Susceptibility of 1,500 Isolates of Pseudomonas aeruginosa to Gentamicin, Carbenicillin, Colistin, and Polymyxin B

Abstract

A series of 1,500 strains of Pseudomonas aeruginosa was collected from a variety of sources to provide a group of strains which would truly represent the species. All of them were pyocine typed, and a wide range of types was included among the isolates from each source. The gentamicin, carbenicillin, colistin, and polymyxin minimal inhibitory concentration of each strain was measured by the agar dilution method employing the Steers inocula replicator. Over 99% of strains were inhibited by 8 ,g of gentamicin per ml, by 256

Gentamicin Resistance in Pseudomonas aeruginosa : R-Factor-Mediated Resistance

“…Recently, the aminoglycosides tobramycin and BBK-8 have shown potential therapeutic promise by in vitro antibiotic susceptibility testing (4,17). The frequency of resistance to gentamicin among strains of P. aeruginosa has been reported by several groups (10,13,14). Resistance has been a particular problem in the treatment of burns where large quantities of topical gentamicin cream have been used frequently.…”

“…DISCUSSION The assessment of susceptibility to gentamicin is somewhat confused by the influence of testing medium (specifically divalent cations) on MIC values for P. aeruginosa. We used media (Mueller-Hinton agar; Trypticase soy broth) (BBL) that gave relatively low MICs of gentamicin, when compared to most other testing media (13), in an effort to avoid an overestimation of the frequency of gentamicin resistance. In addition, the increase in resistance described for the periods in 1972 and 1973 occurred with exactly the same media and testing procedures.…”

Comparative in vitro activities of SCE-129, sulbenicillin, gentamicin, and dibekacin against Pseudomonas

“…In the chemotherapy of P. aeruginosa infection, sulbenicillin, carbenicillin, and several aminoglycoside antibiotics have been routinely administered. Recently, however, an increasing number of strains of P. aeruginosa resistant to those antibiotics has been reported (2,3,6,8,18). Furthermore, aminoglycoside antibiotics such as gentamicin and dibekacin often develop oto-and nephrotoxicities (1,4,7,9,10,14,20,21).…”

Activity of Netilmicin Compared with Those of Gentamicin and Tobramycin Against Enterobacteria and Pseudomonas aeruginosa

“…The 4-h cultures were diluted 10-1 and 10-2 in broth, also in flasks, and viable counts were performed on these cultures by the Miles and Misra method (10). Immediately, one antibiotic was added to each of a series of three flask cultures to give a final concentration of 4 ,ig/ml. For P. aeruginosa the procedure was similar except that the overnight broth culture was diluted only 1:10.…”

“…The plates were incubated at 37°C for 18 h. For both undiluted and 302 CHADWICK, SALMON, AND TAYLOR Determination of bactericidal activity. The bactericidal activity of the antibiotics was estimated by exposing various-sized bacterial populations to gentamicin, tobramycin, or netilmicin at the single concentration of 4 ,ug/ml in Mueller-Hinton broth. Overnight Mueller-Hinton broth cultures of enterobacteria were diluted 1:400 in broth and then incubated in flasks for 4 h at 370C.…”