209 research outputs found
Transferable plasmid mediating resistance to multiple antimicrobial agents in Klebsiella pneumoniae isolates in Greece
AbstractObjective To investigate the underlying resistance mechanisms in 10 Klebsiella pneumoniae isolates.Methods Ten K. pneumoniae strains according to distinct bacteriocin typing and REP-PCR, were examined for their plasmid content, their ability to transfer their resistance to aminoglycosides and third-generation cephalosporins, and their production of aminoglycoside-modifying enzymes and β-lactamases.Results Transfer of resistance to the above-mentioned antibiotics as well as to co-trimoxazole and tetracycline in Escherichia coli strain RC 85 at a frequency of 5–106 was achieved for all strains by conjugation. Similar strains harbor a self-transferable multiresistant plasmid (80 kb) with similar EcoRI and HindIII restriction patterns. This plasmid encodes an extended-spectrum β-lactamase which confers high-level resistance to third-generation cephalosporins and aztreonam. It produces SHV-5 β-lactamase, as demonstrated by isoelectric focusing and DNA sequencing. Aminoglycoside resistance was co-transferred, and AAC(6′)-I, mediating resistance to gentamicin, tobramycin, netilmicin and amikacin, and AAC(3)-I, mediating resistance to gentamicin and sisomycin, were encoded in all isolates and their transconjugants, while APH(3′)-I, mediating resistance to kanamycin and neomycin, was encoded in seven strains.Conclusions It appears that a multiresistant transferable plasmid encoding the SHV-5 β-lactamase, causing unusually high resistance to ceftazidime and aztreonam, and the combination AAC(6′)-I + AAC(3)-I of acetylating enzymes causing, also resistance to all clinically available aminoglycosides, is established in K. pneumoniae in Greece
The Importance of Fever as a Predictive Symptom for the Potency of Host's Monocytes to Release Pro- and Anti-Inflammatory Mediators
Objective. To clarify whether time lapsing from advent of fever as a first sign of sepsis may be indicative of the potency of monocytes for the release of pro- and anti-inflammatory mediators.
Methods. Monocytes were isolated from blood of 51 septic patients and 9 healthy donors. Monocytes were incubated in the absence and presence of patients' serum and concentrations of tumour necrosis factor-alpha (TNF
α), interleukin (IL)-6, IL-10, and malondialdehyde (MDA) were estimated in supernatants. Patients were divided into three groups: group A:
<12 hours; group B: 12—24 hours, and group C:
>24 hours between initiation of fever and blood sampling.
Results. TNF
α of supernatants of groups B and C was higher than controls, as also were IL-6 of A and C, IL-10 of A and B, and MDA of A. IL-6 of group A was increased after addition of patients serum. A negative correlation was found between time from initiation of symptoms and IL-6 of monocyte supernatants incubated in the presence of patients serum. Median IL-6 of survivors was higher than nonsurvivors.
Conclusion. Monocytes are potent for the release of pro- and anti-inflammatory mediators within the first 24 hours upon advent of fever related to sepsis; serum stimulates further release of IL-6 within the first 12 hours
Effect of the Novel Influenza A (H1N1) Virus in the Human Immune System
BACKGROUND: The pandemic by the novel H1N1 virus has created the need to study any probable effects of that infection in the immune system of the host. METHODOLOGY/PRINCIPAL FINDINGS: Blood was sampled within the first two days of the presentation of signs of infection from 10 healthy volunteers; from 18 cases of flu-like syndrome; and from 31 cases of infection by H1N1 confirmed by reverse RT-PCR. Absolute counts of subtypes of monocytes and of lymphocytes were determined after staining with monoclonal antibodies and analysis by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and stimulated with various bacterial stimuli. Concentrations of tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-18, interferon (FN)-alpha and of IFN-gamma were estimated in supernatants by an enzyme immunoassay. Infection by H1N1 was accompanied by an increase of monocytes. PBMCs of patients evoked strong cytokine production after stimulation with most of bacterial stimuli. Defective cytokine responses were shown in response to stimulation with phytohemagglutin and with heat-killed Streptococcus pneumoniae. Adaptive immune responses of H1N1-infected patients were characterized by decreases of CD4-lymphocytes and of B-lymphocytes and by increase of T-regulatory lymphocytes (Tregs). CONCLUSIONS/SIGNIFICANCE: Infection by the H1N1 virus is accompanied by a characteristic impairment of the innate immune responses characterized by defective cytokine responses to S.pneumoniae. Alterations of the adaptive immune responses are predominated by increase of Tregs. These findings signify a predisposition for pneumococcal infections after infection by H1N1 influenza
Risk factors for nasopharyngeal carriage of drug-resistant Streptococcus pneumoniae: data from a nation-wide surveillance study in Greece
<p>Abstract</p> <p>Background</p> <p>A nation-wide surveillance study was conducted in Greece in order to provide a representative depiction of pneumococcal carriage in the pre-vaccination era and to evaluate potential risk factors for carriage of resistant strains in healthy preschool children attending daycare centers.</p> <p>Methods</p> <p>A study group was organized with the responsibility to collect nasopharyngeal samples from children. Questionnaires provided demographic data, data on antibiotic consumption, family and household data, and medical history data. Pneumococcal isolates were tested for their susceptibility to various antimicrobial agents and resistant strains were serotyped.</p> <p>Results</p> <p>Between February and May 2004, from a total population of 2536 healthy children, a yield of 746 pneumococci was isolated (carriage rate 29.41%). Resistance rates differed among geographic regions. Recent antibiotic use in the last month was strongly associated with the isolation of resistant pneumococci to a single or multiple antibiotics. Serotypes 19F, 14, 9V, 23F and 6B formed 70.6% of the total number of resistant strains serotyped.</p> <p>Conclusion</p> <p>Recent antibiotic use is a significant risk factor for the colonization of otherwise healthy children's nasopharynx by resistant strains of <it>S pneumoniae</it>. The heptavalent pneumococcal conjugate vaccine could provide coverage for a significant proportion of resistant strains in the Greek community. A combined strategy of vaccination and prudent antibiotic use could provide a means for combating pneumococcal resistance.</p
Ampicillin/Sulbactam versus Cefuroxime as antimicrobial prophylaxis for cesarean delivery: a randomized study
<p>Abstract</p> <p>Background</p> <p>The efficacy and safety of a single dose of ampicillin/sulbactam compared to a single dose of cefuroxime at cord clamp for prevention of post-cesarean infectious morbidity has not been assessed.</p> <p>Methods</p> <p>Women scheduled for cesarean delivery were randomized to receive a single dose of either 3 g of ampicillin-sulbactam or 1.5 g of cefuroxime intravenously, after umbilical cord clamping. An evaluation for development of postoperative infections and risk factor analysis was performed.</p> <p>Results</p> <p>One hundred and seventy-six patients (median age 28 yrs, IQR: 24-32) were enrolled in the study during the period July 2004 - July 2005. Eighty-five (48.3%) received cefuroxime prophylaxis and 91 (51.7%) ampicillin/sulbactam. Postoperative infection developed in 5 of 86 (5.9%) patients that received cefuroxime compared to 8 of 91 (8.8%) patients that received ampicillin/sulbactam (p = 0.6). In univariate analyses 6 or more vaginal examinations prior to the operation (p = 0.004), membrane rupture for more than 6 hours (p = 0.08) and blood loss greater than 500 ml (p = 0.018) were associated with developing a postoperative surgical site infection (SSI). In logistic regression having 6 or more vaginal examinations was the most significant risk factor for a postoperative SSI (OR 6.8, 95% CI: 1.4-33.4, p = 0.019). Regular prenatal follow-up was associated with a protective effect (OR 0.04, 95% CI: 0.005-0.36, p = 0.004).</p> <p>Conclusions</p> <p>Ampicillin/sulbactam was as safe and effective as cefuroxime when administered for the prevention of infections following cesarean delivery.</p> <p>Trial registration</p> <p>Clinicaltrials.gov identifier: NCT01138852</p
A biodegradable antibiotic delivery system based on poly-(trimethylene carbonate) for the treatment of osteomyelitis
Background and purpose Many investigations on biodegradable materials acting as an antibiotic carrier for local drug delivery are based on poly(lactide). However, the use of poly(lactide) implants in bone has been disputed because of poor bone regeneration at the site of implantation. Poly(trimethylene carbonate) (PTMC) is an enzymatically degradable polymer that does not produce acidic degradation products. We explored the suitability of PTMC as an antibiotic releasing polymer for the local treatment of osteomyelitis
Antimicrobial functionalized genetically engineered spider silk
Genetically engineered fusion proteins offer potential as multifunctional biomaterials for medical use.
Fusion or chimeric proteins can be formed using recombinant DNA technology by combining nucleotide
sequences encoding different peptides or proteins that are otherwise not found together in nature. In the
present study, three new fusion proteins were designed, cloned and expressed and assessed for function,
by combining the consensus sequence of dragline spider silk with three different antimicrobial peptides.
The human antimicrobial peptides human neutrophil defensin 2 (HNP-2), human neutrophil defensins 4
(HNP-4) and hepcidin were fused to spider silk through bioengineering. The spider silk domain maintained
its self-assembly features, a key aspect of these new polymeric protein biomaterials, allowing the
formation of b-sheets to lock in structures via physical interactions without the need for chemical crosslinking.
These new functional silk proteins were assessed for antimicrobial activity against Gram e
Escherichia coli and Gram þ Staphylococcus aureus and microbicidal activity was demonstrated. Dynamic
light scattering was used to assess protein aggregation to clarify the antimicrobial patterns observed.
Attenuated-total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and circular dichroism
(CD) were used to assess the secondary structure of the new recombinant proteins. In vitro cell studies
with a human osteosarcoma cell line (SaOs-2) demonstrated the compatibility of these new proteins
with mammalian cells.Fundação para a Ciência e a Tecnologia (FCT) - Bolsa de doutoramento (SFRH/BD/28603/2006); Chimera project (PTDC/EBB-EBI/109093/2008); NIH and Tissue Engineering Resource Center EB003210, P41
EB002520, DE017207
Injectable gellan gum-based nanoparticles-loaded system for the local delivery of vancomycin in osteomyelitis treatment
Infection spreading in the skeletal system
leading to osteomyelitis can be prevented by the prolonged
administration of antibiotics in high doses. However systemic
antibiotherapy, besides its inconvenience and often
low efficacy, provokes numerous side effects. Thus, we
formulated a new injectable nanoparticle-loaded system for
the local delivery of vancomycin (Vanc) applied in a
minimally-invasive way. Vanc was encapsulated in poly(Llactide-
co-glycolide) nanoparticles (NPs) by double-emulsification.
The size (258 ± 11 nm), polydispersity index
(0.240 ± 0.003) and surface potential (-25.9 ± 0.2 mV)
of NPs were determined by dynamic light scattering and
capillary electrophoresis measurements. They have a
spherical morphology and a smooth topography as
observed using atomic force microscopy. Vanc loading and
encapsulation efficiencies were 8.8 ± 0.1 and
55.2 ± 0.5 %, respectively, based on fluorescence spectroscopy
assays. In order to ensure injectability, NPs were
suspended in gellan gum and cross-linked with ; also a
portion of dissolved antibiotic was added to the system.
The resulting system was found to be injectable (extrusion
force 11.3 ± 1.1 N), reassembled its structure after
breaking as shown by rheology tests and ensured required
burst release followed by sustained Vanc delivery. The
system was cytocompatible with osteoblast-like MG-63
cells (no significant impact on cells’ viability was detected). Growth of Staphylococcus spp. reference strains
and also those isolated from osteomyelitic joints was
inhibited in contact with the injectable system. As a result
we obtained a biocompatible system displaying ease of
application (low extrusion force), self-healing ability after
disruption, adjustable drug release and antimicrobial
properties
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