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P C Fuchs

Publications and source records attributed to P C Fuchs.

At least 145 records · Page 8Linked to original sources
PubMed1991

Proposed interpretive criteria and quality control parameters for testing in vitro susceptibility of Neisseria gonorrhoeae to ciprofloxacin.

Ciprofloxacin was subjected to a multilaboratory study designed to determine its in vitro susceptibility criteria for Neisseria gonorrhoeae and its quality control parameters for both agar dilution and disk diffusion susceptibility testing for this species. All clinical isolates were susceptible, i.e., MICs were less than or equal to 0.06 microgram/ml and zones of inhibition were greater than or equal to 36 mm. A resistant category could not be defined, but in vitro-selected mutants gave zones of less than or equal to 35 mm, and MICs for these strains were greater than or equal to 0.12 microgram/ml. For quality control of ciprofloxacin agar dilution tests on supplemented GC agar, MICs for Staphylococcus aureus ATCC 29213 ranged from 0.12 to 0.5 microgram/ml. For quality control of 5-micrograms ciprofloxacin disk tests, N. gonorrhoeae ATCC 49226 and S. aureus ATCC 25923 produced acceptable zone diameter ranges of 48 to 58 mm and 22 to 26 mm, respectively.

Ciprofloxacin↗
PubMed1990

In vitro antibacterial spectrum of E1040 compared with those of cefpirome and ceftazidime and disk diffusion interpretive criteria for E1040.

E1040 is a new parenteral cephalosporin which was tested against 690 clinical isolates and compared with cefpirome and ceftazidime. E1040 had the best activity of the three drugs against Pseudomonas aeruginosa, inhibiting 89% of strains at 8.0 micrograms/ml. E1040 demonstrated good activity against members of the family Enterobacteriaceae, including cefpirome-resistant and ceftazidime-resistant strains. E1040 also had good activity against streptococci but much poorer activity against enterococci and staphylococci. When E1040 broth microdilution and disk diffusion susceptibility test results were compared, the 30-micrograms disk was recommended, with the following tentative interpretive criteria: susceptible, greater than or equal to 18 mm (MIC, less than or equal to 8.0 micrograms/ml); intermediate, 15 to 17 mm (MIC, 16 micrograms/ml); and resistant, less than or equal to 14 mm (MIC, greater than or equal to 32 micrograms/ml).

Bacteria↗
PubMed1990

Interpretive criteria for disk diffusion susceptibility testing of mupirocin, a topical antibiotic.

Five hundred gram-positive clinical bacterial isolates were tested for susceptibility to mupirocin by broth microdilution and disk diffusion methods (5- and 10-micrograms disks). All but 1 of 330 staphylococci (including 100 oxacillin-resistant Staphylococcus aureus) were susceptible to less than or equal to 1.0 micrograms of mupirocin per ml. With a susceptible MIC breakpoint of less than or equal to 2.0 micrograms/ml, the corresponding zone diameter breakpoints were greater than or equal to 14 mm for 5-micrograms disks and greater than or equal to 16 mm for 10-micrograms disks. With either disk potency, susceptible staphylococci were effectively separated from more resistant gram-positive species such as the enterococci and gram-positive bacilli.

Anti-Bacterial Agents↗
PubMed1990

Implications of beta-lactamase-inhibitor combinations.

Resistance of many species of bacteria to beta-lactam antibiotics is mediated via inactivation by beta-lactamase. Beta-lactamase inhibitors irreversibly bind to beta-lactamases and thus can prevent the destruction of active beta-lactam antibiotics. In the United States three beta-lactam-antibiotic/beta-lactam-inhibitor combinations are commercially available--the orally absorbed amoxicillin/clavulanic acid (A/C), the parenteral formulations of ampicillin/sulbactam (A/S) and ticarcillin/clavulanate (T/C). In a multicenter study that focused on T/C, the in vitro activity of amoxicillin (AMOX), ampicillin (AMP) and ticarcillin (TIC) against Neisseria gonorrhoeae and Haemophilus influenzae was obliterated when beta-lactamase-positive strains were tested, but all tested strains were susceptible to the antibiotics in combination with their respective beta-lactamase inhibitors. Clavulanic acid improved the activity of TIC against most species of Enterobacteriaceae but not against those Enterobacteriaceae that elaborate type I beta-lactamase or against non-Enterobacteriaceae gram-negative bacilli (except for Pseudomonas maltophilia). Staphylococci are generally beta-lactamase positive and considered resistant to AMP and TIC, but greater than 99% of 1,137 Staphylococcus aureus isolates and 92% of coagulase-negative staphylococcal isolates were susceptible to T/C, with comparable figures obtained for A/C and A/S. The activity of TIC against Bacteroides fragilis was improved up to 64-fold by clavulanic acid, with a definite but less pronounced effect on the non-fragilis Bacteroides species. Ninety-seven percent of strains of other anaerobic genera were susceptible to both TIC and T/C.(ABSTRACT TRUNCATED AT 250 WORDS)

Amoxicillin↗
PubMed1989

In vitro antimicrobial activity and susceptibility testing of ofloxacin. Current status.

The fluoroquinolone, ofloxacin, exhibits a broad antibacterial spectrum. Based on our data and a review of the literature, ofloxacin inhibited essentially 100 percent of staphylococci, including oxacillin-resistant strains, Haemophilus influenzae, Neisseria spp. and Branhamella catarrhalis. Ninety-five percent of Enterobacteriaceae were susceptible to ofloxacin. Pseudomonas aeruginosa and enterococci were less susceptible: 79 and 63 percent, respectively, were susceptible (minimal inhibitory concentration [MIC], less than or equal to 2.0 micrograms/ml); 15 and 25 percent, respectively, were intermediate (MIC, 4 micrograms/ml); 3 and 6 percent, respectively, were resistant (MIC, more than or equal to 4 micrograms/ml). Clostridium spp., including Clostridium difficile, were resistant to ofloxacin, but other anaerobic species, including the Bacteroides fragilis group (over 90 percent) were either susceptible or intermediate to ofloxacin. Ofloxacin is bactericidal; minimal bactericidal concentrations of ofloxacin rarely exceed the MICs by one doubling concentration. A modest inoculum effect has been observed with ofloxacin: MICs with inocula of 10(7) colony-forming units/ml are often two- to fourfold higher than those with inocula of 5 x 10(5) colony-forming units/ml. Susceptible organisms exposed serially to increasing concentrations of nalidixic acid developed increasing resistance to not only nalidixic acid, but also to all other quinolones, including ofloxacin. Correlations of disk diffusion inhibitory zone diameters using the 5-micrograms ofloxacin disk with ofloxacin MICs have been performed, and the disk diffusion zone diameter breakpoints recommended are: susceptible, greater than or equal to 16 mm; intermediate, 13 to 15 mm; resistant, less than or equal to 12 mm. Quality control parameters also are summarized.

Bacteria↗
PubMed1989

Multicenter in vitro evaluation of SM-7338, a new carbapenem.

A new carbapenem, SM-7338, was compared with imipenem, cefotaxime, and ceftazidime at five medical centers. Nearly 6,000 strains were tested by reference methods of the National Committee for Clinical Laboratory Standards, and SM-7338 inhibited the largest percentage of gram-negative bacilli. Its spectrum included all members of the family Enterobacteriaceae (99.7% were susceptible to less than or equal to 4 micrograms/ml), Pseudomonas spp. (but not Xanthomonas maltophilia), and Acinetobacter spp. The potency and spectrum of SM-7338 against the gram-positive organisms were less than those of imipenem and superior to those of ceftazidime. Only the enterococci and some oxacillin-resistant staphylococci were less susceptible to SM-7338 (MICs for 90% of isolates, greater than or equal to 8 micrograms/ml). Organisms resistant to ceftazidime were generally susceptible to SM-7338 and imipenem (76%). However, for one-third of the imipenem-resistant gram-negative bacilli (MICs, greater than 8 micrograms/ml), SM-7338 MICs were less than or equal to 4 micrograms/ml. Some endemic differences in patterns of SM-7338 activity against selected gram-negative species were found among some medical centers.

Anti-Bacterial Agents↗
PubMed1989

Quality control guidelines for testing cefotetan in the reference agar dilution procedure for susceptibility testing of anaerobic bacteria.

Reference values for quality control of in vitro susceptibility tests with cefotetan against anaerobic bacteria were determined in two independent multilaboratory studies with the approved National Committee for Clinical Laboratory Standards agar dilution method and three control strains (Bacteroides fragilis ATCC 25285, Bacteroides thetaiotaomicron ATCC 29741, and Clostridium perfringens ATCC 13124). The results of the two studies were in agreement. The recommended MIC control limits for B. fragilis ATCC 25285 and B. thetaiotaomicron ATCC 29741 are 4.0 to 16 micrograms/ml and 32 to 128 micrograms/ml, respectively. MICs for C. perfringens ATCC 13124 were too variable to be useful for controlling tests with cefotetan.

Bacteria, Anaerobic↗
PubMed1989

Quality control limits for the standard anaerobic reference agar dilution susceptibility test procedure of the National Committee for Clinical Laboratory Standards.

Multilaboratory studies were performed to develop MIC quality control limits for the National Committee for Clinical Laboratory Standards reference agar dilution method for anaerobic susceptibility tests. Acceptable MICs were defined as those which include greater than 95% of all 100 MICs generated by the study. Most MIC control limits included either 2- or 3-dilution intervals rather than the more traditional 3-dilution intervals that are described as the mode +/- 1 doubling dilution.

Amoxicillin↗
PubMed1989

Ofloxacin susceptibility testing quality control parameters for microdilution and disk diffusion, and confirmation of disk diffusion interpretive criteria.

The susceptibilities of 221 clinical isolates to ofloxacin were tested simultaneously by broth microdilution and disk diffusion methods with commercially prepared 5-micrograms ofloxacin disks. The acceptability of the following previously proposed zone diameter breakpoints was confirmed: greater than or equal to 16 mm, susceptible; 13 to 15 mm, intermediate; less than or equal to 12 mm, resistant. On the basis of a multilaboratory collaborative study, the following are proposed as acceptable ofloxacin MIC ranges for quality control organisms: Escherichia coli ATCC 25922, 0.03 to 0.06 micrograms/ml; Staphylococcus aureus ATCC 29213, 0.12 to 0.5 micrograms/ml; Pseudomonas aeruginosa ATCC 27853 and Enterococcus faecalis ATCC 29212, 1.0 to 4.0 micrograms/ml. Ofloxacin quality control zone diameter ranges for the disk diffusion test are tentatively proposed, but variations in the performance of different lots of Mueller-Hinton agar may prove to be a serious problem for users.

Bacteria↗
PubMed1989

Reassessment of susceptibility test interpretive criteria for ticarcillin and ticarcillin-clavulanic acid.

There are at least four different existing or proposed interpretive criteria for the disk diffusion susceptibility testing of ticarcillin and ticarcillin plus clavulanic acid (T/C). To assess these criteria, 570 gram-negative bacillary isolates were tested for susceptibility to ticarcillin and T/C by both disk diffusion and broth microdilution methods. These included 53 strains of the family Enterobacteriaceae selected for ticarcillin resistance and high-level beta-lactamase production. The broth microdilution test results were more influenced by increased beta-lactamase production than were disk diffusion results. In the absence of published data indicating which of the two standardized test methods better predicts clinical response, we conclude that until such data are available the more conservative National Committee for Clinical Laboratory Standards tentative criteria for tests with members of the Enterobacteriaceae are appropriate. Our data do not support the use of separate T/C interpretive criteria for Pseudomonas spp. and members of the Enterobacteriaceae. The appropriateness of different interpretive criteria needs further evaluation.

Anti-Bacterial Agents↗
PubMed1989

Standardization of disk diffusion and agar dilution susceptibility tests for Neisseria gonorrhoeae: interpretive criteria and quality control guidelines for ceftriaxone, penicillin, spectinomycin, and tetracycline.

A six-laboratory study developed a standardized method for determining the susceptibilities of Neisseria gonorrhoeae strains to penicillin, tetracycline, spectinomycin, and ceftriaxone. Three quality control organisms were also selected, and quality assurance guidelines were initially generated for the disk diffusion and agar dilution methods. The medium recommended for gonococcal susceptibility testing was GC agar with a defined "XV-like" supplement. The supplement should be free of cysteine, a component implicated in the inactivation of some newer beta-lactam compounds. Penicillin, tetracycline, spectinomycin, and ceftriaxone were stable in agar plates stored at 3 to 5 degrees C for at least 2 weeks. Numerous GC agar and drug disk lots were used during the trials without significant variation in test results. Several other gonococcal strains were recommended for additional medium quality assurance. The disk quality control zone limits were established for N. gonorrhoeae ATCC 49226 (formerly CDC F-18) and Staphylococcus aureus ATCC 25923. MIC quality control ranges were also developed for N. gonorrhoeae ATCC 49226 and S. aureus ATCC 29213. The interpretive criteria for penicillin were as follows: susceptibility, greater than or equal to 47 mm (diameter of inhibition zone) (less than or equal to 0.06 micrograms/ml [MIC]); resistance, less than or equal to 26 mm (greater than or equal to 2 micrograms/ml). For tetracycline they were as follows: susceptibility, greater than or equal to 38 mm (less than or equal to 0.25 microgram/ml); resistance, less than or equal to 30 mm (greater than or equal to 2 micrograms/ml). For spectinomycin they were as follows: susceptibility, >/= 18 mm (</= 32 micrograms/ml); resistance, </= 14 mm (>/= 128 micrograms/ml). For ceftriaxone susceptibility, the criterion was >/= 35 mm (</= 0.25 micrograms/ml) with no other category. Criteria of </= 19 mm for plasmid-mediated resistances to penicillin and tetracycline were also confirmed. The false-susceptibility errors were </= 1% with these criteria.

Ceftriaxone↗
PubMed1988

In vitro activity of FCE 22101, imipenem, and ceftazidime against over 6,000 bacterial isolates and MIC quality control limits of FCE 22101.

Six geographically separate laboratories within the USA tested 6,198 bacterial isolates against FCE 22101 (a penem), imipenem (a carbapenem) and ceftazidime (a third-generation cephalosporin). Ninety-three percent of 2,749 Enterobacteriaceae were inhibited by FCE 22101, while 95% were susceptible to ceftazidime and 99% were susceptible to imipenem. FCE 22101 had little activity against Pseudomonas spp. but was active against most gram-positive pathogens, including enterococci. FCE 22101 MICs for standard quality control strains were defined as 0.5-2.0 micrograms/ml for Escherichia coli ATCC 25922, 2-8 micrograms/ml for Enterococcus faecalis ATCC 29212 and 0.06-0.25 microgram/ml for Staphylococcus aureus ATCC 29213.

Anti-Bacterial Agents↗
PubMed1988

Effect of clavulanic acid on the susceptibility of clinical anaerobic bacteria to ticarcillin: a multicenter study.

Over 2,000 recent clinical isolates of anaerobic bacteria were tested at five medical centers for susceptibility to ticarcillin, ticarcillin plus clavulanic acid, clindamycin, and metronidazole. At 64 micrograms/ml, ticarcillin inhibited 92% of all isolates, but 98% were inhibited at this concentration when 2 micrograms/ml of clavulanic acid was added. With different Bacteroides species, clavulanic acid reduced ticarcillin MICs 2- to 32-fold; other anaerobic species were not significantly affected.

Bacteria, Anaerobic↗
PubMed1988

Antimicrobial activity of U-76,252 (CS-807), a new orally administered cephalosporin ester, including recommendations for MIC quality control.

U-76,253A (R-3746), the active metabolite of the new cephalosporin ester, U-76,252 (CS-807), was tested against 4,742 fresh clinical isolates from four large medical centers. U-76,253A was very active against nearly all species of Enterobacteriaceae (87.7% inhibited at less than or equal to 4.0 micrograms/ml). Staphylococcus spp., and the streptococci. The U-76,253A spectrum was superior to the comparison orally administered cephalosporins (cephalexin, cephradine, cefaclor). Pseudomonas spp., Acinetobacter spp., and the enterococci were resistant to U-76,253A and the other tested drugs. Broth microdilution MIC quality control (QC) limits were established for U-76,253A in a multilaboratory investigation using a minimum of 125 MIC determinations per organism. The following MIC QC ranges were recommended; Escherichia coli (ATCC 25922) = 0.25-1.0 micrograms/ml, Staphylococcus aureus (ATCC 29213) = 2.0-4.0 micrograms/ml and Pseudomonas aeruginosa (ATCC 27853) = greater than 32 micrograms/ml.

Administration, Oral↗