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1.
Appl Environ Microbiol ; 81(21): 7633-43, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26341200

RESUMO

Colonization of livestock with bacteria resistant to antibiotics is considered a risk for the entry of drug-resistant pathogens into the food chain. For this reason, there is a need for novel concepts to address the eradication of drug-resistant commensals on farms. In the present report, we evaluated the decontamination measures taken on a farm contaminated with methicillin-resistant Staphylococcus aureus (MRSA) and Enterobacteriaceae expressing extended-spectrum ß-lactamases (ESBL-E). The decontamination process preceded the conversion from piglet breeding to gilt production. Microbiological surveillance showed that the decontamination measures eliminated the MRSA and ESBL-E strains that were detected on the farm before the complete removal of pigs, cleaning and disinfection of the stable, and construction of an additional stable meeting high-quality standards. After pig production was restarted, ESBL-E remained undetectable over 12 months, but MRSA was recovered from pigs and the environment within the first 2 days. However, spa (Staphylococcus aureus protein A gene) typing revealed acquisition of an MRSA strain (type t034) that had not been detected before decontamination. Interestingly, we observed that a farmworker who had been colonized with the prior MRSA strain (t2011) acquired the new strain (t034) after 2 months. In summary, this report demonstrates that decontamination protocols similar to those used here can lead to successful elimination of contaminating MRSA and ESBL-E in pigs and the stable environment. Nevertheless, decontamination protocols do not prevent the acquisition of new MRSA strains.


Assuntos
Animais Domésticos , Desinfecção/métodos , Infecções por Enterobacteriaceae/veterinária , Enterobacteriaceae/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Infecções Estafilocócicas/veterinária , beta-Lactamases/metabolismo , Agricultura , Animais , Portador Sadio/microbiologia , Portador Sadio/prevenção & controle , Infecções por Enterobacteriaceae/microbiologia , Infecções por Enterobacteriaceae/prevenção & controle , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/prevenção & controle , Suínos
2.
Int J Med Microbiol ; 304(8): 1018-23, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25116838

RESUMO

A small peptide called PSM-mec is encoded on the type II, III and VIII SCCmec cassettes present in the genomes of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) strains. This peptide is excreted by agr-positive strains, which represent about 89% of the strains of our collection and can be identified by the presence of delta toxin in mass spectrometry. The presence of the peptide in the MALDI-TOF MS spectra of whole cells was proved by a knock-down experiment employing a clone that expressed antisense RNA to psm-mec. Furthermore, evaluation of a collection of clinical agr-positive MRSA and MSSA isolates and type strains showed that, using a detection window of m/z 2411-2419, the PSM-mec is detected by mass spectrometry of whole cells with a sensitivity of 0.95 and a specificity of 1, thereby enabling rapid identification of a subgroup of MRSA with a method that is used during routine identification procedures.


Assuntos
Toxinas Bacterianas/análise , Staphylococcus aureus Resistente à Meticilina/química , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Proteínas de Bactérias/genética , Humanos , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/genética , Proteínas de Ligação às Penicilinas , Sensibilidade e Especificidade , Transativadores/genética
3.
J Clin Microbiol ; 51(6): 1809-17, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23554199

RESUMO

Nosocomial infections involving epidemic methicillin-resistant Staphylococcus aureus (MRSA) strains are a serious problem in many countries. In order to analyze outbreaks, the infectious isolates have to be typed; however, most molecular methods are expensive or labor-intensive. Here, we evaluated matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) of cell extracts for the molecular characterization of S. aureus strains. The peak patterns of 401 MRSA and methicillin-susceptible S. aureus (MSSA) strains, including clinical and laboratory strains, were analyzed. Database searches indicated the peptides that were represented by the corresponding peaks in the spectra. The identities of the peptides were confirmed by the sequencing of mutants, the expression of antisense RNA fragments that resulted in the knockdown of the peptide of interest and the concomitant loss of the signal, or tandem MALDI-TOF MS (MALDI-TOF/TOF MS). It was shown that the signals derive mainly from stress proteins and ribosomal proteins. Peak shifts that differentiate the main S. aureus clonal complexes CC5, CC22, CC8, CC45, CC30, and CC1 correlate to point mutations in the respective genes. Retrospective typing of an MRSA outbreak showed that it is possible to differentiate unrelated MSSA, MRSA, and borderline resistant S. aureus (BORSA) strains isolated from health care workers. In conclusion, this method allows for the detection of the epidemic lineages of S. aureus during species identification by MALDI-TOF MS analysis.


Assuntos
Proteínas de Bactérias/análise , Técnicas de Tipagem Bacteriana/métodos , Mutação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Staphylococcus aureus/química , Staphylococcus aureus/classificação , Humanos , Proteínas Mutantes/análise , Staphylococcus aureus/genética
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