PER-1 extended-spectrum β-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 cephalosporins and aztreonam was isolated from the urine of an inpatient at the Intensive Care Unit of the Varese Hospital (Northern Italy) after antimicrobial chemotherapy with cefazolin, vancomycin, and amikacin, Clavulanic acid restored the activity of expanded-spectrum cephalosporins, suggesting the production of an extended-spectrum beta-lactamase (ES beta L), A crude extract of FL-424/98 showed the presence of two beta-lactamase activities focusing at pH 5.3 and 7.6, respectively. The ES beta L activity, purified by means of three chromatographic steps, was found to correspond to the pI 5.3 enzyme, Determination of kinetic parameters confirmed that,the enzyme efficiently: hydrolyzed expanded-spectrum cephalosporins and aztreonam, A colony-blot 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 Salmonella clinical isolates from Turkey. Finding of bla(PER-1) in a species that can be part of the resident human microbiota raises the possibility that it could be an efficient shuttle for spreading of this resistance gene among other opportunistic pathogens that are normally members of the resident microbiota, Kinetic parameters determined for the PER-1 enzyme with some cephalosporin substrates were somewhat different from those previously reported.