Ampicillin Resistance and Beta-Lactamase Activity in Clinical Isolates of Shigella Sonnei
There has been a marked increase in the resistance of Shigella sonnei to ampicillin in the past decade. This has been seen in England (Davies et al 1970) New Zealand (Smith et al 1974) and New York (Neu et al 1975). The precise mechanism of resistance has not been defined in each instance, but the studies in London (Davies et al 1970) and those of the strains from New Zealand (Smith et al 1974) suggested that these were two kinds of resistance: low level, nontransmissible; and high level, transmissible. The nontransmissible was due to a B-lactamase that hydrolyzed cephalospoxins rapidly. The transmissible resistance is due to an R-factor mediating a B-lactamase that does not confir cephalosporin resistance. We (Neu 1969) had described similar type of resistance in Escherichia coli and we wished to see if the increased resistance of Shigella to ampicillin that we (Neu et al 1975) had noted in 1972—73 was similar to that seen in England and New Zealand.
KeywordsNalidixic Acid Shigella Sonnei Muller Hinton Agar Hinton Agar Plate 25mM Potassium Phosphate
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