Multicentre investigation of carbapenemase-producing Klebsiella pneumoniae and Escherichia coli in Bulgarian hospitals - Interregional spread of ST11 NDM-1-producing K. pneumoniae.

Aim: The aim of this study was to investigate the mechanisms of beta-lactam-resistance and the clonal relatedness of carbapenem-nonsusceptible Klebsiella pneumoniae and Escherichia coli isolates, collected consecutively in eight centers in five Bulgarian cities from November 2014 to March 2018. Carbapenemase-producing enterobacteria were detected in all but one centers. Overall, 104 K.

Dissemination of a Multidrug-Resistant VIM-1- and CMY-99-Producing Proteus mirabilis Clone in Bulgaria.

The aim of this study was to analyze the beta-lactamases and the molecular epidemiology of 19 clinically significant isolates of Proteus mirabilis with decreased susceptibility to imipenem, which have been collected from seven hospitals, located in different Bulgarian towns (Sofia, Varna, and Pleven). The isolates were obtained from blood, urine, tracheal and wound specimens. One additional isolate from hospital environment was included.

Intrinsic carbapenem-hydrolyzing oxacillinases from members of the genus Pandoraea.

We analyzed the oxacillinases of isolates of six different species of Pandoraea, a genus that colonizes the respiratory tract of cystic fibrosis patients. The isolates produced carbapenem-hydrolyzing enzymes causing elevated MICs for amoxicillin, piperacillin, meropenem, and imipenem when expressed in an Escherichia coli host strain. Sequencing revealed nine new oxacillinases (OXA-151 to OXA-159) with a high degree of identity among isolates of the same species; however, they had much lower interspecies similarities.

New variant of CTX-M-type extended-spectrum beta-lactamases, CTX-M-71, with a Gly238Cys substitution in a Klebsiella pneumoniae isolate from Bulgaria.

A single Klebsiella pneumoniae strain isolated in a Bulgarian hospital was found to produce CTX-M-71, a new CTX-M variant characterized by one amino acid substitution from glycine to cysteine at position 238 in comparison to CTX-M-15. This exchange decreased the hydrolytic activity of the beta-lactamase for cefotaxime, ceftazidime, and cefepime.

VIM-15 and VIM-16, two new VIM-2-like metallo-beta-lactamases in Pseudomonas aeruginosa isolates from Bulgaria and Germany.

Two Pseudomonas aeruginosa urine isolates from Bulgaria and Germany produced two new VIM-2 variants. VIM-15 had one amino acid substitution (Tyr218Phe) which caused a significant increase in hydrolytic efficiency. The substitution Ser54Leu, characterizing VIM-16, showed no influence on enzyme activity.

Dissemination and persistence of a plasmid-mediated TEM-3-like beta-lactamase, TEM-139, among Enterobacteriaceae in Bulgaria.

During a survey of extended-spectrum beta-lactamases (ESBLs) in Bulgaria from 1996 to 2003, a TEM-3-like ESBL was detected in strains of Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii and Klebsiella oxytoca from three centres in three different towns. The nucleotide sequence of the cloned gene was identical to that of TEM-3, except for one substitution (C347A) causing an amino acid exchange at position 49 from leucine to methionine. This TEM-3 variant with both a unique nucleotide and amino acid sequence was designated TEM-139.

Novel carbapenem-hydrolyzing oxacillinase OXA-62 from Pandoraea pnomenusa.

Pandoraea spp. are gram-negative, glucose nonfermenting rods detectable in blood cultures and sputa of cystic fibrosis patients. They are resistant to various antibiotic groups, with imipenem being the only active beta-lactam.