Failure to detect resistance in antimicrobial susceptibility tests

Sanders, Christine C.

doi:10.1016/0738-1751(84)90006-6

Cited by 30 publications

(12 citation statements)

References 28 publications

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“…The alginate produced by old biofilm cells may bind the antibiotic molecules and therefore impede the penetration of the antibiotics (7,24,28). The ability of antibiotic molecules to cross the outer membrane of the old biofilm cells may be reduced significantly as a result of the alteration of the composition of the outer membrane (2,7,23 (27). The use of MIC in describing the susceptibility of bacterial pathogens to antibiotics has been scrutinized.…”

Section: Discussionmentioning

confidence: 99%

Dynamic interactions of biofilms of mucoid Pseudomonas aeruginosa with tobramycin and piperacillin

Anwar

Strap

et al. 1992

Antimicrob Agents Chemother

122

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The dynamic interaction of planktonic and biofilm cells of mucoid Pseudononas aeruginosa with tobramycin and piperacillin was investigated in a chemostat system. The results indicated that planktonic and young biofilm cells of the 2-day-old chemostat culture of P. aeruginosa were susceptible to killing by chemostatcontrolled doses of either 250 ,ug of piperacillin per ml plus 5 ,ug of tobramycin per ml or 500 ,ug of piperacillin per ml plus 5 jig of tobramycin per ml. Complete eradication of the planktonic and young biofilm cells was observed after exposure of the cells to six chemostat-controlled doses of these antibiotics at 8-h intervals for 7 days. Regrowth of the organism was not observed after the termination of antibiotic therapy on day 7. A different picture was observed when antibiotic treatment was initiated on day 10 after inoculation. Viable old biofilm cells were reduced to approximately 20%o after exposure to the chemostat-controlled doses of500 jLg ofpiperacillin per ml plus 5 jig of tobramycin per ml. Complete eradication of old biofilm cells could not be achieved, and regrowth of the organism occurred after the termination of antibiotic therapy. These data suggest that young biofilm cells of mucoid P. aeruginosa can be effectively eradicated with the combination of piperacillin and tobramycin, while old biofilm cells are very resistant to these antibiotics and eradication of old biofilm cells is not achievable with the chemostat-controlled doses of piperacillin and tobramycin used in this study.

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Section: Discussionmentioning

confidence: 99%

Dynamic interactions of biofilms of mucoid Pseudomonas aeruginosa with tobramycin and piperacillin

Anwar

Strap

et al. 1992

Antimicrob Agents Chemother

122

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“…Therapeutic failure occurring when the pathogen is classified as susceptible to the antibiotic administered in vitro represents a very major error of susceptibility testing which has been seen with recent broad spectrum /Mactam compounds used for treating non-fastidious Gram-negative aerobic bacteria like E. cloacae and P. aeruginosa (Sanders, 1984). In this setting, both animal and clinical studies (Michea-Hamzehpour et at., 1989) have shown that MICs (or their equivalent in disc diffusion techniques) were poor predictors of emergence of resistance, at least when the strains were 'socalled' susceptible.…”

Section: Discussionmentioning

confidence: 99%

Development of resistance during ceftazidime and cefepime therapy in a murine peritonitis model

Péchère¹,

Vladoianu²

1992

J Antimicrob Chemother

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Resistance emerging after ceftazidime or cefepime therapy was investigated in a peritonitis model. Mice were given a peritoneal challenge (10* cfu plus talcum) and treated by either antibiotic (50 mg/kg/dose, which produced similar antibiotic concentrations in peritoneal fluid in both cases). After one or three doses, resistance never developed in Serratia marcescens or Citrobacter freiouiii infections. After Enterobacter cloacae and Pseudomonas aeruginosa challenge, ceftazidime selected more resistance (21/36 cases) than did cefepime (1/36 cases). In mice challenged with resistant strains selected by ceftazidime therapy, cefepime (six doses) successfully treated 7/18 E. cloacae infections but 0/18 P. aeruginosa infections; ceftazidime was never effective. Neither cefepime nor ceftazidime cured mice infected with the resistant strain selected by cefepime. MICs were poor predictors of further emergence of resistance in mice inoculated with strains classified as susceptible, but antibiotic-containing agar gradients plated with a high inoculum (10* cfu) allowed better prediction. In selected clinical situations, cefepime may be preferable because it may be associated with less frequent emergence of resistance.

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“…Similarly, an agar for analysis of this inhibitor-drug combination. This approach of using a test-specific or antibiotic-specific panel of organisms has an advantage over the use of a single set panel of organisms (1), as it allows changes in the composition of the panel to fit the needs of the investigation (19). All in all, the use of a predictor panel in the design of disks for diffusion testing appears to be a useful approach that avoids many of the problems that have been encountered in the past in studies utilizing clinical isolates chosen at random.…”

Section: Discussionmentioning

confidence: 99%

“…In the initial phase, the disk masses of both components of the combination were varied to determine the impact upon zone diameters obtained with a small test panel of organisms spanning the range of possible susceptibilities to cefoperazone-sulbactam. From these initial studies, 10 candidate disks were chosen for analysis against a larger predictor panel of organisms chosen to represent (i) each of the diverse genera for which the new combination may be a potentially useful therapeutic agent; (ii) a complete range of strains, from the most susceptible to the highly resistant; (iii) strains with both natural and acquired resistances to the drug; and (iv) strains with diverse mechanisms of resistance (19). From the data generated with this predictor panel, a disk capable of accurately discriminating between susceptible and resistant strains could be chosen.…”

mentioning

confidence: 99%

Use of a predictor panel for development of a new disk for diffusion tests with cefoperazone-sulbactam

Bradford

Sanders

1992

Antimicrob Agents Chemother

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Failure to detect resistance in antimicrobial susceptibility tests

Cited by 30 publications

References 28 publications

Dynamic interactions of biofilms of mucoid Pseudomonas aeruginosa with tobramycin and piperacillin

Dynamic interactions of biofilms of mucoid Pseudomonas aeruginosa with tobramycin and piperacillin

Development of resistance during ceftazidime and cefepime therapy in a murine peritonitis model

Use of a predictor panel for development of a new disk for diffusion tests with cefoperazone-sulbactam

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