Negative Bacterial Infections Research Articles

An immunocompetent patient presenting with severe septic arthritis due to Ralstonia pickettii identified by molecular-based assays: a case report

IntroductionRalstonia pickettii is an infrequent pathogen of invasive infections in healthy individuals. The microorganism is supposed to be of relatively low virulence, but can cause infections, mainly of the respiratory tract, in immunocompromised and cystic fibrosis patients. Ralstonia pickettii has also been associated with hospital outbreaks related to contamination of products used for medical care and laboratory diagnosis.Case presentationWe report here a case of septic arthritis due to Ralstonia pickettii in a female diabetic patient. The microorganism was identified from the synovial fluid by molecular-based methods, while the conventional synovial and blood cultures proved to be negative. The patient was treated by intravenous ceftazidime with complete remission of her symptoms; she was discharged 3 weeks after admission in a very good health. At follow-up examination 3 weeks later, she was still in good health condition without any sign of arthritis of the right knee and afebrile.ConclusionIn culture negative serious bacterial infections, as septic arthritis, the use of molecular-based techniques might be of outmost importance as additional and rapid diagnostic tools for the identification of the causative agent allowing a prompt and appropriate antimicrobial therapy and a favourable outcome.

Protection of Immuno-Compromised Mice from Lethal Infection of Klebsiella Pneumonia by rAAV2-BPI23-Fcγ1 Gene Transfer

In previous research, chimerical BPI23-Fcgamma1 gene which consisted of human bactericidal/permeability increasing protein (BPI) gene of encoding the functional N terminus (amino acid residues 1 to 199) of human BPI and Fcgamma1 gene of encoding the Fc segment of human immunoglobulin G1 was successfully reconstructed within a recombinant adeno-associated virus serotype 2 (rAAV2) vector as rAAV2-BPI23-Fcgamma1. Here, to evaluate the potentiality of applying gene therapy to gram negative bacterial (GNB) infection in high-risk patients, we investigated protection of immuno-compromised mice and immunocompetent mice from challenge with minimal lethal dose (MLD) Klebsiella pneumonia infection after rAAV2-BPI23-Fcgamma1 gene transferred. The results showed that the survival rate of rAAV2-BPI23-Fcgamma1 transferred immunocompetent mice as well as immuno-compromised mice (40.0% and 44.4%, respectively) were significantly higher than that of corresponding control mice (6.7% and 4.4%, respectively); the bacteria counting, level of endotoxin and proinflammatory cytokines in the rAAV2-BPI23-Fcgamma1 transferred immuno-compromised mice were markedly lower than that of rAAV2-EGFP and rAAV2-Null transferred immuno-compromised mice. Our data suggest that rAAV2-BPI23-Fcgamma1 gene transferring offered immuno-compromised mice with resistance against GNB infection, so it is quite potential in preventing GNB infection of clinical high-risk patients.

Histopathologic study on the effects of methionine in reduction of hepatotoxicity and gastritis due to co-administration of gentamicin and indomethacin in rats

Gentamicin is a wide spectrum aminoglycoside used against gram negative bacterial infections, therapeutic does of this drug resulted in nephrotoxicity and hepatotoxicity. Indomethacin is one of the NSAIDs with side effects on stomach, liver and Kidney. Co-administration of indomethacin and gentamicin may resulted in exaggeration of their side efects .In this research, 42 male Sprague dawley rats were divided randomly into 6 equal groups. In the period of 14 days group 1-6 received normal saline (I.P), gentamicin (I.M), indomethaci (I.M), gentamicin (I.M) plus indomethacin (I.M), L-methionine (I.P), and gentamicin (I.M) plus indomethacin (I.M) and L-methionine(I.P) respectively once a day. In day 15, rats were euthanized and histopathologic slides of the liver and stomach were prepared. Histopathologic examination revealed and edema in tunica mucosa and submucosa of stomach in group 3 and 4, and mild hemorrahage in tunica mucosa of stomach of group 3 .In group 2 and 4 capillarization , deformed hepatocytes , apoptosis and mononuclear cell infiltration in portal area were seen in liver . Fibrosis of portal area was obvious in group 4. For the first time the results of the peresent study showed that methionine can prevent form side effects of Co-administration of indomethacin and gentamicin in liver and stomach.

Histopathologic study on the effects of methionine in reduction of nephrotoxicity due to co-administration of gentamicin and indomethacin in rats

Gentamicin is a wide spectrum aminoglycoside used against gram negative bacterial infections, but its clinical utility is restricted due to nephrotoxicity.Indomethacin is one of the NSAIDs with side effects on Kidney. Co-administration of indomethacin and gentamicin is necessary in some cases and may exaggerate gentamicin nephrotoxic effects. L-methionine can reduce gentamicin nephrotoxicity, so it may protect kidney from gentamicin and indomethacin co-administrative side effects.In this research, 42 male Sprague dawley rats were divided randomly into 6 equal groups. In the period of 14 days group 1-6 received normal saline (I.P),gentamicin (80 mg/kg BW, intramuscularly (I.M)), indomethacin ( I.M), gentamicin (I.M) plus indomethacin (I.M), L-methionine ( I.P),and gentamicin (I.M) plus indomethacin (I.M)and L-methionine(I.P) respectively once a day. In day 15, rats were euthanized and histopathologic slides of the kidneys were prepared.Histopatho logic examination revealed renal congestion, severe acute tubular necrosis, interstitial nephritis, glomerular atrophy and tubular dilatation in cortex in group 2. Glomerular hypercellularity was seen in group 3. In group 4, renal congestion, severe acute tubular necrosis,interstitial nephritis, glomerular hypercellularity and hyaline casts were seen. In group 5, medullary congestion and in group 6, renal congestion, tubular epithelial regeneration and normal tubules were seen. There was no microscopic lesion in group 1. The results of the present study showed that co-administration of gentamicin and indomethacin caused severe nephrotoxicity and L-methionine could ameliorate this effect.

Identification and Evolution of Drug Efflux Pump in Clinical Enterobacter aerogenes Strains Isolated in 1995 and 2003

BackgroundThe high mortality impact of infectious diseases will increase due to accelerated evolution of antibiotic resistance in important human pathogens. Development of antibiotic resistance is a evolutionary process inducing the erosion of the effectiveness of our arsenal of antibiotics. Resistance is not necessarily limited to a single class of antibacterial agents but may affect many unrelated compounds; this is termed ‘multidrug resistance’ (MDR). The major mechanism of MDR is the active expulsion of drugs by bacterial pumps; the treatment of Gram negative bacterial infections is compromised due to resistance mechanisms including the expression of efflux pumps that actively expel various usual antibiotics (ß-lactams, quinolones, …).Methodology/Principal Findings Enterobacter aerogenes has emerged among Enterobacteriaceae associated hospital infections during the last twenty years due to its faculty of adaptation to antibiotic stresses. Clinical isolates of E. aerogenes belonging to two strain collections isolated in 1995 and 2003 respectively, were screened to assess the involvement of efflux pumps in antibiotic resistance. Drug susceptibility assays were performed on all bacterial isolates and an efflux pump inhibitor (PAßN) previously characterized allowed to decipher the role of efflux in the resistance. Accumulation of labelled chloramphenicol was monitored in the presence of an energy poison to determine the involvement of active efflux on the antibiotic intracellular concentrations. The presence of the PAßN-susceptible efflux system was also identified in resistant E. aerogenes strains.Conclusions/SignificanceFor the first time a noticeable increase in clinical isolates containing an efflux mechanism susceptible to pump inhibitor is report within an 8 year period. After the emergence of extended spectrum ß-lactamases in E. aerogenes and the recent characterisation of porin mutations in clinical isolates, this study describing an increase in inhibitor-susceptible efflux throws light on a new step in the evolution of mechanism in E. aerogenes.

Time dependent effect of gentamicin on enzymes of carbohydrate metabolism and terminal digestion in rat intestine

Gentamicin (GM) is an aminoglycoside antibiotic commonly used against life threatening gram negative bacterial infections, however, nephrotoxicity remains the major concern for its long term use. Although its effects on kidney are well characterized but there have been no studies regarding its effects on intestine. We hypothesize that GM causes adaptive coordinated effect on enzymes of carbohydrate metabolism and terminal digestion/ absorption in rat intestine. Rats were administered a nephrotoxic dose of GM (80 mg /kg body weight) daily for 15 days and a time dependent effect was observed on various enzyme activities. Activities of lactate (LDH), malate (MDH) and isocitrate (ICDH) dehydrogenases, significantly increased and peaked at different time intervals of GM treatment. Whereas LDH activity remained higher, MDH and ICDH activity slowly declined from their peak values. Activities of fructose-1,6-bisphosphatase, glucose-6-phosphatase and glucose-6-phosphate dehydrogenase increased but malic enzyme decreased in a time dependent manner. Activity of alkaline phosphatase and sucrase significantly increased but gamma-glutamyl transpeptidase activity decreased. GM administration increased lipid peroxidation, glutathione peroxidase but decreased superoxide dismutase and catalase activities. The results indicate that GM treatment selectively upregulated certain enzymes of carbohydrate metabolism and terminal digestion/absorption and perturbed antioxidant defenses.

Tigecycline: a novel glycylcycline antibiotic

Tigecycline, the first-in-class glycylcycline, was developed to recapture the broad spectrum of activity of the tetracycline class and to treat patients with difficult-to-treat bacterial infections. Tigecycline’s in vitro spectrum of activity encompasses aerobic, facultative and anaerobic Gram-positive and -negative bacteria, including antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis and Enterococcus faecium, and extended-spectrum β-lactamase-producing Enterobacteriaceae. Clinical trials involving patients with complicated skin and skin-structure infections and complicated intra-abdominal infections, including patients infected with methicillin-resistant S. aureus, demonstrated that tigecycline was bacteriologically and clinically effective with mild-to-moderate gastrointestinal adverse events (i.e., nausea, vomiting and diarrhea) the most commonly reported. Tigecycline is a promising new broad-spectrum parenteral monotherapy for the treatment of patients with Gram-positive and -negative bacterial infections.

The TLR4 +896 polymorphism is not associated with lipopolysaccharide hypo-responsiveness in leukocytes

Toll-like receptor 4 (TLR-4) is required for detection of Gram negative bacterial infections by binding lipopolysaccharide (LPS) and for the initiation of inflammatory signaling. Recent studies have demonstrated that a nonsynonymous single-nucleotide polymorphism (Asp299Gly, A+896G) is associated with decreased endotoxin responsiveness and poor outcomes from sepsis. We show that human carriers of this polymorphism show no deficit in LPS induced peripheral blood mononuclear cell (PBMC) mitogen-activated protein kinase (MAPK) activity, no reduction in sensitivity to endotoxin, and variable differences in whole-blood inflammatory cytokine production. These results indicate that this mutation is not a primary determinant of human endotoxin sensitivity.

Augmentation of Mast Cell Bactericidal Activity by the Anti-leukemic Drug, 4-(3'bromo-4'-hydroxylphenyl)-amino-6,7-dimethoxyquinazoline

Mast cells play a pivotal role in host innate immune defense against gram negative bacterial infections by killing gram negative bacteria and recruiting neutrophils to the sites of active infection through the release of TNFα and leukotrienes. Here, we report that the anti-leukemic compound 4-(3'bromo-4'-hydroxylphenyl)-amino-6,7-dimethoxyquinazoline, designated as MASTPROM, augments the bactericidal activity of mast cells by increasing the binding of bacteria to and their phagocytosis by mast cells. MASTPROM also promoted the bacterial clearance in a mouse model of bacterial peritonitis. MASTPROM may provide the basis for novel supportive care regimens aimed at augmenting the bactericidal activity of mast cells and thereby potentiating the innate immune response against gram negative organisms.

Risk factors that modulate periodontal diseases

Periodontal diseases now is a chronic inflammatory disease caused by Gram negative bacterial infection. Recently, it is of interest to evaluate risk factors that modulate initiation and development of this disease. A recent study have suggested that obesity is one of the risk factors. In this regard, most recently, we found that leptin, a regulator of food intake and whole-body energy metabolism, acts as a negative regulator of LPS-induced expression of inflammatory cytokines of macrophages via inhibition of NF-kB.

Endogenous Endotoxemia in Patients with Liver Cirrhosis

INTRODUCTION Since the limulus test, a method for the evaluation of endotoxin levels using extract from horsehoe crabs (limulus, spp), was developed in the year 1969 by Levin and Bang, there have been reports on endotoxin from portal blood without negative gram bacterial infection, a condition known as endogenous endotoxemia. Up to now, endogenous endotoxemia in patients with liver cirrhosis (LC) is still controversial. This can be seen from the great variation in the prevalence of endotoxemia in peripheral vein in patients with liver cirrhosis, ranging from 0 to 80%. The main cause for this difference is the methodological factor, reflecting a difference in examination technique. Most studies conducted without a specific method demonstrate endotoxemia in patients with liver cirrhosis. While studies using a sensitive method of evaluation for endotoxin found the opposite, detecting no increase in endotoxin in patients with liver cirrhosis.

Role of mast cell leukotrienes in neutrophil recruitment and bacterial clearance in infectious peritonitis.

Stimulated mast cells release a variety of chemotactic factors such as tumor necrosis factor alpha (TNF-alpha) and leukotriene B4. Recent studies have shown that mast cell-derived TNF-alpha plays a critical role in host defense against Gram negative bacterial infections by the recruitment of neutrophils to the sites of infection. In the present study, we sought to investigate if mast cells release leukotriene (LT) B4 in response to bacteria and, if so, to establish its in vivo relevance. We show that mast cells release significant amounts of LTB4 and LTC4 in response to exposure to FimH-expressing type 1 fimbriated Escherichia coli in vitro. To test the functional significance of mast cell-derived LTs during an E. coli infection in vivo, we examined the effect of a LT-synthesis inhibitor, A-63162, on bacterial clearance and neutrophil influx in an infectious peritonitis model in mast cell-deficient mice (WBB6F1-W/WV) and their normal congenic control (WBB6F1-+/+) mice. Our results show that a treatment with A-63162 reduced neutrophil influx and bacterial clearance in the peritoneal cavities of mast cell-sufficient but not -deficient mice. Thus, mast cell-derived LTs contribute to host defense by mediating early neutrophil influx and bacterial clearance at sites of infection.

Bacteria-host cell interaction mediated by cellular cholesterol/glycolipid-enriched microdomains.

Gram negative bacterial infection is a leading cause of fatality and is attributed, at least in part, to the bacteria's capacity to persist in the host in spite of appropriate antibiotic therapy. It has been suggested that bacteria evade antibiotics by hiding within host cells. We sought to investigate this important aspect of infections in mast cells, which are inflammatory cells found in close proximity to the host-environment interface and which have recently been reported to play a crucial role in the early innate immune response to bacteria. We examined mast cell interactions with FimH-expressing E. coli, one of the major opportunistic pathogens of humans. We determined that in serum free conditions, these bacteria were able to trigger mast cell uptake without loss of bacterial viability. CD48, a mannose containing GPI (glycosylphosphatidylinositol)-linked molecule was found to be the receptor of FimH-expressing E. coli in mouse mast cells. We found that the internalization via CD48 was blocked by filipin, a cholesterol binding drug known to disrupt cholesterol/glycolipid-enriched microdomains and the bacteria-encasing vacuoles were rich in cholesterol inside cells. Interestingly, we found that mast cells subsequently expelled majority of the intracellular bacteria in 24 hours. This expulsion process was blocked by lovastatin/cyclodextrin treatment, which is known to inhibit cellular trafficking of cholesterol/glycolipid-enriched microdomains. Thus, the bacterial entry into and expulsion from mast cells were critically dependent on cholesterol/glycolipid-enriched microdomains, which represents a novel mode of tussle between the pathogen and the mast cell occurring in opsonin deficient sites in the body or even at other sites in naive or immunocompromised hosts which have low systemic levels of E. coli specific antibody.

Differential Induction of Cytokine mRNA by Gram Negative and Gram Positive Bacterial Infections in a Rabbit Ileal Loop Model of Necrotizing Enterocolitis

Differential Induction of Cytokine mRNA by Gram Negative and Gram Positive Bacterial Infections in a Rabbit Ileal Loop Model of Necrotizing Enterocolitis

A clinical evaluation of the new laboratory method that diagnoses bacterial infection, using silkworm larvae plasma

Based upon the phenomenon that the peptidoglycan, a common component of Gram positive and negative bacteria, reacts specifically with silkworm larvae plasma (SLP), a new laboratory method named "SLP test" was developed to measure the reaction products in plasma quantitatively as SLP. This SLP test seems to be able to diagnose both Gram positive and negative bacterial infection. So we evaluated its usefulness in diagnosing clinical infectious diseases. This study included 14 patients with result to positive bacterial blood culture, 22 patients with bacterial local infection, 7 patients without any evidence of bacterial infection, and 19 healthy volunteers. It seemed that the cut-off value of this SLP test should be set at 0.6 ng/ml. The sensitivity and specificity of this SLP test were 57.1%, 100%, respectively. A significant difference was not detected statistically between SLP values of patients with Gram positive and Gram negative bacterial infectious diseases. So the SLP test did not appeared specific to either Gram positive or Gram negative bacteria. This test may become a new method diagnosing bacterial infectious disease.

A Safe, Rapid, Reproducible, and Easily Interpreted Stain for Gram Positive and Gram Negative Microorganisms

Procedures for the demonstration of gram positive and negative microorganisms are a critical function of every histology laboratory but may yield inconsistent results. In addition, concerns about the safety of some components have recently been raised. This report describes a modification of the gram stain that eliminates the need for picric acid, acetone, ethyl ether and ethylene glycol monoethyl ether and makes use of a light green background. These modifications have not only improved the procedure's safety but have improved diagnostic interpretation by pathologists. This modification is highly reproducible and provides a rapid diagnosis of gram positive and negative bacterial infection. (The J Histotechnol 21:155, 1998)

A Safe, Rapid, Reproducible, and Easily Interpreted Stain for Gram Positive and Gram Negative Microorganisms

Procedures for the demonstration of gram positive and negative microorganisms are a critical function of every histology laboratory but may yield inconsistent results. In addition, concerns about the safety of some components have recently been raised. This report describes a modification of the gram stain that eliminates the need for picric acid, acetone, ethyl ether and ethylene glycol monoethyl ether and makes use of a light green background. These modifications have not only improved the procedure's safety but have improved diagnostic interpretation by pathologists. This modification is highly reproducible and provides a rapid diagnosis of gram positive and negative bacterial infection. (The J Histotechnol 21:155, 1998)

Removal of cytokine inducing substances by polymyxin-B immobilized polystyrene-derivative fibers during in vitro hemoperfusion of 10% human plasma containing Staphylococcus aureus challenge.

Staphylococcus aureus (S. aureus) is frequently isolated from blood cultures in the hospital setting. The pathogenesis of S. aureus bacteremia probably replicates mechanisms implicated in gram negative bacterial infections. Cell wall components, such as peptidoglycans and lipoteichoic acids (LTA), can trigger cytokine production. Polymyxin-B (PMX-B) is a cationic peptide that binds endotoxin (ET) and inhibits its activity. Based on this principle, PMX-B was incorporated in polystyrene-derivative fibers, creating a hemoperfusion column (PMX-20R) that removes ET. The authors assessed whether S. aureus possesses PMX-B suppressible cytokine-inducing substances, and whether LTA, an anionic molecule, is one such substance. Heparinized blood was obtained from healthy volunteers, peripheral blood mononuclear cells (PBMC) were isolated by Ficoll-Hypaque separation, and 10% human plasma prepared. PBMC were incubated with 1, 5, or 10 microg/ml of S. aureus LTA, with and without 10 microg/ml of PMX-B. Also, using PMX-20R, in vitro hemoperfusion (IVH) was performed with 10% human plasma containing a 1:1,000 dilution of S. aureus challenge at 100 ml/min for 2 hours at 37 degrees C, and plasma obtained before and after IVH was incubated with PBMC. After a 24 hour incubation at 37 degrees C, PBMC were subjected to three freeze-thaw cycles, and total TNFalpha was measured by radioimmunoassay. TNFalpha production by PBMC incubated with LTA was 164+/-4 pg, 324+/-54 pg, 657+/-55 pg, and 1143+/-215 pg in control, and LTA 1, 5, and 10 microg/ml, respectively. The addition of PMX-B resulted in a 40+/-12% (p = 0.02), 61+/-6% (p = 0.002), and 62+/-14% (p = 0.02) decrease in TNFalpha production, respectively. Before IVH, TNFalpha production by PBMC incubated with 10% plasma containing S. aureus challenge was 1275+/-70 pg. After 2 hours of IVH, the decrease in TNFalpha production was 20+/-4% (p = 0.002). In conclusion, S. aureus LTA induces TNFalpha production that is significantly suppressed by PMX-B. Consequently, S. aureus cytokine-inducing substances are removed during IVH with PMX-20R, and this may be due to stoichiometric binding of LTA to PMX-B.

A randomized prospective comparison of oral versus intraperitoneal ofloxacin as the primary treatment of CAPD peritonitis

Summary: Oral ofloxacin has been successfully used in our centres for the primary treatment of peritonitis complicating continous ambulatory peritoneal dialysis (CAPD). In view of the progressive rise in the resistance rate to ofloxacin among peritoneal bacterial isolates, a study was conducted to determine if oral ofloxacin remains a viable first line treatment for CAPD peritonitis in our centres and if the result can be improved by changing from an oral to an intraperitoneal (i.p.) route. In patients on three 2 L daily CAPD exchanges, ofloxacin given at the i.p. dosage of 200 mg loading followed by 25 mg/L of peritoneal dialysate achieved overnight trough peritoneal levels which are at least four times the minimal 90% inhibitory concentration (MIC90) of most bacterial pathogens without significant accumulation in the systemic circulation. This i.p. dosage was therefore chosen for the clinical study and the result was compared to that using ofloxacin given in the oral dosage of 400 mg loading followed by 300 mg once daily as maintenance. of all the recruited episodes, 35 were eligible for analysis. the overall primary cure rate including primary failures and relapses was 55.6% (10/18) in the oral treatment group and 70.6% (12/17) in the i.p. treatment group. the corresponding figures for gram positive bacterial (g +) infections were 36.4% and 50%, for gram negative bacterial (g ‐) infections were 66.7 and 80% and for culture negative infections were 75 and 80%. In culture positive cases, all treatment failures were due to resistant infections which were observed in 42.3% of all bacterial isolates, 47.1% of g + isolates and 33.3% of g ‐ isolates. Due to the high background level of bacterial resistance among our CAPD population, ofloxacin monotherapy given either by the oral or the i.p. route can no longer be recommended for the primary treatment of CAPD peritonitis.

5484591 Method for treating gram negative bacterial infections in humans : Young Lowell San Francisco, CA, United States assigned to The Regents of the University of California

5484591 Method for treating gram negative bacterial infections in humans : Young Lowell San Francisco, CA, United States assigned to The Regents of the University of California