ABSTRACT
Of two patients in the same intensive care unit who were treated with linezolid, one yielded linezolid-resistant Enterococcus faecalis, whereas the other yielded linezolid-resistant Enterococcus faecium. In each case, molecular typing indicated that the resistant isolates were related to linezolid-susceptible isolates from the same patient, but differed from them by the same G2576U ribosomal RNA mutation. This is the first clinical case report of emerging resistance to linezolid among Enterococcus faecalis and also the first report of resistance involving vancomycin-susceptible rather than vancomycin-resistant enterococci. The linezolid-resistant isolates showed cross-resistance to the experimental oxazolidinone AZD2563, suggesting that oxazolidinone resistance might be a class effect.
Subject(s)
Acetamides/pharmacology , Anti-Bacterial Agents/pharmacology , Cross Infection/microbiology , Enterococcus faecalis/drug effects , Enterococcus faecium/drug effects , Gram-Positive Bacterial Infections/diagnosis , Oxazolidinones/pharmacology , Aged , Austria , Base Sequence , Cross Infection/diagnosis , DNA, Bacterial , Drug Resistance, Microbial , Enterococcus faecalis/isolation & purification , Enterococcus faecium/isolation & purification , Humans , Intensive Care Units , Linezolid , Male , Microbial Sensitivity Tests , Middle Aged , Molecular Sequence Data , Polymerase Chain Reaction , Sensitivity and SpecificityABSTRACT
Eighty-two carbapenem-resistant isolates of Acinetobacter baumannii from a single hospital in Bilbao were typed into two major clusters and several subclusters. Disk synergy tests and PCR indicated the production of a zinc-independent OXA-class carbapenemase. Sequencing identified this enzyme, OXA-40, as a variant of the OXA-24-OXA-25-OXA-26 cluster.
Subject(s)
Acinetobacter baumannii/drug effects , Bacterial Proteins , Carbapenems/pharmacology , Drug Resistance, Bacterial , beta-Lactamases , Acinetobacter Infections/epidemiology , Acinetobacter Infections/microbiology , Acinetobacter baumannii/enzymology , Amino Acid Sequence , Endemic Diseases , Hospital Bed Capacity, 100 to 299 , Hospitals, Urban , Humans , Microbial Sensitivity Tests , Molecular Sequence Data , Sequence Analysis, DNA , Spain/epidemiology , beta-Lactamases/chemistry , beta-Lactamases/genetics , beta-Lactamases/metabolismABSTRACT
The novel ketolide telithromycin (formerly HMR-3647) was tested against a collection of pneumococci of varying sensitivity to erythromycin and clindamycin, isolated in geographically diverse UK hospitals. Telithromycin was highly active against erythromycin-susceptible pneumococci, the MIC(90) being 0.015 mg/l. Erythromycin-resistant pneumococci that contained the ermB gene, either alone or together with the mefE gene, were cross-resistant to other macrolides and to clindamycin, while erythromycin-resistant pneumococci that contained only the mefE gene were cross-resistant to azithromycin, clarithromycin and roxithromycin but remained susceptible to josamycin and clindamycin. Telithromycin was active against erythromycin-resistant pneumococci irrespective of their mechanism of macrolide resistance, although the MIC(90) (0.25 mg/l) was higher than that seen with erythromycin-sensitive isolates. Telithromycin thus appears to be a potentially useful drug in settings where pneumococcal resistance to macrolides is prevalent.
