Cation Components of Mueller-Hinton Agar Affecting Testing of
            <i>Pseudomonas aeruginosa</i>
            Susceptibility to Gentamicin

Kenny, Margaret A.; Pollock, Helen M.; Minshew, Barbara H.; Casillas, Edmundo; Schoenknecht, Fritz D.

doi:10.1128/aac.17.1.55

Cited by 38 publications

(33 citation statements)

References 13 publications

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“…Reller and co-workers recommended that Mueller-Hinton medium be supplemented to 50 to 100 mg of calcium and 20 to 35 mg of magnesium per liter for the susceptibility testing of P. aeruginosa (18). Subsequently, Kenny and co-workers reported that the soluble and ionized fraction of the total calcium and magnesium in agar correlates with susceptibility of P. aeruginosa to gentamicin (2,12). Washington and coworkers reported, using a regression analysis, that zinc is the cation most highly correlated with aminoglycoside MIC in Mueller-Hinton agar (20).…”

Section: Resultsmentioning

confidence: 99%

“…The susceptibility of the 36 strains of P. aeruginosa was determined for ticarcillin and tobramycin alone and in combination by a previously described microtiter broth dilution checkerboard method (8,17). Each test was performed in duplicate, and all strains were tested in parallel in each of 12 media by this method. The minimal inhibitory concentration (MIC) was designated as the lowest concentration of antibiotic(s) in a column of the plate needed to inhibit visible turbidity.…”

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confidence: 99%

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Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa

Zuravleff¹,

Yu²,

Yee³

et al. 1982

Antimicrob Agents Chemother

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Correlation between in vitro and in vivo test results for synergy between carboxypenicillins and aminoglycosides against Pseudomonas aeruginosa is poor. Although the divalent cation content of culture media is known to affect aminoglycoside susceptibility testing for P. aeruginosa, this effect of divalent cations has not been examined for synergy testing of carboxypenicillin-aminoglycoside interaction against P. aeruginosa. The minimal inhibitory concentrations (MICs) of tobramycin and ticarcillin and the interaction of these drugs in combination were studied by a microtitration method for 36 strains of P. aeruginosa in Mueller-Hinton broth with varying supplements of calcium, magnesium, and zinc. Boston, Mass., abstr. no. 1071) studied the efficacy of ticarcillin and tobramycin, singly and in combination, in a guinea pig model for P. aeruginosa bacteremia; they were unable to show an improvement in survival with combinations demonstrated to be synergistic in vitro against strains of Pseudomonas, as compared to a single-drug therapy. The results of in vitro studies examining the interaction between carboxypenicillin and aminoglycosides against P. aeruginosa are not easily compared. This is due to several reasons. First, the definition of synergy varies from study to study. Second, the divalent cation content of the culture media, which will affect aminoglycoside susceptibility (18,22,23), can also vary from study to study; unfortunately, the cation content is not even reported in a number of synergy studies of P. aeruginosa. We wondered whether some of the discrepancies in the literature concerning penicillin and aminoglycoside synergy might be due to differences in divalent cation content of the test media. To our knowledge the effect of divalent cations on the synergistic interaction of carboxypenicillins and aminoglycosides has not been systematically evaluated. We sought to do so by testing the interaction between ticarcillin and tobramycin against 36 clinical isolates of P. aeruginosa in 12 cation-defined media.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa

Zuravleff¹,

Yu²,

Yee³

et al. 1982

Antimicrob Agents Chemother

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“…The in vitro activity of the aminoglycoside antibiotics against Pseudomonas aeruginosa may be profoundly influenced by the concentration of unbound cations in the test medium (2,4,(7)(8)(9). Calcium and magnesium cations are particularly antagonistic to the activity of aminoglycosides against P. aeruginosa.…”

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confidence: 99%

Influence of cation supplements on activity of netilmicin against Pseudomonas aeruginosa in vitro and in vivo

Barry¹,

Miller²,

Thornsberry³

et al. 1987

Antimicrob Agents Chemother

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In vitro studies were performed with 74 Pseudomonas aeruginosa isolates which were collected during a multicenter trial. The isolates were obtained from 70 patients who had been treated with netilmicin as the only antipseudomonal antibiotic. Clinically Strains that produced aminoglycoside-inactivating enzymes were similarly affected by cations. Some strains with aminoglycoside permeability defects were also affected by the addition of calcium and magnesium cations, but other strains showed only modest increases in aminoglycoside MICs.When

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“…This subcommittee has the responsibility for testing and selecting a reference lot of Mueller-Hinton agar (the so-called golden kilo) to be used as a physical reagent standard in evaluating production lots of the dehydrated agar (M6-P) (9). Batch-tobatch and lot-to-lot variabilities in the antipseudomonal activity of aminoglycosides have been reported by a number of investigators (4,26,29) and were found, as the result of an elegant series of experiments by Kenny et al (6), to correlate with the sums of soluble calcium and magnesium and with the amount of ionized calcium in various batches or lots of the medium. Factors such as autoclaving caused shifts among soluble, ionized, and bound pools of cation which in turn affected the aminoglycoside activity (6).…”

Section: Introductionmentioning

confidence: 89%

“…Batch-tobatch and lot-to-lot variabilities in the antipseudomonal activity of aminoglycosides have been reported by a number of investigators (4,26,29) and were found, as the result of an elegant series of experiments by Kenny et al (6), to correlate with the sums of soluble calcium and magnesium and with the amount of ionized calcium in various batches or lots of the medium. Factors such as autoclaving caused shifts among soluble, ionized, and bound pools of cation which in turn affected the aminoglycoside activity (6). For this reason, selection of a reference lot of medium was of considerable importance (25 …”

Section: Introductionmentioning

confidence: 89%

Functions and activities of the Area Committee on Microbiology of the National Committee for Clinical Laboratory Standards

Washington

1991

Clin Microbiol Rev

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The Area Committee on Microbiology of the National Committee for Clinical Laboratory Standards has responsibility for the development of guidelines and standards in the field of clinical microbiology. Through the consensus process, representatives from government, industry, and professional societies have developed standards on antibacterial susceptibility testing (M2, M7, and M11), antimycobacterial susceptibility testing (M24), quality assurance on commercially prepared microbiological culture media (M22), evaluation of production lots of dehydrated Mueller-Hinton agar (M6), and preparation and testing of fetal bovine serum for use as cell culture growth supplement (M25) and guidelines on bactericidal tests (M26), protection of laboratory workers from infections transmitted by blood, body fluids, and tissue (M29), blood film examination for parasites (M15), and development of in vitro susceptibility testing criteria and quality control parameters (M23).

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Cation Components of Mueller-Hinton Agar Affecting Testing of Pseudomonas aeruginosa Susceptibility to Gentamicin

Cited by 38 publications

References 13 publications

Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa

Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa

Influence of cation supplements on activity of netilmicin against Pseudomonas aeruginosa in vitro and in vivo

Functions and activities of the Area Committee on Microbiology of the National Committee for Clinical Laboratory Standards

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