RESUMEN
Epidemic C. difficile (027/BI/NAP1) has rapidly emerged in the past decade as the leading cause of antibiotic-associated diarrhea worldwide. However, the key events in evolutionary history leading to its emergence and the subsequent patterns of global spread remain unknown. Here, we define the global population structure of C. difficile 027/BI/NAP1 using whole-genome sequencing and phylogenetic analysis. We show that two distinct epidemic lineages, FQR1 and FQR2, not one as previously thought, emerged in North America within a relatively short period after acquiring the same fluoroquinolone resistance-conferring mutation and a highly related conjugative transposon. The two epidemic lineages showed distinct patterns of global spread, and the FQR2 lineage spread more widely, leading to healthcare-associated outbreaks in the UK, continental Europe and Australia. Our analysis identifies key genetic changes linked to the rapid transcontinental dissemination of epidemic C. difficile 027/BI/NAP1 and highlights the routes by which it spreads through the global healthcare system.
Asunto(s)
Clostridioides difficile/genética , Diarrea/epidemiología , Enterocolitis Seudomembranosa/epidemiología , Clostridioides difficile/clasificación , Epidemias , Genoma Bacteriano , Genotipo , Humanos , Filogenia , Filogeografía , Polimorfismo de Nucleótido SimpleRESUMEN
A fatal case of nosocomial legionellosis in a low prevalence region (Calgary, Alberta, Canada) prompted investigation into the source of infection. Hospital water systems contaminated with Legionella pneumophila have been shown to pose a risk to compromised patients. Typing of an L. pneumophila serogroup 1 strain isolated from the patient using sequence-based typing (SBT) and amplified fragment length polymorphism (AFLP) analysis linked it to a persistent and widespread strain isolated from the hospital water system establishing a nosocomial mode of acquisition. Different SBT and AFLP patterns were determined for non-epidemiologically linked cases and isolates from different hospitals.
Asunto(s)
Infección Hospitalaria/etiología , Legionella pneumophila/clasificación , Legionelosis/etiología , Neumonía Bacteriana/etiología , Anciano , Proteínas Bacterianas/genética , Canadá/epidemiología , Infección Hospitalaria/epidemiología , ADN Bacteriano/genética , Resultado Fatal , Femenino , Humanos , Legionella pneumophila/genética , Legionella pneumophila/aislamiento & purificación , Legionelosis/epidemiología , Metaloendopeptidasas/genética , Datos de Secuencia Molecular , Neumonía Bacteriana/epidemiología , Polimorfismo de Longitud del Fragmento de Restricción , Porinas/genética , Factores de Riesgo , Análisis de Secuencia de Proteína , Especificidad de la Especie , Microbiología del Agua , Abastecimiento de Agua/análisisRESUMEN
BACKGROUND: The USA300 strain of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) can cause severe infection and is increasingly recognized as a cause of community outbreaks. In 2004, an outbreak was identified in the Calgary Health Region (CHR). METHODS: MRSA isolates were identified with standard methods at a central regional laboratory and typed via pulsed-field gel electrophoresis (PFGE). Isolates were tested by PCR for mecA, Panton-Valentine leukocidin (PVL), SCCmec, and spa genes. Cases were defined as such if a clinical isolate of the USA300 strain was noted between January 1 and September 30, 2004, and the patient had lived or traveled in CHR within 2 years before symptom onset. Demographic, clinical and risk data on all such cases were collected from several sources for statistical analysis. A case was defined as high-risk if the patient had a history of drug use, homelessness or incarceration. RESULTS: Of 40 isolates with the USA300 PFGE pattern, all tested positive for PVL, SCCmec type IVa and spa type 008. Almost all infections (39/40, 98%) involved skin and soft tissues, except for 1 death from necrotizing hemorrhagic pneumonia; a notable proportion (38%) required hospital admission or intravenous antimicrobial therapy. The outbreak centred on the high-risk population in CHR (70%; risk ratio 169.4, 95% confidence interval 86.1-333.0). INTERPRETATION: People with histories of illicit drug use, homelessness or recent incarceration were at highest risk for infection with CA-MRSA. The emergence and spread of this virulent strain has important implications for treatment and public health in Canada.