The microbiota consists of a dynamic multispecies community of bacteria, fungi, archaea, and protozoans, bringing to the host organism a dowry of cells and genes more numerous than its own. Among the different non-sterile cavities, the human gut harbors the most complex microbiota, with a strong impact on host homeostasis and immunostasis, being thus essential for maintaining the health condition. In this review, we outline the roles of gut microbiota in immunity, starting with the background information supporting the further presentation of the implications of gut microbiota dysbiosis in host susceptibility to infections, hypersensitivity reactions, autoimmunity, chronic inflammation, and cancer. The role of diet and antibiotics in the occurrence of dysbiosis and its pathological consequences, as well as the potential of probiotics to restore eubiosis is also discussed.

Antibiotic resistance is one of the biggest challenges for the clinical sector and industry, environment and societal development. One of the most important pathogens responsible for severe nosocomial infections is Acinetobacter baumannii, a Gram-negative bacterium from the Moraxellaceae family, due to its various resistance mechanisms, such as the β-lactamases production, efflux pumps, decreased membrane permeability and altered target site of the antibiotic. The enormous adaptive capacity of A. baumannii and the acquisition and transfer of antibiotic resistance determinants contribute to the ineffectiveness of most current therapeutic strategies, including last-line or combined antibiotic therapy. In this review, we will present an update of the antibiotic resistance profiles and underlying mechanisms in A. baumannii and the current progress in developing innovative strategies for combating multidrug-resistant A. baumannii (MDRAB) infections.

BackgroundThe purpose of this study was to evaluate the virulence profiles of Pseudomonas aeruginosa clinical strains recently isolated from patients hospitalized for chronic leg ulcers in the Dermatology Department of Central Military Emergency University Hospital “Carol Davila”, Bucharest, Romania.MethodsThe phenotypic screening evaluated eight soluble virulence factors (haemolysins, lecithinase, lipase, caseinase, gelatinase, amylase, DNase, aesculin hydrolysis), as well as adherence ability (Cravioto adapted method) and invasion capacity on HeLa cells (gentamicin protection assay). Seven virulence genes encoding for protease IV, 3 exoenzymes (exoS, exoT, exoU), two phospholipases plcH- haemolytic phospholipase C and plcN- non-haemolytic phospholipase C) and alginate were investigated by PCR.ResultsThe pore forming toxins and enzymes were expressed in variable proportions, the majority of the tested strains producing beta haemolysin (92.3 %), lipase (76.9 %) and lecithinase (61.5 %). The most frequent virulence genes detected in the analyzed strains were the ExoT (100 %) and AlgD (92.3 %) genes, genes codifying for phospholipases (84.6 % each of them) and for protease IV (61.5 %).ConclusionsThis study reveals that correlating virulence profiles and infection clinical outcome is very useful for setting up efficient preventive and therapeutic procedures for hospitalized patients with chronic leg ulcers and positive P. aeruginosa cultures.

We report on the genomic characterization of 47 multi-drug resistant, carbapenem resistant and ESBL-producing K. pneumoniae isolates from the influent (I) and effluent (E) of three wastewater treatment plants (WWTPs) and from Romanian hospital units which are discharging the wastewater in the sampled WWTPs. The K. pneumoniae whole genome sequences were analyzed for antibiotic resistance genes (ARGs), virulence genes and sequence types (STs) in order to compare their distribution in C, I and E samples. Both clinical and environmental samples harbored prevalent and widely distributed ESBL genes, i.e. bla SHV , bla OXA , bla TEM and bla CTX M . The most prevalent carbapenemase genes were bla NDM-1 , bla OXA-48 and bla KPC-2 . They were found in all types of isolates, while bla OXA-162 , a rare bla OXA-48 variant, was found exclusively in water samples. A higher diversity of carbapenemases genes was seen in wastewater isolates. The aminoglycoside modifying enzymes (AME) genes found in all types of samples were aac(6'), ant(2'') Ia, aph(3'), aaD, aac(3) and aph(6). Quinolone resistance gene qnrS1 and the multi-drug resistance oqxA/B pump gene were found in all samples, while qnrD and qnrB were associated to aquatic isolates. The antiseptics resistance gene qacEdelta1 was found in all samples, while qacE was detected exclusively in the clinical ones. Trimethroprim-sulfamethoxazole (dfrA, sul1 and sul2), tetracyclines (tetA and tetD) and fosfomycin (fosA6, known to be located on a transpozon) resistance genes were found in all samples, while for choramphenicol and macrolides some ARGs were detected in all samples (catA1 and catB3 / mphA), while other (catA2,

Decades of antibiotic misuse in clinical settings, animal feed, and within the food industry have led to a concerning rise in antibiotic-resistant bacteria. Every year, antimicrobial-resistant infections cause 700,000 deaths, with 10 million casualties expected by 2050, if this trend continues. Hence, innovative solutions are imperative to curb antibiotic resistance. Bacteria produce a potent arsenal of drugs with remarkable diversity that are all distinct from those of current antibiotics. Bacteriocins are potent small antimicrobial peptides synthetized by certain bacteria that may be appointed as alternatives to traditional antibiotics. These molecules are strategically employed by commensals, mostly Firmicutes, to colonize and persist in the human gut. Bacteriocins form channels in the target cell membrane, leading to leakage of low-molecular-weight, causing the disruption of the proton motive force. The objective of this review was to list and discuss the potential of bacteriocins as antimicrobial therapeutics for infections produced mainly by resistant pathogens.

Oral cavity represents an ideal environment for the microbial cell growth, persistence, and dental plaque establishment. The presence of different microniches leads to the occurrence of different biofilm communities, formed on teeth surface, above gingival crevice or at subgingival level, on tongue, mucosa and dental prosthetics too. The healthy state is regulated by host immune system and interactions between microbial community members, maintaining the predominance of "good" microorganisms. When the complexity and volume of biofilms from the gingival crevice increase, chronic pathological conditions such as gingivitis and periodontitis can occur, predisposing to a wide range of complications. Bacteria growing in biofilms exhibit a different behavior compared with their counterpart, respectively planktonic or free cells. There have been described numerous mechanisms of differences in antibiotic susceptibility of biofilm embedded cells. Resistance to antibiotics, mediated by genetic factors or, phenotypical, due to biofilm formation, called also tolerance, is the most important cause of therapy failure of biofilm-associated infections, including periodontitis; the mechanisms of tolerance are different, the metabolic low rate and cell's dormancy being the major ones. The recent progress in science and technology has made possible a wide range of novel approaches and advanced therapies, aiming the efficient management of periodontal disease.

This is the first study, to our knowledge, performed on a significant number of strains (79 carbapenem-resistant Enterobacteriaceae and 84 carbapenem-resistant non-fermenting Gramnegative rods, GNRs) isolated from tissue samples taken from patients in the intensive care units of two large hospitals in Bucharest, Romania, between 2011 and 2012. The results revealed a high prevalence and great diversity of carbapenemase genes (CRG), in both fermenting and non-fermenting Gram-negative carbapenem-resistant strains. The molecular screening of carbapenem-resistant GNRs revealed the presence of worldwide-distributed CRGs (i.e. bla and bla NDM-1 in Enterobacteriaceae and bla , bla , bla OXA-10-like , bla OXA-60-like , bla SPM-like and bla GES-like in non-fermenting GNRs), reflecting the rapid evolution and spread of carbapenemase producers, particularly in hospitals. Rapid identification of the colonized or infected patients is required, as are epidemiological investigations to establish the local or imported origin of the respective strains. INTRODUCTIONCarbapenemases represent the most versatile family of blactamases, with a breadth of spectrum unrivalled by other b-lactam-hydrolysing enzymes (Queenan & Bush, 2007). Although known as carbapenemases, many of these enzymes recognize almost all hydrolysable b-lactams, and most are resilient against inhibition by all commercially available b-lactamase inhibitors ; this resilience is often accompanied by resistance to other classes of antibiotics. Carbapenem-resistant Enterobacteriaceae represent a cause of difficult-to-treat infections in hospitalized patients associated with high mortality, and these strains have also been spreading in long-term care facilities (CDC, 2013;Perez & Van Duin, 2013; Tzouvelekis et al., 2012). Although most carbapenem resistance in Pseudomonas aeruginosa is due to porin loss, hospital outbreaks of metallo-blactamase-producing P. aeruginosa have occurred worldwide 3These authors contributed equally to this work.Abbreviations: Amc, amoxicillin+clavulanic acid; Amk, amikacin; Atm, aztreonam; Caz, ceftazidime; Chl, chloramphenicol; Cip, ciprofloxacin; Col, colistin; CRG, carbapenemase gene; Cro, ceftriaxone; Ctx, cefotaxime; Cxm, cefuroxime; Etp, ertapenem; ESBL, extended-spectrum b-lactamase; Fep, cefepime; Fox, cefoxitin; Gen, gentamicin; GNR, Gram-negative rod; ICU, intensive care unit; Imp, imipenem; Lvx, levofloxacin; MBL, metallo-b-lactamase; Mem, meropenem; Min, minocycline; Nit, nitrofurantoin; Nor, norfloxacin; Pip, piperacillin; Prl, piperacillin; Sxt, trimethoprim+sulfamethoxazole; Tgc, tigecycline; Tet, tetracycline; Tic, ticarcillin; Tic+clav, ticarcillin+clavulanic acid; Tob, tobramycin; Tzp, piperacillin-tazobactam. METHODSCarbapenem-resistant strains identified in tissue samples.Using clinical samples collected from patients hospitalized in the ICUs of two large hospitals in Bucharest, Romania, between 2011 and 2012, 347 carbapenem-resistant Gram-negative rod (GNR) strains (143 Enterobacteriaceae and 204 non-fermenting GNR) we...

Background. Urinary tract infections (UTIs) caused by Uropathogenic Escherichia coli (UPEC) are among the most common infections worldwide, including Romania. To the best of our knowledge, this is the first study performed on a significant number of community-acquired (CA) UPEC strains isolated from Romanian outpatients, aiming to evaluate and establish potential correlations among the phylogenetic groups (PG), resistance profiles, and the virulence factors (VF) genes of the CA-UPEC isolates. Materials/Methods. The present study was performed on a total of 787 UPEC nonrepetitive isolates consecutively isolated during one month from outpatients with CA-UTIs, visiting one of the biggest laboratories in Bucharest, Romania, receiving patients from all over the country. The strains identification was performed by MALDI TOF and the susceptibility patterns were tested using Microscan according to CLSI guidelines. PCR assays were performed to detect the presence of different VFs (fimH gene encoding for type 1 fimbriae, afaBC for A fimbriae, sfaDE for S fimbriae, KpsMTII for capsule, hlyA for haemolysin A, hlyD for haemolysin D, and cnf-1 for tumor necrosis factor), the phylogenetic groups (PG) A, B1, B2, and D, and the extended spectrum beta-lactamases (ESBLs) genes. Results. The 787 CA-UPEC strains were isolated predominantly from female patients (90.95%) of >30 years (~74%). The resistance rates were 47.52% for ampicillin, 41.16% for tetracycline, 24.39% for cotrimoxazole, 19.18% for amoxicillin-clavulanic acid, 15.50% for cefazolin, 14.99% for ciprofloxacin, and 14.86% for levofloxacin; 35.19% of the investigated strains were MDR and 9.03% ESBL producers (from which 42.25% were positive for blaCTX-M, 38.02% for blaTEM, and 19.71% for blaSHV). FimH was the most frequent virulence gene (93.90%) followed by hlyD (44.34%); afaBC (38.24%); KpsMTII (32.65%); sfaDE (23.88%); hlyA (12.45%); and cnf-1 (7.75%). The distribution of the analyzed UPEC strains in phylogenetic groups was different for non-MDR and MDR strains. Overall, 35% of the strains belonged to the phylogenetic group B2 (harboring the yjaA gene); 27% to group B1 (confirmed by the presence of the TspE4C2 fragment); 16% to group D; and 22% to group A. The CA-UPEC strains included in PG B1 and PG B2 proved to be the most virulent ones, the number of strains carrying multiple VFs (>3) being significantly larger as compared to strains belonging to PG A and PG D) (p<0,0001). The presence of one or two ESBL genes was significantly associated (p =0.0024) with PGs A and D. Conclusions. Our findings showed that the community UPEC strains circulating in Bucharest, Romania, belong predominantly to group B2 and >90% harbored the fimH gene. High MDR resistance rates were observed, as well as extended VF profiles, highlighting the importance of this type of studies for improving the epidemiological surveillance and the therapeutic or prophylactic management of the respective infections, in the context of antibiotic resistance emergence.