microbiological diagnosis is based on specific antibody detection. Polymerase chain reaction (PCR) techniques performed on sputum or pharyngeal/nasopharyngeal exudates, as well as the development of multiplex PCR reactions allowing identification of M. pneumoniae and other respiratory pathogens, would by highly useful in routine diagnosis. The most common serological techniques are complement fixation, immunofluorescence, particle agglutination, and enzyme immunoassay. Diagnosis should be performed by selecting the most appropriate test according to functional criteria and population groups. Specific detection of IgM antibodies should not be included in the differential diagnosis in adults and young people. Diagnostic criteria including seroconversion or rising IgG titers may not be clinically useful, because of the time delay and the difficulty of obtaining a second serum specimen for testing, given the mildness of the clinical symptoms.

Background Tuberculosis (TB) is a disease of poverty that contributes significantly to ill-health in developing countries. Drug resistant TB is a major challenge to disease control. Early diagnosis and rapid determination of drug sensitivity is of paramount importance in eradication of TB. Although automated liquid culture based methods are available for rapid detection of drug resistance, the high cost of these tests prevent them from being used routinely in low resource settings. This study compares two phenotypic methods, the manual Mycobacteria Growth Indicator Tube (MGIT) and the Nitrate Reductase Assay (NRA) in liquid medium, with the agar proportion method (APM), the gold standard for susceptibility testing of Mycobacterium tuberculosis. Methodology Fourteen day old M. tuberculosis strains (n=373) grown on solid media were used for drug susceptibility testing by APM, NRA and the manual MGIT method. Rifampicin free and rifampicin incorporated (final concentration, 1 μg/ml) media were inoculated with the recommended concentrations of mycobacterial suspensions and incubated at 37°C in 5% CO2. In the APM, the proportion of colonies in the drug containing medium was determined. In the NRA, the colour change in the medium was compared with a standard colour series after day 6 and day 12 of incubation. Growth in the MGIT was detected using the manual MGIT reader from day 2 onwards. The 2 methods were compared with the gold standard, APM to determine sensitivity and specificity and agreement between the methods was calculated using kappa statistics. Results Thirty one (31) rifampicin resistant isolates were identified. When compared with the APM, the sensitivity of detection of rifampicin resistance was 85% for the NRA and 93% for the manual MGIT and the specificity was 99% and 100% respectively. Both assays, NRA (κ=0.86) and manual MGIT method (κ= 0.94) were in excellent agreement with the APM. The mean turnaround time for manual MGIT method and NRA were 08 days and 10 days respectively. Conclusion The NRA in liquid medium and manual MGIT are useful alternatives to APM for drug susceptibility testing of M. tuberculosis in low resource settings.

Only about 50% of patients chronically infected with hepatitis C virus genotype 1 achieve a successful response to standard treatment with pegylated interferon-alfa and ribavirin. Moreover, the recently approved protease inhibitors will have to be administered together with these drugs. Consequently, predicting response to standard treatment, ideally before starting it, remains an important challenge. Although several baseline predictors of treatment failure have been described, including clinical and virological factors, none of them is able to provide reliable predictions at the individual level. In addition, the development of multivariate models combining several predictive factors has not yet yielded predictions with the requisite reliability for use in clinical practice. Therefore, further research is needed to improve predictive models and to describe new factors that would enable us to predict treatment outcome with greater reliability and reproducibility. The development of candidate selection algorithms that help clinicians to identify which patients could benefit from the new therapies on the basis of their chances of responding to standard therapy is of major interest for both patient well-being and healthcare expense. This review attempts to provide a view of the current options for predicting the response to pegylated interferon-alfa plus ribavirin therapy in patients chronically infected with hepatitis C virus genotype 1.

Resumen Actualmente, las enfermedades infecciosas siguen causando una elevada mortalidad y morbilidad. Los métodos de diagnóstico microbiológico se basan en el cultivo seguido de la identificación fenotípica del microorganismo una vez aislado, y el tiempo necesario para su obtención puede variar de 24 a 48 h. Dado que la identificación microbiológica repercute directamente en el manejo del paciente y su pronóstico, son necesarias nuevas herramientas diagnósticas capaces de detectar e identificar cualquier microorganismo de manera rápida y fiable. A lo largo de los últimos años se han desarrollado diferentes técnicas moleculares basadas en la amplificación genética con el objetivo de reducir el tiempo necesario para la identificación de los microorganismos implicados en diferentes tipos de procesos infecciosos. Por otro lado, la espectrometría de masas ha surgido como una alternativa rápida y eficaz a los métodos convencionales para la identificación de microorganismos. En esta revisión se describe la tecnología en sus dos formas más utilizadas —desorción/ionización por láser asistida por matriz (MALDI-TOF) e ionización por electrospray (ESI-TOF)— para el análisis tanto de las proteínas como de los ácidos nucleicos microbianos, así como las diferentes plataformas comerciales disponibles. Así mismo, se hace una revisión de los trabajos de mayor interés en microbiología clínica.

The creation of the European Higher Education Area provides a series of opportunities for far-reaching reform of medical education and changes in the way both students and teachers work. The Bologna process must be implemented before 2010 in signatory countries, which include Spain, and must allow education and academic titles to be homologated. Medical degrees must consist of 360 European Credit Transfer System (ECTS) credits, divided into six academic years (60 credits per academic year). The Faculty of Medicine of the Autonomous University of Barcelona has already put the finishing touches to a proposal for the distribution of subjects in the new curriculum. This proposal strengthens and reassesses the teaching of microbiology and parasitology compared with current curricula, giving these subjects appropriate weight in undergraduate medical education. The teaching of medical microbiology and parasitology is included as a core subject worth 8 ECTS in the third year and two free-choice modules of 2.5 and 3 ECTS to be taken in the first semesters of the fifth and sixth years as part of the minor in "Clinical and Experimental Laboratory"(30 ECTS). The teaching of microbiology will also play an important role in the Integrated Learning in Medicine (INTEL-M) course in the third, fourth and fifth years. INTEL-M is an innovation in the syllabus based on the joint planning, organization and evaluation of a series of subjects (24.5 ECTS) that are developed in small groups of students and in the form of problem-based learning.

Mycoplasma pneumoniae is a human pathogen with worldwide distribution. This microorganism is a common cause (10-30%) of community-acquired pneumonia, also called primary atypical pneumonia because of the spectrum of clinical and radiological findings. The immune response is mainly based on rapid antibody production against peptide and glycolipid antigens derived from this microorganism. During the primary infection, IgM levels generally rise within the first week, and are then followed by an IgG response. Titers of IgG and IgA increase in reinfections. Microbiological diagnosis is based on specific antibody detection. Polymerase chain reaction (PCR) techniques performed on sputum or pharyngeal/nasopharyngeal exudates, as well as the development of multiplex PCR reactions allowing identification of M. pneumoniae and other respiratory pathogens, would by highly useful in routine diagnosis. The most common serological techniques are complement fixation, immunofluorescence, particle agglutination, and enzyme immunoassay. Diagnosis should be performed by selecting the most appropriate test according to functional criteria and population groups. Specific detection of IgM antibodies should not be included in the differential diagnosis in adults and young people. Diagnostic criteria including seroconversion or rising IgG titers may not be clinically useful, because of the time delay and the difficulty of obtaining a second serum specimen for testing, given the mildness of the clinical symptoms.