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Biomedical subjects

A I Suárez

Publications and source records attributed to A I Suárez.

At least 19 recordsLinked to original sources
PubMed2001

Activities of gemifloxacin and five other antimicrobial agents against Listeria monocytogenes and coryneform bacteria isolated from clinical samples.

The in vitro activities of gemifloxacin, ciprofloxacin, ampicillin, doxycycline, gentamicin, and vancomycin were evaluated against 15 Listeria monocytogenes strains and 205 coryneform bacteria isolated from clinical samples. The percentages of strains inhibited by gemifloxacin at 0.5 microg/ml were 100% (L. monocytogenes), 93.3% (Brevibacterium spp.), 90% (Corynebacterium minutissimum), 42.5% (Corynebacterium amycolatum), 20% (Corynebacterium striatum), 12.5% (Corynebacterium jeikeium), and 10% (Corynebacterium urealyticum). One hundred percent of the L. monocytogenes strains were inhibited by 0.25 microg of gemifloxacin per ml, whereas 0% of the strains were inhibited by 0.25 microg of ciprofloxacin per ml. Vancomycin at 2 microg/ml inhibited all strains. Doxycycline and gentamicin at 4 microg/ml inhibited 94 and 49% of the strains, respectively, while ampicillin at 0.5, 2, and 8 microg/ml inhibited 24, 61, and 66% of the strains, respectively. It is concluded that gemifloxacin shows good in vitro activity against L. monocytogenes and coryneform bacteria except C. jeikeium and C. urealyticum.

Anti-Bacterial Agents↗
PubMed1999

In-vitro activity of levofloxacin, ofloxacin and D-ofloxacin against coryneform bacteria and Listeria monocytogenes.

The objective of this study was to evaluate the in-vitro activity of levofloxacin, ofloxacin and D-ofloxacin compared with ciprofloxacin, norfloxacin and sparfloxacin against coryneform bacteria and Listeria monocytogenes isolated from clinical samples. The following organisms (and number of strains) were studied: Corynebacterium jeikeium (20), Corynebacterium urealyticum (20), Corynebacterium minutissimum (20), Corynebacterium striatum (20), Corynebacterium amycolatum (30), Brevibacterium spp. (15) and Listeria monocytogenes (15). Antimicrobial activity was determined by microdilution using cation-adjusted Mueller-Hinton broth supplemented with 0.5% Tween 80 when testing C. jeikeium or C. urealyticum. Fluoroquinolones were used in the range 0.015-16 mg/L. Plates were incubated in air at 35 degrees C for 18-20 h (24 h when testing C. jeikeium or C. urealyticum). The following MIC50 values were obtained for all 140 organisms tested: levofloxacin, 1 mg/L; ofloxacin, 2 mg/L; D-ofloxacin, > 16 mg/L; ciprofloxacin, 1 mg/L; norfloxacin, 16 mg/L; sparfloxacin, 1 mg/L. MIC90 values were > 16 mg/L for all test antibiotics with the exception of levofloxacin, which had an MIC90 value of 16 mg/L. At a concentration of 2 mg/L, levofloxacin inhibited all L. monocytogenes strains and 35-93% of the remaining species. MIC90 values of ofloxacin were one dilution step higher than those of levofloxacin against C. minutissimum, C. striatum, Brevibacterium spp. and L. monocytogenes. Levofloxacin showed similar (C. jeikeium, C. urealyticum, C. amycolatum and Brevibacterium spp.) or greater (C. minutissimum and C. striatum) activity than ciprofloxacin and sparfloxacin, and higher than D-ofloxacin or norfloxacin against all species studied. In conclusion, levofloxacin was the most active of the six fluoroquinolones evaluated against coryneform bacteria isolated from clinical samples and could therefore be a promising treatment option in this setting.

Anti-Infective Agents↗
PubMed1999

Roles of beta-lactamases and porins in activities of carbapenems and cephalosporins against Klebsiella pneumoniae.

Two clinical isolates of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of beta-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC beta-lactamase types, by studying the effect of an increased inoculum, and by evaluating interactions with beta-lactamase inhibitors. The contribution of porin deficiency was investigated by restoring a functional ompK36 gene on a plasmid. Plasmids encoding AmpC-type beta-lactamases provided resistance to imipenem (up to 64 microg/ml) and meropenem (up to 16 microg/ml) in strains deficient in porins. Carbapenem resistance showed little inoculum effect, was not affected by clavulanate but was blocked by BRL 42715, and was diminished if OmpK36 porin was restored. Plasmids encoding TEM- and SHV-type ESBLs conferred resistance to cefepime and cefpirome, as well as to earlier oxyimino-beta-lactams. This resistance was magnified with an increased inoculum, was blocked by clavulanate, and was also lowered by OmpK36 porin restoration. In addition, SHV-2 beta-lactamase had a small effect on carbapenem resistance (imipenem MIC, 4 microg/ml, increasing to 16 microg/ml with a higher inoculum) when porins were absent. In K. pneumoniae porin loss can thus augment resistance provided either by TEM- or SHV-type ESBLs or by plasmid-mediated AmpC enzymes to include the latest oxyimino-beta-lactams and carbapenems.

Carbapenems↗
PubMed1998

In vitro activities of ketolide HMR 3647, macrolides, and clindamycin against Coryneform bacteria.

The in vitro activity of ketolide HMR 3647 against coryneform bacteria isolated from clinical samples was evaluated. Except against Corynebacterium jeikeium and C. urealyticum, HMR 3647 showed high activity against Corynebacterium spp., being more active than 14- and 16-membered macrolides, azithromycin, or clindamycin. HMR 3647 also had high in vitro activity against Brevibacterium spp. and Listeria monocytogenes.

Anti-Bacterial Agents↗
PubMed1997

[Usefulness of the disk diffusion method for evaluating the sensitivity of Neisseria meningitidis to penicillin and cefotaxime].

BACKGROUND: Routine susceptibility testing of Neisseria meningitidis to penicillin and other beta lactams is recommended after the isolation of N. meningitidis of moderately resistant to penicillin (MRP). We have evaluated the disk-diffusion method to determine susceptibility of N. meningitidis to penicillin (using disks of either penicillin or oxacillin) and to cefotaxime. METHODS: Fifty-four strains of N. meningitidis isolated from clinical samples were studied. MICs of penicillin and cefotaxime were determined by microdilution. Disks of 2 U of penicillin, 1 microgram of oxacillin and 30 micrograms of cefotaxime and two culture media, Mueller-Hinton agar (MHA) and MHA supplemented with 5% sheep blood (MHS) were used in the disk-diffusion assay. RESULTS: For disk of 2 U of penicillin assayed in MHA, 86.4% of the susceptible strains and 20% of MRP strains were considered susceptible when a breakpoint of 28 mm was considered. None of the MRP strains was considered susceptible when using MHS, but only 38.6% of susceptible strains appeared as such on this medium. When a 1 microgram oxacillin disk was used all MRP strains presented an inhibition zone < or = 10 mm on both MHA and MHS, but 54.4 and 4.5% of susceptible strains presented an inhibition zone > or = 11 mm on MHA and MHS, respectively. All strains were susceptible to cefotaxime, showing inhibition zones around a 30 micrograms disk on MHA and MHS of > or = 35 mm and > or = 25 mm, respectively. CONCLUSION: Disk diffusion with cefotaxime (30 micrograms) allows to determine susceptibility of N. meningitidis to this antimicrobial agent. Discs of penicillin (2 U) and oxacillin (1 microgram) are not useful for screening of MRP N. meningitidis.

Cefotaxime↗
PubMed1996

Sulfonylureas stimulate glucose uptake through GLUT4 transporter translocation in rat skeletal muscle.

We studied the effect of gliclazide on glucose uptake and GLUT4 translocation in skeletal muscle. Rat hindquarters were perfused in the absence or presence of gliclazide (300 micrograms/ml), insulin or both drugs. The basal glucose uptake was increased 2.7-fold by gliclazide (p < 0.05). Gastrocnemius muscles perfused with gliclazide had a significant increase (2.4-fold) in the GLUT4 content in plasma membranes compared to basal conditions (p < 0.05). The stimulations produced by 1 nM insulin on muscle glucose uptake (2.8-fold) and on GLUT4 level in plasma membranes (2.5-fold) were similar to those produced by gliclazide. The effect of insulin on the glucose uptake and on the GLUT 4 translocation was significantly enhanced by gliclazide (3.4-fold and 3.7-fold vs basal, respectively). These data show that sulfonylureas stimulate glucose uptake in skeletal muscle by promoting the movement of GLUT4 to the plasma membrane.

Animals↗
PubMed1996

Glucose tolerance, insulin secretion, insulin sensitivity and glucose effectiveness in normal and overweight hyperthyroid women.

OBJECTIVE: Inter-relationships between insulin sensitivity and body weight in patients with hyperthyroidism remain incompletely understood. We have examined whether a mild excess of body weight exacerbates the metabolic abnormalities of spontaneous hyperthyroidism. DESIGN AND PATIENTS: Insulin-modified intravenous glucose tolerance tests were performed on 14 hyperthyroid women with body mass indices (BMI) ranging from 21 to 31 kg/m2. A control group of 19 healthy women matched for age and BMI was also studied. MEASUREMENTS: Intravenous glucose tolerance (KG), first and second-phase integrated insulin responses to glucose, the integrated glucose area under the curve (AUC), and minimal model parameters of insulin sensitivity (SI) and glucose effectiveness (SG) were determined. RESULTS: Hyperthyroid women had mean KG, glucose-induced insulin secretion and SG values similar to those in control women. The mean glucose AUC was higher in hyperthyroid patients (P < 0.05). Lower insulin sensitivity was observed in hyperthyroid patients than in control women (SI = 0.38 +/- 0.07 vs 0.59 +/- 0.07 l/min pmol 10(4) (mean +/- SEM), P < 0.05). A steeper decline in insulin sensitivity with increase in body mass index was found in hyperthyroid women when compared with the control group, after adjusting for age. When groups were compared according to their BMI, hyperthyroid women with normal weight (BMI < or = 25 kg/m2, n = 8) had mean KG, insulin response to glucose, glucose AUC, SG and SI values similar to those in normal weight control women (n = 11). Overweight hyperthyroid patients (BMI > 25 kg/m2, n = 6) had a higher (P < 0.05) second-phase insulin response to glucose than normal weight patients, a higher glucose AUC (P < 0.05) than normal weight patients and overweight controls (n = 8), and a lower SI (P < 0.05) than normal weight patients and overweight controls. SG was not influenced by BMI in hyperthyroid patients. CONCLUSIONS: These results suggest that overall glucose tolerance was not significantly affected in normal weight hyperthyroid women. However, when a moderate excess of weight is also present, a state of clear insulin resistance occurs.

Adult↗
PubMed1996

Antimicrobial susceptibility pattern of Corynebacterium striatum.

The in vitro activities of 16 antimicrobial agents against 86 strains of Corynebacterium striatum were evaluated by microdilution using cation-adjusted Mueller-Hinton broth. MICs at which 90% of strains were inhibited were 0.06 microgram/ml for teicoplanin, 1 microgram/ml for vancomycin, 0.03 to 8 micrograms/ml for beta-lactams, 8 micrograms/ml for sparfloxacin, 16 micrograms/ml for ciprofloxacin, 16/304 micrograms/ml for co-trimoxazole (trimethoprim-sulfamethoxazole), 64 micrograms/ml for tetracycline, 128 micrograms/ml for gentamicin, and > 128 micrograms/ml for amikacin, erythromycin, and rifampin.

Anti-Bacterial Agents↗
PubMed1995

Comparison of E-test with broth microdilution and disk diffusion for susceptibility testing of coryneform bacteria.

The susceptibilities of 135 coryneform bacteria isolated from clinical samples to ampicillin (AMP), cephalothin (CR), cefoxitin (FOX), cefotaxime (CTX), erythromycin (E), ciprofloxacin (CIP), tetracycline (TE), amikacin (AK), vancomycin (VA), and rifampin (R) were determined by disk diffusion, broth microdilution, and the E-test. The following species (number of isolates in parentheses) were included: Corynebacterium urealyticum (30), Corynebacterium minutissimum (20), coryneform CDC group ANF-1 (20), Corynebacterium striatum (20), Corynebacterium jeikeium (15), coryneform CDC group I2 (8), Listeria monocytogenes (7), Corynebacterium xerosis (5), and other coryneform bacteria (10). Agreement within one twofold dilution between the E-test and broth microdilution was 31% (VA), 64% (AK), 71% (CTX), 77% (FOX and CIP), 79% (TE), 84% (AMP), 87% (E), and 88% (CR and R). For the 1,350 combinations of microorganisms and antimicrobial agents, 85 (6.3%) discrepancies in interpretive category were found (4.2% minor, 1.2% major, and 0.9% very major). Seventy (5.1%) disagreements in interpretive category were found between disk diffusion and the E-test (3.8% minor, 0.4% major, and 0.9% very major), and 85 (6.3%) disagreements were found between microdilution (reference method) and disk diffusion (4.2% minor, 0.5% major, and 1.5% very major). MICs obtained with the E-test were highly reproducible. No category discrepancy was observed for VA, despite quantitative results. Considering interpretive categories, there is a good overall agreement between the three methods studied here, but further evaluation of current methodologies for susceptibility testing is required when considering coryneform bacteria and determination of quantitative activity of antimicrobial agents.

Actinomycetales↗
PubMed1995

Phenotypic characteristics of 31 strains of Corynebacterium striatum isolated from clinical samples.

During a 34-month period (January 1991 to October 1993), 31 Corynebacterium striatum stains recovered from clinical samples from 24 patients were characterized. Twenty (64%) strains were isolated from wound exudates, 5 (16%) were isolated from bronchial aspirates, 2 (7%) were isolated from urine, 2 (7%) were isolated from endotracheal tubes, 1 (3%) was isolated from a catheter, and 1 (3%) was isolated from empyema. The organisms were identified by conventional culture and phenotypic characterization, the API CORYNE system, and cellular fatty acid composition analyses. The colonies of C. striatum could be confused with those of coagulase-negative staphylococci upon primary isolation from clinical material. A consistent phenotypic pattern was observed: all strains reduced nitrate, hydrolyzed tyrosine, and produced acid from glucose, fructose, and sucrose but not from maltose. API CORYNE profile numbers were 3100105 (28 strains) and 3000105 (3 strains). Susceptibility testing of C. striatum was performed by disk diffusion. All strains were susceptible to both imipenem and vancomycin and resistant to fosfomycin; most strains were susceptible to ampicillin and cephalosporins and resistant to clindamycin, erythromycin, and tetracycline. Performing a Gram stain of fosfomycin-resistant "Staphylococcus-like" colonies was critical in order to identify C. striatum.

Anti-Bacterial Agents↗
PubMed1995

[False sensitivity of Enterococcus faecium to amoxicillin-clavulanic acid with the MicroScan system].

BACKGROUND: We have observed by using MicroScan automatic system discrepancies in susceptibility results of Enterococcus faecium strains to ampicillin and amoxicillin/clavulanic acid. METHODS AND RESULTS: Seventy-six strains of E. faecium were studied with MicroScan; 98.7% of them were inhibited by 16 mg/l of amoxycillin-clavulanic acid versus 60.5% inhibited by the same concentration of ampicillin. We have evaluated the susceptibility to ampicillin, amoxicillin and amoxicillin-clavulanic acid of 7 strains of E. faecium by both MicroScan and standard microdilution assay. MIC values of ampicillin were similar by both methods but MIC values of amoxicillin/clavulanic acid obtained by MicroScan (< or = 4/2 mg/l in 6 strains) were considerably lower than those obtained by standard microdilution (> or = 16/8 in 6 strains). This phenomenon was not dependent of betalactamase production or bacterial inocula. CONCLUSIONS: When using MicroScan, E. faecium strains resistant to ampicillin (betalactamase non producers) must be also considered resistant to amoxicillin/clavulanic acid without considering the values obtained by this system.

Amoxicillin↗
PubMed1994

Comparative in vitro activities of new quinolones against coryneform bacteria.

The in vitro activities of eight quinolones against 115 coryneform bacteria (20 Corynebacterium jeikeium, 15 Corynebacterium minutissimum, 15 Corynebacterium striatum, 25 Corynebacterium urealyticum, 10 Corynebacterium xerosis, 10 Corynebacterium group ANF-1, 10 Corynebacterium group 12, and 10 Listeria monocytogenes) were determined. The MICs of ciprofloxacin, ofloxacin, and sparfloxacin for 90% of C. jeikeium, C. urealyticum, and C. xerosis isolates tested were > 16 micrograms/ml. Those of BAY Y 3118 and clinafloxacin against these species were 0.5 and 1 to 2 micrograms/ml, respectively. The MICs for 90% of all 115 strains tested were 0.5 microgram/ml for BAY Y 3118, 1 microgram/ml for clinafloxacin, 2 micrograms/ml for E-5068, 4 micrograms/ml for E-5065, and > 16 micrograms/ml for ciprofloxacin, ofloxacin, sparfloxacin, and E-4868.

Anti-Infective Agents↗