RESUMO
Staphylococcal cassette chromosome mec (SCCmec) represents a sequence of clear clinical and diagnostic importance in staphylococci. At a minimum the chromosomal cassette contains the mecA gene encoding PBP2a but frequently also includes additional antibiotic resistance genes (e.g., ermA and aadC; macrolide and aminoglycoside resistance, respectively). Certain regions within SCCmec elements are hot spots for sequence instability due to cassette-specific recombinases and a variety of internal mobile elements. SCCmec changes may affect not only cassette stability but the integrity of adjacent chromosomal sequences (e.g., the staphylococcal protein A gene; spa). We investigated SCCmec stability in methicillin-resistant Staphylococcus aureus (MRSA) strains carrying one of four SCCmec types cultured in the absence of antimicrobial selection over a 3-month period. SCCmec rearrangements were first detected in cefoxitin-susceptible variants after 2 months of passage, and most commonly showed precise excision of the SCCmec element. Sequence analysis after 3 months revealed both precise SCCmec excision and a variety of SCCmec internal deletions, some including extensive adjacent chromosomal loss, including spa. No empty cassettes (i.e., loss of just mecA from SCCmec) were observed among the variants. SCCmec stability was influenced both by internal mobile elements (IS431) as well as the host cell environment. Genotypically similar clinical isolates with deletions in the spa gene were also included for purposes of comparison. The results indicate a role for host-cell influence and the IS431 element on SCCmec stability.
Assuntos
Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Cromossomos , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/genética , Proteína Estafilocócica A/genética , Staphylococcus aureus/genéticaRESUMO
Multiresistant Staphylococcus capitis pulsotype NRCS-A has been reported to be a major pathogen causing nosocomial bacteremia in preterm infants. We report that the NRCS-A strain CR01 harbors a novel 60.9-kb composite staphylococcal cassette chromosome mec (SCCmec) element, composed of an SCCmec with strong homologies to Staphylococcus aureus ST398 SCCmec and of an SCCcad/ars/cop harboring resistance genes for cadmium, arsenic, and copper. Whole-genome-based comparisons of published S. capitis strains suggest that strain CR01 acquired the two elements independently.
Assuntos
Staphylococcus aureus Resistente à Meticilina/genética , Sepse/microbiologia , Arsênio/farmacologia , Cádmio/farmacologia , Cromossomos Bacterianos/genética , Cobre/farmacologia , Feminino , Humanos , Recém-Nascido , MasculinoRESUMO
The persistence and transmission of infectious disease is one of the most enduring and daunting concerns in healthcare. Over the years, epidemiological analysis especially of bacterial etiological agents has undergone a remarkable evolutionary metamorphosis. While initially relying on purely phenotypic characterisation, advances in molecular biology have found translational application in a number of approaches to strain typing which commonly centre either on 'epityping' (molecular epidemiology) to characterise outbreaks, perform surveillance, and trace evolutionary pathways, or 'pathotyping' to compare strains based on the presence or absence of specific virulence or resistance genes. A perspective overview of strain typing is presented here considering the issues surrounding analyses which are employed in the localised clinical setting as well as at a more regional/national public health level. The discussion especially considers the shortcomings inherent in epidemiological analysis: less than full isolate characterisation by the typing method and limitations imposed by the available data, context, and time constraints of the epidemiological investigation (i.e. the available epidemiological window). However, the promises outweigh the pitfalls as one considers the potential for advances in genomic characterisation and information technology to provide an unprecedented aggregate of epidemiological information and analysis.
Assuntos
Epidemiologia Molecular/métodos , Tipagem Molecular , Saúde Pública , Análise de Sequência/métodos , Bases de Dados Genéticas , Humanos , Processamento de Imagem Assistida por ComputadorRESUMO
During a ß-lactam resistance surveillance study, 12 IMP-18-positive Pseudomonas aeruginosa isolates belonging to 9 different pulsed-field gel electrophoresis groups were identified. In nine isolates, a class I integron with a novel gene array was identified that contained bla(IMP-18) and bla(OXA-224), while in two isolates the class I integron contained bla(IMP-18) and bla(OXA-2) but in a new arrangement. Our findings show the dissemination of two novel class I integrons in P. aeruginosa from different regions of Puerto Rico.
Assuntos
Integrons/genética , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/genética , beta-Lactamases/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Eletroforese em Gel de Campo Pulsado , Feminino , Humanos , Lactente , Masculino , Análise em Microsséries , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Pseudomonas aeruginosa/efeitos dos fármacos , Porto RicoRESUMO
The usefulness of mec-associated dru typing in the epidemiological analysis of methicillin-resistant Staphylococcus aureus (MRSA) isolated in Malaysia was investigated and compared with pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and spa and SCCmec typing. The isolates studied included all MRSA types in Malaysia. Multilocus sequence type ST188 and ST1 isolates were highly clonal by all typing methods. However, the dru typing of ST239 isolates produced the clearest discrimination between SCCmec IIIa and III isolates, yielding more subtypes than any other method. Evaluation of the discriminatory power for each method identified dru typing and PFGE as the most discriminatory, with Simpson's index of diversity (SID) values over 89%, including an isolate which was non-typeable by spa, but dru-typed as dt13j. The discriminatory ability of dru typing, especially with closely related MRSA ST239 strains (e.g., Brazilian and Hungarian), underscores its utility as a tool for the epidemiological investigation of MRSA.
Assuntos
Técnicas de Tipagem Bacteriana/métodos , Staphylococcus aureus Resistente à Meticilina/classificação , Infecções Estafilocócicas/microbiologia , Antibacterianos/farmacologia , Análise por Conglomerados , Intervalos de Confiança , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Genótipo , Humanos , Malásia/epidemiologia , Resistência a Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Tipagem de Sequências Multilocus , Sequências Repetitivas de Ácido Nucleico/genética , Análise de Sequência de DNA , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/genéticaRESUMO
BACKGROUND: Healthcare-associated infections (HCAIs) continue to be a major cause of morbidity and mortality. Many HCAI pathogens, including multidrug-resistant organisms (MDROs), colonize the gastrointestinal tract. AIM: To determine the frequency of MDRO carriage in patients who do and do not harbour toxigenic Clostridioides difficile in their stools. METHODS: Stool specimens received from nine US laboratories were cultured using media selective for C. difficile, Staphylococcus aureus, vancomycin-resistant enterococci (VRE), and carbapenem-resistant Gram-negative organisms (CROs). Specimens and isolates were also tested by polymerase chain reaction (PCR). Bacterial isolates underwent susceptibility testing and genotyping. FINDINGS: Among 363 specimens, 175 yielded toxigenic C. difficile isolates spanning 27 PCR ribotypes. C. difficile (TCD+) stools harboured an additional 28 organisms, including six CROs (3.4%), of which two (1.1%) were carbapenemase-producing organisms (CPOs), 19 VRE (10.9%), and three meticillin-resistant S. aureus isolates (MRSA, 1.7 %). Stools that were culture negative for toxigenic C. difficile (TCD-) yielded 26 organisms, including four CROs (2.1%), 20 VRE (10.6), and two MRSA (1.1%). Excluding C. difficile, no significant differences were seen in the rates of the MDROs between TCD+ and TCD- specimens. CONCLUSION: Overall, 15.4% of the TCD+ stools and 11.2% of the TCD- stools carried at least one non-C. difficile MDRO pathogen, indicating that multiple MDROs may be present in the gastrointestinal tracts of patients, including those that harbour C. difficile.
Assuntos
Clostridioides difficile/isolamento & purificação , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Farmacorresistência Bacteriana Múltipla , Fezes/microbiologia , Clostridioides difficile/genética , Infecções por Clostridium/epidemiologia , Infecções por Enterobacteriaceae/epidemiologia , Infecções por Enterobacteriaceae/microbiologia , Trato Gastrointestinal/microbiologia , Hospitalização , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Estados Unidos/epidemiologia , Enterococos Resistentes à Vancomicina/genética , Enterococos Resistentes à Vancomicina/isolamento & purificaçãoRESUMO
BACKGROUND: Whole genome sequence (WGS)-based strain typing finds increasing use in the epidemiologic analysis of bacterial pathogens in both public health as well as more localized infection control settings. AIMS: This minireview describes methodologic approaches that have been explored for WGS-based epidemiologic analysis and considers the challenges and pitfalls of data interpretation. SOURCES: Personal collection of relevant publications. CONTENT: When applying WGS to study the molecular epidemiology of bacterial pathogens, genomic variability between strains is translated into measures of distance by determining single nucleotide polymorphisms in core genome alignments or by indexing allelic variation in hundreds to thousands of core genes, assigning types to unique allelic profiles. Interpreting isolate relatedness from these distances is highly organism specific, and attempts to establish species-specific cutoffs are unlikely to be generally applicable. In cases where single nucleotide polymorphism or core gene typing do not provide the resolution necessary for accurate assessment of the epidemiology of bacterial pathogens, inclusion of accessory gene or plasmid sequences may provide the additional required discrimination. IMPLICATIONS: As with all epidemiologic analysis, realizing the full potential of the revolutionary advances in WGS-based approaches requires understanding and dealing with issues related to the fundamental steps of data generation and interpretation.
Assuntos
Infecções Bacterianas/diagnóstico , Infecções Bacterianas/epidemiologia , Técnicas de Genotipagem/métodos , Epidemiologia Molecular/métodos , Tipagem Molecular/métodos , Sequenciamento Completo do Genoma/métodos , Técnicas Bacteriológicas/métodos , Humanos , Polimorfismo de Nucleotídeo Único , Homologia de SequênciaRESUMO
Community-associated methicillin-resistant Staphylococcus aureus isolates characteristically contain the genes for Panton-Valentine leukocidin (PVL), which is a proposed virulence factor. To determine whether different alleles of the PVL genes lukS-PV and lukF-PV occur, and whether they are associated with specific genetic lineages of S. aureus, sequences from 28 S. aureus isolates, representing four different multilocus sequence types, and bacteriophages SLT and PVL were compared. Seven nucleotide polymorphisms were identified, which defined three groups of the lukS-PV and lukF-PV sequence. Only one polymorphism resulted in an amino-acid change. Bacteriophage SLT and isolates of bacteriophage type 80/81 contained the prototypic (founder) lukS-PV and lukF-PV sequence. The alleles were not lineage-specific.
Assuntos
Toxinas Bacterianas/genética , Exotoxinas/genética , Leucocidinas/genética , Polimorfismo de Nucleotídeo Único/genética , Staphylococcus aureus/genética , Alelos , Infecções Comunitárias Adquiridas , Ligação Genética/genética , Humanos , Resistência a Meticilina/genética , Dados de Sequência MolecularRESUMO
Nosocomial late-onset sepsis represents a frequent cause of morbidity and mortality in preterm neonates. The Staphylococcus capitis clone NRCS-A has been previously described as an emerging cause of nosocomial bacteraemia in French neonatal intensive-care units (NICUs). In this study, we aimed to explore the possible unrecognized dissemination of this clone on a larger geographical scale. One hundred methicillin-resistant S. capitis strains isolated from neonates (n = 86) and adult patients (n = 14) between 2000 and 2013 in four different countries (France, Belgium, the UK, and Australia) were analysed with SmaI pulsed-field gel electrophoresis (PFGE) and dru typing. The vast majority of NICU strains showed the NRCS-A pulsotype and the dt11c type (96%). We then randomly selected 14 isolates (from neonates, n = 12, three per country; from adult patients, n = 2), considered to be a subset of representative isolates, and performed further molecular typing (SacII PFGE, SCCmec typing, and multilocus sequence typing-like analysis), confirming the clonality of the S. capitis strains isolated from neonates, despite their distant geographical origin. Whole genome single-nucleotide polymorphism-based phylogenetic analysis of five NICU isolates (from the different countries) attested to high genetic relatedness within the NRCS-A clone. Finally, all of the NRCS-A strains showed multidrug resistance (e.g. methicillin and aminoglycoside resistance, and decreased vancomycin susceptibility), with potential therapeutic implications for infected neonates. In conclusion, this study represents the first report of clonal dissemination of methicillin-resistant coagulase-negative Staphylococcus clone on a large geographical scale. Questions remain regarding the origin and means of international spread, and the reasons for this clone's apparent predilection for neonates.
Assuntos
Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Genótipo , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus/classificação , Staphylococcus/isolamento & purificação , Adolescente , Adulto , Antibacterianos/farmacologia , Austrália/epidemiologia , Criança , Pré-Escolar , Farmacorresistência Bacteriana Múltipla , Europa (Continente)/epidemiologia , Feminino , Humanos , Lactente , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Masculino , Epidemiologia Molecular , Tipagem Molecular , Filogenia , Polimorfismo de Nucleotídeo Único , Sepse/epidemiologia , Sepse/microbiologia , Staphylococcus/genéticaRESUMO
Recombination-deficient mutants of Staphylococcus aureus have been isolated and found to have properties similar to those of recombination-deficient Escherichia coli. In addition, one Rec(-) mutant was found to be defective in the restriction and modification of DNA. There is a marked reduction ( approximately 10(4)-fold) in recombination between penicillinase plasmids in the Rec(-) mutants suggesting that these elements do not encode an efficient recombination system. There is, however, a demonstrable residuum of interplasmid recombination; evidence is lacking on whether this residuum is a plasmid or host function. In the absence of the generalized host recombination system it has been possible to demonstrate that interplasmid recombination occurs during vegetative bacteriophage growth and is presumably mediated by a phage-determined recombination system.
Assuntos
Cromossomos Bacterianos , Herança Extracromossômica , Recombinação Genética , Staphylococcus , Conjugação Genética , DNA Bacteriano , Resistência Microbiana a Medicamentos , Genótipo , Mutação , Radiogenética , Staphylococcus/efeitos dos fármacos , Staphylococcus/efeitos da radiação , Fagos de Staphylococcus , Transdução Genética , Raios UltravioletaRESUMO
Typing of healthcare-associated methicillin-resistant Staphylococcus aureus (MRSA) from Australia in the 1970s revealed a novel clone, ST2249-MRSA-III (CC45), present from 1973 to 1979. This clone was present before the Australian epidemic caused by the recombinant clone, ST239-MRSA-III. This study aimed to characterize the genome of ST2249-MRSA-III to establish its relationship to other MRSA clones. DNA microarray analysis was conducted and a draft genome sequence of ST2249 was obtained. The recombinant structure of the ST2249 genome was revealed by comparisons to publicly available ST239 and ST45 genomes. Microarray analysis of genomic DNA of 13 ST2249 isolates showed gross similarities with the ST239 chromosome in a segment around the origin of replication and with ST45 for the remainder of the chromosome. Recombination breakpoints were precisely determined by the changing pattern of nucleotide polymorphisms in the genome sequence of ST2249 isolate SK1585 compared with ST239 and ST45. One breakpoint was identified to the right of oriC, between sites 1014 and 1065 of the gene D484_00045. Another was identified to the left of oriC, between sites 1185 and 1248 of D484_01632. These results indicate that ST2249 inherited approximately 35.3% of its chromosome from an ST239-like parent and 64.7% from an ST45-like parent. ST2249-MRSA-III resulted from a major recombination between parents that resemble ST239 and ST45. Although only limited Australian archival material is available, the oldest extant isolate of ST2249 predates the oldest Australian isolate of ST239 by 3 years. It is therefore plausible that these two recombinant clones were introduced into Australia separately.
Assuntos
Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Genótipo , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Recombinação Genética , Infecções Estafilocócicas/epidemiologia , Austrália/epidemiologia , Cromossomos Bacterianos , DNA Bacteriano/química , DNA Bacteriano/genética , Evolução Molecular , Genoma Bacteriano , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Análise em Microsséries , Análise de Sequência de DNA , Infecções Estafilocócicas/microbiologiaRESUMO
Ciprofloxacin is a new 6-fluoro-7-piperazino-4-quinolone that is highly active against a broad array of microbial pathogens. Minimal inhibitory concentrations (MICs) of ciprofloxacin are generally below 0.5 micrograms/ml for Hemophilus, Neisseria, and Enterobacteriaceae and are 1.0 microgram/ml or less for many non-fermentative gram-negative bacteria. Most staphylococci, including strains resistant to methicillin, are inhibited by 1.0 microgram/ml or less of ciprofloxacin, whereas streptococci are somewhat less susceptible. Obligate anaerobes are generally not susceptible to ciprofloxacin at concentrations below 1.0 microgram/ml. The antimicrobial potency of ciprofloxacin is twofold to fourfold greater than that of norfloxacin and is considerably greater than that of cephalosporins and aminoglycosides in tests with most gram-negative bacteria. Factors diminishing the in vitro activity of ciprofloxacin include acidic pH, high levels of magnesium ions, and an inoculum size of 10(7) colony-forming units/ml or greater. Ciprofloxacin is bactericidal at concentrations near its MIC for most bacteria. In vivo tests with experimentally induced infections in animals confirm the potency of ciprofloxacin. Doses required to protect 50 percent of animals from death are generally less than 2.0 mg/kg for gram-negative infections and range from 0.7 to 7.0 mg/kg for staphylococcal infections. The antimicrobial spectrum and potency of ciprofloxacin demonstrated in these preclinical studies make this quinolone a promising new antimicrobial agent.
Assuntos
Infecções Bacterianas/tratamento farmacológico , Ciprofloxacina/farmacologia , Animais , Avaliação Pré-Clínica de Medicamentos , Feminino , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/genética , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/genética , Masculino , Meticilina/farmacologia , Camundongos , Mutação , Resistência às PenicilinasRESUMO
OBJECTIVES: To determine the prevalence of penicillin-nonsusceptible Streptococcus pneumoniae (NS-SP) at 12 child-care centers (CCC) in urban and rural Nebraska and to evaluate the genetic diversity of pneumococcal strains present in the CCC environment. METHODS: Nasopharyngeal cultures for S. pneumoniae were obtained from children 2 to 24 months old. Capsular serotyping, pulsed field gel electrophoresis (PFGE) and microbroth dilution MICs were performed for all S. pneumoniae. Antibiotic exposure was also evaluated as a potential risk factor for colonization with NS-SP. RESULTS: Nasopharyngeal colonization with S. pneumoniae was present in 121 (56%) of 215 children. The MICs of penicillin were 0.12 to 1.0 microgram/ml for 57 (47%) and > 1.0 microgram/ml for 10 (8%) isolates. Clindamycin MICs of > 0.5 microgram/ml were found in 6 isolates (5%). MICs of ceftriaxone were 0.5 microgram/ml in 28% of S. pneumoniae and 1.0 microgram/ml in 7%. PFGE and capsular serotyping demonstrated multiple strains that were penicillin-nonsusceptible in both the urban and rural CCC. PFGE and capsular serotype defined shared strains within each CCC, but some PFGE "types" could be found in multiple serotypes. Antibiotic exposure during the 2 months before nasopharyngeal culture was not a statistically significant risk factor for nasopharyngeal colonization with NS-SP. CONCLUSIONS: NS-SP are highly prevalent in urban and rural Nebraska. PFGE similarities between serotypes may reflect "serotype switching" but may also reflect genetic similarity between S. pneumoniae strains.
Assuntos
Portador Sadio/microbiologia , Resistência às Penicilinas , Infecções Pneumocócicas/microbiologia , Streptococcus pneumoniae , Portador Sadio/epidemiologia , Creches , Humanos , Lactente , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Nasofaringe/microbiologia , Nebraska/epidemiologia , Infecções Pneumocócicas/epidemiologia , Prevalência , População Rural , Sorotipagem , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/isolamento & purificação , População UrbanaRESUMO
A prolonged outbreak of Citrobacter diversus central nervous system infection among hospitalized term infants, peaking in 1979, ceased with establishment of nurse-patient cohorting. The outbreak was attributed to dissemination of an epidemic strain among infants in an antiquated neonatal intensive care unit. When C. diversus colonization recurred within the new neonatal intensive care unit in 1984, cohorting and bacteriologic surveillance were reinstituted. By utilizing biotypes, plasmid profiles and antibiograms, four different C. diversus strains were identified circulating during 1979. Strains recovered between 1984 and 1988 from neonatal intensive care unit infants were similar to those from community-acquired sources. A strain considered avirulent in 1979 was found causing bacteremia in two infants (one with central nervous system disease) in 1984 to 1988. During cohorting C. diversus acquisition was 0.019/patient-month; after cohorting ceased it was 0.017/patient-month. Multiple source introductions appeared to occur with different C. diversus strains, some causing infant disease. No efficacy of cohorting was evident.
Assuntos
Citrobacter , Infecção Hospitalar/epidemiologia , Infecções por Enterobacteriaceae/epidemiologia , Infecções por Enterobacteriaceae/microbiologia , Unidades de Terapia Intensiva Neonatal/estatística & dados numéricos , Citrobacter/classificação , Citrobacter/isolamento & purificação , Infecção Hospitalar/microbiologia , Florida/epidemiologia , Humanos , Recém-Nascido , Estudos Longitudinais , Enfermagem Primária , Especificidade da EspécieRESUMO
We obtained nasopharyngeal cultures for Streptococcus pneumoniae from 54 children ages 2 to 24 months attending an Omaha child-care center (CCC) in April 1994. Thirty-two (59%) of the 54 children were colonized with S. pneumoniae belonging to serotypes 23, 19, 6 and 11. Seventeen (53%) of the pneumococcal isolates were highly resistant to penicillin (minimal inhibitory concentration > or = 2.0 micrograms/ml; HR-SP) and 7 (22%) were intermediately resistant to penicillin (0.12 < or = minimal inhibitory concentration < or = 1.0 microgram/ml; IR-SP). Within each pneumococcal capsular serotype, there were 1 to 3 DNA subtypes based on pulsed field gel electrophoresis analysis. A single pulsed field gel electrophoresis strain predominated in most CCC rooms, suggesting horizontal transmission among cohorted children. Nasopharyngeal cultures obtained 4 months later revealed similar S. pneumoniae colonization rates (28 of 52, 54%); however, only 2 (7%) of 28 isolates were HR-SP and 11 (39%) were IR-SP. Colonization with resistant pneumococci persisted after 4 months in 4 (12%) of 34 children cultured on both occasions. Antibiotic use by attendees had decreased notably between the two sampling periods, suggesting that selective pressure within the CCC might contribute to seasonal variation in colonization rates with HR-SP and IR-SP. We conclude that multiple genetic clones of penicillin-resistant pneumococci can occur simultaneously in a single CCC, especially during periods of heavy antibiotic selection pressure. However, individual clones of penicillin-resistant S. pneumoniae may be spread from child to child, suggesting that colonization with penicillin-resistant S. pneumoniae should now be considered a CCC-associated phenomenon.
Assuntos
Nasofaringe/microbiologia , Resistência às Penicilinas , Streptococcus pneumoniae/isolamento & purificação , Antibacterianos/farmacologia , Creches , Pré-Escolar , Eletroforese em Gel de Campo Pulsado , Humanos , Lactente , Testes de Sensibilidade Microbiana , Sorotipagem , Streptococcus pneumoniae/classificação , Streptococcus pneumoniae/genéticaRESUMO
Strain typing is an integral part of epidemiological investigations of nosocomial infections. Methods for distinguishing among bacterial strains have improved dramatically over the last 5 years, due mainly to the introduction of molecular technology. Although not all molecular techniques are equally effective for typing all organisms, pulsed-field gel electrophoresis is the technique currently favored for most nosocomial pathogens. Criteria to aid epidemiologists in interpreting results have been published. Nucleic acid amplification-based typing methods also are applicable to many organisms and can be completed within a single day, but interpretive criteria still are under debate. Strain typing cannot be used to replace a sound epidemiological investigation, but serves as a useful adjunct to such investigations.
Assuntos
Técnicas de Tipagem Bacteriana , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Técnicas Genéticas , Estudos Soroepidemiológicos , Interpretação Estatística de Dados , Humanos , Avaliação da Tecnologia BiomédicaRESUMO
Although Corynebacterium minutissimum is well-known as the cause of erythrasma, it is noted as the etiologic agent of nondermatologic disease only rarely. We document this organism as a cause of central venous catheter-associated bacteremia and report the use of pulsed-field gel electrophoresis to characterize its molecular epidemiology.
Assuntos
Bacteriemia/diagnóstico , Bacteriemia/etiologia , Cateterismo Venoso Central/efeitos adversos , Infecções por Corynebacterium/diagnóstico , Bacteriemia/microbiologia , Infecções por Corynebacterium/etiologia , Diagnóstico Diferencial , Eletroforese em Gel de Campo Pulsado , Evolução Fatal , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
One hundred penicillin-resistant Streptococcus pneumoniae (PRSP) strains from Asia, Europe, and North America were analyzed using pulsed-field gel electrophoresis; fingerprinting of penicillin binding protein (pbp) genes; and BOX PCR. Results show that six PFGE patterns (three patterns comprising > or = 2 serotypes) were found widespread and accounted for 64 of the 100 PRSP strains.
Assuntos
Proteínas de Bactérias , Hexosiltransferases , Resistência às Penicilinas , Peptidil Transferases , Infecções Pneumocócicas/microbiologia , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/genética , Antibacterianos/farmacologia , Ásia/epidemiologia , Proteínas de Transporte/genética , Impressões Digitais de DNA , Eletroforese em Gel de Campo Pulsado , Europa (Continente)/epidemiologia , Genes Bacterianos , Humanos , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Muramilpentapeptídeo Carboxipeptidase/genética , América do Norte/epidemiologia , Proteínas de Ligação às Penicilinas , Infecções Pneumocócicas/epidemiologia , Reação em Cadeia da Polimerase/métodos , Sorotipagem , Streptococcus pneumoniae/classificaçãoRESUMO
Bacteriophage typing is currently the recognised methodology for the typing of methicillin-resistant Staphylococcus aureus (MRSA) in the UK. Bacteriophage typing is less discriminatory and does not type all isolates compared with some molecular methods for typing MRSA. Chromosomal genotyping by pulsed-field gel electrophoresis (PFGE) is increasingly recognised as an improved method for typing MRSA, providing increased discrimination and typability. In this study the results of a comparison of bacteriophage typing and PFGE typing and subtyping are presented for a large collection of isolates from the North-West of England. Isolates belonging to the most frequently isolated epidemic methicillin-resistant Staphylococcus aureus (EMRSA) bacteriophage types 15 and 16 were typed by PFGE with further discrimination of common PFGE types possible into a number of subtypes. These results for a large collection of isolates demonstrate the improved typing of MRSA with PFGE. The widespread acceptance of PFGE for typing MRSA isolates has been hampered by the lack of standardised methodologies. Recently, a standardised PFGE strain typing system, known as the GenePath system has become available. The results of an inter-laboratory comparison of PFGE typing for a collection of isolates demonstrated good reproducibility with this system.
Assuntos
Tipagem de Bacteriófagos , Eletroforese em Gel de Campo Pulsado , Resistência a Meticilina , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/classificação , Técnicas de Tipagem Bacteriana , Inglaterra , Humanos , Laboratórios/normas , Reprodutibilidade dos Testes , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/isolamento & purificaçãoRESUMO
Recombination-deficient (rec) mutants of Staphylococcus aureus strains 152 and Ps29 were sought by initially screening mutagenized cultures for mutants exhibiting increased sensitivity to both ultraviolet (UV) radiation and N-methyl-N'-nitro-N-nitrosoguanidine (NG). Mutants thus isolated were analyzed for recombinational ability by transduction, and further characterized in terms of sensitivity to UV, NG, ability to repair UV-irradiated bacteriophage, and spontaneous and UV-induced DNA degradation. Mutagenesis of strain 152 yielded three isolates, one of which was rec, the second potentially lex, and the third possessing an undetermined repair deficiency. Mutagenesis of strain Ps29 resulted in the isolation of one mutant, which exhibited a rec genotype. In searching for rec mutants of S. aureus, the value of initially screening mutagenized cultures for mutants exhibiting concurrent sensitivity to UV and NG, as opposed to screening for UV sensitivity alone, is discussed.