[Susceptibility of Enterococcus genus to new antimicrobial agents]. / Sensibilidad del género Enterococcus a nuevos antimicrobianos.

The aim of this study was to determine the prevalence of resistance to different antibiotics in 109 clinical strains of Enterococcus isolated consecutively in hospital over a four-month period in 2002. The strains were identified by species using the semiautomatic system Microscan walk away 40 (Dade Behring) and the API20 STREP system (Biomerieux). Three different methods for the susceptibility study were used: Sensititre, E-test and disc diffusion. The percentage of Enterococcus faecalis and Enterococcus faecium isolated was 92% and 8%, respectively. The following resistance to Enterococcus faecalis was detected: erythromycin (53%), telithromycin (36%), penicillin (2%), ampicillin (1%), vancomycin, teicoplanin and linezolid (0%), high level resistance to streptomycin (51%) and gentamicin (32%). A high percentage of strains resistant to penicillin and ampicillin was detected in E. faecium (six of nine strains). For two species, high susceptibility to linezolid and glycopeptides was found.

Comparación del método de microdilución (sensititre®) con el E-test® para el estudio de sensibilidad de Streptococcus pneumoniae / Comparison of the microdilution methos (Sensititre) with E-Test to study of susceptibility of streptococcus pneumoniae

La aparición de resistencias frente Streptococcus pneumoniae ha incrementado la necesidad de procesos seguros para estudiar la sensibilidad. Se han estudiado las características analíticas de dos sistemas comerciales de sensibilidad: E-test® (Ab Biodisk, Solna, Suecia) y Sensititre® (AcuMed, Westlake, Ohio). Cuando se usa E-test®, el 77 por ciento de los aislamientos mostraron resistencia de alto nivel a la penicilina y eritromicina. Por otra parte, cuando se emplea Sensititre® los resultados de resistencia obtenidos fueron: 83 por ciento y 79 por ciento para penicilina y eritromicina, respectivamente. Cuando se compara los resultados de los dos métodos, para la eritromicina, se encontraron dos discrepancias graves. El método Sensititre® permite analizar la resistencia de otros trece antibióticos (AU)

Estudio de la sensibilidad de Streptococcus pneumoniae en La Rioja / Study of the susceptibility of Streptococcus pneumoniae in La Rioja

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Clonal diversity among erythromycin-resistant beta-haemolytic Streptococcus isolates in La Rioja, Spain.

OBJECTIVE: To analyse clonal diversity in 72 erythromycin-resistant beta-haemolytic streptococci. METHODS: Clonal relationships were studied for streptococci of groups A (GAS, n = 30), B (GBS, n = 34), C (GCS, n = 4) and G (GGS, n = 4) by means of PFGE. Streptococcal isolates were obtained from a 450-bed hospital in Spain during the following periods: GAS (1996-2001), GBS (1999-2001), GCS and GGS (1997-2000). RESULTS: Twenty-two of the 30 GAS isolates showed the M resistance phenotype and harboured the mef(A) gene. Five unrelated PFGE patterns were identified among these 22 GAS isolates. Sixteen of them, obtained during four different years of the study, showed one of the two predominant PFGE patterns. The remaining eight GAS isolates showed the MLSB resistance phenotype, and four unrelated PFGE patterns were detected. All but one erythromycin-resistant GBS showed the MLSB resistance phenotype, and an erm gene was identified in all cases [erm(B) or erm(A)]. Twenty-two unrelated PFGE patterns were demonstrated among 25 GBS with the MLSB resistance phenotype; the remaining eight MLSB GBS isolates could not be typed by PFGE. The eight erythromycin-resistant GGS and GCS isolates of this study presented seven unrelated PFGE patterns. GGS and GCS strains showed an MLSB resistance phenotype and had the erm(A) gene. CONCLUSIONS: High clonal diversity was detected in this series of erythromycin-resistant GBS, whereas lower diversity was seen in the GAS isolates.

Sensibilidad de Streptococcus pneumoniae a nuevos fármacos / Susceptibility of Sreptococcus pneumoniae to new antibiotics

La resistencia de Streptococcus pneumoniae a diferentes antimicrobianos ha aumentado en todo el mundo. Nuevos antibióticos como estreptograminas, ketólidos y oxazolidinonas pueden ser una buena alternativa a otros antimicrobianos, beta-lactámicos o macrólidos. La sensibilidad a Quinupristin/Dalfopristin, Telitromicina y Linezolid fue determinada en 54 cepas de Streptococcus pneumoniae aisladas en el laboratorio de microbiología del Hospital San Millán-San Pedro. Ninguna fue resistente. Todas las cepas tenían valores de CMI <_ 1 mg/l para la Quinupristin/Dalfopristin. Los diámetros de inhibición obtenidos para Telitromicina y Linezolid oscilaron entre 23 y 37 mm para la Telitromicina y 28 y 45 mm para Linezolid. Por lo tanto, estos antibióticos pueden utilizarse en un futuro en el tratamiento de infecciones del tracto respiratorio. (AU)

Antibiotic resistance in Campylobacter strains isolated from animals, foods, and humans in Spain in 1997-1998.

Colonization by Campylobacter strains was investigated in human, broiler, and pig fecal samples from 1997-1998, as well as in foods of animal origin, and antibiotic susceptibility testing was carried out for these strains. Campylobacter strains were isolated in the foods of animal origin (55 of 101 samples; 54.4%), intestinal samples from broilers (85 of 105; 81%), and pigs (40 of 45; 88.9%). A total of 641 Campylobacter strains were isolated from 8,636 human fecal samples of clinical origin (7.4%). Campylobacter jejuni was the most frequently isolated species from broilers (81%) and humans (84%), and Campylobacter coli was most frequently isolated from pigs (100%). An extremely high frequency of ciprofloxacin resistance was detected among Campylobacter strains, particularly those isolated from broilers and pigs (99%), with a slightly lower result for humans (72%); cross-resistance with nalidixic acid was almost always observed. A higher frequency of resistance to erythromycin (81.1%), ampicillin (65.7%), gentamicin (22.2%), and amikacin (21.6%) was detected in C. coli strains isolated from pigs compared to those isolated from humans (34.5, 29.3, 8.6, and 0%, respectively). A low frequency of erythromycin resistance was found in C. jejuni or C. coli isolated from broilers. A greater resistance to ampicillin and gentamicin (47.4 and 11.9%, respectively) was detected in C. jejuni isolated from broilers than in human strains (38 and 0.4%, respectively). Beta-lactamase production was found in 81% of the Campylobacter strains tested, although 44% of them were characterized as ampicillin susceptible. The increasing rates of Campylobacter resistance make advisable a more conservative policy for the use of antibiotics in farm animals.

Macrolide resistance phenotypes and mechanisms of resistance in Streptococcus pyogenes in La Rioja, Spain.

One hundred and thirty seven consecutive clinical Streptococcus pyogenes isolates were evaluated for macrolide-lincosamide-streptogramin resistance (MLS). Forty of these isolates were resistant to erythromycin (29.2%), 36 of them showed the new M resistance phenotype (erythromycin resistant and clindamycin susceptible) and four isolates had the MLS(B) resistance phenotype (erythromycin and clindamycin resistant). In all 36 isolates with the M resistance phenotype, the mef gene was identified by polymerase chain reaction (PCR). In two of the four S. pyogenes isolates with the MLS(B) phenotype, both ermB and ermTR genes were found; negative results were obtained with the other two isolates which might possess a new mechanism of high level resistance against erythromycin not previously described. In summary, a high rate of erythromycin resistance was found in S. pyogenes isolates and the active efflux pump mediated by the mef gene was the mechanism most frequently involved.

[The microbiology of secretory otitis]. / Microbiología de la otitis seromucosa

The AA. realize a comparative study on the differences between the nasopharyngeal microbial flora of 50 children suffering a secretory otitis and other 40 children without middle ear disease. In nasopharyngeal cultures the pathogenic flora (Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, Streptococcus beta hemoliticus group A, Staphilococcus aureus) amounted for 96 percent in children with secretory otitis, which figure was reduced to 80 percent in healthy infants (p < 0.05). Haemophilus influenzae was the most identified microorganism in a both nasopharyngeal and otic flora. We have found a significative association (p < 0.001) among nasopharyngeal and otic flora of each individual.

High-level penicillin resistance and penicillin-gentamicin synergy in Enterococcus faecium.

Thirty-seven Enterococcus faecium strains with different levels of penicillin susceptibility were studied in time-kill experiments with a fixed concentration (5 micrograms/ml) of gentamicin combined with different penicillin concentrations (6 to 600 micrograms/ml). Synergy was defined as a relative decrease in counts of greater than 2 log10 CFU per milliliter after 24 h of incubation when the combination of the antibiotics was compared with its most active component alone. The minimal synergistic penicillin concentrations found were 6 micrograms/ml for 16 of 16 strains for which penicillin MICs were < or = 25 micrograms/ml, 20 to 100 micrograms/ml for 14 of 17 strains for which penicillin MICs were 50 to 200 micrograms/ml, and 200 to 500 micrograms/ml for 4 of 4 strains for which MICs penicillin were > 200 micrograms/ml. Penicillin-gentamicin synergy was observed even in high-level penicillin-resistant E. faecium strains at penicillin concentrations close to one-half the penicillin MIC. The possibility of treating infections caused by high-level penicillin-resistant E. faecium strains with penicillin-gentamicin combinations in particular cases may depend on the penicillin levels attainable in vivo.

IgG interference in second generation enzymeimmunoassays for anti-hepatitis C virus antibodies.

The interference of endogenous IgG in the identification of anti-HCV antibodies was studied in three second-generation enzymeimmunoassays. The addition of increasing concentrations of this immunoglobulin led to the appearance of false positives. The results obtained confirm the hypothesis that a non-specific binding of the IgG with the support material used was responsible for this interference.