Comparative susceptibilities of clinical isolates of Serratia marcescens to newer cephalosporins, alone and in combination with various aminoglycosides

Markowitz, Sheldon M.; Sibilla, Denisej .

doi:10.1128/aac.18.5.651

Cited by 19 publications

(5 citation statements)

References 31 publications

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“…Antagonism with azlocillin-cefotaxime was observed with 11% of the Enterobacteriaceae. [10][11][12]14). Although antagonism was not observed in the present study, it has been occasionally observed with both types of combinations against Enterobacteriaceae and P. aeruginosa (3,5,6,8,11,14).…”

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confidence: 40%

Comparative in vitro activities of azlocillin-cefotaxime and azlocillin-tobramycin combinations against blood and multi-drug resistant bacterial isolates

Fass¹

1982

Antimicrob Agents Chemother

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The in vitro activities of azlocillin and cefotaxime in combination and of azlocillin and tobramycin in combination against 100 blood isolates and 50 multidrug-resistant isolates were compared. With both combinations, antibacterial spectrums were complementary. Although synergy against individual strains was infrequently observed (except for azlocillin-cefotaxime against Streptococcus faecalis and azlocillin-tobramycin against Pseudomonas aeruginosa), 97% of blood isolates and 76% of multidrug-resistant isolates were susceptible to azlocillin-cefotaxime, and 94% of blood isolates and 36% of multidrug-resistant isolates were susceptible to azlocillin-tobramycin.Penicillin-aminoglycoside and cephalosporinaminoglycoside antibiotic combinations have broad antibacterial spectrums, are frequently synergistic in vitro, and are commonly used to treat a variety of serious bacterial infections (9). To avoid aminoglycoside toxicity, penicillincephalosporin combinations have also been used, but results using early derivatives have not been optimal (2). In recent years, new penicillins and cephalosporins which have greater potencies and spectrums of activity than their prototypes have been developed (4, 7). Therefore, a reexamination of the potential for using penicillin-cephalosporin combinations as alternatives to 3-lactam-aminoglycoside combinations for treating certain types of infections seems appropriate.In this study, we compared the in vitro activity of azlocillin (a new antipseudomonal penicillin) and cefotaxime (a third generation of cephalosporin) in combination with the activity of azlocillin and tobramycin (an aminoglycoside) (Difco Laboratories, Detroit, Mich.) and an inoculum size of approximately 2 x 105 colony-forming units per ml were used (6). Antibiotics were considered synergistic when there was a fourfold or greater reduction in MICs of both drugs in a combination compared with MICs of individual drugs, antagonistic when there was a fourfold or greater increase in MICs of both drugs or when the addition of an inactive antibiotic to an active antibiotic increased the MIC of the latter by fourfold or more, and indifferent when the results were intermediate. Results were considered indeterminate if the endpoints were not in the range of concentrations tested (0.25 to 256 ,ug/ml for azlocillin and 0.25 to 16 ,ug/ml for cefotaxime and tobramycin).

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confidence: 40%

Comparative in vitro activities of azlocillin-cefotaxime and azlocillin-tobramycin combinations against blood and multi-drug resistant bacterial isolates

Fass¹

1982

Antimicrob Agents Chemother

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“…Most of the strains reported have been highly resistant to the currently available antibiotics, except to a few aminoglycosides, including gentamicin and amikacin (4,18,19). Recently, however, increasing numbers of reports have pointed out the rise in epidemics due to strains resistant even to gentamicin or to amikacin (3,5,6,12,15,18), thus posing difficulties in the control of S. marcescens infections.…”

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confidence: 99%

Outbreak of nosocomial urinary tract infections caused by Serratia marcescens

Okuda¹,

Endo²,

Osada³

et al. 1984

J Clin Microbiol

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of nosocomial urinary tract infections appeared to be due to strains of Serratia marcescens that were resistant to currently available antibiotics. The serotyping and antibiotic susceptibility patterns suggested a few endemic strains of serotypes 013, 02/3, 012/14, and nontypable strains. These strains were isolated from the urine samples of inpatients with urinary tract infections in the urology ward and in other wards. The strains of 012/14 (gentamicin susceptible) were replaced with those of 02/3 (gentamicin resistant) between June and September 1981, whereas the other serotypes were isolated continuously. They were resistant to sulbenicillin, cefmetazole, gentamicin, and amikacin, and susceptible to micronomicin and ofloxacin, a new quinolone antibiotic. Most of them were also resistant to the disinfectant chlorhexidine, which had been used widely for hand washing in the hospital.

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“…Several investigators have shown notable in vitro synergy between amikacin and semisynthetic penicillins or cephalosporins against highly resistant Pseudomonas aeruginosa and Serratia marcescens (12,13,15), as well as against multiply resistant strains of Enterobacteriaceae. Using the checkerboard technique, Jones and Packer (7) found that the combinations of amikacin plus cefotaxime or moxalactam produced synergism against 67 and 54%, respectively, of their Enterobacteriaceae strains, whereas D'Alessandri and co-workers (2) demonstrated synergism between cephalothin and amikacin for 26 of 38 Klebsiella isolates (68%).…”

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confidence: 99%

Early synergistic interactions between amikacin and six beta-lactam antibiotics against multiply resistant members of the family Enterobacteriaceae

Glew

Pavuk

1984

Antimicrob Agents Chemother

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An in vitro comparison of the early synergistic interaction between amikacin and each of six IT-lactam antibiotics was made by using time-kill curves against 48 multiply resistant members of the family Enterobacteriaceae. Overall, these six combinations demonstrated early synergism (x2 logs of increased kill after 7 h of incubation) against the 48 strains on 74% (range, 67 to 85%) of occasions; cefotaxime-amikacin and piperacilin-amikacin were the most efficacious combinations. Antagonism was not observed with any of the combinations against any of the 48 Enterobacteriaceae strains tested.Combination therapy with an aminoglycoside plus a semisynthetic penicillin or cephalosporin commonly is used in the treatment of life-threatening infections caused by gramnegative bacilli, especially in the immunocompromised patient (1, 16). These antibiotic combinations, shown to be synergistic both in vivo (1, 11) and in vitro (7-9), are used in place of single-drug therapy with the aim of obtaining increased therapeutic efficacy as well as reducing the likelihood of emergence of resistance among infecting gramnegative bacilli (5,18).In a prior investigation with timne-kill curves to evaluate the early synergistic interaction between gentamicin or amikacin and three ,-lactams against 48 members of the family Enterobacteriaceae, we demonstrated that amikacin ih combination with carbenicillin, ticarcillin, or piperacillin produced early synergism against 46% of the strains, whereas gentamicin in combination with these same P-lactams exhibited early synergism against only 28% of the strains (4). Of the P-lactams studied previously, piperacillin in combination with either amikacin or gentamicin demonstrated early synergism against 71% of the strains, whereas carbenicillin plus amikacin or gentamicin and ticarcillin plus amikacin or gentamicin produced early synergism against 16 (14).Susceptibility testing. Antimicrobial susceptibility testing was performed by the agar dilution method (19). Serial twofold dilutions of the respective antibiotics were incorporated into Mueller-Hinton agar, and an inoculum of 1 organisms per ml was delivered onto each plate with a Steers replicator (Craft Machine, Inc., Chester, Pa.). The MIC was defined as the lowest concentration of antibiotic producing no visible growth after 18 h of incubation at 37°C.Ahtibiotic synergism. The synergistic interaction between amikacin and each of the six P-lactam drugs was evaluated by time-kill curves during 7 h of incubation, as described previously (4). The following concentrations of antibiotics in the flasks were selected to be at or below the MIC for each drug and within a clinically achievable range (10, 17) for each drug: <125 ,ug/ml for piperacillin, -62 ,ug/ml for each of the cephalosporins, and s8 ,ug/ml for amikacin. A starting inoculum of 105 organisms per ml was prepared by appropriate dilutiod of an overnight broth culture and added to each flask (final volume, 20 ml of Mueller-Hinton broth). The culture flasks were incubated without agitation at 37...

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Comparative susceptibilities of clinical isolates of Serratia marcescens to newer cephalosporins, alone and in combination with various aminoglycosides

Cited by 19 publications

References 31 publications

Comparative in vitro activities of azlocillin-cefotaxime and azlocillin-tobramycin combinations against blood and multi-drug resistant bacterial isolates

Comparative in vitro activities of azlocillin-cefotaxime and azlocillin-tobramycin combinations against blood and multi-drug resistant bacterial isolates

Outbreak of nosocomial urinary tract infections caused by Serratia marcescens

Early synergistic interactions between amikacin and six beta-lactam antibiotics against multiply resistant members of the family Enterobacteriaceae

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