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M E Erwin

Publications and source records attributed to M E Erwin.

At least 55 records · Page 3Linked to original sources
PubMed1994

Validation of NCCLS macrolide (azithromycin, clarithromycin, and erythromycin) interpretive criteria for Haemophilus influenzae tested with the Haemophilus test medium. National Committee for Clinical Laboratory Standards.

Some recently marketed macrolide antimicrobial agents possess physiochemical, antimicrobial, and pharmacokinetic advantages that enable their wider clinical use against Haemophilus influenzae infections. A five-laboratory study assessed the validity of existing or proposed azithromycin, clarithromycin, and erythromycin interpretive criteria for tests with H. influenzae isolates. National Committee for Clinical Laboratory Standards (NCCLS) methods, criteria, and quality-control guidelines were used. A total of 350 H. influenzae strains were processed, including fresh clinical isolates (250 strains) and replicate tests of 100 stock cultures sampling strains isolated from 1984 to 91. Azithromycin interpretive criteria (susceptible at < or = 4 micrograms/ml, > or = 12 mm) produced a 99.8% absolute agreement between the minimum inhibitory concentrations and disk diffusion results (0.2% false-susceptible error). Clarithromycin breakpoint criteria (susceptible at < or = 8 micrograms/ml, > or = 13 mm; and resistant at > or = 32 micrograms/ml, < or = 10 mm) produced high minor interpretive error, but < or = 1% combined false-susceptible and false-resistant discrepancies. Erythromycin interpretive guidelines were initially proposed for susceptible at < or = 0.5 microgram/ml, > or = 26 mm. This categorizes nearly all H. influenzae strains as resistant to this older macrolide. The NCCLS should consider the proposed erythromycin criteria for publication in appropriate tables, and a class drug should also be selected (azithromycin) that would best predict macrolide-class susceptibility for those agents indicated by the US Food and Drug Administration for H. influenzae infection chemotherapy (azithromycin and clarithromycin). No serious interpretive problems were observed with the current NCCLS criteria using Haemophilus test medium.

Anti-Bacterial Agents↗
PubMed1994

Prevalence of important pathogens and antimicrobial activity of parenteral drugs at numerous medical centers in the United States, I. Study on the threat of emerging resistances: real or perceived? Fluoroquinolone Resistance Surveillance Group.

Forty-three medical centers participated in a national (United States) surveillance study of parenteral antimicrobial agents as empiric therapy of pathogens isolated from blood, skin wounds, respiratory tract, and urine (> 8500 strains, 200 per laboratory). All laboratories tested each organism by the same reagent disks and/or Etest (AB Biodisk, Solna, Sweden) strips. Quality control results validated all laboratories for analyses. The most common isolates were Escherichia coli (1648), Staphylococcus aureus (1408), Pseudomonas aeruginosa (1003), Klebsiella species (792), and the enterococci (684). Among the tested drugs the percent susceptible rates observed were ofloxacin (83.4%), ciprofloxacin (82.0%), and cefuroxime (62.9%) tested against all organisms; cefazolin (54.7%) and ceftazidime (76.7%) tested against all nonfastidious aerobes; gentamicin (91.2%), imipenem (95.3%), ticarcillin-clavulanate (78.2%), and ceftriaxone (66.2%) tested against Gram-negative organisms only; and vancomycin (97.9%) and erythromycin (49.2%) tested against Gram-positive aerobes. Several drug-resistant species appear to be emerging or increasing in the United States: (a) vancomycin-resistant enterococci (7.9%, mostly Enterococcus faecium); (b) oxacillin-resistant S. aureus (21.0%); (c) third-generation cephalosporin-resistant Enterobacteriaceae, including E. coli and Klebsiella species with extended-spectrum beta-lactamases (approximately 1.3%-8.6%); (d) penicillin-resistant Streptococcus pneumoniae (17.8%); and (e) ciprofloxacin-resistant P. aeruginosa (14.9%). Fluoroquinolone resistance among the enteric bacilli was confirmed in 60 of 66 referred strains (0.8% of total strains), and cross-resistance was high among ciprofloxacin, ofloxacin, lomefloxacin, fleroxacin, and norfloxacin (98.3%-100%). Seventeen strains of fluoroquinolone-resistant enteric bacilli (0.2% of total) also harbored an ESBL and resistance to aminoglycosides. Clonal spread within medical centers was observed with the ESBL-producing Klebsiella pneumoniae. This national clinical isolate data base continues to demonstrate broad fluoroquinolone efficacy (ofloxacin > ciprofloxacin) against hospital-based pathogens and many strains of emerging resistant bacteria. Continued US surveillance studies are urged to monitor emerging antimicrobial resistance and to guide interventions to minimize its occurrence.

Anti-Bacterial Agents↗
PubMed1994

Minimum inhibitory concentration quality-control guidelines for biapenem, DU-6859a, FK-037, levofloxacin, grepafloxacin, and ceftizoxime when using various National Committee for Clinical Laboratory Standards susceptibility test methods. Quality Control Study Group.

Several multilaboratory collaborative studies using broth microdilution and agar dilution (gonococcal tests only) methods of susceptibility testing were performed to establish quality-control (QC) giudelines. Replicate dilution tests with multiple lots of media were performed with National Committee for Clinical Laboratory Standards recommended QC strains (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 29212, and Staphylococcus aureus ATCC 29213) by using the following antimicrobials: biapenem, DU-6859a, FK-037, levofloxacin, and grepafloxacin. In addition QC MIC ranges, using appropriate medium modification for Haemophilus influenzae ATCC 49247 and Neisseria gonorrhoeae ATCC 49226 were reported on four (DU-6859a, FK-037, levofloxacin, and grepafloxacin) and two (ceftizoxime and FK-037) antimicrobials, respectively.

Anti-Bacterial Agents↗
PubMed1994

Etest for routine clinical antimicrobial susceptibility testing of rapid-growing mycobacteria isolates.

The Etest has become a widely accepted alternative susceptibility-testing method for difficult-to-assess organisms, including rapid-growing Mycobacterium spp. Following an internal validation and literature reviews, the Etest was applied as the routine method for testing Mycobacterium chelonae and Mycobacterium fortuitum isolates. Results from testing 31 strains confirmed the utility of the Etest and the simplicity of the procedure. Mycobacterium chelonae were generally more resistant to all drugs except amikacin (MIC90, 32 micrograms/ml), compared with M. fortuitum strains that were inhibited (MIC50 in the susceptible range) by amikacin (1 microgram/ml), ciprofloxacin (0.032 microgram/ml), doxycycline (0.125 microgram/ml), and trimethoprim-sulfamethoxazole (0.032 microgram/ml). The polymyxin-B disk used as an identification method was confirmed (> or = 10 mm = M. fortuitum). The Etest provides a simple and accurate method for selecting appropriate therapy for infections caused by rapid-growing mycobacteria (a typical case report is presented).

Amikacin↗
PubMed1994

Interpretive criteria for DU-6859a disk diffusion tests using 5-micrograms disks.

In vitro disk diffusion test interpretive criteria were developed for DU-6859a, a new difluorinated quinolone, using a 5-micrograms disk. Included in the 494 organisms tested were 84 (17%) ciprofloxacin-resistant > or = 4 micrograms/ml) clinical isolates. The following interpretive criteria were proposed for two possible susceptible breakpoint minimum inhibitory concentrations: > or = 16 mm (< or = 2 micrograms/ml) = susceptible and < or = 12 mm (> or = 8 micrograms/ml) = resistant and; > or = 19 mm (< or = 1 microgram/ml) = susceptible and < or = 15 mm (> or = 4 micrograms/ml) = resistant. These criteria demonstrated > or = 97% absolute interpretive agreement between test methods with no major (false resistant) or very major (false susceptible) errors.

Anti-Infective Agents↗
PubMed1994

Update of lomefloxacin in vitro activity and spectrum. A multicenter trial testing contemporary pathogens following Food and Drug Administration validation guidelines. Lomefloxacin Activity Study Group.

The United States Food and Drug Administration recently recommended that the antimicrobial product package insert (PPI) subsection on microbiology be annually validated with regard to the compound's spectrum and potency. To address this request, a nine-laboratory trial was organized to test (two methods) lomefloxacin, a newer fluoroquinolone, and nine comparison drugs against PPI-listed pathogens (1934 strains). A broad geographic sampling (nine medical centers) was achieved, and lomefloxacin was determined to be active [minimum inhibitory concentration (MICs), < or = 2 micrograms/ml for > or = 90% of strains] for all PPI-listed species except Pseudomonas aeruginosa, Citrobacter freundii, and Providencia rettgeri (42%-87% inhibited). Comparison fluoroquinolones also had a similarly compromised spectrum of activity against these species. Additional organism species, including Neisseria gonorrhoeae, N. meningitidis, Salmonella enteriditis, and Shigella species, should be added to the lomefloxacin PPI (MIC90s, 0.03-0.25 microgram/ml) following data generated in this study. These in vitro results indicate that lomefloxacin remains active against the vast majority of clinically "indicated" species, and that it has a spectrum compatible with other marketed fluoroquinolones for these tested pathogens, monitored in 1994.

Anti-Bacterial Agents↗
PubMed1993

In vitro activity of E-4868, a new trifluoroquinolone, compared to six similar compounds.

The compound E-4868 (Laboratorios Dr. Esteve) is a trifluoro, 7-azetidinyl quinolone with properties resembling those of other fluoroquinolones. Its activity in vitro was compared to that of six other similar drugs against more than 700 nosocomial isolates using standard methods. The MIC50s of E-4868 for enteric bacilli ranged from 0.015 to 0.25 micrograms/ml, being highest for Providencia spp. Pseudomonas aeruginosa strains were two-fold more susceptible to E-4868 than to ofloxacin. MICs of E-4868 for Haemophilus influenzae, Moraxella catarrhalis and pathogenic Neisseria spp. were all < or = 0.12 micrograms/ml. E-4868 was equal in activity to or eight-fold more active than ciprofloxacin against gram-positive cocci. The MICs of E-4868 for pneumococci were all < or = 0.5 micrograms/ml but anaerobes such as Bacteroides fragilis were generally less susceptible (MIC90, 4 micrograms/ml). There was almost complete cross-resistance to several other fluoroquinolones. Resistant mutants were selected by a multiple passage technique but the rate of mutation to resistance was very low (< 10(-8)) at an 8 x MIC.

Anti-Infective Agents↗
PubMed1993

In vitro antimicrobial activity of tioconazole and its concentrations in vaginal fluids following topical (vagistat-1 6.5%) application.

In vitro assays demonstrated that clinical yeasts were significantly more inhibited by tioconazole (MIC50, < or = 0.5 microgram/ml) than by fluconazole (MIC50, 8 micrograms/ml). Tioconazole also exhibited high potency against most molds (Alterneria spp. and Acremonium spp.). All Candida tropicalis isolates had MICs of 8 micrograms/ml, four-fold greater than any other Candida spp. Generally Gram-negative bacteria were less susceptible to tioconazole. Moraxella catarrhalis (MIC90, 2 micrograms/ml) was the most susceptible Gram-negative species. Staphylococci and enterococci were the most susceptible to tioconazole Gram-positive species (MIC50s, 1-8 micrograms/ml). Bacterial species associated with vaginosis. [Gardnerella vaginalis (MIC90, 16 micrograms/ml), Mobiluncus spp. (MIC90, 16 micrograms/ml) and Prevotella biviadisiens (MIC90, 64 micrograms/ml)] were inhibited by tioconazole. Isolates of Lactobacillus spp. were most resistant (MIC90, > or = 256 micrograms/ml) to tioconazole. Vaginal fluid levels of tioconazole (mean, 91.4 micrograms/ml) persisted above the MIC90 levels (1-64 micrograms/ml) for most fungal and bacterial pathogens for 72 h in 19 evaluable female human subjects receiving 300 mg tioconazole in an intravaginal ointment.

Administration, Topical↗
PubMed1993

In vitro antimicrobial activity of CP-99433 compared with other fluoroquinolones.

CP-99433 is a new C-7 diazabicyclofluoroquinolone with a broad spectrum of activity that includes Enterobacteriaceae, Gram-positive cocci, and nonenteric Gram-negative bacilli. Potent activity was demonstrated against Pseudomonas aeruginosa [minimum inhibitory concentration (MIC90, 0.5 microgram/ml), Xanthomonas maltophilia (MIC90, 1 microgram/ml), and all Streptococcus species (MIC90s, 0.25-1 microgram/ml). Only CP-99433 was active against Enterococcus faecium (MIC50, 2 micrograms/ml). CP-99433 also demonstrated activity against several ciprofloxacin-resistant staphylococci. Additional studies of CP-99433 activity appear indicated.

Anti-Infective Agents↗
PubMed1993

Interlaboratory variations of fluoroquinolone susceptibility testing. An international study to validate the quality of microbiology results reported during the fleroxacin clinical trials.

Fleroxacin, a newer fluoroquinolone, has been investigated extensively in worldwide clinical trials by laboratories using a variety of in vitro susceptibility testing methods. These methods differ in their technical details, leading to applied interpretive criteria that can also differ from nation to nation and from method to method. This retrospective three-phase investigation was designed to assess the disk diffusion and minimum inhibitory concentration (MIC) result variations produced by European laboratories participating in fleroxacin clinical trials as compared with the results of a reference laboratory performing National Committee for Clinical Laboratory Standards (NCCLS) tests. In "phase I," 105 clinical trial strains (1988-1989) from six European investigators were processed by the reference laboratory. In comparison of participant and reference laboratory zone diameters, absolute qualitative agreement was 88.7% for the approved NCCLS interpretive criteria and 94.8% for the criteria used in the fleroxacin urinary tract infection clinical trials. Only three false-susceptible results (3.1%) were reported by the investigators. In the remaining phases of this study (unknown challenge strains and contemporary clinical isolates), the investigator laboratory zone diameters and MICs were within limits of acceptable test variation, that is, +/- 4 mm by disk diffusion and +/- 1 log2 dilution step by the MIC method. For laboratories using the German (DIN) and French (SFM) methods, however, a trend toward larger zones was observed. The greatest variation between participant and NCCLS results was produced when fastidious isolates such as Haemophilus influenzae (significantly smaller zone diameters) were tested. In general, the European fleroxacin clinical trial laboratory results (organism identification and susceptibility tests) could be considered comparable to data produced with NCCLS reference methods, indicating that clinical trial results from wider sources could be used for drug registry by the US Food and Drug Administration (FDA) or by other national agencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteria↗
PubMed1993

Interpretive criteria for cefodizime in vitro susceptibility tests with Neisseria gonorrhoeae.

Cefodizime was tested against 100 strains of Neisseria gonorrhoeae with varying susceptibility patterns to penicillin. Agar-dilution minimum inhibitory concentrations (MIC) and disk diffusion susceptibility testing were performed in triplicate for each strain according to National Committee for Clinical Laboratory Standards (NCCLS) guidelines to establish susceptibility interpretive criteria for this beta-lactamase-stable cephalosporin. Cefodizime was very active against these strains of N. gonorrhoeae, with a MIC50 of only 0.008 microgram/ml. Because no resistant strains were documented, a single susceptible criterion of < or = 0.05 microgram/ml (> or = 31 mm) was proposed to predict clinical success after a single intramuscular (i.m.) dose.

Cefotaxime↗
PubMed1993

Interpretive accuracy of the disk diffusion method for testing newer orally administered cephalosporins against Morganella morganii.

Eight newer orally administered cephems (cefdinir, cefetamet, cefixime, cefpodoxime, cefprozil, ceftibuten, cefuroxime, and loracarbef) were tested against 100 clinical strains of Morganella morganii to determine the extent of serious interpretive very major (false-susceptible) errors when current criteria for the disk diffusion test are applied. Agar dilution MICs and disk diffusion tests were performed as recommended by the National Committee for Clinical Laboratory Standards (Villanova, Pa.) (NCCLS), and the methods were compared by regression analysis using the method of least squares and by error rate bounding. The following results are listed in the order of increasing error rates: cefdinir, loracarbef, and cefprozil, < or = 1% very major error; ceftibuten, 8% minor errors; cefuroxime, 21% minor errors; cefixime, cefpodoxime, and cefetamet, very major errors of 15, 24, and 36%, respectively. M. morganii produces unacceptable rates of test error with cefuroxime, cefixime, cefpodoxime, and cefetamet. The latter two cephalosporins currently have NCCLS table footnote warnings covering the problem observed with this organism. The inclusion of cefuroxime and cefixime in the NCCLS table footnote is strongly recommended.

Administration, Oral↗
PubMed1993

E test as susceptibility test and epidemiologic tool for evaluation of Neisseria meningitidis isolates.

The E test (AB Biodisk, Solna, Sweden), a new approach developed to test antimicrobial susceptibility, was compared with the agar dilution method for seven-drug antibiogram analysis of Neisseria meningitidis isolates. The overall E-test quantitative accuracy (+/- 1 log2 dilution) was 93% compared with that of agar dilution testing. The E test was then used to perform the susceptibility tests on a 10-year sample of 102 N. meningitidis isolates, including 5 from a recent epidemic outbreak in the University of Iowa (Iowa City) community. The E test proved to be an efficient methodology for identifying common source clusters of meningococcal disease having resistance to rifampin or sulfonamides. Moreover, the data demonstrated a recent increase in penicillin MICs (MIC for 90% of strains, 0.094 microgram/ml) and an escalation of high-level resistance to trimethoprimsulfamethoxazole (33%) and rifampin (14%). The E test should be considered a simple and accurate susceptibility method for the emerging need to test meningococci and other pathogenic neisserias. Chocolate Mueller-Hinton agar was observed to provide the best support of growth and E-test MIC results that correlated well with results of the reference agar dilution method previously used for neisserias.

Agar↗
PubMed1993

Ceftizoxime interpretive criteria for in vitro susceptibility tests with Neisseria gonorrhoeae.

Ceftizoxime was tested in triplicate against 100 clinical strains of Neisseria gonorrhoeae in accordance with National Committee for Clinical Laboratory Standards guidelines to establish susceptibility testing interpretive criteria. The MICs for 50 and 90% of the strains tested were 0.008 and 0.03 microgram/ml, respectively. These results confirm those of other studies reporting ceftizoxime's excellent activity against gonococci. Because no resistant strains were identified, a breakpoint MIC of < or = 0.5 microgram/ml was selected, with a correlate zone diameter of > or = 32 mm. Ceftizoxime appears to represent an alternative to other beta-lactamase-stable beta-lactams for cost-effective therapy of uncomplicated gonorrhea.

Ceftizoxime↗
PubMed1992

In vitro activity of OPC-17116 compared to other broad-spectrum fluoroquinolones.

The in vitro activity of OPC-17116 was compared to that of five similar fluoroquinolones (ciprofloxacin, enoxacin, norfloxacin, ofloxacin and temafloxacin). A total of 700 isolates from recent cases of clinical bacteremia were tested. Fifty additional stock strains with well-characterized resistance mechanisms were also processed. The minimal concentrations inhibiting 90% of strains (MIC90) of Enterobacteriaceae species were for OPC-17116 0.015-0.5 micrograms/ml and for ciprofloxacin 0.015-0.25 micrograms/ml. Moraxella catarrhalis, Haemophilus influenzae and Neisseria gonorrhoeae were very susceptible to OPC-17116 (MIC90 0.015 micrograms/ml) thus being fourfold more active than ciprofloxacin. For all beta-hemolytic streptococci and pneumococci OPC-17116 MICs were less than or equal to 0.5 micrograms/ml. The most resistant enteric bacilli were among the Citrobacter freundii and Providencia rettgeri strains (MIC90 0.5 micrograms/ml). Pseudomonas aeruginosa strains were comparably susceptible to OPC-17116 (MIC90 0.5 micrograms/ml). Low pH and CO2 incubation had an adverse effect on OPC-17116 MICs, and resistance development was documented among current clinical isolates of staphylococci, pseudomonas and some Enterobacteriaceae.

Anti-Infective Agents↗