In vitro susceptibilities of clinical isolates of cysteine-requiring Escherichia coli to 12 antimicrobial agents.

The MICs of 12 antimicrobial agents for 42 cysteine-requiring strains of Escherichia coli showed a high concordance when determined on three different media, one of which was supplemented with cysteine. Differences in the MICs of several agents were detected between 18 prototrophic revertants and their parent auxotrophs. A total of 64.7% of the isolates were fully susceptible to all agents, and no particular resistance pattern was evident.     

In vitro susceptibilities of Campylobacter-like organisms to twenty antimicrobial agents.

We determined MICs of 20 antimicrobial agents for 50 representative strains of four subgroups of Campylobacter-like organisms (CLOs) by agar dilution. Ampicillin, gentamicin, doxycycline, tetracycline, ceftriaxone, rifampin, spectinomycin, nalidixic acid, and chloramphenicol were active against all strains of CLOs. Most CLO strains (83%) were inhibited by 4 micrograms of sulfamethoxazole per ml and by 8 micrograms of trimethoprim-sulfamethoxazole per ml. Of type 1 strains, 28% were resistant to 8 micrograms of erythromycin per ml. In addition, cross resistance between erythromycin and clindamycin was always present. Type 1 strains exhibited a broad distribution of MICs of metronidazole and streptomycin, whereas all type 2 strains were uniformly susceptible to metronidazole and resistant to streptomycin. Unlike type 1 and 3 strains, type 2 CLOs were susceptible to cephalothin and penicillin G and highly resistant to streptomycin. The type 3 strain was uniquely resistant to cefazolin. The majority of strains were not inhibited by cefoperazone; and all were resistant to trimethoprim. In contrast to Campylobacter jejuni and Campylobacter fetus subsp. fetus, all CLOs tested were susceptible to 0.5 microgram of rifampin per ml.     

In vitro susceptibilities of Aeromonas hydrophila to 32 antimicrobial agents.

Minimal inhibitory concentrations of 32 antimicrobial agents for 20 strains fo Aeromonas hydrophila were determined by a microdilution method. Moxalactam was the most active drug tested. All strains were also susceptible to clinically achievable concentrations of mecillinam, cefamandole, cefuroxime, cefotaxime, aminoglycosides (except streptomycin), tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole.     

In vitro susceptibilities of Pseudomonas pseudomallei to 27 antimicrobial agents.

Clinical isolates of Pseudomonas pseudomallei isolated in Thailand from 1981 to 1989 were tested for their in vitro susceptibilities to 27 antimicrobial agents, including older and newer quinolones, broad-spectrum cephems, carbapenems, monobactams, penicillins, tetracyclines, chloramphenicol, rifamycin, sulfamethoxazole, trimethoprim, and fosfomycin. Tosufloxacin, meropenem, CS-533, and minocycline were active against P. pseudomallei at levels comparable to or even greater than those of antimicrobial agents tested in previous studies, such as ciprofloxacin, ceftazidime, imipenem, carumonam, and piperacillin. Drug-resistant P. pseudomallei was found in only 1% of the isolates. The drug-resistant P. pseudomallei isolates displayed a unique pattern of susceptibility to the above-listed drugs.     

In vitro susceptibilities of Mycobacterium tuberculosis to 10 antimicrobial agents.

After preliminary in vitro screening of 10 antimicrobial agents against Mycobacterium tuberculosis, the MICs of the 6 most promising agents against 27 clinical isolates were determined by agar dilution. The two quinolone compounds tested (difloxacin and A-56620) were the most active, each inhibiting 50% of the strains at concentrations of 4 micrograms/ml. M. tuberculosis strains previously shown to be resistant to isoniazid, streptomycin, rifampin, or ethambutol were as susceptible to these quinolone compounds as susceptible strains.     

In vitro susceptibilities of Nocardia species to newer antimicrobial agents.

The in vitro activities of various quinolones, two newer cephalosporins, and imipenem against 23 strains of Nocardia asteroides, 4 strains of Nocardia brasiliensis, and 4 strains of Nocardia caviae were determined by an agar dilution method. PD-117558, a newer carboxyquinolone, and imipenem were the most active agents tested, inhibiting 90% of N. asteroides isolates at an MIC of 2 micrograms/ml. Of the 23 strains of N. asteroides, 15 were susceptible to cefpirome and 10 were susceptible to ciprofloxacin. The N. brasiliensis and N. caviae strains were very susceptible to PD-117558 (MIC, less than or equal to 1 microgram/ml), moderately susceptible to ciprofloxacin, and resistant to most of the other tested drugs.     

In vitro susceptibilities of zygomycetes to combinations of antimicrobial agents

Combinations of antimicrobial agents were tested against 35 strains of zygomycetes. The interaction between amphotericin B and rifampin was synergistic or additive. Flucytosine alone was inactive and, upon combination with amphotericin B, synergy was not achieved. The combination of amphotericin B with terbinafine was synergistic for 20% of strains, and the interaction between terbinafine and voriconazole was synergistic for 44% of strains. Antagonism was not observed.     

In vitro susceptibilities of rapidly growing mycobacteria to newer antimicrobial agents.

The in vitro antimicrobial susceptibilities of 42 isolates of rapidly growing mycobacteria (Mycobacterium fortuitum, M. chelonae, and Mycobacterium species [other than M. fortuitum and M. chelonae]) to nine quinolones, including newer agents, two new aminoglycosides, and an aminocyclitol (trospectomycin) were determined by a broth microdilution method. The new quinolones, PD 117596, PD 127391, and PD 117558, showed excellent in vitro activities against M. fortuitum (MICs for 90% of isolates [MIC90s], 0.06, 0.06, and 0.12 microgram/ml, respectively). The MIC90 of ciprofloxacin for M. fortuitum was 0.5 microgram/ml. Only 14 to 28% of isolates of M. chelonae were susceptible to various quinolones. Most isolates of all three species were susceptible to the new aminoglycosides SCH 21420 and SCH 22591. The MIC90s of trospectomycin were 8 micrograms/ml for M. chelonae, 32 micrograms/ml for Mycobacterium species, and > 64 micrograms/ml for M. fortuitum.     

In vitro susceptibilities of five Leptospira strains to 16 antimicrobial agents.

The in vitro activities of 16 antibiotics against five serovar strains of the genus Leptospira were determined. Five of the antibiotics (ampicillin, cefmetazole, moxalactam, ceftizoxime, and cefotaxime) exhibited a lower minimal inhibitory concentration than did penicillin G. In tests for minimal bactericidal concentration, ceftizoxime and cefotaxime were found to be more effective than penicillin G, streptomycin, tetracycline, ampicillin, and cefmetazole.     

In vitro susceptibilities of Aeromonas hydrophila, Aeromonas sobria, and Aeromonas caviae to 22 antimicrobial agents.

MICs of 22 antimicrobial agents for 60 strains of three Aeromonas species were determined by a microdilution method. The newer cephalosporins such as moxalactam, cefotaxime, and cefoperazone, the aminoglycosides, and chloramphenicol, tetracycline, nitrofurantoin, and trimethoprim-sulfamethoxazole inhibited most of the strains studied. Within the genus, A. hydrophila was more resistant than either A. caviae or A. sobria to the antibiotics tested.     

In vitro susceptibilities of 400 Spanish isolates of Neisseria gonorrhoeae to gemifloxacin and 11 other antimicrobial agents

The in vitro activity of gemifloxacin versus those of 11 other antimicrobial agents against 400 strains of Neisseria gonorrhoeae was determined by microdilution with supplemented GC agar. A total of 37.5% of the strains were beta-lactamase positive. A total of 70 and 6.4% of the beta-lactamase-negative strains exhibited intermediate and high-level penicillin resistance, respectively. Ceftriaxone and gemifloxacin were the most active drugs (MICs at which 90% of isolates are inhibited, 0.01 versus 0.007 microg/ml, respectively), with 100% of strains inhibited by 0.12 microg/ml.     

In vitro susceptibilities of tropical strains of Aeromonas species from Queensland, Australia, to 22 antimicrobial agents.

Greater than 90% of 131 strains of Aeromonas species were susceptible to the aminoglycosides, ureidopenicillins, extended-spectrum cephalosporins, aztreonam, quinolones, tetracycline, and chloramphenicol, and all were uniformly resistant to ampicillin. Except for amoxicillin-clavulanate, sulfonamide, trimethoprim, and trimethoprim-sulfamethoxazole, there was good correlation between the results obtained by the agar dilution and disk diffusion techniques.     

In vitro susceptibilities of Edwardsiella tarda to 22 antibiotics and antibiotic-beta-lactamase-inhibitor agents

The in vitro susceptibilities of 22 isolates of Edwardsiella tarda were studied with 22 antibiotics and antibiotic-beta-lactamase-inhibitor agents. Results indicated that all isolates were susceptible to the aminoglycosides, cephalosporins, penicillins, imipenem, aztreonam, ciprofloxacin, and antibiotic-beta-lactamase-inhibitor agents. Each strain produced a beta-lactamase even though no resistance was detected to the beta-lactams.     

嗜麦芽窄食单胞菌体外药物敏感性研究

目的比较10种抗菌药物（莫西沙星、加替沙星、左氧氟沙星、环丙沙星、头孢哌酮-舒巴坦、替卡西林-克拉维酸、哌拉西林-三唑巴坦、头孢吡肟、头孢他啶、复方磺胺甲嗯唑）对临床分离嗜麦芽窄食单胞菌的体外抗菌活性。方法琼脂稀释法测定10种抗菌药物对来自北京3所医院的200株嗜麦芽窄食单胞菌的MIC值，用WHONET5．3软件进行药敏数据统计分析。结果200株菌对药物的敏感率排序为莫西沙星（84．5％）、加替沙星（79．5％）、左氧氟沙星（76％）、复方磺胺甲嗯唑（72．5％）、头孢哌酮-舒巴坦（41．5％）、替卡西林-克拉维酸（34％）、头孢他啶（23％）、环丙沙星（15％）、头孢吡肟（7％）和哌拉西林-三唑巴坦（4．5％）。结论新一代氟喹诺酮类药物如莫西沙星对嗜麦芽窄食单胞菌有较高的体外抗菌活性，是临床治疗嗜麦芽窄食单胞菌感染的较好选择。     

In vitro susceptibilities of the Bacteroides fragilis group to 14 antimicrobial agents in Korea.

The susceptibilities to 14 antimicrobial agents of 172 clinical isolates of the Bacteroides fragilis group from Korean patients during 1989 and 1990 were tested by an agar dilution method. All the isolates tested were susceptible to imipenem, chloramphenicol, and metronidazole. The rate of resistance to cefoxitin was 6%.     

In vitro susceptibilities of oral bacterial isolates to spiramycin.

Four hundred strains of oral bacteria were tested for their susceptibility to spiramycin. Actinobacillus actinomycetemcomitans and most species of Lactobacillus were resistant to the antibiotic. All strains of cariogenic Streptococcus mutans and most strains of bacterial species implicated in adult chronic periodontitis (Bacteroides gingivalis, B. intermedius, and Treponema denticola) were susceptible to spiramycin.     

In vitro susceptibilities of Campylobacter jejuni and Campylobacter coli to azithromycin and erythromycin.

MICs of azithromycin and erythromycin for 20 Campylobacter coli and 20 Campylobacter jejuni strains were determined. The results demonstrated that, for Campylobacter species, all high-level erythromycin-resistant strains were also resistant to azithromycin and that azithromycin did not exhibit increased potency in comparison with that of erythromycin.     

In vitro antimicrobial susceptibilities of Nocardia species.

The in vitro activities of various quinolones, two new aminoglycosides, a new cephamycin analog (cefmetazole) and a new spectinomycin analog (trospectomycin), imipenem, and trimethoprim-sulfamethoxazole against 26 isolates of Nocardia asteroides, 7 isolates of N. brasiliensis, and 6 isolates of N. caviae were determined by a broth microdilution method. The three new quinolones, PD 117558, PD 117596 and PD 112739, inhibited 90% of N. asteroides at 1 to 2 micrograms/ml, and two new aminoglycosides, SCH 21420 and SCH 22591, inhibited 90% of N. asteroides at 2 to 4 micrograms/ml. Among the beta-lactams, cefmetazole was more active than imipenem. N. brasiliensis and N. caviae isolates were also very susceptible to the three quinolones (MICs for 50% of the isolates, 0.25 to 1 microgram/ml) and the two aminoglycosides (MICs for 50% of the isolates, 1 to 2 micrograms/ml). Cefmetazole was moderately active against N. brasiliensis, whereas imipenem showed poor activity against both of these species.     

Susceptibility of clinical isolates of Campylobacter pyloridis to 11 antimicrobial agents.

The activities of 11 antimicrobial agents, including two bismuth salts, against 70 strains of Campylobacter pyloridis isolated from gastric biopsy specimens were tested. The isolates were very susceptible to penicillin (the MIC for 90% of the strains tested [MIC90] was 0.03 microgram/ml), erythromycin, cefoxitin (MIC90, 0.12 microgram/ml), gentamicin, and ciprofloxacin (MIC90, 0.25 microgram/ml). The bismuth salts and nalidixic acid had moderate activity (MIC90, 16 to 64 micrograms/ml). Twenty percent of the isolates were resistant to metronidazole (MIC, greater than 1 micrograms/ml), and all were resistant to sulfamethoxazole and trimethoprim (MIC90, greater than 256 micrograms/ml).     

Susceptibility of clinical isolates of Campylobacter jejuni to sixteen antimicrobial agents.

The activities of 16 antimicrobial agents against 103 clinical isolates of Campylobacter jejuni were tested. All the strains were susceptible to kanamycin and gentamicin. Chloramphenicol, nalidixic acid, and clindamycin were active against most of the strains. More than one-third of the strains were resistant to the tetracyclines and 12.5% were resistant to erythromycin.