Comparison of biofilm-producing Enterococcus faecalis, Enterococcus faecium, and unusual Enterococcus strains

The present study focused on determining the prevalence of biofilm-forming ability in Enterococ-cus faecalis, E. faecium, and unusual Enterococcus clinical isolates, and comparison of resistance and the prevalence of selected virulence factors among biofilm-positive strains. The ability to form biofilm was detected in 13.3% of E. faecalis, 90% of E. faecium, and 57.1% of unusual Enterococcus strains (p=0.026). All E. faecalis strains were susceptible to β-lactams, while 37.5% of unusual and all E. faecium isolates were resistant to these antibiotics. Resistance to gentamicin was detected in 75% of E. faecalis, 55.5% of E. faecium, and 25% of other strains; resistance to streptomycin in 25%, 83.3%, and 50%, respectively. Analysis of the virulence revealed that the enterococcal surface protein (esp) gene was found in all E. faecium, 75.0% of E. faecalis, and 37.5% of other strains; collagen adhesin gene (ace) in 100%, 25.0%, and 37.5%; and hyaluronidase gene (hyl) in 83.3%, 0%, and 37.5%, respectively. Analysis of the resistance and virulence patterns showed that E. faecium isolates had the greatest variety of virulence and resistance determinants, while the lowest variety was exhibited by unusual strains. These findings indicate that unusual biofilm-producing Enterococcus strains have lower resistance and virulence potency than E. faecalis and E. faecium. DOI: http://dx.doi.org/10.5281/zenodo.100083

Profiles of phenotype resistance to antibiotic other than β-lactams in Klebsiella pneumoniae ESBLs-producers, carrying blaSHV genes.

Extended spectrum β-lactamases production is one of the most common mechanism of resistance to extended spectrum β-lactam antibiotics is increasing worldwide. Twenty five strains of Klebsiella pneumoniae isolated from clinical specimens were tested. Based on the phenotypic confirmatory test all these strains were defined as ESBL producers named ESBL(+). The plasmid DNA from each strains was used to investigate the presence of blaSHV genes responsible for extended spectrum β-lactamases production. Moreover, susceptibility of these strains to antibiotic other than β-lactams in was tested

Influence of Unmodified and β-Glycerophosphate Cross-Linked Chitosan on Anti-Candida Activity of Clotrimazole in Semi-Solid Delivery Systems

The combination of an antifungal agent and drug carrier with adjunctive antimicrobial properties represents novel strategy of complex therapy in pharmaceutical technology. The goal of this study was to investigate the unmodified and ion cross-linked chitosan’s influence on anti-Candida activity of clotrimazole used as a model drug in hydrogels. It was particularly crucial to explore whether the chitosans’ structure modification by β-glycerophosphate altered its antifungal properties. Antifungal studies (performed by plate diffusion method according to CLSI reference protocol) revealed that hydrogels obtained with chitosan/β-glycerophosphate displayed lower anti-Candida effect, probably as a result of weakened polycationic properties of chitosan in the presence of ion cross-linker. Designed chitosan hydrogels with clotrimazole were found to be more efficient against tested Candida strains and showed more favorable drug release profile compared to commercially available product. These observations indicate that novel chitosan formulations may be considered as promising semi-solid delivery system of clotrimazole

Occurrence of the aacA4 gene among multidrug resistant strains of Pseudomonas aeruginosa isolated from bronchial secretions obtained from the Intensive Therapy Unit at University Hospital in Bialystok, Poland

The aim of this study was to investigate the prevalence of the aacA4 gene in a population of multidrug resistant strains of P. aeruginosa isolated from bronchial secretions obtained from the Intensive Therapy Unit (ITU). Twelve MDR isolates were tested for antibiotic susceptibility and the presence of the aacA4 gene. In this study, 58.3% of the strains contained (6’)-Ib’ aminoglycoside acetyltransferase gene. All of the studied strains (aacA4-positive and aacA4-negative) were susceptible only to colistine (100%). Among other antibiotics, the lowest resistance rates were those shown against ceftazidime (14.3% to 20%) and imipenem (28.6% to 40%). Our studies frequently revealed the presence of the aacA4 gene as a factor responsible for resistance; it is probable that other mechanisms of resistance to aminoglycoside antibiotics also occurred

Occurrence of the <i>aacA4</i> gene among multidrug resistant strains of <i>Pseudomonas aeruginosa</i> isolated from bronchial secretions obtained from the Intensive Therapy Unit at University Hospital in Bialystok, Poland

The aim of this study was to investigate the prevalence of the <em>aacA4</em> gene in a population of multidrug resistant strains of <em>P. aeruginosa</em> isolated from bronchial secretions obtained from the Intensive Therapy Unit (ITU). Twelve MDR isolates were tested for antibiotic susceptibility and the presence of the <em>aacA4</em> gene. In this study, 58.3% of the strains contained (6’)-Ib’ aminoglycoside acetyltransferase gene. All of the studied strains (<em>aacA4</em>-positive and <em>aacA4</em>-negative) were susceptible only to colistine (100%). Among other antibiotics, the lowest resistance rates were those shown against ceftazidime (14.3% to 20%) and imipenem (28.6% to 40%). Our studies frequently revealed the presence of the <em>aacA4</em> gene as a factor responsible for resistance; it is probable that other mechanisms of resistance to aminoglycoside antibiotics also occurred

Comparison of biofilm-producing Enterococcus faecalis, Enterococcus faecium, and unusual Enterococcus strains

The present study focused on determining the prevalence of biofilm-forming ability in Enterococ-cus faecalis, E. faecium, and unusual Enterococcus clinical isolates, and comparison of resistance and the prevalence of selected virulence factors among biofilm-positive strains. The ability to form biofilm was detected in 13.3% of E. faecalis, 90% of E. faecium, and 57.1% of unusual Enterococcus strains (p=0.026). All E. faecalis strains were susceptible to β-lactams, while 37.5% of unusual and all E. faecium isolates were resistant to these antibiotics. Resistance to gentamicin was detected in 75% of E. faecalis, 55.5% of E. faecium, and 25% of other strains; resistance to streptomycin in 25%, 83.3%, and 50%, respectively. Analysis of the virulence revealed that the enterococcal surface protein (esp) gene was found in all E. faecium, 75.0% of E. faecalis, and 37.5% of other strains; collagen adhesin gene (ace) in 100%, 25.0%, and 37.5%; and hyaluronidase gene (hyl) in 83.3%, 0%, and 37.5%, respectively. Analysis of the resistance and virulence patterns showed that E. faecium isolates had the greatest variety of virulence and resistance determinants, while the lowest variety was exhibited by unusual strains. These findings indicate that unusual biofilm-producing Enterococcus strains have lower resistance and virulence potency than E. faecalis and E. faecium. DOI: http://dx.doi.org/10.5281/zenodo.100083

Comparison of antibiotic resistance and virulence between biofilm-producing and non-producing clinical isolates of Enterococcus faecium

An increase in the antibiotic resistance among Enterococcus faecium strains has been observed worldwide. Moreover, this bacteria has the ability to produce several virulence factors and to form biofilm that plays an important role in human infections. This study was designed to compare the antibiotic resistance and the prevalence of genes encoding surface protein (esp), aggregation substance (as), surface adhesin (efaA), collagen adhesin (ace), gelatinase (gelE), and hialuronidase (hyl) between biofilm-producing and non-producing E. faecium strains. Therefore, ninety E. faecium clinical isolates were tested for biofilm-forming ability, and then were assigned to two groups: biofilm-positive (BIO+, n =70) and biofilm-negative (BIO-, n = 20). Comparison of these groups showed that BIO+ isolates were resistant to β-lactams, whereas 10% of BIO- strains were susceptible to ampicillin (statistically significant difference, p = 0.007) and 5% to imipenem. Linezolid and tigecycline were the only antibiotics active against all tested isolates. Analysis of the virulence factors revealed that ace, efaA, and gelE genes occurred more frequently in BIO- strains (ace in 50% BIO+ vs. 75% BIO-; efaA 44.3% vs. 85%; gelE 2.9% vs. 15%, respectively), while hyl gene appeared more frequently in BIO+ isolates (87.1% BIO+ vs. 65% BIO-). These differences were significant (p < 0.05). We concluded that BIO+ strains were more resistant to antibiotics than BIO- strains, but interestingly, BIO- isolates were characterized by possession of higher virulence capabilities

Emergence of a multidrug-resistant Citrobacter freundii ST8 harboring an unusual VIM-4 gene cassette in Poland

Objectives: The growing incidence of multidrug-resistant (MDR) bacteria is an emerging challenge in modern medicine. The utility of carbapenems, which are considered ‘last-line’ agents, is being diminished by the growing incidence of various resistance mechanisms in Gram-negative bacteria. A molecular investigation was performed of an MDR carbapenem-resistant Citrobacter freundii of sequence type 8 (ST8) isolated from a hematology patient with acute myeloid leukemia. Methods: Multilocus sequence typing and analysis of the nucleotide sequence of the class I integron were performed using PCR and Sanger sequencing. Transformation of the resistance plasmid isolated following the alkaline lysis method was performed using chemically competent E. coli TOP10. Results: Molecular analysis of the carbapenem-resistant C. freundii revealed the presence of the VIM-4 isoenzyme located on the ∼55-kb transferable resistance plasmid. Interestingly, the blaVIM-4 gene was inserted into an unusual gene cassette containing a 169-bp direct repeat of the 3′ segment of the blaVIM-4 gene. Conclusions: All unusual gene cassettes containing VIM-DR (direct repeat) described thus far have been harbored by non-fermenters, i.e., Acinetobacter and Pseudomonas, underscoring the importance of resistance determinant mobility, which may go even beyond genus, family, and order boundaries. Great efforts need to be taken to explore pathways of resistance to ‘last-resort’ antimicrobials, especially among clinically relevant pathogens