RESUMEN
BACKGROUND: In January 2011, there was an outbreak of Panton-Valentine Leukocidin-positive methicillin-sensitive Staphylococcus aureus (PVL-MSSA) infection in a neonatal unit (NNU). We describe the investigation and control of an outbreak of PVL-MSSA infection in neonates. SETTING: Neonatal unit in West London. METHODS: We performed descriptive and analytical (case-control study) epidemiological investigations. Microbiological investigations including screening of MSSA isolates by PCR for the presence of the luk-PV, mecA and mecC genes and comparison of isolate with Pulsed field gel electrophoresis (PFGE). Control measures were also introduced. RESULTS: Sixteen babies were infected/colonised with the outbreak strain. Of these, one baby developed blood stream infection, 12 developed skin pustules and four babies were colonised. Four mothers developed breast abscesses. Eighty-seven babies in the unit were screened and 16 were found to have same PVL-MSSA strain (spa type t005, belonging to MLST clonal complex 22). Multivariate analysis showed gestational age was significantly lower in cases compared to controls (mean gestational age: 31.7 weeks v 35.6 weeks; P = 0.006). Length of stay was significantly greater for cases, with a median of 25 days, compared to only 6 days for controls (P = 0.01). Most (88%) cases were born through caesarean section, compared to less than half of controls. (P = 0.002). No healthcare worker carriers and environmental source was identified. The outbreak was controlled by stopping new admissions to unit and reinforcing infection control precautions. The outbreak lasted for seven weeks. No further cases were reported in the following year. CONCLUSIONS: Infection control teams have to be vigilant for rising prevalence of particular S. aureus clones in their local community as they may cause outbreaks in vulnerable populations in healthcare settings such as NNUs.
Asunto(s)
Toxinas Bacterianas/metabolismo , Exotoxinas/metabolismo , Enfermedades del Recién Nacido , Control de Infecciones/métodos , Leucocidinas/metabolismo , Complicaciones del Trabajo de Parto , Infecciones Estafilocócicas , Staphylococcus aureus , Adulto , Enfermedades de la Mama/epidemiología , Enfermedades de la Mama/microbiología , Enfermedades de la Mama/prevención & control , Lactancia Materna/estadística & datos numéricos , Estudios de Casos y Controles , Infecciones Comunitarias Adquiridas/epidemiología , Infecciones Comunitarias Adquiridas/microbiología , Brotes de Enfermedades , Femenino , Humanos , Lactante , Recién Nacido , Enfermedades del Recién Nacido/epidemiología , Enfermedades del Recién Nacido/microbiología , Enfermedades del Recién Nacido/prevención & control , Unidades de Cuidado Intensivo Neonatal/estadística & datos numéricos , Londres/epidemiología , Masculino , Madres , Complicaciones del Trabajo de Parto/epidemiología , Complicaciones del Trabajo de Parto/microbiología , Complicaciones del Trabajo de Parto/prevención & control , Embarazo , Complicaciones Infecciosas del Embarazo/epidemiología , Complicaciones Infecciosas del Embarazo/microbiología , Complicaciones Infecciosas del Embarazo/prevención & control , Prevalencia , Infecciones Estafilocócicas/congénito , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/prevención & control , Staphylococcus aureus/aislamiento & purificación , Staphylococcus aureus/metabolismoRESUMEN
Whole-genome sequencing (WGS) makes it possible to determine the relatedness of bacterial isolates at a high resolution, thereby helping to characterize outbreaks. However, for Staphylococcus aureus, the accumulation of within-host diversity during carriage might limit the interpretation of sequencing data. In this study, we hypothesized the converse, namely, that within-host diversity can in fact be exploited to reveal the involvement of long-term carriers (LTCs) in outbreaks. We analyzed WGS data from 20 historical outbreaks and applied phylogenetic methods to assess genetic relatedness and to estimate the time to most recent common ancestor (TMRCA). The findings were compared with the routine investigation results and epidemiological evidence. Outbreaks with epidemiological evidence for an LTC source had a mean estimated TMRCA (adjusted for outbreak duration) of 243 days (95% highest posterior density interval [HPD], 143 to 343 days) compared with 55 days (95% HPD, 28 to 81 days) for outbreaks lacking epidemiological evidence for an LTC (P = 0.004). A threshold of 156 days predicted LTC involvement with a sensitivity of 0.875 and a specificity of 1. We also found 6/20 outbreaks included isolates with differing antimicrobial susceptibility profiles; however, these had only modestly increased pairwise diversity (mean 17.5 single nucleotide variants [SNVs] [95% confidence interval {CI}, 17.3 to 17.8]) compared with isolates with identical antibiograms (12.7 SNVs [95% CI, 12.5 to 12.8]) (P < 0.0001). Additionally, for 2 outbreaks, WGS identified 1 or more isolates that were genetically distinct despite having the outbreak pulsed-field gel electrophoresis (PFGE) pulsotype. The duration-adjusted TMRCA allowed the involvement of LTCs in outbreaks to be identified and could be used to decide whether screening for long-term carriage (e.g., in health care workers) is warranted. Requiring identical antibiograms to trigger investigation could miss important contributors to outbreaks.
Asunto(s)
Portador Sano/epidemiología , Brotes de Enfermedades , Tipificación Molecular , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureus/clasificación , Staphylococcus aureus/genética , Secuenciación Completa del Genoma , Adulto , Portador Sano/microbiología , Electroforesis en Gel de Campo Pulsado , Genotipo , Humanos , Pruebas de Sensibilidad Microbiana , Filogenia , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
Limited data are available on the prevalence of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in the UK. We tested 124 raw meat samples for MRSA including pork (n = 63), chicken (n = 50) and turkey (n = 11) collected from retail outlets in North West England between March and July 2015. MRSA was recovered from nine (7·3%) samples (four chicken, three pork and two turkey) from different butchers and supermarkets. Four were labelled of UK origin, three were from continental Europe; the origin was not specified for two samples. Whole-genome sequencing (WGS), spa typing and the presence of lineage-specific canonical single nucleotide polymorphisms confirmed that they belonged to the livestock-associated clade of clonal complex (CC) 398. Seven (77·8%) isolates were multi-drug resistant. Phylogenetic analyses showed the isolates were diverse, suggesting multiple silent introductions of LA-MRSA into the UK food chain. Two chicken meat isolates belonged to a sub-clade recently reported from human cases in Europe where poultry meat was the probable source. The low levels of MRSA identified (<20 CFU per g) and absence of enterotoxin genes suggest the risk of acquisition of, or food-poisoning due to, LA-MRSA is low. Nevertheless, the MRSA contamination rate is higher than previously estimated; further evaluation of the public health impacts of LA-MRSA is warranted. SIGNIFICANCE AND IMPACT OF THE STUDY: Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is a public health concern worldwide, but has only been reported sporadically in the UK. In the largest UK study to date, samples of raw meat at retail sale were examined for both the presence and levels of MRSA. We report the first isolations of CC398 LA-MRSA from poultry meat in the UK including representatives of a particular sub-clade associated with cases of human infection/colonization in Europe. Although levels were low (<20 CFU per g), the contamination rate was higher than previous UK studies. Moreover, whole-genome sequencing revealed multiple independent introductions of LA-MRSA into the UK food chain.
Asunto(s)
Contaminación de Alimentos/análisis , Contaminación de Alimentos/legislación & jurisprudencia , Ganado/microbiología , Carne/microbiología , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Animales , Pollos , Inglaterra , Enfermedades Transmitidas por los Alimentos/microbiología , Humanos , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/genética , Filogenia , Infecciones Estafilocócicas/microbiología , Porcinos , PavosRESUMEN
Sixty percent of all meat consumed in the UK is imported from European countries where there have been increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) identified in food-producing animals, but rarely from such animals in the UK. Thirty samples each of raw chicken, pork and beef, sourced in England, were collected from retail outlets in Greater Manchester. MRSA was recovered from three chicken samples and one each of pork and beef, all from prepackaged supermarket meat. Four isolates were identified as representatives of the most common human healthcare-associated MRSA clone in the UK [EMRSA-15, spa type t032, belonging to multilocus sequence type clonal complex 22 (MLST-CC22)], suggesting contamination from human source(s) during meat processing. The fifth isolate (from chicken) was multiply-resistant (including oxacillin, ciprofloxacin, erythromycin, clindamycin and tetracycline), identified as ST9-SCCmecIV, spa type t1939 and lacked the immune evasion cluster, a characteristic of livestock-associated strains. This lineage has been identified previously from animals and meat products in Asia and mainland Europe but not the UK.
Asunto(s)
Genotipo , Carne/microbiología , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Tipificación de Secuencias Multilocus , Animales , Bovinos , Pollos , Farmacorresistencia Bacteriana Múltiple , Inglaterra , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/genética , Ovinos , Proteína Estafilocócica A/genéticaRESUMEN
Whole-genome sequencing (WGS) could potentially provide a single platform for extracting all the information required to predict an organism's phenotype. However, its ability to provide accurate predictions has not yet been demonstrated in large independent studies of specific organisms. In this study, we aimed to develop a genotypic prediction method for antimicrobial susceptibilities. The whole genomes of 501 unrelated Staphylococcus aureus isolates were sequenced, and the assembled genomes were interrogated using BLASTn for a panel of known resistance determinants (chromosomal mutations and genes carried on plasmids). Results were compared with phenotypic susceptibility testing for 12 commonly used antimicrobial agents (penicillin, methicillin, erythromycin, clindamycin, tetracycline, ciprofloxacin, vancomycin, trimethoprim, gentamicin, fusidic acid, rifampin, and mupirocin) performed by the routine clinical laboratory. We investigated discrepancies by repeat susceptibility testing and manual inspection of the sequences and used this information to optimize the resistance determinant panel and BLASTn algorithm. We then tested performance of the optimized tool in an independent validation set of 491 unrelated isolates, with phenotypic results obtained in duplicate by automated broth dilution (BD Phoenix) and disc diffusion. In the validation set, the overall sensitivity and specificity of the genomic prediction method were 0.97 (95% confidence interval [95% CI], 0.95 to 0.98) and 0.99 (95% CI, 0.99 to 1), respectively, compared to standard susceptibility testing methods. The very major error rate was 0.5%, and the major error rate was 0.7%. WGS was as sensitive and specific as routine antimicrobial susceptibility testing methods. WGS is a promising alternative to culture methods for resistance prediction in S. aureus and ultimately other major bacterial pathogens.
Asunto(s)
Biología Computacional/métodos , Farmacorresistencia Bacteriana , Genoma Bacteriano , Análisis de Secuencia de ADN/métodos , Staphylococcus aureus/genética , Antibacterianos/farmacología , Humanos , Sensibilidad y Especificidad , Staphylococcus aureus/efectos de los fármacosRESUMEN
Methicillin-resistant Staphylococcus aureus (MRSA) from humans can be broadly separated into 3 groups: healthcare-associated (HA), community-associated (CA), and livestock-associated (LA) MRSA. Initially based on epidemiological features, division into these classes is becoming increasingly problematic. The sequencing of S. aureus genomes has highlighted variations in their accessory components, which likely account for differences in pathogenicity and epidemicity. In particular, temperate bacteriophages have been regarded as key players in bacterial pathogenesis. Bacteriophage-associated Panton-Valentine leukocidin genes (luk-PV) are regarded as epidemiological markers of the CA-MRSA due to their high prevalence in CA strains. This paper describes the development and application of a partial composite S. aureus virulence-associated gene microarray. Epidemic, pandemic, and sporadic lineages of UK HA and CA S. aureus were compared. Phage structural genes linked with CA isolates were identified and in silico analysis revealed these to be correlated with phage serogroup. CA strains predominantly carried a PVL-associated phage either of the A or Fb serogroup, whilst HA strains predominantly carried serogroup Fa or B phages. We speculate that carriage of a serogroup A/Fb PVL-associated phage rather than the luk-PV genes specifically is correlated with CA status.
Asunto(s)
Infecciones Comunitarias Adquiridas/microbiología , Staphylococcus aureus Resistente a Meticilina/virología , Profagos/clasificación , Infecciones Estafilocócicas/microbiología , Fagos de Staphylococcus/clasificación , Toxinas Bacterianas/genética , Exotoxinas/genética , Genes Bacterianos , Genes Virales , Humanos , Leucocidinas/genética , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Análisis por Micromatrices , Profagos/aislamiento & purificación , Serotipificación , Fagos de Staphylococcus/aislamiento & purificación , Reino Unido , Factores de Virulencia/genéticaRESUMEN
Genetically diverse community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) can harbor a bacteriophage encoding Panton-Valentine leukocidin (PVL) lysogenized into its chromosome (prophage). Six PVL phages (ΦPVL, Φ108PVL, ΦSLT, ΦSa2MW, ΦSa2USA, and ΦSa2958) are known, and single-nucleotide polymorphisms (SNPs) in the PVL genes have been reported. We sought to determine the distribution of lysogenized PVL phages among MRSA strains with PVL (PVL-MRSA strains), the PVL gene sequences, and the chromosomal phage insertion sites in 114 isolates comprising nine clones of PVL-MRSA that were selected for maximal underlying genetic diversity. The six PVL phages were identified by PCR; ΦSa2USA was present in the highest number of different lineages (multilocus sequence type clonal complex 1 [CC1], CC5, CC8, and sequence type 93 [ST93]) (n = 37 isolates). Analysis of 92 isolates confirmed that PVL phages inserted into the same chromosomal insertion locus in CC22, -30, and -80 but in a different locus in isolates of CC1, -5, -8, -59, and -88 and ST93 (and CC22 in two isolates). Within the two different loci, specific attachment motifs were found in all cases, although some limited inter- and intralineage sequence variation occurred. Overall, lineage-specific relationships between the PVL phage, the genes that encode the toxin, and the position at which the phage inserts into the host chromosome were identified. These analyses provide important insights into the microepidemiology of PVL-MRSA, will prove a valuable adjunct in outbreak investigation, and may help predict the emergence of new strains.
Asunto(s)
Toxinas Bacterianas/genética , Exotoxinas/genética , Variación Genética , Leucocidinas/genética , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/virología , Infecciones Estafilocócicas/microbiología , Fagos de Staphylococcus/clasificación , Fagos de Staphylococcus/genética , Toxinas Bacterianas/biosíntesis , Técnicas de Tipificación Bacteriana , ADN Bacteriano/genética , ADN Viral/química , ADN Viral/genética , Exotoxinas/biosíntesis , Humanos , Leucocidinas/biosíntesis , Lisogenia , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Datos de Secuencia Molecular , Tipificación de Secuencias Multilocus , Profagos/clasificación , Profagos/genética , Profagos/aislamiento & purificación , Análisis de Secuencia de ADN , Fagos de Staphylococcus/aislamiento & purificaciónRESUMEN
OBJECTIVES: Skin and soft tissue infections (SSTIs) are a serious health issue for military personnel. Of particular importance are those caused by methicillin-resistant Staphylococcus aureus and Panton-Valentine leucocidin (PVL)-positive S. aureus (PVL-SA), as they have been associated with outbreaks of SSTIs. A prospective observational study was conducted in Royal Marine (RM) recruits to investigate the prevalence of PVL-SA carriage and any association with SSTIs. METHODS: A total of 1012 RM recruits were followed through a 32-week training programme, with nose and throat swabs obtained at weeks 1, 6, 15 and 32. S. aureus isolates were characterized by antibiotic susceptibility testing, spa typing, presence of mecA/C and PVL genes. Retrospective review of the clinical notes for SSTI acquisition was conducted. RESULTS: S. aureus colonization decreased from Week 1 to Week 32 (41% to 26%, p < 0.0001). Of 1168 S. aureus isolates, three out of 1168 (0.3%) were MRSA and ten out of 1168 (0.9%) PVL-positive (all MSSA) and 169 out of 1168 (14.5%) were resistant to clindamycin. Isolates showed genetic diversity with 238 different spa types associated with 25 multi-locus sequence type (MLST) clonal complexes. SSTIs were seen in 35% (351/989) of recruits with 3 training days lost per recruit. SSTI acquisition rate was reduced amongst persistent carriers (p < 0.0283). CONCLUSIONS: Nose and throat carriage of MRSA and PVL-SA was low among recruits, despite a high incidence of SSTIs being reported, particularly cellulitis. Carriage strains were predominantly MSSA with a marked diversity of genotypes. Persistent nose and/or throat carriage was not associated with SSTI acquisition. Putative person-to-person transmission within troops was identified based on spa typing requiring further research to confirm and explore potential transmission routes.
Asunto(s)
Personal Militar , Infecciones de los Tejidos Blandos/epidemiología , Infecciones de los Tejidos Blandos/microbiología , Infecciones Cutáneas Estafilocócicas/epidemiología , Infecciones Cutáneas Estafilocócicas/microbiología , Staphylococcus aureus , Adolescente , Adulto , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Estudios Prospectivos , Vigilancia en Salud Pública , Infecciones de los Tejidos Blandos/tratamiento farmacológico , Infecciones Cutáneas Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/clasificación , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/genética , Adulto JovenRESUMEN
We aimed to enhance our case ascertainment of meticillin-resistant Staphylococcus aureus encoding Panton-Valentine leucocidin (PVL-MRSA), determine the patient demographic, risk factor and disease associations, and define the clonal diversity amongst isolates referred to the UK Health Protection Agency's Staphylococcus Reference Unit. PVL-MRSA collected during 2005-6 from community-based and hospitalised patients located across England and Wales were identified by polymerase chain reaction (PCR). Representative geographically and temporally unrelated isolates were characterised via toxin gene profiling, SCCmec, spa and agr typing, multilocus sequence typing (MLST) and minimum inhibitory concentration (MIC) determinations. PVL-MRSA were identified from 275 patients. Affected individuals were <1 to 95 years of age (mean 30, median 27 years). Forty-five isolates were from 18 household or community-based clusters and 23 isolates were from outbreaks in healthcare settings. Overall, 58% (n = 161) had skin and soft tissue infections and 9% (n = 25) presented with or developed more serious disease, including eight patients (3%) with necrotising pneumonia, five of whom subsequently died. PVL-MRSA were genetically diverse and harboured SCCmecIV or V(T)/VII. Representatives of MLST clonal complexes (CCs) 8, 30 and 80 were identified the most often. The 275 PVL-MRSA included internationally disseminated community-associated MRSA (CA-MRSA) strains, as well as other minor lineages, and were associated with typical risk factors and disease presentations.
Asunto(s)
Antibacterianos/farmacología , Toxinas Bacterianas/biosíntesis , Ciprofloxacina/farmacología , Exotoxinas/biosíntesis , Leucocidinas/biosíntesis , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Técnicas de Tipificación Bacteriana , Niño , Preescolar , Análisis por Conglomerados , Infecciones Comunitarias Adquiridas/epidemiología , Infecciones Comunitarias Adquiridas/microbiología , Dermatoglifia del ADN , Inglaterra/epidemiología , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Epidemiología Molecular , Factores de Riesgo , Gales/epidemiología , Adulto JovenRESUMEN
In total, 100 Staphylococcus aureus isolates from diverse cases of skin and soft-tissue infection at a university hospital in Saxony, Germany, were characterised using diagnostic microarrays. Virulence factors, including Panton-Valentine leukocidin (PVL), were detected and the isolates were assigned to clonal groups. Thirty isolates were positive for the genes encoding PVL. Only three PVL-positive methicillin-resistant S. aureus (MRSA) isolates were found, two of which belonged to European clone ST80-MRSA IV and one to USA300 strain ST8-MRSA IV. The remaining methicillin-susceptible PVL-positive isolates belonged to a variety of different multilocus sequence types. The predominant strains were agrI/ST22, agrII/CC5, agrIII/CC30 and agrIV/ST121. In order to check for possible bias caused by regional or local outbreak strains, an additional 18 methicillin-susceptible, PVL-positive isolates from the UK were tested. Approximately two-thirds of the UK isolates belonged to types that also comprised approximately two-thirds of the isolates from Saxony. Some methicillin-susceptible PVL-positive isolates (agrI/ST152, agrIII/ST80 and agrIII/ST96) closely resembled known epidemic community-acquired MRSA (CaMRSA) strains. These findings indicate that the current rise in PVL-positive CaMRSA could be caused by the dissemination of novel SCCmec elements among pre-existing PVL-positive strains, rather than by the spread of PVL phages among MRSA strains.
Asunto(s)
Toxinas Bacterianas/genética , Infecciones Comunitarias Adquiridas/microbiología , Evolución Molecular , Exotoxinas/genética , Variación Genética , Leucocidinas/genética , Resistencia a la Meticilina/genética , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/clasificación , Técnicas de Tipificación Bacteriana , Transferencia de Gen Horizontal , Genotipo , Alemania , Humanos , Análisis por Micromatrices , Análisis de Secuencia por Matrices de Oligonucleótidos , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación , Factores de Virulencia/genéticaRESUMEN
We report the identification and control of an outbreak of a ciprofloxacin-susceptible strain of UK epidemic meticillin-resistant Staphylococcus aureus (EMRSA)-15 on a neonatal unit (NNU). All babies were screened for MRSA on admission using ciprofloxacin-containing media which did not detect the outbreak strain. The first identified case was a premature baby who developed MRSA bacteraemia with associated tibial osteomyelitis and multiple subcutaneous abscesses. The outbreak strain was subsequently identified in the nasopharyngeal secretions of a second child who was not clinically infected. Screening of all patients on the NNU using non-ciprofloxacin-media identified two other colonised babies. All four patient isolates were EMRSA-15, spa type t022, SCCmec IV, Panton-Valentine leucocidin (PVL) negative, indistinguishable by pulsed-field gel electrophoresis and susceptible to all non-beta-lactam antimicrobials tested. The outbreak strain was cultured from four of 48 environmental sites in a communal milk-expressing room. Unsupervised movement of mothers to and from the milk-expressing room may have contributed to the outbreak. Control measures included cohort isolation of affected babies, improved environmental cleaning, increased emphasis on hand hygiene and education of mothers. Ciprofloxacin-containing media should be used with caution for MRSA screening in settings where ciprofloxacin-susceptible strains (including community-associated MRSA) are increasing in prevalence.
Asunto(s)
Antibacterianos/farmacología , Ciprofloxacina/farmacología , Infección Hospitalaria/epidemiología , Brotes de Enfermedades , Farmacorresistencia Bacteriana , Eritromicina/farmacología , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureus/efectos de los fármacos , Absceso/microbiología , Bacteriemia/microbiología , Técnicas de Tipificación Bacteriana , Técnicas Bacteriológicas/métodos , Portador Sano/microbiología , Infección Hospitalaria/diagnóstico , Infección Hospitalaria/microbiología , Medios de Cultivo/química , Educación , Microbiología Ambiental , Femenino , Genotipo , Desinfección de las Manos , Servicio de Limpieza en Hospital , Humanos , Lactante , Recién Nacido , Londres/epidemiología , Pruebas de Sensibilidad Microbiana , Nasofaringe/microbiología , Osteomielitis/microbiología , Aislamiento de Pacientes , Fenotipo , Infecciones Estafilocócicas/diagnóstico , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/aislamiento & purificaciónRESUMEN
Community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen, increasingly reported worldwide to cause infections in individuals without classical risk factors for acquiring healthcare-associated MRSA (HA-MRSA). This report describes the first documented transmission of CA-MRSA in a healthcare setting in the UK, involving four babies and a member of staff in a neonatal unit. Detailed microbiological characterization of the isolates revealed that they represented a single clone with the following characteristics: multi-locus sequence type (MLST) 1; staphylococcal cassette chromosome mec (SCCmec) type IVa; protein A (spa) type t127; agr group 3, and encoding enterotoxins A and H. The Panton-Valentine leukocidin genes were not detected. The CA-MRSA strain appeared to be circulating alongside several subtypes of epidemic MRSA-15, the most prevalent HA-MRSA in the UK. A combination of infection control measures contained the outbreak. This report highlights the changing epidemiology of MRSA in the UK, and emphasizes the need for healthcare personnel to be alert to the fact that CA-MRSA can occur not only in the community but also in the healthcare setting.
Asunto(s)
Infecciones Comunitarias Adquiridas/microbiología , Infección Hospitalaria/microbiología , Control de Infecciones/métodos , Transmisión de Enfermedad Infecciosa de Profesional a Paciente , Resistencia a la Meticilina/efectos de los fármacos , Infecciones Estafilocócicas/transmisión , Staphylococcus aureus/patogenicidad , Infección Hospitalaria/transmisión , Edad Gestacional , Humanos , Recién Nacido , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus/efectos de los fármacosRESUMEN
A rapid in-house polymerase chain reaction (PCR) assay is described for the direct detection of Mycobacterium tuberculosis complex in clinical material. Its performance is compared with two kit based systems. The results of the in-house assay were comparable with the commercial assays, detecting M tuberculosis in 100% of smear positive, culture positive samples. The in-house assay proved to be rapid, easy, and inexpensive to perform, and the inclusion of an internal inhibitor control permitted validation of the PCR results.
Asunto(s)
ADN Bacteriano/aislamiento & purificación , Mycobacterium tuberculosis/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Líquido del Lavado Bronquioalveolar/microbiología , ADN Bacteriano/líquido cefalorraquídeo , ADN Bacteriano/orina , Humanos , Ganglios Linfáticos/microbiología , Mycobacterium tuberculosis/genética , Juego de Reactivos para Diagnóstico/normas , Sensibilidad y Especificidad , Esputo/microbiologíaRESUMEN
AIM: To investigate a possible outbreak of tuberculosis in a hostel for homeless men using IS6110 profiling, a polymerase chain reaction (PCR) based fingerprinting technique. METHODS: Eight cases of tuberculosis were diagnosed in residents of the hostel over a period of 28 months. To provide epidemiological data, a heminested inverse PCR (HIP) assay targeting the insertion sequence IS6110 together with its upstream flanking region was used to fingerprint the eight isolates of M tuberculosis under investigation. RESULTS: The HIP technique gave IS6110 profiles which showed that while three isolates were clearly distinct, the remaining five strains were indistinguishable, suggesting the latter were representatives of a single outbreak strain. CONCLUSIONS: The HIP assay proved discriminatory and facilitated repeated testing for the direct comparison of strains as more patients presented over the protracted course of this outbreak.
Asunto(s)
Brotes de Enfermedades , Personas con Mala Vivienda , Mycobacterium tuberculosis/clasificación , Tuberculosis Pulmonar/epidemiología , Adulto , Anciano , Técnicas de Tipificación Bacteriana , Dermatoglifia del ADN , ADN Bacteriano/genética , Inglaterra/epidemiología , Vivienda , Humanos , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/genética , Tuberculosis Pulmonar/microbiología , Tuberculosis Pulmonar/transmisiónRESUMEN
Mycoplasma fermentans has attracted much interest both as a cofactor for the progression of AIDS and as a pathogenic agent in non-AIDS related diseases. Previous studies with serological and genetic techniques suggest that M. fermentans represents a homogeneous group of organisms, with no significant differences identified among the strains examined. In this study, 25 cultures of M. fermentans, including isolates from human sources and tissue culture cells, were compared by pyrolysis mass spectrometry (PMS). It was possible to distinguish the 'type' strain PG-18 from an AIDS-associated M. fermentans strain 'incognitus' by this technique. PMS was also able to differentiate laboratory-induced aminoglycoside-resistant variants from their fully susceptible parents. Four AIDS-associated isolates were distinguished from each other, whilst five European cell culture isolates were shown to be closely related, as were six M. fermentans isolates from an outbreak of acute respiratory infection in Canada. PMS has proved useful in distinguishing isolates of M. fermentans, providing epidemiological data. In addition, PMS may help in determining the likely origin of a given isolate, and in the future may be of use in assessing the role of this micro-organism in human disease.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/complicaciones , Espectrometría de Masas/métodos , Infecciones por Mycoplasma/microbiología , Mycoplasma fermentans/aislamiento & purificación , Análisis por Conglomerados , Humanos , Infecciones por Mycoplasma/complicaciones , Mycoplasma fermentans/clasificación , Reproducibilidad de los ResultadosRESUMEN
A novel real-time quantitative PCR (QPCR) assay is described for monitoring CMV DNA load in clinical specimens using the LightCycler. The assay is rapid (< 40 min), easy to carry out, robust, reliable and is capable of detecting from 10 to over 2 x 10(5) CMV DNA copies with a wide linear range. Amplification and detection occur simultaneously, avoiding the need for post-PCR analysis and thereby minimising the risk of carryover contamination. The assay proved to be accurate, specific and reproducible when evaluated in three different laboratories. In addition, LightCycler results were comparable with those of TaqMan, an independent real-time QPCR assay.
Asunto(s)
Citomegalovirus/aislamiento & purificación , ADN Viral/análisis , Citomegalovirus/genética , Humanos , Reacción en Cadena de la Polimerasa/métodosRESUMEN
The BCG vaccine strain cannot, with confidence, be differentiated from other members of the Mycobacterium tuberculosis complex on phenotypic tests alone. Isolates from clinical sites not associated with vaccination may be confused with M. tuberculosis. A characteristic of BCG strains is the deletion of the genomic region RD1; detection of this forms the basis of a multiplex polymerase chain reaction (PCR) assay to distinguish BCG strains. In this study, 28 M. tuberculosis complex strains were analysed by the PCR assay. A DNA sequence displaying the characteristic deletion was detected in all eleven of the BCG strains tested and was not found in representatives of other members of the complex, including M. bovis. Thus, the assay affords a rapid, simple and effective method for the discrimination of the BCG vaccine strain from other members of the M. tuberculosis complex.
Asunto(s)
Vacuna BCG/microbiología , Eliminación de Gen , Genes Bacterianos/genética , Mycobacterium bovis/genética , Mycobacterium tuberculosis/genética , Reacción en Cadena de la Polimerasa/métodos , Tuberculosis/diagnóstico , Femenino , Humanos , Lactante , Masculino , Mycobacterium bovis/clasificación , Mycobacterium tuberculosis/clasificación , Sensibilidad y Especificidad , Tuberculosis/microbiologíaRESUMEN
A study was carried out of the microbial content of three types of incontinence underpads and a clinical absorbent protection pad. Coagulase-negative staphylococci and Bacillus spp. were isolated from unused samples of all makes of pad examined. Clostridium spp., including C. tetani and C. perfringens, were isolated from a proportion of pads containing re-cycled waste material. We recommend that incontinence underpads are used solely for the purpose for which they were marketed, namely, the containment of excreta.
Asunto(s)
Bacillus/aislamiento & purificación , Ropa de Cama y Ropa Blanca/normas , Clostridium/aislamiento & purificación , Equipos y Suministros de Hospitales/normas , Incontinencia Urinaria , Técnicas Bacteriológicas , Equipos Desechables/normas , Inglaterra , Contaminación de Equipos , Humanos , Incontinencia Urinaria/prevención & controlRESUMEN
Six strains each of Enterococcus faecium and E. faecalis were investigated with respect to their resistance to heat and sodium hypochlorite. All enterococci survived the temperatures and holding times specified by the Department of Health (DoH) for the disinfection of 'foul and used' or 'infected' linen (65 degrees C for 10 min or 71 degrees C for 3 min). In addition, three strains (one E. faecium and two E. faecalis) could withstand 150 ppm available chlorine for 5 min, the treatment suggested by the DoH for the disinfection of heat labile materials. Further, our results showed that four strains of E. faecium were able to survive the British Standard for heat disinfection of bedpans (80 degrees C for 1 min). The significance of these findings with particular reference to the potential for enterococci to survive and disseminate in the hospital environment is discussed.
Asunto(s)
Desinfectantes/farmacología , Desinfección/métodos , Enterococcus faecalis/efectos de los fármacos , Enterococcus faecium/efectos de los fármacos , Calor , Hipoclorito de Sodio/farmacología , Infección Hospitalaria/microbiología , Enterococcus faecalis/crecimiento & desarrollo , Enterococcus faecium/crecimiento & desarrollo , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Especificidad de la EspecieRESUMEN
A multiplex PCR was developed to detect the coagulase gene (coa; pathognomic of Staphylococcus aureus) and the mecA gene (characteristically encoding for methicillin resistance in staphylococci) in a single, rapid test. Suitable primers for the gene targets and an internal, amplification control were incorporated into a multiplex PCR assay, which was then optimized on a capillary air thermal cycler to improve the turnaround time of the test to approximately 1.5 hours. The assay was evaluated with 111 fresh clinical isolates of staphylococci. The multiplex PCR correctly distinguished between isolates of S. aureus, which were sensitive to methicillin (MSSA) and those resistant to it (MRSA). It also correctly differentiated between similar isolates of coagulase negative staphylococci (MSSE and MRSE respectively). It was concluded that this multiplex PCR was a rapid and reliable method for the detection of methicillin-resistant staphylococci.