Time filter

Source Type

Warsaw, Poland

The pathogens commonly causing the upper respiratory tract infections: Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, nontypeable Haemophilus influenzae and Moraxella catarrhalis are able to exist within host cells in human upper respiratory tract. They may be found both in homogenates of the adenoids and tonsils and inside epithelial and monocyte/macrophage cells isolated from these tissues. The bacteria also invade epithelium of middle ear mucosa. They are alive and can multiply in the cytoplasm. Numerous adhesins are responsible for a tight attachment of bacterial cells to epithelial and endothelial cells as well as to lymphocytes. These adhesins mediate bacterial internalization by human cells. Some bacteria, e.g. S. aureus, are able to persist viable within host cell compartments for several days in high numbers. Bacterial persistence in the cellular interior allows evading immunological defences and bactericidal activity of antimicrobials, thereby creating an intercellular reservoir of pathogenic and/or opportunistic bacteria. Antibacterial agents, even when are applied in doses exceeding the MIC values, do not eradicate these bacteria from the intracellular compartment. This feature of intracellular bacteria resembles the characteristic attributes of biofilms, i.e. their increased tolerance to bactericidal antimicrobials.

Multi-species biofilms form in many natural settings: water, soil or even on dust particles in the air. These biofilms can be also found in the industrial water distribution systems, on surfaces of the metalworking fluids tanks, in food production plants, etc. Many chronic infections involve multi-species biofilms; moreover, commensal vaginal flora or dental plaque bacteria may create such complex microbial consortia. In order to study the composition of microbial community several molecular methods have to be employed; among them metagenomics and proteomics are the most promising. Confocal microscopy in conjunction with fluorescence in situ hybridization as well as the atomic force microscopy are both very useful techniques to study the three-dimensional structure of the mixed-species biofilms. However, many technical obstacles may occur with these consortia during experimentation, e.g., how to grow multi-species biofilms with high reproducibility regarding the quantitative composition of these communities, and whether it is possible to quantitative by assess the metabolic activity and virulence of particular species when grown together in multi-species biofilm. The knowledge of specific traits of multi-species biofilms may contribute to better understanding of the etiology of infectious diseases, increase the efficiency of energy production in microbial fuel cells and lower the cost of biofouling prevention.

BACKGROUND: Metallo-beta-lactamases (MBL) are the enzymes that are able to hydrolyse almost the full range of beta-lactame antibiotics--penicillins, cephalosporins and carbapenems. The latter are the drugs of choice for treatment of serious infections caused by Enterobacteriaceae strains, which produce extended-spectrum-beta-lactamases. The presence of MBL-producing strains markedly decreases the therapeutic possibilities in severe, life-threatening infections. CASE REPORT: We present the case of a 61-yr-old man who underwent surgery for acute leg ischemia, and in whom a bifurcation prosthesis was implanted. The postoperative course was complicated with serious nosocomial infection, caused by MBL-positive Klebsiella pneumoniae strains. Despite multi drug treatment and intensive care, the patient died 30 days after surgery due to multi organ failure. All isolates cultured from the patient were resistant to carbapenems with their MICs exceeding 32 microg mL(-1). The presence of MBLs was detected with the double-disk synergy test. The presence of genes encoding MBLs was determined with a commercial kit, hyplex MBL ID (Bag Health Care, USA). The isolate from blood was found to carry the blaVIM-like family gene, located in a conjugative plasmid. CONCLUSION: The MBL-producing isolates were the first K. pneumoniae isolates of the kind identified in Poland. They present a serious danger, limiting the usefulness of carbapenems in ITU patients. We recommend that detection of MBLs in Enterobacteriaceae should be regarded as a standard in Polish hospitals.

OBJECTIVE: Determination of sensitivity to antibiotics and chemotherapeutics of 160 E. coli strains isolated from 2007 to 2008 from cases of hospital urinary tract infections and assessment the ability to produce ESBL by these strains. METHODS: The susceptibility of E. coli strains to ampicillin, amikacin, amoxicillin with clavulanic acid, aztreonam, cephalothin, cefotaxime, ceftazidime, cefuroxime, ciprofloxacin, ertapenemem, gentamicin, imipenem, meropenemem, nitrofurantoin, piperacillin, piperacillin with tazobactam, tetracycline, and trimethoprim with sulfamethoxazole was tested by using a disc-diffusion method. Ability to producing ESBL was detected by using double disc synergy test. RESULTS: The analysis revealed a high percentage of strains resistant to ampicillin (56.8%). Strains showing resistance to tetracycline (35%), trimethoprim with sulfamethoxazole (23.1%), ciprofloxacin (19.4%), gentamicin (3.75%) and nitrofurantoin (3.75%) were also obtained. The percentage of strains resistant to amoxicillin with clavulanic acid among those isolated in 2007 was 2.9%, and in group of strains obtained in 2008 was 20.6%. Production of ESBL was observed in 4.4% of strains, which in addition to resistance to penicillin and cephalosporins showed resistance to antibiotics belonging to other groups. Multi-drug resistant strains were also obtained, which did not produce ESBL. CONCLUSIONS: Increasing resistance to some of the antibiotics and the emergence of multi-drug resistant strains clearly indicate the need for continuous monitoring of antibiotic susceptibility in uropathogenic E. coli strains.

Recent study on intestinal microbiome irrevocably altered the view that mammalian metabolism is solely influenced by their genome. Intestinal microbiota harbor a repertoire of protein encoding genes that by far exceed the gene pool found in the host genome. This has established the importance of the gut microbiome, because part of the responsibility for host metabolic regulation is devolved to the microbial symbionts. Subtle changes in co-metabolic profiles in response to physiological perturbations or environmental factors lead to many diverse disease processes including inflammatory bowel diseases, colorectal cancer, obesity, circulatory disease, and others. In most mammals, the gut microbiome is dominated by four phyla: Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria. The host has evolved to establish many processes that sustain unresponsiveness toward the commensal bacteria while at the same time maintaining responsiveness toward pathogens. The intestinal microbiome and mucosal tissues are intertwined by multiple interactions influencing host health or disease. Microbes, in response to environmental or host cues, form highly coordinated, multi-cellular networks trough intercellular cross-species and cross-domain signaling pathways, resulting in potent expansion of adaptive response to environmental changes. Similarly, the host is constantly sampling and assessing colonizing organisms and regulates defense mechanism. Under physiological conditions, the intestinal community serves the host via several ways including maturation and regulation of intestinal immune system, energy metabolism, intestinal response to epithelial cell injury and others. Changes to the intestinal milieu influence this advantageous balance is seriously injured, as benign commensals sensing danger rapidly switch to feared pathogens and initiate a coordinated program to invade the succumbed tissues. Molecular mechanisms responsible for recognizing the intestinal microflora are diverse, including numerous pathways like Toll-like receptors (TLRs), formylated peptide receptors (FPRs), nucleotide binding oligomerization-like receptors (NODs) and others with corresponding signal transduction routs. NF-κB depending signaling induce the inflammatory and proapoptotic response. Gastric and mucosal mucosa is engaged, with the ability to respond to inflammatory signals via production of different mediators, i.e. TNFα, IL-1, Il-6, IL-8 and IL-12. Many commensal bacteria have the ability to activate antiinflammatory responses inducing expression of target genes mediating anti-inflammatory and antiapoptotic effects i.e. IL-10 and TGF-β. Under physiological circumstances, these host-microbiome interactions are considered to be placed at the exquisitely equilibrated state between pro-inflammatory and anti-inflammatory responses.

Discover hidden collaborations