Antimicrobial susceptibility of Gram-negative organisms from intra abdominal infections and evolution of isolates with extended spectrum Beta-lactamases in the SMART study in Spain (2002-2010)

Introducción. El estudio SMART (Study for Monitoring Antimicrobial Resistance Trends) tiene como objetivo monitorizar la sensibilidad a los antimicrobianos de los microorganismos gramnegativos aislados en la infección intraabdominal, con especial seguimiento de los que producen Beta-lactamasas de espectro extendido (BLEE). Material y métodos. Se han analizado por microdulución los datos de sensibilidad de 8.869 aislados recogidos en el estudio SMART en España entre 2002 y 2010 en el que han participado 16 centros. Resultados. Escherichia coli fue el patógeno más frecuente (60,9% en la infección intraabdominal adquirida en la comunidad y 49,9% en la nosocomial) seguido de Klebsiella pneumoniae (8,9% vs 9,2%). Pseudomonas aeruginosa fue más habitual en la infección nosocomial (5,6% comunitaria y 8,6% nosocomial). La frecuencia de aislados con BLEE fue: E. coli 8,7%, K. pneumoniae 8,4%, Klebsiella oxytoca 1,4% y Proteus mirabilis 1,6%. En los pacientes de mayor edad aumentó la proporción global de aislados con BLEE (6,8% en pacientes >60 años). Ertapenem y meropenem fueron los antimicrobianos más activos en el conjunto de las enterobacterias (rango de sensibilidad con criterios EUCAST, 89- 100%) y también entre los aislados con BLEE (95,5-100%). La actividad de amoxicilina/ácido clavulánico y piperacilina/tazobactam fue considerablemente inferior, en particular en los aislados con BLEE. Ertapenem mantuvo una buena actividad (sensibilidad >95%) en los productores de BLEE resistentes a amoxicilina/ácido clavulánico, piperacilina/tazobactam o fluoroquinolonas. Conclusiones. Los datos de sensibilidad del estudio SMART en España avalan las guías terapéuticas actuales de infecciónintraabdominal que sitúan al ertapenem como tratamiento empírico de elección, teniendo en cuenta sobre todo la elevada frecuencia de aislados con BLEE en nuestro medio(AU)

Introduction. The SMART (Study for Monitoring Antimicrobial Resistance Trends) surveillance study records the antimicrobial susceptibility of Gram-negative bacilli obtain from intraabdominal infections with special focus in isolates with extended spectrum Beta-lactamases (ESBLs). Material and Methods. The antimicrobial susceptibility of 8,869 isolates was analyzed by microdilution during the SMART study performed in Spain from 2002 to 2010. Isolates were recovered in 16 centres. Results. Escherichia coli was the most prevalent pathogen (60.9% from intraabdominal infections acquired in the community and 49.9% in those from nosocomial origin) followed by Klebsiella pneumoniae (8.9% vs 9.2%). Pseudomonas aeruginosa was more common in intraabdominal infections from nosocomial origin (5.6% community and 8.6% nosocomial). Frequency of ESBL-producing isolates was: E. coli, 8.7%; K. pneumoniae, 8.4%; Klebsiella oxytoca, 1.4%; and Proteus mirabilis, 1.6%. Overall, ESBL-producing isolates were more frequently isolated from elderly patients (6.8% >60 years). Ertapenem and meropenem were the most active antimicrobials (susceptibility range with EUCAST criteria, 89.0-100%) when considering all Enterobacteriaceae isolates and also against ESBL producers (95.5-100%). Susceptibility of amoxicillin/clavulanic acid and piperacillin/tazobactam was lower, particularly among ESBL-producing isolates. Nevertheless, ertapenem maintained a good activity (susceptibility >95%) in ESBL-producers that were resistant to amoxicillin/clavulanic acid, piperacillin/tazobactam or fluoroquinolones. Conclusions. Antimicrobial susceptibility data from the SMART-Spain study reinforce current therapeutic guidelines of intraabdominal infections that include ertapenem as the empirical choice for treatment. This is also supported by the high frequency of ESBL-producers in our geographic area(AU)

Prevalence and characterization of extended-spectrum beta-lactamases-producing Salmonella enterica isolates in Saragossa, Spain (2001-2008).

We analyzed the prevalence of resistance to extended-spectrum cephalosporins (ESCs) among clinical strains of Salmonella enterica collected by the Laboratory of Clinical Microbiology in the University Clinical Hospital Lozano Blesa in the region of Aragón (Spain), for which very few epidemiological information exists. A total of 2,092 strains of S. enterica were identified in stool samples from patients with gastroenteritis. Five isolates showed an extended-spectrum beta-lactamase (ESBL) phenotype: four isolates of S. enterica serotype Virchow harbored the ESBL-encoding bla(CTX-M-9) gene and an isolate of serotype Enteritidis carried a bla(CTX-M-1) gene, which, to the best of our knowledge, is described here for the first time in this serotype of S. enterica. The five ESC-resistant isolates were also resistant to spectinomycin, streptomycin, kanamycin, sulfonamides, tetracycline, and trimethoprim as well as to nalidixic acid. The ESBL isolate of serotype Enteritidis, however, remained susceptible to kanamycin and nalidixic acid. A class 1 integron of 1.5 kb was detected for the four serotype Virchow isolates with the gene cassette dfrA16-aadA2. The bla(CTX-M-9) gene was carried by an ∼300-kb IncHI2 conjugative plasmid in the case of the S. enterica serotype Virchow isolates. The bla(CTX-M-1) gene was carried by an ∼100-kb IncI1-N conjugative plasmid for the serotype Enteritidis ESC-resistant isolate. All the four ESC-resistant strains of S. enterica serotype Virchow clustered together in a XbaI pulsed-field gel electrophoresis, which also revealed a strong similarity between them and some pulsotypes of S. enterica serotype Virchow from France.

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).

[Susceptibility to betalactam antibiotics, glycopeptides and aminoglycosides in commensal strains of erythromycin-resistant alpha-hemolytic streptococci and Gemella spp]. / Sensibilidad a antibióticos betalactámicos, glucopéptidos y aminoglucósidos en cepas comensales de estreptococos alfahemolíticos y Gemella spp. resistentes a eritromicina.

OBJECTIVE: Susceptibility to seven betalactam antibiotics, glycopeptides and aminoglycosides was investigated in 190 erythromycin-resistant alpha-hemolytic streptococci and 30 Gemella spp, mainly from normal flora. MATERIAL AND METHODS: Antimicrobial susceptibility testing was performed by a standard agar diffusion test and a standard agar dilution method according to NCCLS/CLSI criteria. RESULTS: 62.6% of alfahemolytic streptococci and 53.3% of Gemella spp. were not susceptible to penicillin (MIC50: 0,5 microg/mL). Cefuroxime was the least active cephalosporin (MIC50: 1 microg/mL and 0.5 microg/mL, in streptococci and Gemella spp., respectively), whereas cefotaxime, ceftriaxone (MIC50: 0.25 microg/mL) and cefepime (MIC50: 0.5 microg/mL) were more active than penicillin. All isolates were susceptible to vancomycin, teicoplanin and gentamicin. Four alfahemolytic streptococcal strains showed high-level resistance to streptomycin, and three strains to kanamycin. There were no significant differences in resistance rates to the antibiotics studied between strains with different macrolide resistance phenotypes. Resistance to penicillin and other betalactam antibiotics (73.8%) was prevalent in M phenotype strains and resistance to penicillin and other classes of antibiotics predominated in constitutive (cMLS(B)) strains (71.4%). CONCLUSIONS: Resistance to penicillin in erythromycin-resistant strains was notably high in this study. This fact has important clinical implications because of the endogenous character of alpha-hemolytic streptococcal and Gemella spp. infections. The lower cefuroxime activity suggests that use of this agent against other pathogens would be effective in preserving the oropharyngeal microflora analyzed.

Sensibilidad a antibióticos betalactámicos, glucopéptidos y aminoglucósidos en cepas comensales de estreptococos alfahemolíticos y Gemella spp. resistentes a eritromicina / Susceptibility to betalactam antibiotics, glycopeptides and aminoglycosides in commensal strains of erythromycin resistant alfahemolytic streptococci and Gemella spp

Objetivo. Se investigó la sensibilidad de 190 estreptococos alfahemolíticos y 30 Gemella spp., en su mayoría comensales y resistentes a eritromicina, frente a 7 antibióticos betalactámicos, glucopépticos y aminoglucósidos. Material y métodos. Para determinar la sensibilidad a los antimicrobianos se utilizaron las técnicas de dilución y difusión en agar, según las normas del National Committee for Clinical Laboratory Standards/Clinical and Laboratory Standards Institute (NCCLS/CLSI). Resultados. El 62,6% de los estreptococos alfahemolíticos y el 53,3% de Gemella spp. no fueron sensibles a penicilina (concentración inhibitoria mínima al 50% [CIM50]: 0,5 mg/ml). Cefuroxima fue la cefalosporina que presentó menor actividad (CIM50: 1 mg/ml y 0,5 mg/ml, en estreptococos y Gemella spp.), mientras que cefotaxima, ceftriaxona (CIM50: 0,25 mg/ml) y cefepima (CIM50: 0,5 mg/ml) presentaron una actividad superior a penicilina. El 100% de los aislamientos fueron sensibles a vancomicina, teicoplanina y gentamicina. Cuatro cepas de estreptococos alfahemolíticos presentaron resistencia de alto nivel a estreptomicina y tres a kanamicina. No hubo diferencia significativa en el comportamiento de los antibióticos estudiados frente a las cepas con diferente fenotipo de resistencia a macrólidos. Tanto en los aislamientos con fenotipo M como en aquéllos con fenotipo constitutivo (MLSBc) predominó la resistencia a penicilina y a otros antibióticos betalactámicos frente al patrón de resistencia, que incluye sólo penicilina o bien penicilina, otros antibióticos betalactámicos y aminoglucósidos. Conclusiones. Las tasas de resistencia a penicilina en las cepas comensales resistentes a eritromicina son particularmente elevadas, hecho que tiene una importante implicación clínica por el carácter endógeno de las infecciones causadas por estas bacterias. La menor actividad de cefuroxima podría sugerir que su utilización frente a otros patógenos preservaría en mayor grado a la microbiota orofaríngea estudiada (AU)

Objective. Susceptibility to seven betalactam antibiotics, glycopeptides and aminoglycosides was investigated in 190 erythromycin-resistant alfahemolytic streptococci and 30 Gemella spp, mainly from normal flora. Material and methods. Antimicrobial susceptibility testing was performed by a standard agar diffusion test and a standard agar dilution method according to NCCLS/CLSI criteria. Results. 62.6% of alfahemolytic streptococci and 53.3% of Gemella spp. were not susceptible to penicillin (MIC50: 0,5 mg/mL). Cefuroxime was the least active cephalosporin (MIC50: 1 mg/mL and 0.5 mg/mL, in streptococci and Gemella spp., respectively), whereas cefotaxime, ceftriaxone (MIC50: 0.25 mg/mL) and cefepime (MIC50: 0.5 mg/mL) were more active than penicillin. All isolates were susceptible to vancomycin, teicoplanin and gentamicin. Four alfahemolytic streptococcal strains showed high-level resistance to streptomycin, and three strains to kanamycin. There were no significant differences in resistance rates to the antibiotics studied between strains with different macrolide resistance phenotypes. Resistance to penicillin and other betalactam antibiotics (73.8%) was prevalent in M phenotype strains and resistance to penicillin and other classes of antibiotics predominated in constitutive (cMLSB) strains (71.4%). Conclusions. Resistance to penicillin in erythromycin-resistant strains was notably high in this study. This fact has important clinical implications because of the endogenous character of alfahemolytic streptococcal and Gemella spp. infections. The lower cefuroxime activity suggests that use of this agent against other pathogens would be effective in preserving the oropharyngeal microflora analyzed (AU)