The Role of Penicillin Acylase in the Resistance of Gram-Negative Bacteria to Penicillins

Abstract

SUMMARYThe resistance of 148 clinical isolates of Gram-negative bacteria to ampicillin and benzylpenicillin was determined in serial-dilution sensitivity tests, together with the extent of inactivation of the penicillins, and the production of 6-aminopenicillanic acid (6-APA). Many of the cultures were resistant to the penicillins and inactivated the compounds, but only one culture, a strain of Escherichia coli, showed penicillin acylase activity, as indicated by the production of 6-APA. However, the cultural conditions prevailing in serial-dilution tests, namely, stationary culture at 37O, although favourable for the functioning of penicillin acylases, were shown to be highly unfavourable for production of the enzyme by coliform bacteria.

Bacterial resistance to penicillins and cephalosporins

“…(iv) As the reaction is reversible, deacylation does not go to completion. (v) Both products of the reaction can possess antibacterial properties (see Cole & Sutherland, 1966;Hamilton-Miller, 1966~).…”

Genomic analysis of the original Elberg Brucella melitensis Rev.1 vaccine strain reveals insights into virulence attenuation

“…Point mutations in PBPs reduce the affinity for penicillin, which may increase penicillin resistance [47]. Additionally, penicillin resistance may be the consequence of penicillin acylase activity [48], which has been reported in many species of Gram-negative bacteria [49–51], leading to the hydrolysis of penicillin, with the production of the relatively inactive 6-aminopenicillanic acid. Another common mechanism underlying penicillin resistance is the activity of β-lactamase, which hydrolyzes the β-lactam ring and, consequently, deactivates β-lactam antibiotics [52].…”

A Sensitive Procedure for Screening Microorganisms for the Presence of Penicillin Amidase

“…There are conflicting reports concerning its distribution in bacteria (Holt and Stewart 1964;Cole and Sutherland 1966) but these are primarily due to interpretation of data obtained from different methods of determination of enzyme activity. The usual chemical methods for measuring penicillin amidase activity estimate the 6-aminopenicillanic acid (6-APA) formed from the penicillin substrate (Batchelor et al 1961;Bomstein and Evans 1965), but are neither sensitive nor specific for 6-APA.…”