ABSTRACT
Acquired metallo-beta-lactamases (MBLs) can confer broad-spectrum beta-lactam resistance (including carbapenems) not reversible by conventional beta-lactamase inhibitors and are emerging resistance determinants of remarkable clinical importance. In 2001, multidrug-resistant Pseudomonas aeruginosa carrying bla(VIM) MBL genes were found to be widespread (approximately 20% of all P. aeruginosa isolates and 70% of the carbapenem-resistant isolates) at Trieste University Hospital. Clonal diversity and heterogeneity of resistance determinants (either bla(VIM-1)-like or bla(VIM-2)-like) were detected among MBL producers. This evidence is the first that acquired MBLs can rapidly emerge and establish a condition of endemicity in certain epidemiologic settings.
Subject(s)
Carbapenems/pharmacology , Drug Resistance/genetics , Pseudomonas aeruginosa/genetics , beta-Lactam Resistance/genetics , Europe , Genotype , Humans , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/isolation & purification , Random Amplified Polymorphic DNA Technique , beta-Lactam Resistance/drug effectsABSTRACT
A new rapid microdilution method, employing the dye resazurin as an indicator of mycobacterial growth, was developed to evaluate drug susceptibility of Mycobacterium tuberculosis reference strain H37Rv and of 13 M. tuberculosis susceptible or multidrug-resistant clinical strains. Different growth conditions were evaluated. The MICs of isoniazid, rifampicin, streptomycin and ethambutol were determined by the Microdilution Resazurin Assay (MRA) and the results compared with those obtained by the agar proportion method; complete agreement was always obtained. MRA resulted in a rapid, reliable, simple and inexpensive coloured method suitable for testing the susceptibility of M. tuberculosis clinical strains to first-line drugs; its employment in evaluating new antibacterial molecules is also suggested.
Subject(s)
Antitubercular Agents/pharmacology , Indicators and Reagents/metabolism , Mycobacterium tuberculosis/drug effects , Mycobacterium tuberculosis/growth & development , Oxazines/metabolism , Xanthenes , Agar , Colony Count, Microbial , Culture Media , Humans , Microbial Sensitivity Tests/methods , Tuberculosis, Pulmonary/microbiologyABSTRACT
Integron carriage by 36 epidemiologically unrelated Acinetobacter baumannii isolates collected over an 11-year period from patients in six different Italian hospitals was investigated. Sixteen type 1 integron-positive isolates (44%) were found, 13 of which carried the same array of cassettes, i.e., aacC1, orfX, orfX', and aadA1a. As ribotype analysis of the isolates demonstrated a notable genetic diversity, horizontal transfer of the entire integron structure or ancient acquisition was hypothesized.
Subject(s)
Acinetobacter Infections/microbiology , Acinetobacter baumannii/genetics , Integrons/genetics , Acinetobacter baumannii/drug effects , Blotting, Southern , Genes, Bacterial/genetics , Italy , Molecular Sequence Data , Nucleic Acid Hybridization , Oligonucleotide Array Sequence Analysis , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Eleven strains of Burkholderia cepacia were isolated directly from clinical specimens: 10 from sputum of cystic fibrosis patients, and one from a vaginal swab. They were biochemically identified using API20NE and confirmed by a PCR-based assay. The genomovar characterisation obtained by specific PCR amplification revealed seven strains belonging to genomovar I, three belonging to genomovar IIIA and one belonging to genomovar IV. All isolates were also typed by ribotyping and random amplification of polymorphic DNA analysis. Some of the characterised strains were examined for the ability to produce exopolysaccharides, with the aim of correlating the genomovar with the exopolysaccharide structure. The polysaccharides were analysed by means of methylation analysis and 1H-NMR spectroscopy in order to determine structural similarities. It was shown that different strains are capable of producing chemically different polysaccharides.
