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J Infect ; 79(5): 435-443, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31419474


An outbreak of an uncommon emm type (emm66.0) of group A streptococcus (GAS) occurred in England and Wales between January 2016 and May 2017, involving 52 individuals who were homeless or injecting drugs users. In order to investigate the outbreak, epidemiological and network analysis were performed; moreover 55 isolates (32 outbreak, 5 non-outbreak and 13 historical - 2005-2015) were tested with whole genome sequencing (WGS), antimicrobial resistance determination, Bayesian evolutionary analysis (BEAST). Forty one isolates (including 32 outbreak strains) belonged to a single emm66.0 clade (average SNP difference 6.6; range 0-16 SNPs) separate from the other isolates and two strains previously considered part of the outbreak (SNP average: 5876; range 93-8417 SNPs). Antibiotic resistance was not detected in the outbreak clone. No common source of infection was identified. WGS confirmed expansion of an emm66.0 clone in a hard-to-reach population and enabled refinement of the initial case definition.

Sci Rep ; 9(1): 541, 2019 Jan 24.
Artículo en Inglés | MEDLINE | ID: mdl-30679460


Mycoplasma pneumoniae (MP) is considered a common cause of pneumonia, causing about 15-20% of adult community-acquired pneumonia (CAP) and up to 40% of cases in children. It has often been observed that MP epidemics last approximately 1-2 years and occur every 3-7 years, with the dominant strains alternating between epidemics. However, the underlying mechanism by which these cycles and changes in the dominant strains occur remains unclear. The traditional models for the periodicity of MP epidemics neglected two phenomena: structured contact patterns among people and co-circulating strains of MP. We also believe that the two distinctive aspects of MP epidemics: prevalent serotype shifts among epidemics and incidence cycling of MP, are interconnected. We propose a network transmission model that assumes two strains of MP are transmitted within a network structured population and they can interact as secondary infections with primary infections. Our studies show that multiple strains that co-circulate within a network structured population and interact positively generate the observed patterns of recurrent epidemics of MP. Hence our study provides a possible mechanism for the cycling epidemics of MP, and could provide useful information for future vaccine design and vaccine evaluation/monitoring processes.

J Antimicrob Chemother ; 72(10): 2704-2707, 2017 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-29091185


Background: Like other streptococci, Streptococcus agalactiae typically has intrinsic low-level aminoglycoside resistance. High-level gentamicin resistance was seen in 2 of 1125 isolates collected in the BSAC Bacteraemia Surveillance Programme between 2001 and 2014. These organisms, both isolated in 2014, were characterized. Methods: Identifications were by latex agglutination, MICs by BSAC agar dilution and sequencing by Illumina methodology. Results: Gentamicin MICs were >1024 mg/L versus a species mode of 8 mg/L; both isolates also were unusually ciprofloxacin resistant with MICs of 64 mg/L versus a species mode of 1 mg/L. They were distinct by sequence, but both belonged to the ST19 clone, which occurs globally. Both had aac(6')-aph(2″), carried by different transposons, explaining their gentamicin resistance, and had gyrA[81:S-L];parC[79:S-Y], accounting for ciprofloxacin resistance. Conclusions: These are the first multiresistant S. agalactiae with the bifunctional AAC(6')-APH(2″) enzyme to be reported in the UK for >10 years. Despite belonging to the same clonal complex, the two isolates and their resistance transposons were distinct. Both retained full susceptibility to penicillin, but any penicillin/gentamicin synergy is likely to be lost.

Antibacterianos/farmacología , Bacteriemia/epidemiología , Farmacorresistencia Bacteriana/genética , Gentamicinas/farmacología , Análisis de Secuencia de ADN/métodos , Infecciones Estreptocócicas/epidemiología , Streptococcus agalactiae/genética , Bacteriemia/microbiología , Elementos Transponibles de ADN , Monitoreo Epidemiológico , Genoma Bacteriano , Genómica/métodos , Humanos , Pruebas de Sensibilidad Microbiana/métodos , Infecciones Estreptocócicas/microbiología , Streptococcus agalactiae/efectos de los fármacos , Streptococcus agalactiae/aislamiento & purificación
Euro Surveill ; 22(19)2017 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-28537550


Invasive group A streptococcal infection has a 15% case fatality rate and a risk of secondary transmission. This retrospective study used two national data sources from England; enhanced surveillance (2009) and a case management system (2011-2013) to identify clusters of severe group A streptococcal disease. Twenty-four household pairs were identified. The median onset interval between cases was 2 days (range 0-28) with simultaneous onset in eight pairs. The attack rate during the 30 days after first exposure to a primary case was 4,520 per 100,000 person-years at risk (95% confidence interval (CI): 2,900-6,730) a 1,940 (95% CI: 1,240-2,880) fold elevation over the background incidence. The theoretical number needed to treat to prevent one secondary case using antibiotic prophylaxis was 271 overall (95% CI: 194-454), 50 for mother-neonate pairs (95% CI: 27-393) and 82 for couples aged 75 years and over (95% CI: 46-417). While a dramatically increased risk of infection was noted in all household contacts, increased risk was greatest for mother-neonate pairs and couples aged 75 and over, suggesting targeted prophylaxis could be considered. Offering prophylaxis is challenging due to the short time interval between cases emphasising the importance of immediate notification and assessment of contacts.

Profilaxis Antibiótica/métodos , Vigilancia de la Población/métodos , Infecciones Estreptocócicas/prevención & control , Infecciones Estreptocócicas/transmisión , Streptococcus pyogenes/aislamiento & purificación , Adolescente , Transmisión de Enfermedad Infecciosa/prevención & control , Transmisión de Enfermedad Infecciosa/estadística & datos numéricos , Inglaterra/epidemiología , Composición Familiar , Femenino , Humanos , Incidencia , Recién Nacido , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/fisiología , Virulencia
J Med Microbiol ; 65(6): 484-493, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27046155


Legionella pneumophila is the leading cause of Legionnaires' disease, a severe pneumonia that can occur as sporadic cases or point-source outbreaks affecting multiple patients. The infection is acquired by inhalation of aerosols from contaminated water systems. In order to identify the probable source and prevent further cases, clinical and environmental isolates are compared using phenotypic and genotypic methods. Typically up to 10 days are required to isolate L. pneumophila prior to the application of standard typing protocols. A rapid protocol using a real-time PCR specific for L. pneumophila and serogroup 1, combined with nested direct molecular typing, was adopted by Public Health England in 2012 to reduce reporting time for preliminary typing results. This rapid protocol was first used to investigate an outbreak that occurred in July/August 2012 and due to the positive feedback from that investigation, it was subsequently applied to other incidents in England and Wales where faster typing results would have aided incident investigation. We present here results from seven incidents that occurred between July 2012 and June 2015 where the use of this rapid approach provided preliminary characterization of the infecting strain in an average 1.58 days (SD 1.01) after sample receipt in contrast to 9.53 days (SD 3.73) when standard protocols were applied.

Legionella pneumophila/aislamiento & purificación , Enfermedad de los Legionarios/epidemiología , Tipificación Molecular/métodos , Análisis por Conglomerados , ADN Bacteriano/genética , Brotes de Enfermedades , Inglaterra/epidemiología , Humanos , Enfermedad de los Legionarios/microbiología , Reacción en Cadena en Tiempo Real de la Polimerasa , Gales/epidemiología
J Clin Microbiol ; 50(3): 909-14, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22189123


Multiplex, real-time PCR for the identification of Ureaplasma urealyticum and Ureaplasma parvum was performed on nucleic acids extracted from sequential endotracheal aspirates obtained from preterm neonates born at <29 weeks of gestation and ventilated for more than 48 h admitted to two level 3 neonatal intensive care units. Specimens were obtained shortly after birth and sequentially up until extubation. One hundred fifty-two specimens (93.8%) contained material suitable for analysis. Ureaplasma spp. were identified in 5 of 13 neonates studied. In most cases, the DNA load of the detected Ureaplasma species was low and decreased over time. In addition, changes in detectable Ureaplasma species DNA did not relate to changes in the inflammatory marker C-reactive protein (CRP) or respiratory status. All but two blood samples obtained at times of suspected sepsis were culture positive for other microorganisms; the species cultured were typically coagulase-negative staphylococci and were associated with increased levels of CRP (>10 mg/liter). This study was limited by the small number of patients examined and does not have the power to support or contradict the hypothesis that postnatal lung infection with Ureaplasma parvum is causally related to bronchopulmonary dysplasia (BPD) or adverse respiratory outcomes after preterm birth. However, in this study, increases in CRP levels were not associated with patients in whom Ureaplasma parvum was detected, in contrast to the detection of other bacterial species.

Displasia Broncopulmonar/microbiología , Infecciones por Ureaplasma/microbiología , Ureaplasma urealyticum/aislamiento & purificación , Ureaplasma/aislamiento & purificación , Carga Bacteriana , Displasia Broncopulmonar/etiología , Displasia Broncopulmonar/inmunología , Displasia Broncopulmonar/patología , Proteína C-Reactiva/análisis , Humanos , Lactante , Recién Nacido , Unidades de Cuidado Intensivo Neonatal , Reacción en Cadena de la Polimerasa Multiplex/métodos , Nacimiento Prematuro , Respiración Artificial/efectos adversos , Ureaplasma/inmunología , Infecciones por Ureaplasma/inmunología , Infecciones por Ureaplasma/patología , Ureaplasma urealyticum/inmunología