RESUMEN
The purpose of this study was to evaluate a new chromogenic medium, chromID OXA-48, for the isolation of carbapenemase-producing Enterobacteriaceae (CPE) directly from rectal swabs. chromID CARBA and chromID OXA-48 are two chromogenic media that have been commercialized for the isolation of CPE directly from clinical samples. Both media were evaluated alongside a broth enrichment method recommended by the CDC for isolation of CPE, with rectal swabs from 302 unique hospitalized patients at the Hacettepe University Hospital, Ankara, Turkey. A total of 33 patients (11 %) were found to be colonized with CPE using a combination of all methods, and all CPE produced OXA-48 carbapenemase. Klebsiella pneumoniae was by far the most dominant species of CPE and was isolated from 31 patients. Culture on chromID OXA-48 offered the highest sensitivity (75.8 %) for detection of CPE compared with the other two methods (sensitivity for both other methods was 57.6 %) and also offered the highest specificity (99.3 %). However, a combination of methods (either chromID OXA-48 plus CDC method or chromID OXA-48 plus chromID CARBA) was necessary to achieve an acceptable sensitivity (90.9 %). For isolation of CPE, in a setting where OXA-48 carbapenemase is the dominant type of carbapenemase, chromID OXA-48 is a highly useful medium but using a combination of methods is optimal for adequate detection. The combined use of two chromogenic media offered acceptable sensitivity (90.9 %) and the highest specificity (98.5 %) and also allowed for isolation of CPE within 18-20 h.
Asunto(s)
Proteínas Bacterianas/análisis , Técnicas Bacteriológicas/métodos , Medios de Cultivo/química , Infecciones por Enterobacteriaceae/microbiología , Enterobacteriaceae/enzimología , Enterobacteriaceae/aislamiento & purificación , beta-Lactamasas/análisis , Compuestos Cromogénicos/metabolismo , Color , Hospitales Universitarios , Humanos , Recto/microbiología , Sensibilidad y Especificidad , TurquíaRESUMEN
AIMS: To evaluate two chromogenic media, Brilliance CRE and chromID CARBA, with stool samples referred to the Public Health Laboratories Division of the National Institute of Health in Islamabad, and assess the prevalence of carbapenemase-producing Enterobacteriaceae (CPE) in this population. METHODS AND RESULTS: One hundred and fifty-two stool samples from patients with diarrhoea were referred to the Microbiology Department and were investigated for the presence of CPE using two chromogenic culture media, Brilliance CRE and chromID CARBA. Thirteen patients (8·6%) were found to be colonized with CPE and all produced NDM-1 carbapenemase. Twelve of these patients (92%) were found to be colonized by culture on chromID CARBA compared with seven (54%) using Brilliance CRE. CONCLUSIONS: If only coloured colonies were considered as presumptive CPE, the sensitivity, specificity and positive predictive value were 54, 23 and 6% for Brilliance CRE and 85, 85 and 36% for chromID CARBA, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: We conclude that Enterobacteriaceae that produce NDM-1 carbapenemase can be found in patients from all major provinces of Pakistan and that chromID CARBA was the most effective of the two chromogenic media in this setting.
Asunto(s)
Proteínas Bacterianas/metabolismo , Medios de Cultivo , Diarrea/microbiología , Infecciones por Enterobacteriaceae/microbiología , Enterobacteriaceae/enzimología , beta-Lactamasas/metabolismo , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Compuestos Cromogénicos , Enterobacteriaceae/aislamiento & purificación , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Pakistán , Adulto JovenRESUMEN
We investigated the incidence of cases of nosocomial pathogens and risk factors in an intensive treatment unit ward to determine if the number of cases is dependent on location of patients and the colonization/infection history of the ward. A clustering approach method was developed to investigate the patterns of spread of cases through time for five microorganisms [methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter spp., Klebsiella spp., Candida spp., and Pseudomonas aeruginosa] using hospital microbiological monitoring data and ward records of patient-bed use. Cases of colonization/infection by MRSA, Candida and Pseudomonas were clustered in beds and through time while cases of Klebsiella and Acinetobacter were not. We used structural equation modelling to analyse interacting risk factors and the potential pathways of transmission in the ward. Prior nurse contact with colonized/infected patients, mediated by the number of patient-bed movements, were important predictors for all cases, except for those of Pseudomonas. General health and invasive surgery were significant predictors of cases of Candida and Klebsiella. We suggest that isolation and bed movement as a strategy to manage MRSA infections is likely to impact upon the incidence of cases of other opportunist pathogens.
Asunto(s)
Infección Hospitalaria/transmisión , Unidades de Cuidados Intensivos , Infecciones por Acinetobacter/epidemiología , Infecciones por Acinetobacter/transmisión , Candidiasis/epidemiología , Candidiasis/transmisión , Análisis por Conglomerados , Estudios de Cohortes , Infección Hospitalaria/epidemiología , Infección Hospitalaria/prevención & control , Humanos , Infecciones por Klebsiella/epidemiología , Infecciones por Klebsiella/transmisión , Staphylococcus aureus Resistente a Meticilina , Modelos Biológicos , Infecciones por Pseudomonas/epidemiología , Infecciones por Pseudomonas/transmisión , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/transmisiónRESUMEN
How temperate bacteriophages play a role in microbial infection and disease progression is not fully understood. They do this in part by carrying genes that promote positive evolutionary selection for the lysogen. Using Biolog phenotype microarrays and comparative metabolite profiling we demonstrate the impact of the well-characterised Shiga toxin-prophage Ï24B on its Escherichia coli host MC1061. As a lysogen, the prophage alters the bacterial physiology by increasing the rates of respiration and cell proliferation. This is the first reported study detailing phage-mediated control of the E. coli biotin and fatty acid synthesis that is rate limiting to cell growth. Through Ï24B conversion the lysogen also gains increased antimicrobial tolerance to chloroxylenol and 8-hydroxyquinoline. Distinct metabolite profiles discriminate between MC1061 and the Ï24B lysogen in standard culture, and when treated with 2 antimicrobials. This is also the first reported use of metabolite profiling to characterise the physiological impact of lysogeny under antimicrobial pressure. We propose that temperate phages do not need to carry antimicrobial resistance genes to play a significant role in tolerance to antimicrobials.