We report on the identification of two new Francisella-like endosymbionts (FLEs) found in three different tick species from Bulgaria. The FLEs were characterized by 16S rRNA and tul4 gene sequencing and seem to lack the molecular marker RD1. These two new taxa seem to be facultative secondary endosymbionts of ticks.

A panel of 29 multidrug-resistant (MDR) Pseudomonas aeruginosa isolates recovered from seven hospitals as part of a country-wide surveillance of antimicrobial resistance in Bulgarian hospitals was studied. Molecular typing through multiple-locus variable number tandem-repeat analysis (MLVA6) yielded 23 different profiles. Phenotypic and genotypic tests for the detection of acquired carbapenemases yielded negative results in all cases. In contrast, 76% of the isolates produced other acquired β-lactamases, including extended-spectrum β-lactamases (ESBLs). Namely, 6 of the isolates (21%) produced a VEB-1 ESBL; 14 (48%) produced an OXA-10-type enzyme (7 OXA-10 and 7 OXA-10 ESBL variants, including 2 OXA-17 [A218G], 2 OXA-74 [C197T, A218G], and 3 OXA-142 [A218G, G470A]); 8 (28%) an OXA-2-type enzyme (all OXA-2); and 1 (3%) a PSE-1 carbenicillinase. Further analysis through multilocus sequence typing (MLST) revealed that the six VEB-1-producing strains, recovered from four hospitals, belonged to ST111 or ST244 international high-risk clones. Additionally, nearly all of the isolates (97%) lacked OprD production, explaining carbapenem resistance. Overexpression of AmpC was documented in 5 (17%) of the isolates, including most of the MDR isolates not producing any acquired β-lactamase. Particularly noteworthy was the very high prevalence of MexXY-OprM overexpression, documented in 72% of the isolates, whereas the prevalence of MexAB-OprM overexpression was lower (21%). In summary, while the production of metallo-β-lactamases is uncommon among P. aeruginosa isolates from Bulgarian hospitals, MDR profiles frequently result from the production of ESBLs combined with the lack of production of the carbapenem porin OprD and the overexpression of the MexXY-OprM efflux pump.

No abstract

This report describes the first identification of OXA-24 carbapenemase-producing Acinetobacter baumannii isolates from Bulgaria. According to national surveillance data A. baumannii along with Pseudomonas aeruginosa are the most troublesome microorganisms in hospital environment with high rates of acquired carbapenem resistance. In the present study real-time multiplex PCR was performed to identify the most common carbapenemase genes in 15 non-duplicate carbapenem-resistant A. baumannii isolates collected in 2012. The results showed lack of KPC, GES, VIM, IMP-type enzymes. Four A. baumannii isolates tested positive by PCR for the acquired OXA-24 together with the intrinsic OXA-51 carbapenemase. OXA-24 and OXA-23 were determined as co-existent in one isolate. Two isolates were identified with OXA-23 in addition to the OXA-51 carbapenemase.