Efficacy of delafloxacin alone and in combination with cefotaxime against cefotaxime non-susceptible invasive isolates of Streptococcus pneumoniae.

OBJECTIVE: We assessed the in vitro activity of delafloxacin and the synergy between cefotaxime and delafloxacin among cefotaxime non-susceptible invasive isolates of Streptococcus pneumoniae (CNSSP). METHODS: A total of 30 CNSSP (cefotaxime MIC > 0.5 mg/L) were studied. Serotyping was performed by the Pneumotest-Latex and Quellung reaction. Minimum inhibitory concentrations (MICs) of delafloxacin, levofloxacin, penicillin, cefotaxime, erythromycin and vancomycin were determined by gradient diffusion strips (GDS). Synergistic activity of delafloxacin plus cefotaxime against clinical S. pneumoniae isolates was evaluated by the GDS cross method. RESULTS: Delafloxacin showed a higher pneumococcal activity than its comparator levofloxacin (MIC50, 0.004 versus 0.75 mg/L and MIC90, 0.047 versus >32 mg/L). Resistance to delafloxacin was identified in 7/30 (23.3%) isolates, belonging to serotypes 14 and 9V. Synergy between delafloxacin and cefotaxime was detected in 2 strains (serotypes 19A and 9V). Antagonism was not observed. Addition of delafloxacin increased the activity of cefotaxime in all isolates. Delafloxacin susceptibility was restored in 5/7 (71.4%) strains. CONCLUSIONS: CNSSP showed a susceptibility to delafloxacin of 76.7%. Synergistic interactions between delafloxacin and cefotaxime were observed in vitro among CNSSP by GDS cross method.

Service-Learning, Movies, and Infectious Diseases: Implementation of an Active Educational Program in Microbiology as a Tool for Engagement in Social Justice.

Service-Learning is an educational methodology that allows student learning while addressing community needs. A program in microbiology and infectious diseases was implemented in Universidad Complutense de Madrid, Spain. University lecturers, clinical microbiologists, doctorate students, and undergraduates from several Bachelor Degrees and courses worked in an interdisciplinary team along with social institutions that attend disadvantaged persons. Using commercial movies that deal with infectious diseases, the students learn clinical microbiology, prepare divulgation materials, visit social centers to accompany, and help others to know about illnesses and prevention. The program was developed through two academic years and involved 58 voluntary students, 13 teachers and tutors, and 4 social entities as community partners. Postsurvey evaluation of the program revealed a highly satisfactory achievement of goals: acquiring scientific and personal competencies by university students, including critical analysis and science diffusion, solving problems or collaborative team working, and contributing, together with the tutors, to the social responsibility of the university.

[Usefulness of MALDI-TOF and REP-PCR against PFGE for the epidemiological study of Acinetobacter baumannii]. / Utilidad de MALDI-TOF y REP-PCR frente a PFGE para el estudio epidemiológico de Acinetobacter baumannii.

OBJECTIVE: To evaluate the ability of MALDI-TOF MS and rep-PCR to discriminate Acinetobacter baumannii clones. METHODS: A total of 21 strains of A. baumannii with different epidemiological and phenotipycal characteristics were included in the study. All isolates were analyzed in parallel by MALDI-TOF MS and rep-PCR and the spectra obtained were compared with each other and with the results obtained by pulsed field gel electrophoresis (PFGE). Isolates with a similarity equal to or greater than 87% were considered to be part of the same clonal group. RESULTS: The analysis of the 21 isolates included in the study, resulted in 8 clonal groups using PFGE, 3 groups by MALDI-TOF MS and 7 groups by rep-PCR analysis. The isolates that formed the different groups by the 3 techniques used were totally different, so it can be concluded that there is no equivalence between the results obtained with the three typing methods used. CONCLUSIONS: Despite its simplicity, neither MALDI-TOF MS nor rep-PCR can at this time replace PFGE for the epidemiological study of A. baumannii.

Description of carbapenemase-producing Enterobacteriaceae isolates in a Spanish tertiary hospital. Epidemiological analysis and clinical impact.

OBJECTIVE: The aim of the study was to carry out an epidemiological analysis of patients with carbapenemase-producing Enterobacteriaceae (CPE) isolations in our hospital as well as to perform a description of the genotypic temporal evolution of CPE isolated. METHODS: An observational prospective cohort study was performed involving all patients with CPE isolates from clinical samples during November 2014 to November 2016 in a Spanish teaching hospital. Patients were clinically evaluated and classified either as infected or colonized. Information on the consumption of carbapenems in the hospital during the study period was also analyzed. PCR was used for identification of the carbapenemase genes blaKPC, blaVIM, and blaOXA-48. RESULTS: A total of 301 CPE isolates were obtained (107 in 2014, 89 in 2015 and 105 in 2016). Klebsiella pneumoniae (73.4%) was the most prevalent microorganism. Hundred and seventy (56.7%) of carbapenemases detected were blaOXA-48, 73 (24.3%) were blaKPC and 57 (19%) were blaVIM. In year 2014 KPC was predominant while in 2016 OXA-48 predominated. In 2014 we observed a significant association between the medical wards and the ICU with a higher prevalence of OXA-48 (OR 4.15; P<0.001) and VIM (OR 7.40; P<0.001) in the univariate analysis, in the following years there was no association. Regarding the clinical significance of microbiological results after assessing our patients, 60% of isolates represented infection and 40% behaved as colonizers. One third of hospitalized patients with CPE isolation died within 30 days, regardless of whether they were colonized or infected. CONCLUSIONS: We have observed an epidemiological change in the genotypes of our isolates along the study period. A thorough knowledge of the CPE's epidemiological distribution in each hospital is fundamental for optimizing antimicrobial chemotherapy.

Clinical experience with integrase inhibitors in HIV-2-infected individuals in Spain.

BACKGROUND: HIV-2 is a neglected virus despite estimates of 1-2 million people being infected worldwide. The virus is naturally resistant to some antiretrovirals used to treat HIV-1 and therapeutic options are limited for patients with HIV-2. METHODS: In this retrospective observational study, we analysed all HIV-2-infected individuals treated with integrase strand transfer inhibitors (INSTIs) recorded in the Spanish HIV-2 cohort. Demographics, treatment modalities, laboratory values, quantitative HIV-2 RNA and CD4 counts as well as drug resistance were analysed. RESULTS: From a total of 354 HIV-2-infected patients recruited by the Spanish HIV-2 cohort as of December 2017, INSTIs had been given to 44, in 18 as first-line therapy and in 26 after failing other antiretroviral regimens. After a median follow-up of 13 months of INSTI-based therapy, undetectable viraemia for HIV-2 was achieved in 89% of treatment-naive and in 65.4% of treatment-experienced patients. In parallel, CD4 gains were 82 and 126 cells/mm3, respectively. Treatment failure occurred in 15 patients, 2 being treatment-naive and 13 treatment-experienced. INSTI resistance changes were recognized in 12 patients: N155H (5), Q148H/R (3), Y143C/G (3) and R263K (1). CONCLUSIONS: Combinations based on INSTIs are effective and safe treatment options for HIV-2-infected individuals. However, resistance mutations to INSTIs are selected frequently in failing patients, reducing the already limited treatment options.

Useful independent factors for distinguish infection and colonization in patients with urinary carbapenemase-producing Enterobacteriaceae isolation.

OBJECTIVE: The aim of this study is to know epidemiologic and clinical differences among those patients colonized or infected by carbapenemase-producing Enterobacteriaceae (CPE) and develop a predictive model to facilitate the clinical approach concerning to start antimicrobial therapy. METHODS: Observational retrospective cohort study was performed involving all patients with Urine carbapenemase-producing Enterobacteriaceae isolation (UCPEI) between November 2013 and July 2015. Patients were classifieds as colonized or infected considering Center for Disease Control and Prevention (CDC) definition for urinary tract infection (UTI). RESULTS: A total of 72 patients were included, mean age 76.4 (IQR 23-99) years and 40 (55.6%) were women. Thirty-four (47.2%) were colonized and 38 (52.8%) met the criteria of UTI and were considered infected. The independent variables associated to infection were female sex, peripheral vascular disease, admission in medical ward, permanent urinary catheter carrier, previous antimicrobial therapy, and length of stay. Isolation of OXA-48 carbapenemase-producing Enterobacteriaceae behaved as a non UTI (colonization) factor in comparison with KPC or VIM CPE. The developed predictive model showed an area under the curve (AUC) of 0.901 (95% CI: 0.832-0.970; p < 0.001). CONCLUSIONS: The predictive model that includes all this factors has demonstrated a good accuracy for infection diagnosis in these patients, an important issue considering that establishing the diagnosis of infection is not always easy in the profile of patients in which a CPE is isolated.

[Update in Infectious Diseases 2016]. / Actualización en Patología Infecciosa 2016.

Antimicrobial resistance increases it health, social and economic impact. in all areas (state, regional and local), initiatives to try to contain the problem of resistance arise. In the update of this year 2016, we study microbiological, epidemiological and clinical aspects of multi-resistant bacteria, as well as resources for therapeutic approach, from ancient to modern drugs from therapeutic combinations to optimization Stewardship programs. In the case of fungal infection, we analyze clinical scenarios with different species in yeast or new clinical settings in filamentous fungi. Taking paediatric population, homologies and differences with adults in invasive fungal infection were compared. Finally in the field of parasitology, treatment of severe malaria imported or that resistant to antimalarial drugs were reviewed.

Recurrent pneumococcal invasive disease in the region of Madrid during a five-year period.

PURPOSE: The aim of this study was to describe the clinical and microbiological characteristics of recurrent invasive pneumococcal disease (RIPD) cases identified in the Region of Madrid between January 2007 and December 2011. METHODS: Streptococcus pneumoniae serotyping was performed by Pneumotest-Latex and Quellung reaction. Molecular typing was carried out by pulsed-field gel electrophoresis (PFGE). A relapse was defined as any case of RIPD caused by strains with similar PFGE profile. Re-infections were defined by detection of recurrent episodes caused by strains with different PFGE patterns. RESULTS: During the study period, 2,929 S. pneumoniae strains isolated from 2,858 patients with invasive pneumococcal disease (IPD) were studied. In 61 patients (2.1 %), 132 episodes of RIPD were detected (two episodes in 52 patients, three in 8 and four in 1). Twelve patients had relapses, 47 had re-infections and two had re-infections followed by relapses. Common risk factors to developing RIPD were HIV (42.6 %) and haematological malignancies (16.4 %). The most frequent serotypes were 8 (16 episodes) and 19A (15 episodes). Fourteen strains that were resistant to levofloxacin were also resistant to erythromycin. The proportion of strains co-resistant to erythromycin and levofloxacin was significantly higher in relapses (11/29) than in re-infections (3/103). CONCLUSIONS: The occurrence of repeated episodes of IPD in the same patient over the time is not an exceptional issue. Some underlying conditions that may favour these recurrences, mainly immunosuppression, need to be considered in patients having an episode of IPD.

Klebsiella pneumoniae: development of a mixed population of carbapenem and tigecycline resistance during antimicrobial therapy in a kidney transplant patient.

Nine isolates of Klebsiella pneumoniae were isolated from a renal transplant patient suffering from recurrent urosepsis over a period of 4 months. Imipenem resistance was detected after imipenem-ertapenem therapy. When treatment was switched to tigecycline the K. pneumoniae developed resistance to tigecycline (MIC = 8 mg/L). The nine isolates were tested by determination of agar dilution MICs, phenotypic carbapenemase, extended-spectrum beta-lactamases and metallo-beta-lactamase (MBL) testing and pulsed-field gel electrophoresis. Polymerase chain reaction and sequencing analysis were employed for identification of bla genes and mapping of the integron carrying the MBL gene. The nine isolates were clonally related and all produced the SHV-12 enzyme. Five MBL-producing isolates showed imipenem MICs ranging from 2 to 64 mg/L and all were detected by testing with imipenem and EDTA. The five isolates harboured the bla(VIM-1) gene. Three isolates showed increased tigecycline MICs (4-8 mg/L). Serial blood cultures obtained on the same day resulted in a VIM-positive/tigecycline-susceptible and a VIM-negative/tigecycline-resistant K. pneumoniae isolate. No isolate developed concurrent imipenem and tigecycline resistance. The patient had a persistent urinary tract infection and recurrent bacteraemia caused by a mixed population of Klebesiella pneumoniae isolates adapting to the selective pressure of antimicrobial therapy at the time. The present study is a worrisome example of what could happen when an immunocompromised host is subjected to the pressures of antimicrobial therapy. In addition, we report the first treatment-emergent MIC increase of tigecycline from 0.5 to 8 mg/L in K. pneumoniae.

In vitro activity of ceftobiprole and seven other antimicrobial agents against invasive Streptococcus pneumoniae isolates in Spain.

The in vitro activity of ceftobiprole was compared with that of seven antimicrobial agents against invasive Streptococcus pneumoniae isolated from adult patients (>15 years old). Characterization of erythromycin-resistant strains and serotype distribution of all pneumococci were also evaluated. Seventy invasive S. pneumoniae strains were isolated from December 2007 to January 2009. Serotyping was carried out by Quellung reaction. Antibiotic susceptibility was tested by broth microdilution (CLSI guidelines). The comparator agents were penicillin, cefotaxime, erythromycin, clindamycin, telithromycin, tetracycline and moxifloxacin. Phenotypic characterization of macrolide resistance was performed by the double disk method. Macrolide resistance genes [erm(B) and mef(A/E)] and the promoter of erm(B) were detected by PCR. Twenty-five different serotypes were detected of which 87% were non-PCV7 types. The percentages of resistance to erythromycin, clindamycin and tetracycline were 20%, 8.6% and 16%, respectively. A penicillin MIC ≥0.12 mg/L was observed in 14 of the 70 invasive pneumococci strains. The cefotaxime and ceftobiprole MIC(50)/MIC(90) of these 14 strains were 1/4 and 0.03/1 mg/L, respectively. Ceftobiprole showed higher in vitro activity than penicillin and cefotaxime with all isolates being inhibited by ≤1 mg/L. Its high in vitro activity should make ceftobiprole a very promising drug for the treatment of pneumococcal infections.

Multidrug-resistant pneumococci (serotype 8) causing invasive disease in HIV+ patients.

From July 2007 to June 2009, all pneumococci causing invasive pneumococcal disease in our hospital were serotyped. Antimicrobial susceptibility was determined by microdilution. Molecular typing was performed by pulsed-field gel electrophoresis and by multilocus sequence typing. Among 251 invasive pneumococci, serotype 8 was the most frequent (13.5%). All serotype 8 strains were susceptible to penicillin; however, 61.8% (21/34) were co-resistant to erythromycin, levofloxacin and tetracycline and identical to the Sweden(15A) -ST63 clone. Serotype 8 was significantly more frequent among human immunodeficiency virus (HIV)-infected patients (36.5%). The high prevalence of this non-conjugate vaccine multiresistant serotype 8 is a cause for concern mainly in HIV-infected patients.

Clonal and clinical profile of Streptococcus pneumoniae serotype 19A causing pediatric invasive infections: a 2-year (2007-2009) laboratory-based surveillance in Madrid.

UNLABELLED: Studies of clonality and clinical profile of serotype 19A invasive pneumococcal disease in children (IPD-19A) are worthy after PCV7 introduction. A prospective, hospital-based surveillance of IPD-19A, culture and/or PCR confirmed, was performed in 2007-2009 in Madrid (all 22 hospitals with pediatric departments). Sixty-two cases were found: 90.3% in children <5 years, 87.1% in <36 months, and 74.2% in ≤18 months. CLINICAL PRESENTATIONS: meningitis (22.6%), primary bacteremia (19.4%), secondary bacteremia to otic foci (SBOF; 17.7%), bacteremic pneumonia (17.7%), pediatric parapneumonic empyema (PPE; 17.7%) and others (4.8%). Presentations by age: meningitis (35.7%), SBOF (28.6%) and primary bacteremia (21.4%) in children <12 months, bacteremic pneumonia, PPE and primary bacteremia (26.3% each) in 12-23 months, and bacteremic pneumonia (33.3%) and PPE (26.6%) in ≥24 months. Sequence types ST276 and ST320 represented 83.0% isolates, all oral-penicillin/erythromycin non-susceptible. In nonmeningeal isolates, non-susceptibility to parenteral penicillin/cefotaxime was 0%/17.6% (ST276) and 93.8%/75.0% (ST320). Non-susceptibility in ST276 and ST320, prevalence of these STs among 19A isolates, and serotype 19A prevalence among IPDs, indicate the importance of 19A inclusion in PCV13 for IPD-19A prevention and for reducing 19A nasopharyngeal carriage, thus preventing 19A otitis (one-third of 19A bacteremia in this study were from otic origin).

Activity of doripenem against extended-spectrum beta-lactamase-producing Enterobacteriaceae and Pseudomonas aeruginosa isolates.

The in vitro activity of doripenem was evaluated against a recent collection of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and Pseudomonas aeruginosa isolates (201 ESBL-producing Enterobacteriaceae [153 Escherichia coli and 48 Klebsiella pneumoniae] and 201 P. aeruginosa). Comparator agents included amikacin, tobramycin, ciprofloxacin, cefepime, cefotaxime, ceftazidime piperacillin-tazobactam, imipenem, and meropenem. Both doripenem and meropenem inhibited 100% of the ESBL-producing Enterobacteriaceae at 4 microg/mL. Doripenem is active against ESBL-producing Enterobacteriaceae and P. aeruginosa isolates. Its activity is similar to that of meropenem and slightly better than that of imipenem. The results of this study suggest that doripenem could be an alternative therapeutic agent for infections caused by these organisms.

In vitro activity of tigecycline against Bacteroides species.

OBJECTIVES: To ascertain the current susceptibility patterns of members of the Bacteroides fragilis group in our hospital and to assess the in vitro activity of tigecycline against these organisms. METHODS: A total of 400 non-duplicate clinical isolates of the B. fragilis group collected from 2000 to 2002 were studied. Susceptibility testing was performed according to the reference agar dilution method described by the NCCLS. The following antimicrobials were tested: tigecycline, clindamycin, metronidazole, chloramphenicol, cefoxitin, imipenem, amoxicillin-clavulanate and piperacillin-tazobactam. RESULTS: All strains were susceptible to metronidazole and chloramphenicol. For clindamycin and cefoxitin, the overall susceptibility rates were 59.5% and 83%, respectively. Imipenem and piperacillin-tazobactam were the most active beta-lactam agents tested. Tigecycline inhibited 89.8% of the strains at a concentration of 8 mg/L with an MIC range of 16 mg/L. By comparing the MIC50 and MIC90 values of tigecycline among the various species of the group, B. fragilis, Bacteroides thetaiotaomicron and Bacteroides vulgatus were the most susceptible (MIC50/MIC90s of 0.5-1/8 mg/L). CONCLUSIONS: Tigecycline exhibited activity against most isolates of the B. fragilis group tested. These results indicate that tigecycline may be useful in the treatment and prophylaxis of infections involving these organisms.

In vitro activities of tigecycline against erythromycin-resistant Streptococcus pyogenes and Streptococcus agalactiae: mechanisms of macrolide and tetracycline resistance.

The activity of tigecycline was tested against erythromycin-resistant streptococci (107 Streptococcus pyogenes and 98 Streptococcus agalactiae strains). The presence of erythromycin and tetracycline resistance genes was determined by PCR. Among S. pyogenes strains the most prevalent gene was mef(A) (91.6%). The erm(B) gene was the most prevalent (65.3%) among S. agalactiae strains. Tigecycline proved to be very active against all the isolates tested (MIC at which 90% of the isolates tested were inhibited, 0.06 micro g/ml), including those resistant to tetracycline.

Erythromycin and clindamycin resistance and telithromycin susceptibility in Streptococcus agalactiae.

The rates of resistance to erythromycin and clindamycin among Streptococcus agalactiae strains isolated in our hospital increased from 4.2 and 0.8% in 1993 to 17.4 and 12.1%, respectively, in 2001. Erythromycin resistance was mainly due to the presence of an Erm(B) methylase, while the M phenotype was detected in 3.8% of the strains. Telithromycin was very active against erythromycin-resistant strains, irrespective of their mechanisms of macrolide resistance.

[Susceptibility to penicillin and 13 antimicrobial agents in erythromycin-resistant viridans group streptococci isolated from blood cultures]. / Sensibilidad a penicilina y otros 13 antimicrobianos de estreptococos del grupo viridans resistentes a eritromicina aislados de hemocultivos.

From March 1998 to June 1999, we studied 63 sequential blood culture isolates of viridans group streptococci which showed a 49% resistance to erythromycin. A high level of resistance to penicillin (46%) was also found. A statistically significant correlation was detected between the two types of resistance. The erythromycin-resistant strains were phenotypically and genotypically characterized, and no differences were found between the resistance to penicillin and the M or MLS(B) phenotypes. The penicillin-erythromycin-resistant strains included: 16 S. mitis, five S. sanguis and one S. salivarius. The rank order of activity (% of susceptibility) for all 14 agents against 31 erythromycin- resistant isolates was the following: vancomycin = rifampicin (100) > chloramphenicol (98) > meropenem (65) > cefotaxime (61) > amoxicillin- clavulanic acid (42) > cefepime = ciprofloxacin (39) > tetracycline = trimethoprim-sulfamethoxazole (36) > cefuroxime (32) > penicillin = ampicillin = cefaclor (29). The species S. milleri and S. bovis were the most susceptible. The most resistant strains were two S. mitis and one S. sanguis and showed multiresistance to six different groups of antimicrobial agents. The frequent association between macrolide resistance and resistance to other antimicrobial agents suggests that the susceptibility of all clinically significant isolates needs to be evaluated and alternative agents for the prevention and treatment of viridans group streptococci infections should be identified.

Actividad in vitro de seis fluoroquinolonas y penicilina frente a 101 estreptococos del grupo viridans caracterizados en su resistencia a la eritromicina / In vitro activity of six fluoroquinolones and penicillin against 101 viridans group streptococci characterized by their susceptibility to erythromycin

El aumento del uso de fluoroquinolonas, que incluye en la actualidad el tratamiento de las infecciones de vías respiratorias bajas, parece asociarse con un incremento paralelo de la resistencia bacteriana. Hemos estudiado la actividad de la penicilina y seis fluoroquinolonas frente a un total de 101 aislamientos consecutivos de estreptococos del grupo viridans (58 sensibles y 43 resistentes a la eritromicina) procedentes de hemocultivos. El porcentaje de resistencia a la penicilina fue de un 35 por ciento y se asoció significativamente con la resistencia a la eritromicina. Las fluoroquinolonas estudiadas muestran buena actividad frente a los estreptococos del grupo viridans independientemente de su sensibilidad a la eritromicina. La CMI50 y la CMI90 del norfloxacino fueron 8 y 16 mg/l, respectivamente. Ofloxacino y ciprofloxacino muestran la misma actividad (CMI50 1 mg/l y CMI90 2 mg/l); levofloxacino fue similar, con ambos valores de 1 mg/l. Las más activas fueron trovafloxacino y moxifloxacino (CMI50 0,12 mg/l y CMI90 0,25 mg/l). Sin embargo, hemos encontrado dos cepas resistentes al trovafloxacino (CMI 4 mg/l), que muestran sensibilidad reducida a todas las fluoroquinolonas ensayadas, incluido moxifloxacino (CMI 2 mg/l). Es necesario un seguimiento de la actividad de las fluoroquinolonas sobre este grupo de cepas y consideramos que el estudio de los genes de resistencia implicados sería de gran interés (AU)

Sensibilidad a penicilina y otros 13 antimicrobianos de estreptococos del grupo viridans resistentes a eritromicina aislados de hemocultivos / Susceptibility to penicillin and 13 antimicrobial agents in erythromycin-resistant viridans group streptococci isolated from blood

Entre marzo de 1998 y junio de 1999 aislamos 63 estreptococos del grupo viridans procedentes de hemocultivos, de los cuales el 49 por ciento fueron resistentes a eritromicina, y encontramos una resistencia a penicilina del 46 por ciento, con una relación estadísticamente significativa entre ambas resistencias. Las cepas resistentes a eritromicina están caracterizadas fenotípica y genotípicamente, y no se ha encontrado diferencia significativa entre resistencia a penicilina y los fenotipos M y MLSB. Las cepas resistentes a ambos antibióticos fueron: 16 S. mitis, 5 S. sanguis y 1 S. salivarius. Frente a los 31 aislamientos resistentes a eritromicina ensayamos los 14 antibióticos que referimos por orden de actividad ( por ciento de cepas sensibles): vancomicina = rifampicina (100) > cloranfenicol (98) > meropenem (65) > cefotaxima (61) > amoxicilina-ácido clavulánico (42) > cefepima = ciprofloxacino (39) > tetraciclina = trimetoprima-sulfametoxazol (36) > cefuroxima (32) > penicilina = ampicilina = cefaclor (29). Para el conjunto de los antibióticos, las especies más sensibles fueron S. milleri y S. bovis. Las cepas más resistentes fueron dos S. mitis y un S. sanguis en las que se asocia resistencia a seis grupos diferentes de antimicrobianos. Los bajos porcentajes de sensibilidad encontrados, junto a la frecuencia de asociación de resistencias, sugieren la necesidad de determinar la sensibilidad de todos los aislamientos clínicamente significativos y de evaluar nuevos antimicrobianos que nos permitan disponer de agentes alternativos para la prevención y el tratamiento de las infecciones por estreptococos del grupo viridans resistentes a los fármacos de elección (AU)