Most E. faecalis attaches to abiotic surfaces in hospital environment, which correlates with higher prevalence of gene encoding for virulence factors involved in biofilm formation, such as enterococcal surface protein, aggregation substance, and gelatinase. The intestinal tract is an important reservoir for opportunistic enterococcal pathogens and allows them to access infectious sites through different virulence factors, demonstrated in outpatient isolates in this study.
Twelve consecutive carbapenem-resistant Escherichia coli isolates were recovered from patients (infection or colonization) hospitalized between March and September 2012 in different units at a hospital in Bulgaria. They all produced the carbapenemase NDM-1 and the extended-spectrum--lactamase CTX-M-15, together with the 16S rRNA methylase RmtB, conferring high-level resistance to all aminoglycosides. All those isolates were clonally related and belonged to the same sequence type, ST101. In addition to being the first to identify NDM-producing isolates in Bulgaria, this is the very first study reporting an outbreak of NDM-1-producing E. coli in the world. W orldwide occurrence of carbapenemase producers amongEnterobacteriaceae is now well recognized (1, 2). In Europe, there are distinct epidemiological situations corresponding mainly to the diffusion of OXA-48 producers in France, Belgium, The Netherlands, and Turkey (3, 4) and KPC-producing isolates in Italy and Greece (5), while some countries show more diverse distributions, such as in the United Kingdom, where KPC, OXA-48, VIM, and NDM-1 producers are being found (6). The recent emergence of NDM-1 producers (mostly Klebsiella pneumoniae isolates) is often related to imported cases, with a link to the Indian subcontinent (7). In addition, there are sporadic reports of NDM-1 producers (Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa) originating from countries of the Middle East or the Balkan region, including Croatia, Kosovo, and Serbia (7,8). Very little information is available regarding the diffusion of carbapenemase producers in Eastern Europe. Therefore, our study aimed to characterize the mechanisms responsible for carbapenem resistance by investigating a collection of enterobacterial isolates recovered in Bulgaria. From March to September 2012, 12 Escherichia coli isolates being resistant to carbapenems were recovered at the Military Medical Academy hospital of Sofia, Bulgaria. Susceptibility testing was performed by disk diffusion on solid agar plates following the CLSI recommendations (9). Those isolates had been recovered from urine (n ϭ 4), blood (n ϭ 1), respiratory specimens (n ϭ 2), wound (n ϭ 1), catheter (n ϭ 1), abdominal exudate (n ϭ 1), and rectal swabs (n ϭ 2). The MICs of carbapenems were determined by Etest (AB bioMérieux, La Balme-les-Grottes, France) on Mueller-Hinton agar plates at 37°C, and results of susceptibility testing were interpreted according to the CLSI guidelines (10). The MICs of imipenem, meropenem, and ertapenem were 32, Ͼ32, and Ͼ32 g/ml for all the E. coli isolates, respectively. They were resistant to all -lactams, including broad-spectrum cephalosporins (MICs of ceftazidime and cefotaxime being Ͼ32 g/ml) ( Table 1). In addition, they were resistant to all tested aminoglycosides (amikacin, gentamicin, netilmicin, kanamycin) and to fluoroquinolones and sulfonamides. Using the Etest, the MIC of rifampin was elevated (128 g/ml), and that of colistin was found to be 0.5 g/ml.Carbapenemase detecti...
A collection of 40 Bacillus anthracis strains mostly isolated from soil in Bulgaria between 1960 and 1980 were investigated. All strains were proven to be B. anthracis by culture and amplification of a B. anthracis-specific chromosomal marker. PCR demonstrated that in nine strains both virulence plasmids (pX01+/pX02+) and in four strains only one plasmid (pX02+) were present, whereas the majority of strains (n = 27) lacked both plasmids (pX01-/pX02-). Multi-locus-variable number of tandem repeat-analysis (MLVA) using 15 markers differentiated three genotypes. Comparison with typing data of more than 1,000 different B. anthracis strains revealed that Bulgarian genotypes affiliated with the A1.a cluster and form their own unique cluster different from clusters containing strains isolated in geographical proximity, e.g., Turkey, Georgia, Hungary, Albania or Italy. In addition, a new allele of one marker (vrrC2) was identified. Canonical single nucleotide polymorphisms analysis allocated 31 Bulgarian strains into the A.Br.008/009 and nine strains into the A.Br.WNA group, which is the first description of B. anthracis strains of the A.Br.WNA group on the Eurasian continent.
The aim of the study was to describe the emergence, the spread, and the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in Bulgaria. Over eight years (1996-2003), 442 ESBL-screen-positive isolates were collected in nine medical institutions in four Bulgarian towns. Class A ESBLs of the SHV, TEM, and CTX-M groups were identified in seven species. SHV-type enzymes persisted during the whole study period, TEM-ESBLs appeared first in 1999, and CTX-M-types appeared first in 2001. The rate of CTX-M enzyme producers increased rapidly between 2001 and 2003, while the rate of SHV producers decreased. Six different ESBL-types were identified, namely, SHV-2, -5, and -12, CTX-M-3 and -15, and a new TEM-3-like variant (TEM-139). The most widespread enzymes were SHV-12, CTX-M-15, and CTX-M-3 found in seven centers. TEM-139 was identified mainly in one center. A trend for strains harboring more than one ESBL gene, for example, CTX-M + SHV, was observed since 2002. Plasmid fingerprinting and random amplified polymorphic DNA analysis typing revealed wide dissemination of identical plasmids among different bacterial species and hospitals, as well as clonal spread of ESBL producers. Our data contribute to clarify the dynamics in the prevalence of ESBLs in Bulgaria and demonstrate the importance of molecular procedures for their analysis.
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