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M L Beach

Publications and source records attributed to M L Beach.

34 records · Page 2Linked to original sources
PubMed1999

Comparative antimicrobial activity of gatifloxacin tested against Streptococcus spp. including quality control guidelines and etest method validation. Quality Control Study Group.

Gatifloxacin (formerly AM-1155 or CG 5501) is a new 8-methoxy fluoroquinolone with enhanced activity against Gram-positive cocci, especially Streptococcus pneumoniae and other streptococci. Recent clinical strains (599 isolates) were tested against gatifloxacin, three comparison fluoroquinolones, and penicillin by the reference broth microdilution, Etest (AB BIODISK, Solna, Sweden) and standardized disk diffusion methods (5 micrograms gatifloxacin disk). Gatifloxacin (MIC90, 0.5 microgram/ml) activity was generally comparable to that of trovafloxacin (MIC90, 0.25 microgram/ml), or sparfloxacin (MIC90, 0.5 microgram/ ml) and markedly superior to ofloxacin (MIC90, 2-4 micrograms/ml) against the streptococci. Rates of penicillin non-susceptibility were 41.9, 38.0, and 16.2% for S. pneumoniae (301 strains), viridans group streptococci (150 strains), and beta-haemolytic streptococci (148 strains). Etest results correlated well (95.7-100.0% +/- one log2 dilution) with the reference MIC results, but Etest tended to have elevated gatifloxacin MIC results compared to the broth microdilution method for the highly resistant isolates (MICs, > 2 micrograms/ml). Gatifloxacin disk zone diameters correlate well to reference MICs for all streptococci and proposed interpretive criteria (susceptible at < or = 1 microgram/ml or > or = 18 mm, and resistant at > or = 4 micrograms/ml or < or = 14 mm) did not produce discords between method results (absolute agreement). A nine laboratory quality control (QC) study conforming to the National Committee for Clinical Laboratory Standards (NCCLS) Guideline M23-T3 studied S. pneumoniae ATCC 49619 and gatifloxacin. Proposed ranges for QC of NCCLS tests were 0.12-0.5 microgram/ml for the broth microdilution test and 24-31 mm for the disk diffusion method. These reported results indicate that gatifloxacin was a potent fluoroquinolone with extensive activity against streptococcal isolates. In vitro test methods to measure this activity appear accurate and comparable; and QC guidelines have been established for routine clinical laboratory use pending approval by the NCCLS and the Food and Drug Administration (FDA).

Anti-Infective Agents↗
PubMed1999

Gatifloxacin (AM-1155, CG 5501) susceptibility testing interpretive criteria and quality control guidelines for dilution and disk (5-microgram) diffusion methods. The Quality Control Study Group.

Gatifloxacin (formerly AM-1155 and CG5501), a new 8-methoxy fluoroquinolone, has an expanded spectrum of activity against Gram-positive cocci and some anaerobic bacteria. This compound was tested against 600 recent clinical strains of rapidly growing aerobic species to establish susceptibility testing interpretive criteria for the reference broth microdilution and standardized disk (5-microgram) diffusion methods of the National Committee for Clinical Laboratory Standards (NCCLS). These strains included 285 Enterobacteriaceae (17 species), 165 staphylococci, 49 enterococci, and 101 nonfermentative Gram-negative bacilli. Based on achievable serum levels with projected gatifloxacin dosing regimens, MIC break points of < or = 2 micrograms/mL (> or = 18 mm) for susceptibility and > or = 8 micrograms/mL (< or = 14 mm) for resistance were selected. The absolute agreement between tests was 94.3% with no very major false-resistant errors. The quality control ranges (MIC and zone diameters) for the NCCLS recommended strains were determined in a nine-laboratory NCCLS protocol as follows: Escherichia coli ATCC 25922 = 0.008-0.03 microgram/mL and 31-37 mm; Enterococcus faecalis ATCC 29212 = 0.12-1 microgram/mL; Pseudomonas aeruginosa ATCC 27853 = 0.5-2 micrograms/ml and 21-27 mm; Staphylococcus aureus ATCC 25923 = 27-33 mm and S. aureus ATCC 29213 = 0.03-0.12 microgram/mL. Gatifloxacin appears to be a promising new fluoroquinolone with acceptable susceptibility testing methods for routine clinical laboratory use.

Anti-Infective Agents↗
PubMed1999

Survey of blood stream infections attributable to gram-positive cocci: frequency of occurrence and antimicrobial susceptibility of isolates collected in 1997 in the United States, Canada, and Latin America from the SENTRY Antimicrobial Surveillance Program. SENTRY Participants Group.

The SENTRY Antimicrobial Surveillance Program was established in January, 1997 to monitor the predominant pathogens and antimicrobial resistance patterns of nosocomial and community-acquired infections via a network of sentinel hospitals in the United States (30 sites), Canada (eight sites), Latin America (10 sites), and Europe (24 sites). During the first 12-month study period (January to December, 1997), a total of 9519 blood stream infections (BSI) were reported by SENTRY participants in the U.S. (6150), Canada (1727), and Latin America (1642). The Gram-positive cocci, Staphylococcus aureus, coagulase-negative staphylococci (CoNS), enterococci, and streptococci accounted for 53.9% (5131 infections) of all BSI (56.5% U.S., 55.7% Canada, and 42.9% Latin America). The staphylococci, Enterococcus spp., S. pneumoniae, beta-hemolytic streptococci, and viridans group streptococci accounted for 6 of the top 11 BSI pathogens in the U.S. and Canada, whereas only S. aureus (1st), CoNS (3rd), and Enterococcus spp. (9th) were among the top 11 pathogens in Latin American hospitals. The results of this survey affirm the importance of Gram-positive cocci as causes of BSI in both North America and Latin America and demonstrate that important antimicrobial resistance exists among isolates of staphylococci, streptococci, and enterococci from all three geographic regions. This includes oxacillin-resistance among S. aureus (26.9% U.S., 29.2% Latin America, and 4.0% Canada) and CoNS (71.5% U.S., 68.4% Latin America, and 65.6% Canada), penicillin resistance among viridans group streptococci (48.5% U.S., 45.1% Canada, and 33.3% Latin America) and pneumococci (36.1% U.S., 27.5% Canada, and 65.6% Latin America), high-level resistance (HLR) to aminoglycosides among enterococci (27.2 to 70.1% U.S., 33.3 to 75.7% Canada and 16.7 to 51.5% Latin America), and macrolide resistance among beta-hemolytic streptococci (12.4 to 14.2% U.S., 10.5 to 12.3% Canada, and 0.0 to 4.0% Latin America), viridans group streptococci (32.4 to 39.7% U.S., 22.5-35.2% Canada, and 20.0% Latin America), and pneumococci (10.0 to 10.6% U.S., 9.8-10.8% Canada, and 9.4-18.7% Latin America). BSI isolates of Gram-positive cocci from the U.S. and Latin America were considerably more resistant than those from Canada. New agents with Gram-positive activity will be essential for optimal treatment of BSI attributable to Gram-positive cocci in both North and Latin America.

Anti-Bacterial Agents↗
PubMed1999

Bacterial pathogens isolated from patients with skin and soft tissue infections: frequency of occurrence and antimicrobial susceptibility patterns from the SENTRY Antimicrobial Surveillance Program (United States and Canada, 1997). SENTRY Study Group (North America).

As part of the SENTRY Antimicrobial Surveillance Program, 1562 bacterial isolates were recovered from hospitalized patients with skin and soft tissue infections (SSTIs) in 30 United States (U.S.) and 8 Canadian medical centers between October and December, 1997. The overall rank order of recovery of the six most common pathogens was Staphylococcus aureus (42.6%) > Pseudomonas aeruginosa (11.3%) > Enterococcus spp. (8.1%) > Escherichia coli (7.2%) > Enterobacter spp. (5.2%) > beta-hemolytic streptocci (5.1%). With one exception, essentially the same order was observed in both the U.S. and Canada. The single exception was the Enterococcus group, which were the third most common isolate in the U.S. (9.6%), but the seventh most common isolate in Canada (3.7). Of note, 24.0% of S. aureus isolates were oxacillin resistant; vancomycin was uniformly active. Vancomycin resistance among Enterococcus spp. (16.5%) was observed only in the U.S. Several antimicrobial agents remained broadly active for SSTI isolates of P. aeruginosa, including meropenem, amikacin, tobramycin, and piperacillin with or without tazobactam. Imipenem resistance (MICs, > or = 8 micrograms/mL) was observed in 11.9% of isolates of P. aeruginosa and ceftazidime, and cefepime had equivalent activity (85.2% and 85.8% susceptible, respectively). Numerous beta-lactams, aminoglycosides and fluoroquinolones were broadly active against E. coli SSTI isolates (i.e. < 5% resistance). Extended-spectrum beta-lactamase production was uncommon both with E. coli and Klebsiella spp. in both nations. Cefepime, imipenem, and meropenem; the aminoglycosides; and fluoroquinolones were conspicuously more active against Enterobacter spp. than other agents tested. High-level, stably derepressed Amp C beta-lactamase production was commonly observed in this group (26.8%), but cefepime generally retained activity against these ceftazidime-resistant organisms. The results of this study serve to define the most common bacterial causes of SSTIs in North America, elucidate patterns of antimicrobial resistance and can be used as a basis for making initial empiric antimicrobial management decisions in hospitalized patients with such infections.

Anti-Bacterial Agents↗
PubMed1999

Antimicrobial activity of gatifloxacin (AM-1155, CG5501), and four other fluoroquinolones tested against 2,284 recent clinical strains of Streptococcus pneumoniae from Europe, Latin America, Canada, and the United States. The SENTRY Antimicrobial Surveillance Group (Americas and Europe).

The newer fluoroquinolones generally have greater potency against Gram-positive cocci including Streptococcus pneumoniae. In this study, we report the activity of gatifloxacin (formerly AM-1155 or CG5501) compared with penicillin, erythromycin, and four other peer drugs, tested against 2284 strains isolated in North America (Canada and United States), Latin America (six nations), and Europe in 1997. Reference broth microdilution methods were used and results were interpreted by consensus standards. Gatifloxacin demonstrated uniform potency against pneumococci across all monitored geographic areas (MIC90, 0.5 microgram/mL; > or = 99.6% of strains inhibited at < or = 1 microgram/mL). This activity was comparable to trovafloxacin (MIC90, 0.5 microgram/mL) and sparfloxacin (MIC90, 0.5 microgram/mL) and two- to four-fold greater than that of ciprofloxacin or levofloxacin. The most resistant strains to the fluoroquinolones had mutations in both par C (Ser 79-->Phe) and gyr A (Ser83-->Lys or Phe). Penicillin resistance (MIC, > or = 0.12 microgram/mL) rates varied from 27.6% in Europe to 55.7% in Latin America. Macrolide resistance was greatest in Europe and the United States. Gatifloxacin appears to be a promising new fluoroquinolone for clinical use in respiratory tract infections commonly caused by S. pneumoniae.

Anti-Infective Agents↗
PubMed1999

Fracture risk in the U.S. Medicare population.

Using data from the 5% U.S. Medicare sample, we estimated the actuarial (life table) risk that a person aged 65 will fracture the upper or lower limbs or the pelvis, by age 75, 80, 85, and 90, taking into account the chance of dying in the interval. The actuarial risk of a 65-year old white woman sustaining a fracture by age 90 is 16% for the hip, 9% for distal forearm, 5% for proximal humerus, and 4% for ankle. Black women and white men have substantially lower risks, and the risks for black men are very low. Although hip fractures pose the single greatest risk, the risk of all other fractures combined is greater. White women have particularly high risks for all fractures, because of their longevity as well as their high fracture rates. It is important to adjust for the probability of dying when estimating risks in an elderly population.

Actuarial Analysis↗
PubMed1999

Comparison of activities of broad-spectrum beta-lactam compounds against 1,128 gram-positive cocci recently isolated in cancer treatment centers.

We report the in vitro activities of broad-spectrum beta-lactam antimicrobials tested against 1,128 gram-positive pathogens recently isolated from cancer patients. Cefepime and imipenem were more active than ceftazidime and ceftriaxone against these organisms. Only vancomycin demonstrated reliable activity against oxacillin-resistant staphylococci, Enterococcus spp., and Corynebacterium spp. The spectrum of gram-positive organisms against which cefepime and imipenem have activity provides an advantage over ceftazidime as empiric therapy for cancer patients, potentially reducing the need for the empiric addition of glycopeptides.

Anti-Bacterial Agents↗
PubMed1999

Activity of gatifloxacin against Haemophilus influenzae and Moraxella catarrhalis, including susceptibility test development, E-test comparisons, and quality control guidelines for H. influenzae.

In vitro antimicrobial activity and susceptibility testing interpretation criteria and quality control were studied for gatifloxacin, a new 8-methoxy fluoroquinolone, tested against Haemophilus influenzae. Moraxella catarrhalis (600 strains) and H. influenzae (1,400 strains) from the SENTRY Antimicrobial Surveillance Program in North America (Canada and the United States) were also tested against gatifloxacin and 12 other antimicrobial agents. Gatifloxacin (MIC at which 90% of the isolates are inhibited [MIC90], </=0.03 microg/ml; 100.0% of strains inhibited at </=2 microg/ml) was the most active agent tested against H. influenzae and was similar to four comparison fluoroquinolones (MICs, </=0.03 to 2 microg/ml) against M. catarrhalis. A subset of 300 recent clinical isolates of H. influenzae were tested by using media (Haemophilus Test Medium agar and broth) and procedures recommended by the National Committee for Clinical Laboratory Standards (NCCLS) and with the E-test (AB BIODISK, Solna, Sweden). Gatifloxacin (MIC50, 0.008 microg/ml) was slightly more active than levofloxacin, and E-test results were generally elevated by 0.5 log2 dilution step compared to reference MICs. The gatifloxacin 5-microg disk test produced zone diameters that were routinely above 30 mm for H. influenzae strains, corresponding to gatifloxacin MICs of 0.008 or 0. 016 microg/ml. The gatifloxacin susceptibility breakpoint proposed for nonfastidious species (</=2 microg/ml; >/=18 mm) was also suggested for H. influenzae testing. No interpretive errors were observed. Quality control guidelines for H. influenzae ATCC 49247 were determined by using the NCCLS M23-T3 (1998) study design. The results from the nine-laboratory protocol suggested the following control ranges: for broth microdilution tests, 0.004 to 0.03 microg/ml; for disk diffusion testing, 33 to 41 mm. Gatifloxacin appears to be a potent anti-Haemophilus fluoroquinolone compound with in vitro testing interpretive criteria that will produce accurate results (disk diffusion, broth microdilution, and E-test).

Anti-Bacterial Agents↗
PubMed1998

Antimicrobial activity of gatifloxacin tested against 1676 strains of ciprofloxacin-resistant gram-positive cocci isolated from patient infections in North and South America.

Gatifloxacin (formerly AM-115) is a new 8-methoxy fluoroquinolone with an expanded spectrum against Gram-positive cocci and some anaerobes. To assess this new agent's activity, a collection of 1,676 Gram-positive cocci were selected for resistance to ciprofloxacin (> or = 4 micrograms/mL) and tested against gatifloxacin and 18 other compounds by reference broth microdilution methods. The strains (approximately 23,000 total isolates from the SENTRY Antimicrobial Surveillance Program) were from significant blood stream, respiratory tract, wound, and urinary tract infections in patients in North (38 hospitals) and South (10 hospitals) America. Against Enterococcus faecalis and E. faecium, gatifloxacin inhibited only 16% and 10% of strains compared with 12% and 5% for recently released trovafloxacin, respectively. Among Staphylococcus aureus (90% oxacillin-resistant) strains, gatifloxacin was more active (67% susceptible at < or = 4 micrograms/mL) than trovafloxacin (59%) or sparfloxacin (4%). Gatifloxacin had a wider spectrum than trovafloxacin against coagulase-negative staphylococci especially S. epidermidis, 2% versus 58% resistance. The glycopeptides, chloramphenicol and rifampin were most active. Against all genus/species groups with more than 100 sample strains (1,566), high-level resistance to gatifloxacin and trovafloxacin (> 4 micrograms/mL) was not significantly different (41.7% versus 39.1%; p > 0.05). Emerging resistance to the fluoroquinolones remains a clinical problem among Gram-positive species, and gatifloxacin seems to be active in vitro against many of these contemporary strains isolated in the Americas.

Anti-Infective Agents↗
PubMed1998

Antimicrobial activity of gatifloxacin tested against Neisseria gonorrhoeae using three methods and a collection of fluoroquinolone-resistant strains.

Gatifloxacin, a new 8-methoxy fluoroquinolone, was tested against 131 strains of Neisseria gonorrhoeae by reference agar dilution, disk diffusion, and Etest (AB BIODISK, Solna, Sweden) methods on supplemented GC agar. Gatifloxacin activity was equal to ciprofloxacin (MIC50, 0.008 microgram/mL) against strains fully susceptible to fluoroquinolones, but was generally four-fold more active (MIC90, 0.064-0.094 microgram/mL) against strains with par C or gyr A mutations and resistance to ciprofloxacin. Etest results were comparable to those generated by the agar dilution test [correlation coefficient (r) = 0.97]. Gatifloxacin zone diameters using 5-microgram disks also correlated well (r = 0.86-0.87) with the agar dilution and Etest MIC results. Breakpoints for laboratory testing of Neisseria gonorrhoeae strains await clinical trial outcome correlations, but susceptibility at < or = 0.125 or < or = 0.25 microgram/mL (> or = 34 mm) seems appropriate. All three tests used in this study seem applicable for laboratory testing of isolates from patients with uncomplicated gonorrhoeae receiving therapy with gatifloxacin.

Anti-Infective Agents↗
PubMed1998

Microsurgical treatment of arteriovenous malformations: analysis and comparison with stereotactic radiosurgery.

OBJECT: To compare microsurgical and stereotactic radiosurgical treatment of arteriovenous malformations (AVMs), the authors analyzed a prospective series of 72 consecutive patients who were treated microsurgically for cerebral AVMs by one neurosurgeon. The authors then compared the results of microsurgical treatment with published results of stereotactic radiosurgical treatment of small AVMs. METHODS: Patients were categorized by age, gender, presentation, and preoperative neurological status. The AVMs were categorized by size, location, presence of deep venous drainage, and Spetzler-Martin grade. Outcome was assessed for angiographic obliteration, hemorrhage following treatment, presence of a new, persistent postoperative neurological deficit, and Glasgow Outcome Scale (GOS) score. Ordinal logistic regression was used to model the GOS score and to predict new postoperative deficits. Generalized estimating equations were used to compare published results of microsurgical and stereotactic radiosurgical treatment of AVMs. Kaplan-Meier event-free survival plots were generated to compare the two modalities with respect to hemorrhage following treatment. Overall, six patients (8.3%) exhibited a new persistent neurological deficit postoperatively. Sixty-five patients (90.3%) had a GOS score of 5. Three patients were moderately disabled and four patients were severely disabled. No patient was observed to be in a vegetative state and there were no treatment-related deaths. Seventy-one patients (98.6%) underwent intra- or postoperative angiography. Total excision of the AVM was angiographically confirmed in 70 patients (98.6% of those who underwent angiography). To date no patient has suffered from hemorrhage since the microsurgical treatment. When analysis was confined to patients whose AVMs were smaller than 3 cm in maximum diameter, the authors found a 100% angiographic obliteration rate, no new postoperative neurological deficit, and a good recovery in all patients. An analysis of all patients with Spetzler-Martin Grades I to III resulted in a 100% rate of angiographic obliteration, one patient with a new postoperative neurological deficit, and good recovery in 93% of the patients. Size of the AVM, preoperative neurological status, and patient age are associated with GOS score (for all, p < 0.02). The Spetzler-Martin grading system as well as each component of this system are associated with the development of a new postoperative neurological deficit (for all, p < 0.01). For the entire series there were fewer postoperative hemorrhages and deaths than those mentioned in published series of small AVMs treated with stereotactic radiosurgery. When these patients and published series of patients with microsurgically treated AVMs classified as Grade I to III were compared with similar patients treated radiosurgically there were significantly fewer postoperative hemorrhages (odds ratio = 0.210, p = 0.001), fewer deaths (odds ratio = 0.659, p = 0.019), fewer new posttreatment neurological deficits (odds ratio = 0.464, p = 0.013), and a higher incidence of obliteration (odds ratio = 28.2, p = 0.001) for the microsurgical group. Lifetable analysis confirms the statistically significant difference in hemorrhage-free survival time between the two groups (p = 0.002). CONCLUSIONS: Based on this analysis, microsurgical treatment of Grades I to III AVMs is superior to stereotactic radiosurgery.

Adolescent↗
PubMed1997

A comparison of neonatal outcomes of age-matched, growth-restricted twins and growth-restricted singletons.

A retrospective cohort study was performed to determine whether growth-restricted fetuses of a twin gestation are at increased risk of adverse neonatal outcome compared with growth-restricted singletons. One cohort was comprised of 48 growth-discordant twin pregnancies in which the birth weight of the smaller twin was less than the tenth percentile. The neonatal outcomes of the 48 growth-restricted twin infants were compared with a cohort of 96 singleton infants matched by gestational age, degree of growth restriction, and gender. Outcomes evaluated included: length of stay, days of assisted ventilation, and diagnoses of morbidities of prematurity, congenital abnormalities, and neonatal death. No significant difference was detected in rates of neonatal morbidity or mortality. The overall neonatal death rate in the twins was 125 of 1000 and in the singletons was 104 of 1000 (Odds ratio 1.2, 95% confidence interval [CI]0.4-3.3). Growth-restricted twins have similar rates of adverse neonatal outcomes as compared with growth-restricted singletons. Both have high rates of morbidity and neonatal death. Twins and singletons should receive comparable diagnostic evaluation and antepartum management for growth restriction.

Female↗
PubMed1996

Heterogeneity of hip fracture: age, race, sex, and geographic patterns of femoral neck and trochanteric fractures among the US elderly.

To explore potential etiologic differences in the two major types of hip fracture, the authors computed the incidence rates of fractures of the femoral neck and trochanteric region of the proximal femur using a 5 percent sample of the US Medicare population aged 65-99 years. For the period they examined, July 1, 1986, through June 30, 1990, the rates of both hip fracture types increased with age in all race and sex categories. The proportion of hip fractures that occurred in the trochanteric region rose steeply with age among white women, but not among black women, white men, or black men. Within the United States, a north-to-south gradient in rates of both fracture types was observed among women, while no clear pattern was found for men. These findings raise the possibility of etiologic differences in the two fracture types, and the results provide further evidence of sex and racial differences in the risk of osteoporotic fractures.

Black or African American↗
PubMed1996

Ultrasound predictors of neonatal outcome in intrauterine growth restriction.

Our purpose was to assess the value of commonly performed ultrasound parameters in predicting neonatal outcome of fetuses with intrauterine growth restriction (IUGR). One hundred twenty-seven patients were identified on ultrasound examination to have IUGR. Estimated weight percentile, amniotic fluid volume, umbilical artery Doppler velocimetry, and head circumference/abdominal circumference ratio were compared with neonatal outcome. Thirty infants had severely adverse courses. The degree of growth restriction was strongly associated with adverse outcome and neonatal death. Umbilical artery Doppler waveforms with absent or reverse end-diastolic flow were predicted of neonatal death, bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), and adverse outcome in general. Oligohydramnios was predictive of adverse outcome and neonatal death. Logistic regression also showed that absent or reverse end-diastolic flow and oligohydramnios were independent predictors of adverse outcome. Ultrasound findings of low estimated weight percentile, absent or reverse end-diastolic umbilical blood flow, and oligohydramnios are independent predictors of adverse neonatal outcome of growth restricted fetuses.

Adolescent↗
PubMed1989

Choosing covariates in the analysis of clinical trials.

Much of the literature on clinical trials emphasizes the importance of adjusting the results for any covariates (baseline variables) for which randomization fails to produce nearly exact balance, but the literature is very nearly devoid of recipes for assessing the consequences of such adjustments. Several years ago, Paul Canner presented an approximate expression for the effect of a covariate adjustment, and he considered its use in the selection of covariates. With the aid of Canner's equation, using both formal analysis and simulation, the impact of covariate adjustment is further explored. Unless tight control over the analysis plans is established in advance, covariate adjustment can lead to seriously misleading inferences. Illustrations from the clinical trials literature are provided.

Computer Simulation↗