85 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
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
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
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
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
Bacteriologic and therapeutic considerations in intra-abdominal surgical infections
The most important factor in the treatment of intra-abdominal infections
are early diagnosis and prompt surgical intervention while antibiotics
play a secondary role. The goals of surgical procedures should be to
stop peritoneal contamination, to debride necrotic tissue, to remove
debris and foreign bodies and to drain any pus collection. Antibiotics
should be initiated before surgery and they must encompass both colonic
aerobes and anaerobes including Bacteroides fragilis group but not
necessary Enterococcus sp. Antibacterial agents with pure activity
against anaerobes include chloramphenicol, clindamycin and the
nitroimidazoles while ampicillin/sulbactam, amoxicillin/clavulanate,
ticarcillin/clavulanate, cefoxitin, cefotetan, ceftizoxime
imipenem/cilastatin, meropenem and some advanced quinolones Like
sparfloxacin, represent a single drug to cover both aerobic and
anaerobic microflora. Although almost all clinical trials usually result
in a 90% efficacy rate, the final outcome is dependant on the stage of
the infection (early versus late), sepsis score, underlying diseases and
the applied surgical procedures. On the other hand the choice of
antibiotic(s) must be influenced by its toxicity, profile, local
nosocomial susceptibility patterns, resistance inducing ability and
price. (C) 1997 Academic Press
Carrier systems for the local delivery of antibiotics in bone infections
Carriers used for the local delivery of antibacterial agents may be
classified as nonbiodegradable or biodegradable. A major representative
of the former category are the polymethylmethacrylate (PMMA) beads often
impregnated with gentamicin which have been commercially available for
the last 2 decades. Examples of the latter category include the
collagen-gentamicin sponge, apatite-wollastonite glass ceramic blocks,
hydroxyapatite blocks, polylactide/polyglycolide implants and the
polylactate polymers. All of the above systems release antibiotics at
concentrations exceeding those of the minimum inhibitory concentrations
(MICs) for the most common pathogens of chronic osteomyelitis without
releasing any antibiotic in the systemic circulation and without
producing adverse effects. The major disadvantage of the PMMA beads is
the need for their surgical removal at the completion of antibiotic
release, which usually takes place 4 weeks after their implantation. The
biodegradable carriers do not require surgical removal, and of those
listed, the collagen-gentamicin sponge has been applied successfully
over the last decade for bone infections. Among the other biodegradable
systems which are still in experimental stages, polylactate polymers
carrying quinolones seem very promising, since they are characterised by
prolonged duration of release at concentrations 100 to 1000 times the
MICs of the causative bacteria implicated in bone infections;
preliminary results have shown these carriers to be very effective in
the management of experimental osteomyelitis caused by
methicillin-resistant Staphylococcus aureus. Further development of such
biodegradable systems will provide a novel approach in the future for
the eradication of chronic osteomyelitis
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