Pseudomonas aeruginosa Isolates from Spanish Children: Occurrence in Faecal Samples, Antimicrobial Resistance, Virulence, and Molecular Typing.

Pseudomonas aeruginosa is a major opportunistic human pathogen, responsible for nosocomial infections and infections in patients with impaired immune systems. Little data exist about the faecal colonisation by P. aeruginosa isolates in healthy humans. The occurrence, antimicrobial resistance phenotype, virulence genotype, and genetic lineages of P. aeruginosa from faecal samples of children from two different Spanish regions were characterised. Seventy-two P. aeruginosa were isolated from 1,443 faecal samples. Low antimicrobial resistance levels were detected: ceftazidime (8%), cefepime (7%), aztreonam (7%), gentamicin (3%), ciprofloxacin (1%), and imipenem (1%); susceptibility to meropenem, amikacin, tobramycin, levofloxacin, and colistin. Four multidrug-resistant strains were found. Important differences were detected between both geographical regions. Forty-one sequence types were detected among the 48 tested strains. Virulence and quorum sensing genes were analysed and 13 virulotypes were detected, being 26 exoU-positive strains. Alteration in protein OprD showed eight different patterns. The unique imipenem-resistant strain showed a premature stop codon in OprD. Intestinal colonisation by P. aeruginosa, mainly by international clones (as ST244, ST253, and ST274), is an important factor for the systemic infections development and the environmental dissemination. Periodic active surveillance is useful to identify these community human reservoirs and to control the evolution of antibiotic resistance and virulence activity.

Antimicrobial susceptibility trends and evolution of isolates with extended spectrum Beta-lactamases among Gram-negative organisms recovered during the SMART study in Spain (2011-2015) / Evolución de la sensibilidad y de los aislados productores de Beta-lactamasas de espectro extendido en microorganismos gramnegativos en el estudio SMART en España (2011-2015)

Introduction. The SMART (Study for Monitoring Antimicrobial Resistance Trends) surveillance study monitors antimicrobial susceptibility and extended spectrum β-lactamases (ESBLs) in Gram-negative bacilli recovered from intra-abdominal infections (IAI). Material and methods. Antimicrobial susceptibility of 5,343 isolates from IAI recovered in 11 centres during the 2011-2015 SMART-Spain program was analysed by standard microdilution (EUCAST criteria) and compared with that from 2002-2010. ESBLs were phenotypically detected. Results. Escherichia coli, the most common isolate, significantly decreased in community acquired IAI (60.9% 2002-2010 vs. 56.1% 2011-2015, P=0.0003). It was followed in prevalence by Klebsiella pneumoniae that increased both in the community (8.9% vs. 10.8%, P=0.016) and nosocomial (9.2% vs. 10.8%, P=0.029) IAI and P. aeruginosa, which significantly increased in community acquired IAI (5.6% vs. 8.0%, P=0.0003). ESBLs were more prevalent in K. pneumoniae (16.3%) than in E. coli(9.5%) of nosocomial origin and were more frequently isolated from elderly patients (>60 years). Considering all Enterobacteriaceae, ertapenem (92.3-100%) and amikacin (95.5%-100%) were the most active antimicrobials. Ertapenem activity, unlike amoxicillin-clavulanate or piperacillin-tazobactam, remained virtually unchanged in ESBL (100%) and non-ESBL (98.8%) E. coli producers. Its activity decreased in ESBL-K. pneumonia (74.7%) but was higher than that of amoxicillin-clavulanate (14.0%) and piperacillin-tazobactam (24.0%). Interestingly, ertapenem susceptibility was maintained in >60% of ESBL isolates that were resistant to amoxicillin-clavulanate, piperacillin-tazobactam or luoroquinolones. Conclusions. SMART-Spain results support current guidelines which include ertapenem as empiric treatment in mild-moderate community-acquired IAI, particularly with ESBL producers. These recommendations will need to be updated with the recently introduction of new antimicrobials

Introducción. El estudio SMART (Study for Monitoring Antimicrobial Resistance Trends) monitoriza la sensibilidad antimicrobiana y las β-lactamasas de espectro extendido (BLEE) en bacilos gramnegativos obtenidos de infecciones intraabdominales (IIA). Material y Métodos. Se ha analizado la sensibilidad antimicrobiana (microdilución estándar, criterios EUCAST) y las BLEE (detección fenotípica) de 5.343 aislados de IIA en 11 centros del programa SMART-España durante 2011-2015 en comparación con 2002-2010. Resultados. Escherichia coli, el microorganismo más prevalente, disminuyó significativamente en las IIA de origen comunitario (60,9% 2002-2010 vs. 56,1% 2011-2015, P=0,0003). Fue seguido en prevalencia por Klebsiella pneumoniae que aumentó tanto en IIA comunitaria (8,9% vs. 10,8%, P=0,016) como nosocomial (9,2% vs. 10,8%, P=0,029) y por P. aeruginosa que aumentó en la IIA comunitaria (5,6% vs. 8,0%, P=0,0003). Las BLEE fueron más prevalentes en la IIA nosocomial por K. pneumoniae(16,3%) que por E. coli(9,5%), siendo más frecuentes en pacientes de mayor edad (>60 años). Considerando todas las Enterobacteriaceae, ertapenem (92,3-100%) y amikacina (95,5%-100%) fueron los antimicrobianos más activos. La sensibilidad a ertapenem, al contrario que a amoxicilina-clavulánico o piperacilina-tazobactam, se mantuvo sin cambios en E. coli con (98,8%) y sin BLEE (100%). Su sensibilidad disminuyó en BLEE-K. pneumoniae (74,7%) pero fue mayor que la de amoxicilina-clavulánico (14,0%) o piperacilina-tazobactam (24,0%). Es de resaltar que esta actividad se mantuvo >60% en los aislados con BLEE resistentes a amoxicilina-clavulánico, piperacilina-tazobactam o fluoroquinolonas.Conclusiones. El estudio SMART-España sustenta las guías actuales que incluyen al ertapenem como tratamiento empírico en la IIA leve-moderada comunitaria, en particular con BLEE. Estas recomendaciones precisaran actualizarse con la reciente introducción de nuevos antimicrobianos

Espectro y actividad in vitro de ceftazidima/avibactam / Spectrum and in vitro activity of ceftazidime/avibactam

Ceftazidima es una cefalosporina de tercera generación con buena actividad frente a enterobacterias y Pseudomonas spp., que es estable frente a betalactamasas de amplio espectro como TEM, SHV y OXA, y es inactivada por betalactamasas de espectro extendido, cefamicinasas y carbepenemasas. Avibactam es un nuevo inhibidor sintético de betalactamasas, no betalactámico, perteneciente a la clase de los diazabiciclooctanos, que tiene una potente actividad inhibidora sobre betalactamasas de clase A, incluyendo betalactamasas de espectro extendido y carbapenemasas, como las KPC, betalactamasas de clase C y algunas de clase D, entre las que se halla OXA-48, pero no OXA-24. No tiene actividad frente a las carbapenemasas de clase B (metalobetalactamasas). La combinación de ambos restablece la actividad amenazada del betalactámico ocasionada por la emergencia y expansión, en diferentes especies de Enterobacteriaceae, de serinabetalactamasas que hidrolizan la ceftazidima. La excelente actividad in vitro frente a enterobacterias productoras de betalactamasas de espectro extendido, betalactamasas de clase C o carbapenemasas tipos KPC y OXA-48, hace de ceftazidima/avibactam una herramienta con elevado potencial para el tratamiento de infecciones por enterobacterias multirresistentes. De igual forma, la actividad de ceftazidima/avibactam frente a Pseudomonas aeruginosa es muy superior a la de la mayoría de los betalactámicos disponibles, siendo solo comparable a la de ceftolozano/tazobactam. La existencia de cepas resistentes por producción de metalobetalactamasas y otros mecanismos poco frecuentes obliga a la prudencia en su posicionamiento para uso clínico (AU)

Ceftazidime is a third-generation cephalosporin active against Enterobacteriaceae and Pseudomonas spp. It is stable against broad spectrum beta-lactamases such as TEM, SHV or OXA, and is inactivated by the extended spectrum beta-lactamases (ESBLs), class C enzymes (AmpC) and carbapenemases. Avibactam is a new non-beta-lactam synthetic beta-lactamase inhibitor belonging to the diazabicyclooctane class. It shows potent inhibitory activity against class A beta-lactamases, including the ESBLs, AmpC and KPC carbapenemases, and some class D beta-lactamases including the carbapenemase OXA-48 but not OXA-24. On the other hand, avibactam is not active against class B carbapenemases (metallo-beta-lactamases, MBLs). The combination of avibactam with ceftazidime restores the activity of the beta-lactam compromised by the emergence and dissemination in distinct Enterobacteriaceae species of serin-betalactamases that hydrolyse ceftazidime. The excellent in vitro activity against Enterobacteriaceae isolates producing ESBLs, AmpC and carbapenemases from classes A (KPC) and D (OXA-48) makes ceftazidime/ avibactam a highly useful tool for the management of infections by multidrug-resistant strains. Likewise, the activity of ceftazidime/avibactam against P. aeruginosa is higher than that of most other available betalactams, with only ceftolozane/tazobactam showing similar activity. The isolation of resistant strains due to the production of MBLs and other infrequent mechanisms calls for prudent therapeutic use of this valuable combination (AU)

Quantitative Determination of Spring Water Quality Parameters via Electronic Tongue.

The use of a voltammetric electronic tongue for the quantitative analysis of quality parameters in spring water is proposed here. The electronic voltammetric tongue consisted of a set of four noble electrodes (iridium, rhodium, platinum, and gold) housed inside a stainless steel cylinder. These noble metals have a high durability and are not demanding for maintenance, features required for the development of future automated equipment. A pulse voltammetry study was conducted in 83 spring water samples to determine concentrations of nitrate (range: 6.9-115 mg/L), sulfate (32-472 mg/L), fluoride (0.08-0.26 mg/L), chloride (17-190 mg/L), and sodium (11-94 mg/L) as well as pH (7.3-7.8). These parameters were also determined by routine analytical methods in spring water samples. A partial least squares (PLS) analysis was run to obtain a model to predict these parameter. Orthogonal signal correction (OSC) was applied in the preprocessing step. Calibration (67%) and validation (33%) sets were selected randomly. The electronic tongue showed good predictive power to determine the concentrations of nitrate, sulfate, chloride, and sodium as well as pH and displayed a lower R² and slope in the validation set for fluoride. Nitrate and fluoride concentrations were estimated with errors lower than 15%, whereas chloride, sulfate, and sodium concentrations as well as pH were estimated with errors below 10%.

Detection of carbapenemase-producing Enterobacteriaceae in various scenarios and health settings.

Detection of carbapenemase-producing Enterobacteriaceae (CPE) is an important task at microbiology laboratories in hospitals. As the prevalence of CPE is increasing worldwide, the implementation of phenotypically based screening as well as confirmatory procedures to detect CPE are important for microbiologists. In addition to detection of carbapenem hydrolysis, the inhibition of activity against a carbapenem in the presence of several inhibitor compounds specific to class A, B, or class C beta-lactamases is a useful method to confirm the presence of carbapenemases in bacterial isolates. There is also a proteomic approach that compares the MALDI-TOF spectrum generated by the intact carbapenem (non-hydrolyzed) with that obtained after hydrolysis of the beta-lactam ring by beta-lactamase to reveal the presence of carbapenemases in bacterial isolates. Proteomic methods will probably be more frequently implemented in laboratories in the near future. Finally, molecular methods to directly or indirectly detect the presence of a carbapenemase genes are increasingly being used in microbiology laboratories. One of the main advantages of these methods is their speed, and also that they can be used directly with the clinical sample without the need for an isolated bacterial colony. Multiplex PCR, real-time PCR, DNA microarrays and pyrosequencing are some examples of molecular-based tests. Their main disadvantage is their cost, although prices are going down as the range of services increases. Surveillance of carriers is also an important task for infection control purposes. In this case, commercially available chromogenic medium supplemented with low carbapenem concentrations has shown an excellent ability to detect CPE. Moreover, molecular methods to detect specific carbapenemase genes directly from rectal swabs, stools, or other colonization sources have had excellent results.

Detection of carbapenemase-producing Enterobacteriaceae in various scenarios and health settings / Detección de enterobacterias productoras de carbapenemasas en diferentes escenarios y niveles de salud

Detection of carbapenemase-producing Enterobacteriaceae (CPE) is an important task at microbiology laboratories in hospitals. As the prevalence of CPE is increasing worldwide, the implementation of phenotypically based screening as well as confirmatory procedures to detect CPE are important for microbiologists. In addition to detection of carbapenem hydrolysis, the inhibition of activity against a carbapenem in the presence of several inhibitor compounds specific to class A, B, or class C beta-lactamases is a useful method to confirm the presence of carbapenemases in bacterial isolates. There is also a proteomic approach that compares the MALDI-TOF spectrum generated by the intact carbapenem (nonhydrolyzed) with that obtained after hydrolysis of the beta-lactam ring by beta-lactamase to reveal the presence of carbapenemases in bacterial isolates. Proteomic methods will probably be more frequently implemented in laboratories in the near future. Finally, molecular methods to directly or indirectly detect the presence of a carbapenemase genes are increasingly being used in microbiology laboratories. One of the main advantages of these methods is their speed, and also that they can be used directly with the clinical sample without the need for an isolated bacterial colony. Multiplex PCR, real-time PCR, DNA microarrays and pyrosequencing are some examples of molecular-based tests. Their main disadvantage is their cost, although prices are going down as the range of services increases. Surveillance of carriers is also an important task for infection control purposes. In this case, commercially available chromogenic medium supplemented with low carbapenem concentrations has shown an excellent ability to detect CPE. Moreover, molecular methods to detect specific carbapenemase genes directly from rectal swabs, stools, or other colonization sources have had excellent results (AU)

La detección de enterobacterias productoras de carbapenemasas (CPE) es una tarea muy importante de los laboratorios de microbiología en los hospitales. Debido a que la prevalencia de CPE se está incrementando en todo el mundo, la implementación de métodos fenotípicos de cribado, así como de confirmación posterior, orientados a la detección de CPE es una tarea muy relevante para los microbiólogos. Además de la detección de la hidrólisis del antibiótico carbapenémico, la inhibición de la actividad de la enzima sobre estos antibióticos en presencia de compuestos inhibidores específicos para las betalactamasas de clase A, B o C es un buen método validado en la actualidad para la confirmación de carbapenemasas en los aislados bacterianos. Además existen métodos proteómicos que comparan el espectro MALDI-TOF generado por un antibiótico carbapenémico (no hidrolizado), con el que se obtiene tras la hidrólisis del anillo betalactámico por la betalactamasa, en este caso, una carbapenemasa, lo que revela de manera directa la presencia de estas enzimas en los aislados bacterianos. Los métodos basados en proteómica se irán implementando, de manera paulatina, en los laboratorios en un futuro cercano. Últimamente, métodos moleculares capaces de detectar de manera directa o indirecta la presencia de un gen que codifique una carbapenemasa se están introduciendo de modo creciente en los laboratorios de microbiología. Una de sus principales ventajas es su rapidez, además de que pueden usarse directamente en la muestra clínica sin requerir una colonia bacteriana aislada para su realización. Entre ellos destacar la multiplex-PCR, la PCR en tiempo real, los microarrays de ADN o la pirosecuenciación como ejemplos de tests basados en métodos moleculares. Su principal desventaja es el coste, aunque los precios se están abaratando a la par que se incrementa la cartera de servicios. El control y vigilancia de portadores es una tarea importante para el propósito de control de la infección. En este caso, medios cromogénicos disponibles comercialmente y suplementados con bajas concentraciones de carbapenémicos han mostrado un excelente rendimiento para detectar CPE. De igual manera, métodos basados en biología molecular capaces de detectar genes que codifican carbapanemasas directamente de muestras como frotis rectales, heces u otras fuentes de colonización han revelado excelentes resultados (AU)

Usefulness of PCR-RFLP coa gene for clonal classification of methicillin-resistant Staphylococcus aureus isolates in tertiary hospitals.

One hundred and one methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates were classified into 10 genotypes based on their polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) coa pattern. PCR-RFLP coa patterns correlated with the clonal complex (CC) with the exception of CC5, which was related to 2 patterns (B and E). The PCR-RFLP coa gene technique provides a useful preliminary method to monitor variations in MRSA populations.

Resistencia a antibióticos y factores de virulencia en aislados clínicos de Salmonella enterica / Antibiotic resistance and virulence factors in clinical Salmonella enterica isolates

INTRODUCCIÓN: El incremento de Salmonella enterica multirresistente a los antibióticos, incluidos β-lactámicos y fluoroquinolonas, es un problema de importancia clínica. La propagación de Salmonella Typhimurium resistente a ampicilina (AMP)-cloranfenicol (CHL)-estreptomicina (STR)-sulfamidas (SUL)-tetraciclina (TET) portadoras de la Isla Genómica de Salmonella de tipo 1 (SGI1) y la captación de material genético transferible han favorecido la multirresistencia en este género. MÉTODOS: Se estudiaron 114 aislados clínicos de S.enterica (período 2009-2010). Se determinó la sensibilidad a 20 antibióticos por difusión en disco y microdilución. Los mecanismos de resistencia e integrones se analizaron por PCR y secuenciación en los aislados AMPR. En los aislados portadores del gen blaPSE-1 se determinó la relación clonal mediante PFGE, y la presencia de la SGI1 y 29 genes de virulencia mediante PCR. RESULTADOS: Entre los 114aislados analizados se detectaron 18serotipos distintos, destacando entre ellos Typhimurium (61%) y Enteritidis (16%). Se observaron altos porcentajes de resistencia a SUL (68%), TET (58%), AMP (55%) y STR (46%). El 92% de los 63 aislados AMPR fueron multirresistentes, siendo el más frecuente el fenotipo AMP-STR-TET-SUL (19aislados) asociado al genotipo blaTEM-1b+strA-strB+tet(B)+sul2. El 48% de los aislados presentaron integrones de clase1 (7 estructuras distintas), destacando la estructura blaOXA-1+aadA1 (8aislados), un integrón vacío e integrones no clásicos (5aislados). El gen blaPSE-1 se detectó dentro de la SGI1 clásica en 13 aislados clonalmente relacionados y portadores del mismo perfil de virulencia: CONCLUSIONES: El alto porcentaje de S.enterica multirresistentes, especialmente asociado a S.Typhimurium, al fenotipo AMP, STR, TET y SUL y al genotipo blaTEM-1b+strA-strB+tet(B)+sul2 evidencia un riesgo importante de posibles fracasos en el tratamiento de infecciones graves producidas por este serotipo

INTRODUCTION: The increase of Salmonella enterica isolates multi-resistant to different antibiotics, including-lactams and fluoroquinolones, is a problem of clinical importance. The dissemination of Salmonella Typhimurium resistant to ampicillin (AMP)-chloramphenicol (CHL)-streptomycin (STR)-sulphonamides and(SUL)-tetracycline (TET), that harbour the Salmonella Genomic Island type 1 (SGI1), and the acquisitionof transferable genetic material have favoured the multi-resistance in this genus.METHODS: A total of 114 clinical S. enterica isolates were studied (period 2009-2010). The The susceptibility to 20 antibiotics was determined by disc diffusion and microdilution. The antimicrobial resistance mechanisms and the integrons were analysed by PCR, and sequencing in the AMPR isolates. In all the blaPSE-1-positive isolates, the clonal relationship was determined by PFGE, as well as the presence of SGI1 and 29 virulence genes by PCR. RESULTS: Eighteen different serotypes were found among the 114isolates studied, Typhimurium (61%) and Enteritidis (16%) being the most prevalent. High percentages of resistance to SUL (68%), TET (58%), AMP (55%) and STR (46%) were observed. The great majority (92%) of 63 AMPR isolates were multi-resistant, with the AMP-STR-TET-SUL phenotype (19 isolates) being the most frequent one and associated with the blaTEM-1b+strA-strB+tet(B)+sul2 genotype. Class1 integrons (7 different structures) were observed in 48% AMPR isolates, highlighting the blaOXA-1+ aadA1 structure (8 isolates), one empty integron and non-classical integrons (5isolates). The blaPSE-1 gene was detected inside the classical SGI1 structure in 13 clonally-related isolates that showed the same virulence profile. CONCLUSIONS: The high percentage of multi-resistant S.enterica isolates, especially associated to S.Typhimurium, to the AMP, STR, TET and SUL phenotype, and to the blaTEM-1b+strA-strB+tet(B)+sul2 genotype, shows an important risk of possible failures in the treatment of serious infections caused by this serotype

[Antibiotic resistance and virulence factors in clinical Salmonella enterica isolates]. / Resistencia a antibióticos y factores de virulencia en aislados clínicos de Salmonella enterica.

INTRODUCTION: The increase of Salmonella enterica isolates multi-resistant to different antibiotics, including ß-lactams and fluoroquinolones, is a problem of clinical importance. The dissemination of Salmonella Typhimurium resistant to ampicillin (AMP)-chloramphenicol (CHL)-streptomycin (STR)-sulphonamides and (SUL)-tetracycline (TET), that harbour the Salmonella Genomic Island type 1 (SGI1), and the acquisition of transferable genetic material have favoured the multi-resistance in this genus. METHODS: A total of 114 clinical S.enterica isolates were studied (period 2009-2010). The susceptibility to 20 antibiotics was determined by disc diffusion and microdilution. The antimicrobial resistance mechanisms and the integrons were analysed by PCR, and sequencing in the AMP(R) isolates. In all the blaPSE-1-positive isolates, the clonal relationship was determined by PFGE, as well as the presence of SGI1 and 29 virulence genes by PCR. RESULTS: Eighteen different serotypes were found among the 114 isolates studied, Typhimurium (61%) and Enteritidis (16%) being the most prevalent. High percentages of resistance to SUL (68%), TET (58%), AMP (55%) and STR (46%) were observed. The great majority (92%) of 63 AMP(R) isolates were multi-resistant, with the AMP-STR-TET-SUL phenotype (19 isolates) being the most frequent one and associated with the blaTEM-1b+strA-strB+tet(B)+sul2 genotype. Class 1 integrons (7 different structures) were observed in 48% AMP(R) isolates, highlighting the blaOXA-1+aadA1 structure (8 isolates), one empty integron and non-classical integrons (5 isolates). The blaPSE-1 gene was detected inside the classical SGI1 structure in 13 clonally-related isolates that showed the same virulence profile. CONCLUSIONS: The high percentage of multi-resistant S.enterica isolates, especially associated to S.Typhimurium, to the AMP, STR, TET and SUL phenotype, and to the blaTEM-1b+strA-strB+tet(B)+sul2 genotype, shows an important risk of possible failures in the treatment of serious infections caused by this serotype.

Molecular epidemiology, resistance profiles and clinical features in clinical plasmid-mediated AmpC-producing Enterobacteriaceae.

During the 30 months of surveillance period, 85 pAmpC-producing isolates were detected (prevalence 0.56% overall): blaCMY-2 gene in 70 E. coli, 2 K. pneumoniae and 6 P. mirabilis isolates; and the blaDHA-1 gene in 4 E. coli and 3 K. pneumoniae. In 8.23% of them, other ß-lactamases (predominantly OXA-1) were identified. All pAmpC-producing isolates were susceptible to carbapenems, whereas high resistance to nalidixic acid, ciprofloxacin and trimethoprim-sulfamethoxazole was observed among pAmpC-producing isolates (80%, 60%, and 44.7%, respectively). In hospital patients, predisposing factors such as prior antibiotic use, previous hospitalization, presence of an indwelling device, invasive urinary tract procedures and mechanical ventilation were observed. In the community setting, urinary tract infection was the most common type of infection related to pAmpC-producing isolates. A wide heterogeneity of clones was found among our E. coli isolates by PFGE, suggesting that this mechanism of resistance is not due to the dissemination of a clonal strain. Surveillance of these resistance mechanisms in the community is thus needed. Awareness of pAmpC dynamic is required to prevent introduction into hospitals and to control the spread of this emerging resistance within the community.

Caracterización de Shigella sonnei portadora de CTX-M-15 en un paciente español sin antecedentes de viaje al extranjero / Characterisation of a CTX-M-15-producing Shigella sonnei in a Spanish patient who had not travelled abroad

De las 107 Shigella spp. aisladas entre 2000-2010, en una cepa de Shigella sonnei se detectaron los genes codificantes de TEM-1 y CTX-M-15, identificándose la estructura ISEcp1+blaCTX-M-15+orf477. La cepa portaba un integrón de clase 2 con los genes cassettes dfrA1+sat+aadA1. Se detectó un plásmido del grupo IncI1 ST31 (CC-31) demostrando su transferencia por conjugación. Describimos la primera cepa de S. sonnei en nuestra comunidad productora de CTX-M-15 perteneciente a un paciente español que no había viajado al extranjero (AU)

One hundred and seven Shigella spp. strains were isolated in our laboratory during the years 2000 to2010. One Shigella sonnei harboured the genes that coded the -lactamases TEM-1 and CTX-M-15, identifying the structure, ISEcp1 + blaCTX-M-15 + orf477, in their genetic environment. The strain also carrieda class 2 integron with the gene cassettes dfrA1 + sat + aadA1. A plasmid group IncI1 ST31 (CC-31)was detected and its mobilization by conjugation was demonstrated. We describe for the (..) (AU)

[Emergence of plasmid mediated AmpC ß-lactamasas: Origin, importance, detection and therapeutical options]. / Emergencia de ß-lactamasas AmpC plasmídicas (pAmpC ó cefamicinasas): origen, importancia, detección y alternativas terapéuticas.

AmpC ß-lactamases can hydrolyze penicillins, oxyimino-, 7-α-methoxycephalosporins and monobactams. Susceptibility to cefepime or cefpirome is little affected and is unchanged for carbapenems. Originally such genes are thought to have been mobilized to mobile genetic elements from the chromosomal ampC genes from members of Enterobacteriaceae facilitating their spread and now they can appear in bacterial lacking or poorly expressing a chromosomal ampC gene. The prevalence of infection by plasmid mediated AmpC (pAmpC) varies depending on the type of enzyme and geographical location and blaCMY-2 is the most frequently detected worldwide. Typically, pAmpC producing isolates are associated with resistance to multiple antibiotics making the selection of an effective antibiotic difficult. Phenotypic and molecular methods to detect pAmpC are described and the role of different antibiotics in the treatment of these infections is examined. Surveillance studies about the evolution of this emerging resistant mechanism are important in clinical isolates. Evaluate the in vitro susceptibility of these isolates and the clinical efficacy of other therapeutic options is required.

Emergencia de Beta-lactamasas AmpC plasmídicas (pAmpC ó cefamicinasas): origen, importancia, detección y alternativas terapéuticas / Emergence of plasmid mediated AmpC Beta-lactamasas: origin, importance, detection and therapeutical options

Las β-lactamasas AmpC pueden hidrolizar penicilinas, cefamicinas, oximinocefalosporinas y monobactams, pero no son activas frente a cefalosporinas de cuarta generación y carbapenémicos. Los genes blaAmpC, que se encuentran en el cromosoma de algunos bacilos gramnegativos, se han integrado en elementos genéticos transferibles, lo que ha permitido su difusión a microorganismos que carecen de forma natural de ampC cromosómico o lo expresan a bajo nivel. La prevalencia de las infecciones causadas por bacterias productoras de AmpC plasmídica (pAmpC) varía en función del tipo de enzima y la localización geográfica, siendo blaCMY-2 la enzima de distribución más universal. Los aislados clínicos productores de pAmpC son con frecuencia resistentes a otros antimicrobianos, lo que reduce de manera importante las opciones terapéuticas. Se describen los métodos fenotípicos y genotípicos que permiten su detección y se analiza el papel que pueden desempeñar diferentes antimicrobianos en el tratamiento de las infecciones que producen. Este mecanismo emergente de resistencia requiere detectar y vigilar su evolución en los aislados clínicos y evaluar la sensibilidad in vitro y la eficacia clínica de otras opciones terapéuticas(AU)

AmpC β-lactamases can hydrolyze penicillins, oxyimino-, 7-α-methoxycephalosporins and monobactams. Susceptibility to cefepime or cefpirome is little affected and is unchanged for carbapenems. Originally such genes are thought to have been mobilized to mobile genetic elements from the chromosomal ampC genes from members of Enterobacteriaceae facilitating their spread and now they can appear in bacterial lacking or poorly expressing a chromosomal ampC gene. The prevalence of infection by plasmid mediated AmpC (pAmpC) varies depending on the type of enzyme and geographical location and blaCMY-2 is the most frequently detected worldwide. Typically, pAmpC producing isolates are associated with resistance to multiple antibiotics making the selection of an effective antibiotic difficult. Phenotypic and molecular methods to detect pAmpC are described and the role of different antibiotics in the treatment of these infections is examined. Surveillance studies about the evolution of this emerging resistant mechanism are important in clinical isolates. Evaluate the in vitro susceptibility of these isolates and the clinical efficacy of other therapeutic options is required(AU)

[Characterisation of a CTX-M-15-producing Shigella sonnei in a Spanish patient who had not travelled abroad]. / Caracterización de Shigella sonnei portadora de CTX-M-15 en un paciente español sin antecedentes de viaje al extranjero.

One hundred and seven Shigella spp. strains were isolated in our laboratory during the years 2000 to 2010. One Shigella sonnei harboured the genes that coded the ß-lactamases TEM-1 and CTX-M-15, identifying the structure, ISEcp1+bla(CTX-M-15)+orf477, in their genetic environment. The strain also carried a class 2 integron with the gene cassettes dfrA1+sat+aadA1. A plasmid group IncI1 ST31 (CC-31) was detected and its mobilization by conjugation was demonstrated. We describe for the first time a S. sonnei strain producing a CTX-M-15 ß-lactamase recovered from a Spanish patient who had not travelled abroad.

Molecular mechanisms of quinolone resistance in clinical isolates of Aeromonas caviae and Aeromonas veronii bv. sobria.

Mutations in quinolone targets were studied together with quinolone efflux pump activation and plasmid-mediated quinolone resistance determinants in nalidixic-acid-resistant isolates of Aeromonas caviae and Aeromonas veronii. Among 135 clinical Aeromonas spp. isolated from stools of patients with gastrointestinal symptoms, 40 nalidixic acid-resistant strains belonging to A. caviae and A. veronii were selected and their susceptibility to different quinolones (ciprofloxacin, norfloxacin, ofloxacin) further evaluated. Susceptibility to nalidixic acid and ciprofloxacin in the presence/absence of Phe- Arg-ß-naphthylamide was also determined. The 16 nalidixic-acid-resistant strains identified as A. caviae were more resistant than the 24 A. veronii bv. sobria strains to ciprofloxacin, norfloxacin, and ofloxacin. All strains showed a mutation (single or double) at position 83 of the QRDR sequence of gyrA, with Ser-83 → Ile as the most frequent substitution. By contrast, no mutations were found at position 87 of gyrA. Double substitutions (GyrA-ParC) were detected in 50% of A. veronii bv. sobria isolates and in 43.75% of A. caviae strains. Both species showed decreases in the MICs of ciprofloxacin. A qnrS gene was found in an A. caviae strain. Thus, in the two species of nalidixic-acid-resistant Aeromonas isolates examined, resistance mediated by efflux pumps contributed only slightly to ciprofloxacin resistance. While two isolates were positive for the aac(6')-Ib gene, no -cr variants were detected.

Molecular mechanisms of quinolone resistance in clinical isolates of Aeromonas caviae and Aeromonas veronii bv. sobria

Mutations in quinolone targets were studied together with quinolone efflux pump activation and plasmid-mediatedquinolone resistance determinants in nalidixic-acid-resistant isolates of Aeromonas caviae and Aeromonas veronii.Among 135 clinical Aeromonas spp. isolated from stools of patients with gastrointestinal symptoms, 40 nalidixic acid-resistantstrains belonging to A. caviae and A. veronii were selected and their susceptibility to different quinolones (ciprofloxacin,norfloxacin, ofloxacin) further evaluated. Susceptibility to nalidixic acid and ciprofloxacin in the presence/absence of Phe-Arg-β-naphthylamide was also determined. The 16 nalidixic-acid-resistant strains identified as A. caviae were more resistantthan the 24 A. veronii bv. sobria strains to ciprofloxacin, norfloxacin, and ofloxacin. All strains showed a mutation (single ordouble) at position 83 of the QRDR sequence of gyrA, with Ser-83 → Ile as the most frequent substitution. By contrast, nomutations were found at position 87 of gyrA. Double substitutions (GyrA-ParC) were detected in 50% of A. veronii bv. sobriaisolates and in 43.75% of A. caviae strains. Both species showed decreases in the MICs of ciprofloxacin. A qnrS gene wasfound in an A. caviae strain. Thus, in the two species of nalidixic-acid-resistant Aeromonas isolates examined, resistancemediated by efflux pumps contributed only slightly to ciprofloxacin resistance. While two isolates were positive for theaac(6′)-Ib gene, no -cr variants were detected (AU)

In vitro activity of cefditoren and other antimicrobial agents against 288 Streptococcus pneumoniae and 220 Haemophilus influenzae clinical strains isolated in Zaragoza, Spain.

In vitro cefditoren antimicrobial activity was tested against 288 Streptococcus pneumoniae and 220 Haemophilus influenzae clinical strains isolated in our hospital from January 2005 to May 2006 by agar dilution and broth microdilution method, respectively. MICs were also determined for 13 and 10 comparison drugs, respectively. The pneumococci tested comprised 113 (39.2%) penicillin susceptible, 91 (31.6%) penicillin intermediate, and 84 (29.2%) penicillin resistant. Cefditoren was the most active drug on the basis of the MICs (MIC(90)=0.5 microg/mL), followed by ceftriaxone and levofloxacin (MIC(90)=1 microg/mL). Cefditoren MICs ranged from 0.25 to 1 microg/mL for ceftriaxone-resistant isolates, with a modal MIC of 0.5 microg/mL and an MIC(90) of 1.0 microg/mL. No S. pneumoniae isolates evaluated in this study showed MICs to cefditoren higher than 1 microg/mL (MIC range, 4 microg/mL). Against H. influenzae (Hi beta+), the rank order of intrinsic activity (MIC(90), microg/mL) was cefditoren (0.03) < cefixime (0.06)8.0).