title: Incidence of strains producing extended spectrum beta-lactamases in Argentina.
abstract: The incidence of strains producing transferable beta-lactamases capable of hydrolyzing third generation cephalosporins or aminothiazole-oximino substituted monobactams in five Buenos Aires hospitals during a four month period was studied. These enzymes were categorized by 1) MIC greater than or equal to 1 mg/l for third generation cephalosporins; 2) MIC less than 0.06 mg/l for third generation cephalosporins combined with clavulanic acid or sulbactam; 3) sensitivity to imipenem or cephamycins (excluding permeability mutants); and 4) transferable resistance by conjugation. Beta-lactamases hydrolyzing aminothiazole-oximino substituted monobactams were produced by 17.2% of Enterobacteriaceae from intensive care unit patients; 3.6% from inpatients of other units and 1.2% from outpatients. Producers were mainly Klebsiella spp. (45/46) resistant to aminoglycosides (most of them AAC 3'-AAC 6' producers). Three strains had a an isoelectric point of 6.0, two of 6.5 and three of 7.7. TEM-1 beta-lactamase (isoelectric point 5.4) was detected in 6/8 strains. An inocolum effect was observed in 40/46 strains. A Klebsiella pneumoniae strain preserved since 1982 also produced a transferable beta-lactamase hydrolyzing aminothiazole-oximino substituted monobactams.
authors.affiliation: Department of Diseases and Clinical Microbiology, Catholic University, Buenos Aires, Argentina.
authors.forename: J M
authors.initials: JM
authors.lastname: Casellas
authors.forename: M
authors.initials: M
authors.lastname: Goldberg
mesh_terms: D000328:Adult; D001118:Argentina / Q000453:epidemiology; D001424:Bacterial Infections / Q000145:classification / Q000201:enzymology* / Q000453:epidemiology; D003227:Conjugation, Genetic; D004352:Drug Resistance, Microbial / Q000235:genetics; D006801:Humans; D006868:Hydrolysis; D015994:Incidence; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics
chemical_list: D001618:beta-Lactamases