PER-1 extended-spectrum beta-lactamase production in an Alcaligenes faecalis clinical isolate resistant to expanded-spectrum cephalosporins and monobactams from a hospital in Northern Italy

An Alicaligenes faecalis (FL-424/98) resistant to expanded-spectrum cephalo sporins and aztreonam was isolated from the urine of an inpatient at the In tensive Care Unit of the Varese Hospital (Northern Italy) after antimicrobi al chemotherapy with cefazolin, vancomycin, and amikacin, Clavulanic acid r estored the activity of expanded-spectrum cephalosporins, suggesting the pr oduction of an extended-spectrum beta-lactamase (ES beta L), A crude extrac t of FL-424/98 showed the presence of two beta-lactamase activities focusin g at pH 5.3 and 7.6, respectively. The ES beta L activity, purified by mean s of three chromatographic steps, was found to correspond to the pI 5.3 enz yme, Determination of kinetic parameters confirmed that,the enzyme efficien tly: hydrolyzed expanded-spectrum cephalosporins and aztreonam, A colony-bl ot hybridization revealed the presence of bla(PER)-related sequences in FL- 424/98, and sequencing confirmed the identity of this determinant with bla( PER-1), previously detected in Pseudomonas aeruginosa, Acinetobacter, and S almonella clinical isolates from Turkey. Finding of bla(PER-1) in a species that can be part of the resident human microbiota raises the possibility t hat it could be an efficient shuttle for spreading of this resistance gene among other opportunistic pathogens that are normally members of the reside nt microbiota, Kinetic parameters determined for the PER-1 enzyme with some cephalosporin substrates were somewhat different from those previously rep orted.