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E H Gerlach

Publications and source records attributed to E H Gerlach.

At least 19 recordsLinked to original sources
PubMed1995

Comparative antimicrobial activity of piperacillin-tazobactam tested against more than 5000 recent clinical isolates from five medical centers. A reevaluation after five years.

Piperacillin combined with tazobactam at a fixed concentration (4 micrograms/ml) and a ratio (8:1) was tested against 5,029 aerobic isolates and 447 fastidious organisms, including anaerobes. Among the Enterobacteriaceae, > 95% inhibition was shared only by imipenem (99.1% at < or = 4 micrograms/ml), and some newer cephalosporins (95.1% - 99.8% at < or = 8 micrograms/ml), and piperacillin-tazobactam (95.8% at < or = 16/4 micrograms/ml). Piperacillin-tazobactam was the most active agent tested against nonenteric Gram-negative bacilli (93.5% at < or = 8 micrograms/ml). Ampicillin-sulbactam was the most active agent against staphylococci (95.0% at < or = 8 micrograms/ml), followed by imipenem (91.8%), piperacillin-tazobactam (89.3% at < or = 8/4 micrograms/ml), and cefepime (86.2% at < or = 8 micrograms/ml). Against the enterococci, only ampicillin (93.0% at < or = 8 micrograms/ml) with or without sulbactam, piperacillin (91.0% at < or = 16 micrograms/ml) with or without tazobactam, and imipenem (91.0%) had acceptable activity. Piperacillin-tazobactam and imipenem were the most active drugs tested against all aerobic isolates, inhibiting 93.5% of isolates each. Piperacillin-tazobactam inhibited all fastidious isolates tested, including Haemophilus influenzae (MIC90, 0.094/4 micrograms/ml), Moraxella catarrhalis (MIC90, 0.064/4 micrograms/ml), Neisseira gonorrhoeae (MIC90, < or = 0.016/4 micrograms/ml), and Streptococcus pneumoniae (all MICs, < or = 4/4 micrograms/ml). Against the anaerobic isolates, the most broad-spectrum antimicrobial agents tested were imipenem (100.0%), piperacillin-tazobactam (99.5% at < or = 32/4 micrograms/ml), metronidazole (98.4% at < or = 8 micrograms/ml), and ticarcillin-clavulanic acid (95.1% at < or = 32/2 micrograms/ml). These results are nearly identical to a previous study involving the same five medical centers in 1989. Piperacillin-tazobactam appears to remain a highly effective beta-lactamase inhibitor combination with a wide empiric spectrum and potency in teaching hospitals.

Bacteria↗
PubMed1995

Multicenter clinical laboratory evaluation of a beta-lactamase disk assay employing a novel chromogenic cephalosporin, S1.

S1, a new chromogenic cephalosporin (International BioClinical, Inc., Portland, Oreg.), was used to detect beta-lactamase production among a variety of commonly encountered bacteria in a four-center collaborative study. Results of an S1 disk assay were compared with those obtained by a nitrocefin-based disk procedure (Cefinase; Becton-Dickinson Microbiology Systems, Cockeysville, Md.), with repetitive testing of five quality control organisms and with individual tests of recent clinical isolates of Neisseria gonorrhoeae (162 strains), Haemophilus influenzae (162 strains), Moraxella catarrhalis (155 strains), Staphylococcus aureus (161 strains), and Bacteroides fragilis (164 strains). The performances of the two beta-lactamase disk assays were comparable for the first three species cited above. However, the S1 assay appeared to be a more sensitive procedure than the Cefinase assay when applied to S. aureus and B. fragilis, with respect to both total numbers of positive results and length of time to a definitive positive endpoint.

Bacteria↗
PubMed1994

Revised disk diffusion interpretive criteria for cefaclor, loracarbef, cefprozil and cefixime when testing Haemophilus influenzae on haemophilus test medium.

The aim of the current five-center collaborative study was to reassess the interpretive criteria for cefaclor, loracarbef, cefprozil and cefixime previously adopted or proposed by the National Committee for Clinical Laboratory Standards (NCCLS) for disk diffusion susceptibility tests with Haemophilus influenzae on Haemophilus Test Medium (HTM) agar. MICs and zones of inhibition were determined using NCCLS methods, HTM and two collections of strains of Haemophilus influenzae. One group of strains consisted of 118 stock organisms taken largely from various recent U.S. antibiotic resistance surveillance studies. The emphasis in this selected group of organisms was on strains that were beta-lactamase negative but ampicillin resistant (BLNAR) by some other mechanism. The second collection of test organisms consisted of 50 recent clinical isolates of Haemophilus influenzae obtained from each of the five participating study centers. This group was considered representative of the type of Haemophilus influenzae currently recovered from clinical sources in the USA. Frequency distribution assessment and error-rate bounded analysis of scattergram comparisons of MICs and zone sizes were used to develop the following zone diameters interpretive for disk diffusion susceptibility tests with Haemophilus influenzae on HTM agar: cefaclor, > or = 20 mm (susceptible, S) and < or = 16 mm (resistant, R); loracarbef, > or = 19 mm (S) and < or = 15 mm (R); and cefprozil, > 18 mm (S) and < 14 mm (R). The respective MIC correlates for all three antimicrobial agents were < or = 8 micrograms/ml (S) and 32 micrograms/ml (R).(ABSTRACT TRUNCATED AT 250 WORDS)

Cefaclor↗
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

In-vitro activity of five beta-lactam/beta-lactamase inhibitor combinations against consecutive isolates of the Enterobacteriaceae and Pseudomonas aeruginosa.

Susceptibility tests were performed on 2402 of consecutive isolates of Enterobacteriaceae and 254 strains of Pseudomonas aeruginosa in five separate medical centres. Five beta-lactams were evaluated with and without a beta-lactamase inhibitor. The effect of different inhibitors was species specific and the rank order of decreasing efficacy against all enteric bacilli was: cefoperazone-sulbactam > piperacillin-tazobactam > cefoperazone > ticarcillin-clavulanic acid > piperacillin > co-amoxiclav > ampicillin-sulbactam > ticarcillin > ampicillin > amoxycillin.

Anti-Bacterial Agents↗
PubMed1993

Interpretive criteria and quality control parameters for determining bacterial susceptibility to fosfomycin tromethamine.

Studies with fosfomycin tromethamine disks containing 200 micrograms of fosfomycin and 50 micrograms of glucose-6-phosphate confirmed the following zone diameter criteria for the NCCLS method: < or = 12 mm for resistant (MIC > or = 256 micrograms/ml), 13-15 mm for intermediate (MIC 128 micrograms/ml) and > or = 16 mm for susceptible (MIC < or = 64 micrograms/ml). Additional studies defined acceptable MIC and zone diameter ranges for the following quality control strains: Escherichia coli ATCC 25922, MIC 0.5 to 4.0 micrograms/ml, zone diameter 23 to 29 mm; Staphylococcus aureus ATCC 25923, zone diameter 26 to 32 mm; Pseudomonas aeruginosa ATCC 27813, MIC 2.0 to 8.0 micrograms/ml; and Enterococcus faecalis, ATCC 29212, MIC 16 to 64 micrograms/ml.

Bacteria↗
PubMed1993

Comparison of fixed concentration and fixed ratio options for dilution susceptibility testing of gram-negative bacilli to ampicillin and ampicillin/sulbactam.

Ampicillin combined with sulbactam was tested at both fixed ratio (2:1 and 1:1) and fixed sulbactam concentrations (4 micrograms/ml, 8 micrograms/ml and 16 micrograms/ml) against 2440 consecutively isolated gram-negative bacilli. Sulbactam significantly enhanced the spectrum of ampicillin activity. Overall, at 8 micrograms/ml ampicillin inhibited 50% of the Enterobacteriaceae isolates, whereas 69% to 84% of the isolates were inhibited by the various sulbactam combinations. The widest spectrum of activity for ampicillin/sulbactam was achieved by testing at a fixed sulbactam concentration of 16 micrograms/ml, followed by the 1:1 ratio and the fixed 8 micrograms/ml (84%, 76% and 74% inhibited, respectively). The amount of sulbactam at the susceptible breakpoint concentrations of ampicillin markedly affected the percentage of susceptible strains. Combinations that include 8 micrograms/ml of sulbactam are suggested for consideration.

Ampicillin↗
PubMed1993

Antimicrobial activity and spectrum of rifaximin, a new topical rifamycin derivative.

Rifaximin, a rifamycin derivative, was evaluated in vitro to assess its spectrum and potency against a wide variety of bacteria, yeasts, viruses, and parasites. High concentrations of rifaximin were often used to reflect topically achieved levels since this compound is poorly absorbed by oral route. Like rifampin, rifaximin possessed best activity against Staphylococcus spp. (MIC50 < or = 0.015 microgram/ml), Streptococcus spp. (MIC50s, < or = 0.03-0.12 microgram/ml), Enterococcus spp. (MIC50s, 0.25-2 micrograms/ml), Bacillus cereus (MIC50, 0.06 microgram/ml), Moraxella catarrhalis (MIC50, < or = 0.03 microgram/ml), and Haemophilus influenzae (MIC50, 0.25 microgram/ml). Rifaximin demonstrated potential use as a topical agent for bacterial vaginosis by inhibiting Bacteroides bivius-disiens, Gardnerella vaginalis, Lactobacillus spp., and Mobiluncus spp. strains (all MICs < or = 1 microgram/ml). Strains of Haemophilus ducreyi and Neisseria gonorrhoeae (MIC50s, 0.25 microgram/ml) were also inhibited. However, some organisms associated with genital tract infections were rifaximin resistant, for example, Candida spp., herpes virus, mycoplasmas, Trichomonas vaginalis, and Ureaplasma urealyticum. Clinical trials appear warranted using rifaximin topical concentrations that will minimize mutations to rifamycin resistance.

Administration, Topical↗
PubMed1993

In vitro comparison activity of OPC-17116, a new fluoroquinolone, against more than 5,000 recent clinical isolates from five medical centers.

The in vitro activity of OPC-17116, a new fluoroquinolone, was compared with those of ciprofloxacin, ofloxacin and cefixime. A total of 5,231 fresh clinical isolates from five geographically separate US medical centers were tested. The primary results of this study are: 1. OPC-17116 is very active against Enterobacteriaceae [MIC90s, 0.015-1 microgram/ml, except Providencia rettgeri (MIC90, > 8 micrograms/ml)], 2. among nonenteric Gram-negative bacilli (e.g. Xanthomonas maltophilia, MIC90, 2 micrograms/ml) and Gram-positive cocci (e.g. oxacillin-susceptible staphylococci, MIC90s, 0.12-0.5 microgram/ml) OPC-17116 demonstrated higher activity than ciprofloxacin or ofloxacin, 3. the quinolones were more active than cefixime against most of the species tested, especially against Gram-positive and non-enteric Gram-negative organisms. The results of this study, associated with prior documented favorable qualities, support continued investigation of OPC-17116 for clinical use.

Anti-Infective Agents↗
PubMed1993

Multicenter comparison of in vitro activities of FK-037, cefepime, ceftriaxone, ceftazidime, and cefuroxime.

In a multicenter study, the MICs of FK-037 for 90% of the strains tested (MIC90s) were < or = 1 microgram/ml for members of the family Enterobacteriaceae other than Citrobacter freundii, Enterobacter spp., and Serratia marcescens. Activity against Pseudomonas aeruginosa was variable, with a MIC50 and a MIC90 of 4 and 32 micrograms/ml, respectively. Relative to cefepime, however, FK-037 was less active against ceftazidime-resistant isolates of Enterobacter cloacae. The MIC90 of FK-037 for methicillin-resistant staphylococci was > 16 micrograms/ml.

Anti-Bacterial Agents↗
PubMed1992

Error rates in cefoperazone and cefoperazone-sulbactam disk tests with Enterobacteriaceae and Pseudomonas aeruginosa.

In a collaborative study involving five medical centers, 6% of 2,440 consecutive isolates of Enterobacteriaceae were resistant to cefoperazone; resistance to cefoperazone was reduced to < 1% by the addition of sulbactam. Susceptibility to cefoperazone and cefoperazone-sulbactam was accurately predicted by disk diffusion tests. Resistance to cefoperazone, however, was not as reliably detected by disk tests and results of dilution tests were not always consistent. The prevalence of resistance to cefoperazone and/or the ability to detect resistance had a significant influence on very major error rates for individual laboratories.

Agar↗
PubMed1992

Comparison of fixed concentration and fixed ratio options for testing susceptibility of gram-negative bacilli to piperacillin and piperacillin/tazobactam.

Piperacillin combined with tazobactam was tested at both a fixed ratio (8:1) and fixed tazobactam concentration (4 micrograms/ml) against 2,685 consecutively isolated gram-negative bacilli and 56 highly piperacillin-resistant isolates. Tazobactam significantly enhanced the spectrum of piperacillin activity. Overall, at a concentration of 16 micrograms/ml piperacillin alone inhibited 78.8% of the Enterobacteriaceae isolates compared to inhibition of 92.7% and 95.5% by the 8:1 ratio and fixed (4 micrograms/ml) tazobactam combinations, respectively. In MIC tests the two combination options performed comparably against both routine and highly piperacillin-resistant isolates. Synergistic inhibition was observed for comparable numbers of isolates with the two combination options, the most marked effect being seen in the more highly piperacillin-resistant isolates. Both testing options are supported by the available human pharmacokinetic data; however the 8:1 ratio of piperacillin to tazobactam may be preferable given that the clinical formulation contains the two compounds in an 8:1 ratio and this ratio is maintained in vivo.

Drug Synergism↗
PubMed1992

Interpretive criteria and quality control guidelines for lomefloxacin and meropenem in susceptibility tests of Haemophilus influenzae using Haemophilus test medium.

Lomefloxacin and meropenem were tested in a multilaboratory study to establish susceptibility testing interpretive criteria and quality control (QC) guidelines for Haemophilus influenzae using Haemophilus test medium (HTM). Interpretive criteria were established by using triplicate testing of 102 representative H. influenzae strains. Only a susceptible category was proposed for lomefloxacin (greater than or equal to 22 mm and less than or equal to 2 micrograms/ml) and meropenem (greater than or equal to 13 mm and less than or equal to 4 micrograms/ml) due to the lack of resistant isolates. QC range for H. Influenzae ATCC 49247 were established using multiple HTM agar and broth base lots, three disk lots for each drug, and a number of test replicates consistent with the National Committee for Clinical Laboratory Standards M23-T guideline.

Anti-Infective Agents↗
PubMed1992

Cefdinir (FK482), an orally administered cephalosporin in vitro activity comparison against recent clinical isolates from five medical centers and determination of MIC quality control guidelines.

Cefdinir, a new oral cephalosporin, was compared to cefaclor, cefadroxil, cefixime, and cefuroxime against greater than 5000 recent aerobic clinical isolates. This multicenter study revealed broad-spectrum cefdinir activity against all Enterobacteriaceae (MIC50s, 0.06-2 micrograms/ml) except Enterobacter cloacae, Morganella morganii, Proteus vulgaris, and Serratia marcescens (MIC50s, greater than or equal to 4 micrograms/ml). Oxacillin-susceptible staphylococci (MIC90s, 0.5-2 micrograms/ml), beta-hemolytic Streptococcus group B (MIC90, 0.06 micrograms/ml), and Acinetobacter lwoffii were also susceptible to cefdinir. The activity of cefdinir was similar to that of cefixime and cefuroxime against Gram-negative organisms and superior to all tested oral cephems when tested against Gram-positive cocci. None of the cephalosporins were active against oxacillin-resistant Staphylococcus spp., enterococci, Pseudomonas spp., or Xanthomonas maltophilia. MIC quality control range guidelines were established for the strains recommended by the National Committee for Clinical Laboratory Standards documents.

Anti-Bacterial Agents↗
PubMed1992

Ticarcillin and ticarcillin-clavulanic acid susceptibility tests: error rates for disk tests with consecutively isolated members of the family Enterobacteriaceae.

A five-laboratory coordinated study was undertaken to determine whether ticarcillin and ticarcillin-clavulanic acid disk susceptibility tests could accurately detect resistance among enteric bacilli. Each facility performed disk tests and broth microdilution susceptibility tests with reagents distributed from a common source, and appropriate controls were included in order to ensure methodologic uniformity. Each institution tested 500 consecutively isolated enteric bacilli against ticarcillin and ticarcillin-clavulanic acid. The prevalence of discrepancies between disk tests and dilution tests with 2,435 unselected enteric bacilli provided a valid estimate of the true error rate for tests with the two disks. The current interpretive criteria for susceptibility tests with ticarcillin and ticarcillin-clavulanic acid disks were found to be reliable; i.e., there were major or very major discrepancies between MIC categories and disk test results for less than 1% of all strains and minor discrepancies for only 5 to 10%. Even lower error rates would occur if the zone size-interpretive criteria were modified, but at this time it is difficult to determine whether the practical problems created by making such changes can be justified by the magnitude of the problem that is being resolved.

Clavulanic Acids↗
PubMed1992

MIC quality control guidelines for Haemophilus susceptibility tests using cefdinir (FK482), cefepime, cefetamet, cefpirome, ceftibuten, fleroxacin, temafloxacin, clarithromycin, RP59500, and trospectomycin.

A multilaboratory study was performed to establish broth microdilution MIC quality control (QC) guidelines for 10 investigational drugs which previously demonstrated significant activity against Haemophilus influenzae. MIC QC ranges for H. influenzae ATCC 49247 with Haemophilus test medium were determined by using multiple contemporary lots of Haemophilus test medium and the National Committee for Clinical Laboratory Standards' recommended numbers of replicate tests. On the basis of these results, QC ranges (generally modal MIC +/- one log2 dilution) are proposed for cefdinir, cefepime, cefetamet, cefpirome, ceftibuten, fleroxacin, temafloxacin, clarithromycin, RP59500, and trospectomycin. The proposed QC guidelines for clarithromycin and temafloxacin were recently accepted by the National Committee for Clinical Laboratory Standards.

Anti-Bacterial Agents↗
PubMed1992

Disk diffusion quality control guidelines for Haemophilus susceptibility tests using cefdinir, CI-960, fleroxacin, temafloxacin, and trospectomycin.

A multilaboratory study to determine disk diffusion quality control ranges for Haemophilus influenzae ATCC 49247 and five investigational drugs was performed. Multiple lots of Haemophilus Test Medium and antibiotic disks were used for replicate testing in conformance with the recommendations of the National Committee for Clinical Laboratory Standards. Quality control disk zone diameter ranges were proposed for cefdinir, CI-960, fleroxacin, temafloxacin, and trospectomycin.

Anti-Bacterial Agents↗