Adecuación de la prescripción de antibióticos antipseudomónicos tras los cambios en los criterios EUCAST 2019 / Adequacy of the consumption of antipseudomonal antibiotics after changes in the 2019 EUCAST criteria

Introducción. En 2019, el Comité Europeo para el estudio de la sensibilidad antibiótica modificó las categorías de los test de sensibilidad antibiótica incluyendo el término “sensible con exposición incrementada”. Tras la difusión de protocolos locales recogiendo estas modificaciones, el objetivo de nuestro estudio fue analizar si los prescriptores se han adecuado a los mismos y el posible impacto clínico en los casos de inadecuación. Material y métodos. Estudio observacional y retrospecti vo de los pacientes con infección por pseudomonas aeruginosa y que hayan recibido antibiótico antipseudomónico desde ene ro a octubre de 2021 en un hospital terciario. Resultados. La inadecuación a las recomendaciones de la guía fueron un 57,6% en planta y un 40,4% en UCI (p<0,05). Tanto en planta como en UCI el grupo con más prescripción no ajustada a las recomendaciones de la guía fueron los amino glucósidos (92,9% y 64,9% respectivamente) por utilizar dosis subóptimas, seguido de los carbapenémicos (89,1% y 53,7% respectivamente) por no administrarlo en perfusión extendida. En planta, la tasa de mortalidad durante el ingreso o a los 30 días en el grupo de terapia inadecuada fue de 23,3% vs 11,5% en los que recibieron los tratamientos de forma adecuada (OR: 2,34; IC 95% 1,14-4,82); en UCI no hubo diferencias estadísti camente significativas. Conclusiones. Los resultados muestran la necesidad de implementar medidas para garantizar una mejor difusión y co nocimiento de los conceptos claves en el manejo de los antibió ticos, con el objetivo de garantizar exposiciones incrementadas y poder ofrecer una mejor cobertura de la infección, así como de evitar la amplificación de cepas resistente (AU)

Introduction. In 2019, the European Committee for the Study of Antibiotic Susceptibility modified the categories of antibiotic susceptibility tests to include the term “susceptible with increased exposure”. Following the dissemination of local protocols reflecting these modifications, the aim of our study was to analyse whether prescribers have adapted to them and the clinical impact in cases of inadequacy. Material and methods. Observational and retrospective study of patients with infection who received antipseudomonal antibiotics from January to October 2021 in a tertiary hospital.Results. Non adherence to the guideline recommendations was 57.6% in the ward and 40.4% in the ICU (p<0.05). In both the ward and ICU, the group with the most prescriptions not by the guideline ecommendations were aminoglycosides (92.9% and 64.9% respectively) for using suboptimal doses, followed by carbapenems (89.1% and 53.7% respectively) for not administering an extended infusion. On the ward, the mortality rate during admission or at 30 days in the inadequate therapy group was 23.3% vs 11.5% in those who received adequate treatment (OR: 2.34; 95% CI 1.14-4.82); in ICU there were no statistically significant differences.Conclusions. The results show the need to implement measures to ensure better dissemination and knowledge of key concepts in antibiotic management, to ensure increased exposures, and to be able to provide better infection coverage, as well as to avoid amplifying resistant strains (AU)

In vitro synergy screens of FDA-approved drugs reveal novel zidovudine- and azithromycin-based combinations with last-line antibiotics against Klebsiella pneumoniae.

Treatment of infections caused by multi-drug resistant (MDR) enterobacteria remains challenging due to the limited therapeutic options available. Drug repurposing could accelerate the development of new urgently needed successful interventions. This work aimed to identify and characterise novel drug combinations against Klebsiella pneumoniae based on the concepts of synergy and drug repurposing. We first performed a semi-qualitative high-throughput synergy screen (sHTSS) with tigecycline, colistin and fosfomycin (last-line antibiotics against MDR Enterobacteriaceae) against a FDA-library containing 1430 clinically approved drugs; a total of 109 compounds potentiated any of the last-line antibiotics. Selected hits were further validated by secondary checkerboard (CBA) and time-kill (TKA) assays, obtaining 15.09% and 65.85% confirmation rates, respectively. Accordingly, TKA were used for synergy classification based on determination of bactericidal activities at 8, 24 and 48 h, selecting 27 combinations against K. pneumoniae. Among them, zidovudine or azithromycin combinations with last-line antibiotics were further evaluated by TKA against a panel of 12 MDR/XDR K. pneumoniae strains, and their activities confronted with those clinical combinations currently used for MDR enterobacteria treatment; these combinations showed better bactericidal activities than usual treatments without added cytotoxicity. Our studies show that sHTSS paired to TKA are powerful tools for the identification and characterisation of novel synergistic drug combinations against K. pneumoniae. Further pre-clinical studies might support the translational potential of zidovudine- and azithromycin-based combinations for the treatment of these infections.

Beyond CC398: Characterisation of Other Tetracycline and Methicillin-Resistant Staphylococcus aureus Genetic Lineages Circulating in Spanish Hospitals.

Tetracycline resistance (TetR) has been evidenced as a good phenotypic marker for detection of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) isolates of the clonal complex CC398. The aim of this study was to characterise a collection of 95 TetR-MRSA isolates, not belonging to the lineage CC398, that were obtained in a previous multicentre study, to detect other MRSA clonal complexes that could be associated with this phenotypic TetR marker. The TetR-MRSA isolates were recovered from 20 Spanish hospitals during 2016 and they were characterised to determine their antimicrobial resistance and virulence phenotypes/genotypes as well as the presence of the immune evasion cluster (IEC). A high proportion of isolates belonging to the CC1 lineage (46%) were observed, as well as to the CC5, CC8 and CC45 lineages (11% each one). Thirty-two different spa-types were identified, being predominantly CC1-t127 (40%) and CC45-t1081 (11%). The IEC system (with the gene scn as marker) was present in 73% of isolates and 16% produced the Panton Valentine leucocidin (PVL). A high proportion of MRSA-CC1 isolates were scn-negative (38.6%) and 52.9% of them were blaZ-negative. A multidrug resistance (MDR) phenotype was identified in 86% of MRSA isolates. The knowledge of other TetR-MRSA genetic lineages, in addition to CC398, is highly relevant, since most of them were MDR and some of them presented important virulence factors. Strains potentially associated with livestock (as the subpopulation CC1-t127-scn-negative) or with humans (as the CC45 lineage or the subpopulation CC1-scn-positive) have been found in this study. The use of tetracycline-resistance for detection, not only of CC398 but also of other LA-MRSA lineages should be tracked in the future.

Use of MALDI-TOF MS (Bruker Daltonics) for identification of Mycobacterium species isolated directly from liquid medium / Utilización de MALDI-TOF MS (Bruker Daltonics) para la identificación de micobacterias aisladas directamente en medio líquido

Objectives: The aim of this study was to describe the evaluation of the use of MALDI-TOF MS for the identification of non-tuberculous mycobacteria (NTM) and Mycobacterium tuberculosis directly from liquid MGIT cultures from January 2017 to December 2017. Material/methods: A total of 155 isolates (mainly respiratory) were analyzed by MALDI-TOF MS (Bruker Daltonics) directly from MGIT liquid medium with a previous extraction procedure. Results: MALDI-TOF MS generated acceptable scores for 152 isolates (98.06%). Fifty isolates were identified as M. tuberculosis complex and the remaining 105 as NTM (M. abscessus subsp. abscessus, M. avium, M. celatum, M chelonae, M. chimaera, M. fortuitum, M. gordonae, M. intracellulare, M. kansasii, M. lentiflavum, M. mageritense, M. mucogenicum and M. xenopi). Conclusions: These results indicate that MALDI-TOF MS can be useful to identify mycobacteria directly from MGIT cultures and is an accurate, rapid and cost-effective system to be used as a routine method.(AU)

Introducción: Evaluamos la espectrometría de masas (MALDI-TOF MS [Bruker Daltonics]) para la identificación de micobacterias no tuberculosas (MNT) y Mycobacterium tuberculosis a partir de cultivos líquidos (MGIT) desde enero del 2017 a diciembre del 2017. Métodos: Se analizaron mediante MALDI-TOF MS 155 cultivos MGIT positivos, principalmente de origen respiratorio. Previamente a la realización de MALDI-TOF se realizó un procedimiento de extracción directamente del MGIT. Resultados: Mediante MALDI-TOF MS se identificó correctamente a partir del MGIT el 98,06% (n=152) de los aislados. Cincuenta aislados se identificaron como M. tuberculosis complex y los 105 restantes como MNT (M. abscessus subsp. abscessus, M. avium, M. celatum, M chelonae, M. chimaera, M. fortuitum, M. gordonae, M. intracellulare, M. kansasii, M. lentiflavum, M. mageritense, M. mucogenicum y M. xenopi). Conclusiones: Estos resultados indican que MALDI-TOF es una técnica precisa, rápida y coste-efectiva para identificar micobacterias directamente a partir de medios de cultivo líquidos en la rutina diaria.(AU)

Prevalence and Genetic Characteristics of Staphylococcus aureus CC398 Isolates From Invasive Infections in Spanish Hospitals, Focusing on the Livestock-Independent CC398-MSSA Clade.

BACKGROUND: Livestock-associated (LA)-CC398-MRSA is closely related to pigs, being unfrequently detected in human invasive infections. CC398-MSSA is emerging in human invasive infections in some countries, but genetic and epidemiological characteristics are still scarcely reported. OBJECTIVES: To determine the prevalence of Staphylococcus aureus (SA) CC398, both MRSA and MSSA, among blood cultures SA isolates recovered in Spanish hospitals located in regions with different pig-farming densities (PD) and characterize the recovered isolates. METHODS: One thousand twenty-two SA isolates (761 MSSA, 261 MRSA) recovered from blood cultures during 6-12 months in 17 Spanish hospitals (2018-2019) were studied. CC398 lineage identification, detection of spa-types, and antibiotic resistance, virulence and human immune evasion cluster (IEC) genes were analyzed by PCR/sequencing. RESULTS: Forty-four CC398-MSSA isolates (4.3% of SA; 5.8% of MSSA) and 10 CC398-MRSA isolates (1% of SA; 3.8% of MRSA) were detected. Eleven spa-types were found among the CC398-MSSA isolates with t571 and t1451 the most frequent spa-types detected (75%). Most of CC398-MSSA isolates were Immune-Evasion-Cluster (IEC)-positive (88.6%), tetracycline-susceptible (95.5%) and erythromycin/clindamycin-inducible-resistant/erm(T)-positive (75%). No statistical significance was detected when the CC398-MSSA/MSSA rate was correlated to PD (pigs/km2) (p = 0.108). On the contrary, CC398-MRSA isolates were all IEC-negative, predominately spa-t011 (70%), and the CC398-MRSA/MRSA rate was significantly associated to PD (p < 0.005). CONCLUSION: CC398-MSSA is an emerging clade in invasive infections in Spanish hospitals. CC398-MRSA (mostly t011) and CC398-MSSA (mostly t571 and t1451) show important differences, possibly suggesting divergent steps in host-adaptation evolutionary processes. While CC398-MRSA is livestock-associated (lacking IEC-system), CC398-MSSA seems to be mostly livestock-independent, carrying human-adaptation markers.

Use of MALDI-TOF MS (Bruker Daltonics) for identification of Mycobacterium species isolated directly from liquid medium.

OBJECTIVES: The aim of this study was to describe the evaluation of the use of MALDI-TOF MS for the identification of non-tuberculous mycobacteria (NTM) and Mycobacterium tuberculosis directly from liquid MGIT cultures from January 2017 to December 2017. MATERIAL/METHODS: A total of 155 isolates (mainly respiratory) were analyzed by MALDI-TOF MS (Bruker Daltonics) directly from MGIT liquid medium with a previous extraction procedure. RESULTS: MALDI-TOF MS generated acceptable scores for 152 isolates (98.06%). Fifty isolates were identified as M. tuberculosis complex and the remaining 105 as NTM (M. abscessus subsp. abscessus, M. avium, M. celatum, M chelonae, M. chimaera, M. fortuitum, M. gordonae, M. intracellulare, M. kansasii, M. lentiflavum, M. mageritense, M. mucogenicum and M. xenopi). CONCLUSIONS: These results indicate that MALDI-TOF MS can be useful to identify mycobacteria directly from MGIT cultures and is an accurate, rapid and cost-effective system to be used as a routine method.

Characterization of AmpC Beta-lactamase mutations of extensively drug-resistant Pseudomonas aeruginosa isolates that develop resistance to ceftolozane/tazobactam during therapy / Caracterización de las mutaciones en la betalactamasa AmpC de aislados de Pseudomonas aeruginosa XDR que desarrollaron resistencia a ceftolozano/tazobactam durante el tratamiento

INTRODUCTION: We characterized AmpC β-lactamase mutations that resulted in ceftolozane/tazobactam resistance in extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates recovered from patients treated with this agent from June 2016 to December 2018. METHODS: Five pairs of ceftolozane/tazobactam susceptible/resistant P. aeruginosa XDR isolates were included among a total of 49 patients treated. Clonal relationship among isolates was first evaluated by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) was further performed. AmpC mutations were investigated by PCR amplification of the blaPDC gene followed by sequencing. RESULTS: The ST175 high-risk clone was detected in four of the pairs of isolates and the ST1182 in the remaining one. All resistant isolates showed a mutation in AmpC: T96I in two of the isolates, and E247K, G183V, and a deletion of 19 amino acids (G229-E247) in the other three. The G183V mutation had not been described before. The five isolates resistant to ceftolozane/tazobactam showed cross-resistance to ceftazidime/avibactam and lower MICs of imipenem and piperacillin/tazobactam than the susceptible isolates. CONCLUSIONS: Ceftolozane/tazobactam resistance was associated in all of the cases with AmpC mutations, including a novel mutation (G183V) not previously described. There is a vital need for surveillance and characterization of emerging ceftolozane/tazobactam resistance, in order to preserve this valuable antipseudomonal agent

INTRODUCCIÓN: Se han caracterizado las mutaciones en la betalactamasa AmpC que han producido resistencia a ceftolozano/tazobactam en aislados de Pseudomonas aeruginosa extremadamente resistente (XDR) en pacientes tratados con este agente desde junio de 2016 hasta diciembre de 2018. MÉTODOS: Se incluyeron 5 pares de aislados (sensibles/resistentes a ceftolozano/tazobactam) de P. aeruginosa XDR entre un total de 49 pacientes tratados. Se estudió la relación clonal mediante electroforesis en campo pulsado y MLST. Las mutaciones en AmpC se caracterizaron mediante amplificación por PCR del gen blaPDC y posterior secuenciación. RESULTADOS: Se detectó el clon de alto riesgo ST175 en 4 pares de aislados y el ST1182 en el restante. Todos los aislados resistentes mostraron una mutación en AmpC: T96I en 2 aislados, E247K, G183V y una deleción de 19 aminoácidos (G229-E247) en los otros 3. La mutación G183V no había sido descrita antes. Los 5 aislados resistentes a ceftolozano/tazobactam mostraron resistencia cruzada a ceftazidima/avibactam y CMI inferiores de imipenem y piperacilina/tazobactam que los aislados sensibles. CONCLUSIONES: La resistencia a ceftolozano/tazobactam se asoció con mutaciones en AmpC en todos los casos, incluida una nueva mutación G183V no descrita con anterioridad. La vigilancia y caracterización de la resistencia emergente a ceftolozano/tazobactam es de gran importancia para preservar este nuevo agente antipseudomónico

Characterization of AmpC ß-lactamase mutations of extensively drug-resistant Pseudomonas aeruginosa isolates that develop resistance to ceftolozane/tazobactam during therapy.

INTRODUCTION: We characterized AmpC ß-lactamase mutations that resulted in ceftolozane/tazobactam resistance in extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates recovered from patients treated with this agent from June 2016 to December 2018. METHODS: Five pairs of ceftolozane/tazobactam susceptible/resistant P. aeruginosa XDR isolates were included among a total of 49 patients treated. Clonal relationship among isolates was first evaluated by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) was further performed. AmpC mutations were investigated by PCR amplification of the blaPDC gene followed by sequencing. RESULTS: The ST175 high-risk clone was detected in four of the pairs of isolates and the ST1182 in the remaining one. All resistant isolates showed a mutation in AmpC: T96I in two of the isolates, and E247K, G183V, and a deletion of 19 amino acids (G229-E247) in the other three. The G183V mutation had not been described before. The five isolates resistant to ceftolozane/tazobactam showed cross-resistance to ceftazidime/avibactam and lower MICs of imipenem and piperacillin/tazobactam than the susceptible isolates. CONCLUSIONS: Ceftolozane/tazobactam resistance was associated in all of the cases with AmpC mutations, including a novel mutation (G183V) not previously described. There is a vital need for surveillance and characterization of emerging ceftolozane/tazobactam resistance, in order to preserve this valuable antipseudomonal agent.

Multicenter study of clinical non-Beta-lactam-antibiotic susceptible MRSA strains: Genetic lineages and Panton-Valentine leukocidin (PVL) production / Estudio multicéntrico de cepas clínicas de SARM sensibles a antibióticos no-Beta-lactámicos: líneas genéticas y producción de la leucocidina de Panton-Valentine

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) is considered a major cause of healthcare-associated (HA) and community-acquired (CA) infections. Considering non-β-lactam susceptibility as a potential marker for mecC-MRSA and CA-MRSA, the aim of this study was to determine the frequency and the associated genetic lineages of non-beta-lactam-antibiotic susceptible MRSA (NBLS-MRSA) strains in a multicenter study in Spain. METHODS: A collection of 45 NBLS-MRSA strains recovered in the period from January to June 2016 from 12 Spanish hospitals was analyzed. Molecular typing through spa-type characterization, agr group and multi-locus-sequence typing was performed. Methicillin-resistant genes (mecA and mecC) as well as immune evasion cluster (scn-chp-sak-sea-sep, considering scn gene as the marker of IEC system) and Panton-Valentine leukocidin (PVL) genes were determined with PCR/sequencing. RESULTS: The NBLS-MRSA phenotype was uncommon in the 12 hospitals analyzed (NBLS-MRSA/MRSA frequency: 0.3%-7.7%). All strains contained the mecA gene (and none contained mecC). Twenty-two different spa-types were detected among NBLS-MRSA strains, with spa-t008/agr-I the most prevalent (27%). The main clonal complexes were (CC/%): CC8/42.2%, CC5/33.3% and CC30/4.4%, with ST8 and ST5 as the main sequence types. The PVL toxin was present in 38% of strains (with spa-types t008, t024, t019, t044, t068, t318 and t3060). The IEC genes were detected in 78% of strains: IEC type-B (n = 17), type-F (n = 16), type-A (n = 1) and type-E (n = 1); 10 MRSA isolates were scn-negative. CONCLUSION: The NBLS-MRSA phenotype is uncommon in the analyzed hospitals; although no mecC-positive strains were detected, it could be a good marker for MRSA PVL-positive isolates (38%), frequently associated with CA-MRSA infections

INTRODUCCIÓN: Staphylococcus aureus resistente a meticilina (SARM) es una de las principales causas de infecciones tanto relacionadas con la asistencia sanitaria como asociadas a la comunidad (AC). Considerando la sensibilidad a antibióticos no-β-lactámicos como marcador potencial de SARM-mecC y SARM-AC, el objetivo de este estudio fue determinar la frecuencia y líneas genéticas de cepas SARM sensibles a antibióticos no-β-lactámicos (SARM-SNBL) en un estudio multicéntrico en España. MÉTODOS: Se analizaron 45 cepas SARM-SNBL procedentes de 12 hospitales obtenidas durante enero-junio de 2016. El tipado molecular se realizó mediante caracterización del spa-tipo, grupo agr y multi-locus-sequence typing. Mediante PCR/secuenciación se determinaron los genes: de resistencia a meticilina (mecA y mecC), del sistema de evasión inmune humano (scn-chp-sak-sea-sep, usando scn como marcador del sistema IEC) y de la leucocidina de Panton-Valentine (LPV). RESULTADOS: El fenotipo SARM-SNBL fue infrecuente en los 12 hospitales analizados (frecuencia SARM-SNBL/SARM: 0,3-7,7%). Todas las cepas fueron mecA-positivas (ninguna mecC). Se detectaron 22 spa-tipos diferentes, siendo el spa-t008/agr-I el prevalente (27%). Los principales complejos clonales fueron (CC/%): CC8/42,2%, CC5/33,3% y CC30/4,4%, destacando las secuencias tipo ST8 y ST5 como mayoritarias. El 38% de las cepas fue LPV-positiva (spa-tipos t008, t024, t019, t044, t068, t318 y t3060). El 78% de las cepas fue IEC-positivo: tipo-B (n = 17), tipo-F (n = 16), tipo-A (n = 1) y tipo-E (n = 1); 10 aislados fueron scn-negativos. CONCLUSIÓN: El fenotipo SARM-SNBL es poco frecuente en los hospitales analizados; aunque no se detectaron cepas mecC-positivas, este fenotipo puede ser un buen marcador de aislados SARM LPV-positivos, frecuentemente asociados a infecciones por SARM-AC

Multicenter study of clinical non-ß-lactam-antibiotic susceptible MRSA strains: Genetic lineages and Panton-Valentine leukocidin (PVL) production.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) is considered a major cause of healthcare-associated (HA) and community-acquired (CA) infections. Considering non-ß-lactam susceptibility as a potential marker for mecC-MRSA and CA-MRSA, the aim of this study was to determine the frequency and the associated genetic lineages of non-beta-lactam-antibiotic susceptible MRSA (NBLS-MRSA) strains in a multicenter study in Spain. METHODS: A collection of 45 NBLS-MRSA strains recovered in the period from January to June 2016 from 12 Spanish hospitals was analyzed. Molecular typing through spa-type characterization, agr group and multi-locus-sequence typing was performed. Methicillin-resistant genes (mecA and mecC) as well as immune evasion cluster (scn-chp-sak-sea-sep, considering scn gene as the marker of IEC system) and Panton-Valentine leukocidin (PVL) genes were determined with PCR/sequencing. RESULTS: The NBLS-MRSA phenotype was uncommon in the 12 hospitals analyzed (NBLS-MRSA/MRSA frequency: 0.3%-7.7%). All strains contained the mecA gene (and none contained mecC). Twenty-two different spa-types were detected among NBLS-MRSA strains, with spa-t008/agr-I the most prevalent (27%). The main clonal complexes were (CC/%): CC8/42.2%, CC5/33.3% and CC30/4.4%, with ST8 and ST5 as the main sequence types. The PVL toxin was present in 38% of strains (with spa-types t008, t024, t019, t044, t068, t318 and t3060). The IEC genes were detected in 78% of strains: IEC type-B (n=17), type-F (n=16), type-A (n=1) and type-E (n=1); 10 MRSA isolates were scn-negative. CONCLUSION: The NBLS-MRSA phenotype is uncommon in the analyzed hospitals; although no mecC-positive strains were detected, it could be a good marker for MRSA PVL-positive isolates (38%), frequently associated with CA-MRSA infections.

Antimicrobial activity of ceftolozane-tazobactam against multidrug-resistant and extensively drug-resistant Pseudomonas aeruginosa clinical isolates from a Spanish hospita / Actividad de ceftolozano-tazobactam en aislados clínicos de Pseudomonas aeruginosa multirresistente y extremadamente resistente en un hospital español

Objectives: Our objective was to evaluate the in vitro activity of ceftolozane-tazobactam against multidrug resistant (MDR) and extensively drug-resistant (XDR) non metallo-ß-lactamase producing Pseudomonas aeruginosa clinical isolates at Hospital Universitario Miguel Servet (Zaragoza, Spain) from February 2016 to October 2017. Material and methods: We evaluated the in vitro activity of ceftolozane-tazobactam and other antipseudomonal antibiotics against 12 MDR and 117 XDR non metallo-ß-lactamase producing P. aeruginosa isolates. Ceftolozane-tazobactam minimal inhibitory concentrations (MICs) were determined by MIC gradient diffusion test strip. Results: Among the 129 MDR/XDR isolates included, 119 (92.2%) were susceptible to ceftolozane-tazobactam, and ten (7.8%) were resistant. MIC50 was 2 mg/L, and MIC90 4 mg/L. Ceftolozane-tazobactam was the second most active antibiotic after colistin, overtaking amikacin. Conclusions: Ceftolozane-tazobactam is a valuable treatment option for MDR and XDR P. aeruginosa infections in our setting

Objetivos: Nuestro objetivo fue evaluar la sensibilidad in vitro de ceftolozano-tazobactam en aislados clínicos de P. aeruginosa multirresistente (MDR) y extremadamente resistente (XDR) desde Febrero de 2016 a Octubre de 2017 en el Hospital Universitario Miguel Servet, Zaragoza (España). Material y métodos: Evaluamos la actividad in vitro de ceftolozano-tazobactam y otros antibióticos anti-pseudomónicos en 12 aislados de P. aeruginosa MDR y en 117 aislados XDR, no productores de metalo-ß-lactamasas. Se determinó la concentración mínima inhibitoria (CMI) de ceftolozano-tazobactam mediante tiras de difusión en gradiente. Resultados: Entre los 129 aislados MDR/XDR incluidos, 119 (92,2%) fueron sensibles a ceftolozano-tazobactam, y diez (7,8%) presentaron resistencia. La CMI50 fue de 2 mg/L, y la CMI90 de 4 mg/L. Ceftolozano-tazobactam fue el segundo antibiótico más activo después de colistina, superando a amikacina. Conclusiones: Ceftolozano-tazobactam es una opción de tratamiento válida para infecciones causadas por P. aeruginosa MDR y XDR en nuestro entorno

Detection of carbapenemases and other mechanisms of enzymatic resistance to Beta-lactams in Enterobacteriaceae with diminished susceptibility to carbapenems in a tertiary care hospital / Detección de carbapenemasas y otros mecanismos de resistencia enzimáticos a Beta-lactámicos en enterobacterias con sensibilidad disminuida a carbapenems en un hospital de tercer nivel

INTRODUCTION: Our objective was to characterize the enzymatic Beta-lactam resistance in clinical Enterobacteriaceae isolates with diminished susceptibility to carbapenems from 2013 to 2014 at Hospital Universitario Miguel Servet. Material/methods: A total of 63 clinical isolates were analyzed for the presence of carbapenemases (KPC, OXA-48 and MBL), ESBLs and AmpC enzymes by combined disk methods and PCR detection of carbapenemase-encoding and beta-lactamase-encoding genes. RESULTS: Fifteen isolates had a phenotypic test compatible with carbapenemase production; two of these were confirmed by PCR as OXA-48 producers. ESBL detection was positive in 27 isolates (43%); plasmid-mediated AmpC was detected in nine isolates (14.2%) and derepressed AmpC β-lactamase was present in 18 isolates (28%). CONCLUSION: During the study period, the decreased susceptibility to carbapenems in Enterobacteriaceae in our area was not due to true carbapenemases but rather to Beta-lactamase activity (82.5% were ESBL or AmpC producers), probably in combination with decreased permeability of the outer membrane

INTRODUCCIÓN: Nuestro objetivo fue caracterizar la resistencia enzimática a Beta-lactámicos en aislados clínicos de Enterobacteriaceae con sensibilidad disminuida a carbapenems desde 2013 a 2014 en el Hospital Universitario Miguel Servet. Material/métodos: Se analizaron un total de 63 aislados clínicos para presencia de carbapenemasas (KPC, OXA-48 y MBL), BLEE y AmpC por método de discos combinados y detección de genes codificantes de carbapenemasas y betalactamasas por PCR. RESULTADOS: Quince aislados tuvieron un test fenotípico compatible con producción de carbapenemasas; dos de ellos confirmados por PCR como productores de OXA-48. La detección BLEE fue positiva en 27 aislados (43%); se detectó AmpC plasmídica en 9 aislados (14,2%) y se observó β-lactamasa AmpC desreprimida en 18 aislados (28%). CONCLUSIÓN: Durante el período de estudio, la sensibilidad disminuida a carbapenems en Enterobacteriaceae en nuestra área no se debió a verdaderas carbapenemasas sino a actividad Beta-lactamasa (82,5% eran productores de BLEE o AmpC) probablemente en combinación con permeabilidad disminuida de la membrana externa

Detection of carbapenemases and other mechanisms of enzymatic resistance to ß-lactams in Enterobacteriaceae with diminished susceptibility to carbapenems in a tertiary care hospital.

INTRODUCTION: Our objective was to characterize the enzymatic ß-lactam resistance in clinical Enterobacteriaceae isolates with diminished susceptibility to carbapenems from 2013 to 2014 at Hospital Universitario Miguel Servet. MATERIAL/METHODS: A total of 63 clinical isolates were analyzed for the presence of carbapenemases (KPC, OXA-48 and MBL), ESBLs and AmpC enzymes by combined disk methods and PCR detection of carbapenemase-encoding and beta-lactamase-encoding genes. RESULTS: Fifteen isolates had a phenotypic test compatible with carbapenemase production; two of these were confirmed by PCR as OXA-48 producers. ESBL detection was positive in 27 isolates (43%); plasmid-mediated AmpC was detected in nine isolates (14.2%) and derepressed AmpC ß-lactamase was present in 18 isolates (28%). CONCLUSION: During the study period, the decreased susceptibility to carbapenems in Enterobacteriaceae in our area was not due to true carbapenemases but rather to ß-lactamase activity (82.5% were ESBL or AmpC producers), probably in combination with decreased permeability of the outer membrane.

Infección respiratoria por Bordetella hinzii / Respiratory Infection Caused by Bordetella hinzii

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Global study of IS6110 in a successful Mycobacterium tuberculosis strain: clues for deciphering its behavior and for its rapid detection.

The Mycobacterium tuberculosis insertion sequence IS6110, besides being a very useful tool in molecular epidemiology, seems to have an impact on the biology of bacilli. In the present work, we mapped the 12 points of insertion of IS6110 in the genome of a successful strain named M. tuberculosis Zaragoza (which has been referred to as the MTZ strain). This strain, belonging to principal genetic group 3, caused a large unsuspected tuberculosis outbreak involving 85 patients in Zaragoza, Spain, in 2001 to 2004. The mapping of the points of insertion of IS6110 in the genome of the Zaragoza strain offers clues for a better understanding of the adaptability and virulence of M. tuberculosis. Surprisingly, the presence of one copy of IS6110 was found in Rv2286c, as was recently described for a successful Beijing sublineage. As a result of this analysis, a rapid method for detecting this particular M. tuberculosis strain has been designed.

Unsuspected and extensive transmission of a drug-susceptible Mycobacterium tuberculosis strain.

BACKGROUND: A large and unsuspected tuberculosis outbreak involving 18.7% of the total of the tuberculosis cases studied, was detected in a population-based molecular epidemiological study performed in Zaragoza (Spain) from 2001 to 2004. METHODS: The Mycobacterium tuberculosis drug-susceptible strain, named MTZ strain, was genetically characterized by IS6110-RFLP, Spoligotyping and by MIRU-VNTR typing and the genetic patterns obtained were compared with those included in international databases. The characteristics of the affected patients, in an attempt to understand why the MTZ strain was so highly transmitted among the population were also analyzed. RESULTS: The genetic profile of the MTZ strain was rare and not widely distributed in our area or elsewhere. The patients affected did not show any notable risk factor for TB. CONCLUSION: The M. tuberculosis strain MTZ, might have particular transmissibility or virulence properties, and we believe that greater focus should be placed on stopping its widespread dissemination.