Phenotypic and genetic characteristics of fluoroquinolone- and methicillin-resistant Staphylococcus aureus / Características fenotípicas y genéticas de Staphylococcus aureus resistente a meticilina y a fluoroquinolonas

INTRODUCTION: Fluoroquinolon:e resistance in methicillin-resistant Staphylococcus aureus (MRSA) has ncreased in recent years. The objective of this study was to characterise two MRSA populations, one susceptible to fluoroquinolones and other resistant identifying the clonal types and the differential characteristics of both MRSA populations. METHODS: Molecular typing using PFGE, MLST, spa and SSCmec was performed on 192 MRSA strains isolated from 2009 to 2011, 49 only oxacillin-resistant (OX-R) and 143 oxacillin and levofloxacin-resistant (OX-R-LEV-R). Mutations that conferred resistance to fluoroquinolones, hypermutable phenotypes and the presence of eight microbial surface components recognising adhesive matrix molecules (MSCRAMMs) were also studied. RESULTS: A statistically significant increase in the OX-R-LEV-R phenotype was observed (p < 0.05). The most common clone of the OX-R isolates was sequence type (ST) 8 (32.6%), followed by ST72 (26.5%) and ST5 (26.5%). In the OX-R-LEV-R phenotype, the ST5 clone was the most common (65.7%), followed by ST72 (15.4%), and ST125 (12.6%). All isolates except the ST398 clone carried the SCCmecIVc. Clones ST5, ST72, ST125, and ST30 had hypermutable phenotypes. The ST72 clone and the ST30 clone in the OX-R phenotype harboured the highest number of MSCRAMMs. CONCLUSION: ST5 and ST72 clones were the most frequent clones identified in OX-R-LEV-R phenotype. Both clones showed a hypermutable phenotype that favours their selection as the fluoroquinolone resistant clones. The genetic relationships identified indicate that OX-R-LEV-R clones have evolved from OX-R MRSA clones

INTRODUCCIÓN: La resistencia a fluoroquinolonas en Staphylococcus aureus resistente a meticilina (SARM) se ha incrementado en los últimos años. El objetivo de este estudio consistió en caracterizar 2 poblaciones de SARM, una sensible a fluoroquinolonas y otra resistente identificando los tipos clonales y las características diferenciales entre los mismos. MÉTODOS: En un total de 192 SARM aislados entre los años 2009-2011, 49 solo oxacilina resistentes (OX-R) y 143 oxacilina y levofloxacino resistentes (OX-R-LEV-R), se realizó el tipado molecular mediante PFGE, MLST, spa y SSCmec. Además se estudiaron las mutaciones que confieren resistencia a las fluoroquinolonas, los fenotipos hipermutadores y la presencia de 8 componentes de la superficie microbiana que reconocen adhesinas de la matriz extracelular. RESULTADOS: En el periodo de estudio se detectó un incremento estadísticamente significativo del fenotipo OX-R-LEV-R (p < 0,05). Entre los OX-R el clon ST8 (32,6%) fue el más frecuente seguido de los clones ST72 (26,5%) y ST5 (26,5%). Entre los aislados del fenotipo OX-R-LEV-R, el clon ST5 fue el más frecuente (65,7%), seguido de los clones ST72 (15,4%) y ST125 (12,6%). Todos los aislamientos, excepto el clon ST398, portaban el SCCmec-IVc. Los clones ST5, ST30, ST72 y ST125 presentaron un fenotipo hipermutador. Los clones ST72 y ST30 OX-R son los que poseen una mayor dotación de componentes de la superficie microbiana que reconocen adhesinas de la matriz extracelular. CONCLUSIÓN: Los clones ST5 y ST72 fueron los más frecuentes en el fenotipo OX-R-LEV-R. Ambos clones poseían un fenotipo hipermutador. La estrecha relación genética entre los clones OX-R y OX-R-LEV-R pertenecientes al mismo ST sugiere que estos últimos han evolucionado a partir de una población OX-R preexistente

Phenotypic and genetic characteristics of fluoroquinolone- and methicillin-resistant Staphylococcus aureus.

INTRODUCTION: Fluoroquinolone resistance in methicillin-resistant Staphylococcus aureus (MRSA) has increased in recent years. The objective of this study was to characterise two MRSA populations, one susceptible to fluoroquinolones and other resistant identifying the clonal types and the differential characteristics of both MRSA populations. METHODS: Molecular typing using PFGE, MLST, spa and SSCmec was performed on 192 MRSA strains isolated from 2009 to 2011, 49 only oxacillin-resistant (OX-R) and 143 oxacillin and levofloxacin-resistant (OX-R-LEV-R). Mutations that conferred resistance to fluoroquinolones, hypermutable phenotypes and the presence of eight microbial surface components recognising adhesive matrix molecules (MSCRAMMs) were also studied. RESULTS: A statistically significant increase in the OX-R-LEV-R phenotype was observed (p<0.05). The most common clone of the OX-R isolates was sequence type (ST) 8 (32.6%), followed by ST72 (26.5%) and ST5 (26.5%). In the OX-R-LEV-R phenotype, the ST5 clone was the most common (65.7%), followed by ST72 (15.4%), and ST125 (12.6%). All isolates except the ST398 clone carried the SCCmecIVc. Clones ST5, ST72, ST125, and ST30 had hypermutable phenotypes. The ST72 clone and the ST30 clone in the OX-R phenotype harboured the highest number of MSCRAMMs. CONCLUSION: ST5 and ST72 clones were the most frequent clones identified in OX-R-LEV-R phenotype. Both clones showed a hypermutable phenotype that favours their selection as the fluoroquinolone resistant clones. The genetic relationships identified indicate that OX-R-LEV-R clones have evolved from OX-R MRSA clones.

A Pseudo-Outbreak of Pseudomonas putida and Stenotrophomonas maltophilia in a Bronchoscopy Unit.

BACKGROUND: Endoscopes represent the medical devices most commonly linked to health care-associated outbreaks and pseudo-outbreaks. Most of the recent outbreaks and pseudo-outbreaks have resulted from contaminated automated endoscope reprocessors (AER) or the use of damaged or malfunctioning bronchoscopes or contaminated equipment. OBJECTIVES: We investigated a pseudo-outbreak of Pseudomonas putida and Stenotrophomonas maltophilia recovered from bronchial washing (BW) specimens obtained during bronchoscopy in a bronchoscopy unit. METHODS: Samples were obtained from environmental surfaces in the endoscopy suite, bronchoscopes, and bronchoscopic dispensable material, and specimens of cleaning solutions, cleaning brushes, the AER, and the ultrasound system were sent for bacterial culture. Medical records were reviewed to identify possible infections after a bronchoscopy. RESULTS: P. putida and S. maltophilia were isolated from BW samples of 39 patients. The bronchoscopy models Olympus BF-1T160 and BF-160 were contaminated. Both bronchoscopes and other contaminated material (cleaning brushes, diluted cleaning solutions, and the sink) were isolated, but new cases continued to appear. The AER was recently installed, and new connections were used for the water lines and new tubes were connected to the AER. Initially, specimens were obtained from the external circuits and the internal walls of the AER. Finally, cultures were made from the filters on the water lines, and growth of P. putida and S. maltophilia was found. The investigation revealed that the BW specimens were contaminated because sterile saline was injected by means of the biopsy port of the bronchoscope and was recovered through the same channel by means of the proximal suction port. No patients developed clinical signs or symptoms of infection, but the positive cultures did lead to treatment of 21 patients. CONCLUSIONS: We described a pseudo-outbreak related to a contaminated bronchoscope because of inadequate installation of the AER for used new water lines and because the new tubes were connected to the AER. The antibacterial filters of the AER used tap water, and this may have contained low levels of microorganisms. No serious clinical complications derived from this pseudo-outbreak.

Nuevo clon de Acinetobacter baumannii ST187 responsable de un brote en una unidad de cuidados intensivos / New clone of ST-187 Acinetobacter baumannii responsible for an outbreak in an intensive care unit

INTRODUCCIÓN: Se describe un brote causado por un nuevo clon de Acinetobacter baumannii multirresistente (ABMR). MÉTODOS: Se realizó una búsqueda activa de portadores y de reservorios ambientales, detección de carbapenemasas por PCR-multiplex y análisis genotípico por rep-PCR, PFGE y MLST. RESULTADOS: Se identificaron 26 pacientes infectados y 10 colonizados. A. baumannii se recuperó de bombas de infusión, paredes, suelo y lavamanos. El estudio feno/genotípico mostró la expansión clonal de un único clon ST-187 productor de carbapenemasas tipo OXA-24 y OXA-51. DISCUSIÓN: Se trata del primer brote causado por A. baumannii multirresistente ST-187 (EC I/GC I)

INTRODUCTION: An ICU-outbreak caused by a novel Acinetobacter baumannii clone is described. METHODS: An active search of carriers and environmental reservoirs was carried out. Carbapenemases genes were studied using multiplex-PCR and genotypic analysis by rep-PCR, PFGE and MLST. RESULTS: A total 26 infected patients and 10 carriers were identified. A. baumannii was recovered from infusion pumps, walls, floor and washbasins. Phenotypic/genotypic analysis showed clonal expansion of a unique clone ST-187 producer of type OXA-24 and OXA-51 carbapenemases. DISCUSSION: This is the first outbreak caused by ST-187 (ECI/GCI) multiresistant A. baumannii

[New clone of ST-187 Acinetobacter baumannii responsible for an outbreak in an intensive care unit]. / Nuevo clon de Acinetobacter baumannii ST187 responsable de un brote en una unidad de cuidados intensivos.

INTRODUCTION: An ICU-outbreak caused by a novel Acinetobacter baumannii clone is described. METHODS: An active search of carriers and environmental reservoirs was carried out. Carbapenemases genes were studied using multiplex-PCR and genotypic analysis by rep-PCR, PFGE and MLST. RESULTS: A total 26 infected patients and 10 carriers were identified. A.baumannii was recovered from infusion pumps, walls, floor and washbasins. Phenotypic/genotypic analysis showed clonal expansion of a unique clone ST-187 producer of type OXA-24 and OXA-51 carbapenemases. DISCUSSION: This is the first outbreak caused by ST-187 (ECI/GCI) multiresistant A.baumannii.