Negative Bacterial Infections Research Articles

Membrane interactions and biological activity of antimicrobial peptides from Australian scorpion

UyCT peptides are antimicrobial peptides isolated from the venom of the Australian scorpion. The activity of the UyCT peptides against Gram positive and Gram negative bacteria and red blood cells was determined. The membrane interactions of these peptides were evaluated by dye release (DR) of the fluorophore calcein from liposomes and isothermal titration calorimetry (ITC); and their secondary structure was determined by circular dichroism (CD). Three different lipid systems were used to mimic red blood cells, Escherichia coli and Staphylococcus aureus membranes. UyCT peptides exhibited broad spectrum antimicrobial activity with low MIC for S. aureus and multi-drug resistant Gram negative strains. Peptide combinations showed some synergy enhancing their potency but not hemolytic activity. The UyCT peptides adopted a helical structure in lipid environments and DR results confirmed that the mechanism of action is by disrupting the membrane. ITC data indicated that UyCT peptides preferred prokaryotic rather than eukaryotic membranes. The overall results suggest that UyCT peptides could be pharmaceutical leads for the treatment of Gram negative multiresistant bacterial infections, especially against Acinetobacter baumanni, and candidates for peptidomimetics to enhance their potency and minimize hemolysis. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.

Comparative Molecular Docking Analysis of Cytoplasmic Dynein Light Chain DYNLL1 with Pilin to Explore the Molecular Mechanism of Pathogenesis Caused by Pseudomonas aeruginosa PAO

Cytoplasmic dynein light chain 1 (DYNLL1) is a component of large protein complex, which is implicated in cargo transport processes, and is known to interact with many cellular and viral proteins through its short consensus motif (K/R)XTQT. Still, it remains to be explored that bacterial proteins also exhibit similar recognition sequences to make them vulnerable to host defense mechanism. We employed multiple docking protocols including AUTODOCK, PatchDock, ZDOCK, DOCK/PIERR and CLUSPRO to explore the DYNLL1 and Pilin interaction followed by molecular dynamics simulation assays. Subsequent structural comparison of the predicted binding site for DYNLL1-Pilin complex against the experimentally verified DYNLL1 binding partners was performed to cross check the residual contributions and to determine the binding mode. On the basis of in silico analysis, here we describe a novel interaction of DYNLL1 and receptor binding domain of Pilin (the main protein constituent of bacterial type IV Pili) of gram negative bacteria Pseudomonas aeruginosa (PAO), which is the third most common nosocomial pathogen associated with the life-threatening infections. Evidently, our results underscore that Pilin specific motif (KSTQD) exhibits a close structural similarity to that of Vaccinia virus polymerase, P protein Rabies and P protein Mokola viruses. We speculate that binding of DYNLL1 to Pilin may trigger an uncontrolled inflammatory response of the host immune system during P. aeruginosa chronic infections thereby opening a new pioneering area to investigate the role of DYNLL1 in gram negative bacterial infections other than viral infections. Moreover, by manifesting a strict correspondence between sequence and function, our study anticipates a novel drug target site to control the complications caused by P. aeruginosa infections.

Cell cycle arrest in a model of colistin nephrotoxicity

Colistin (polymixin E) is an antibiotic prescribed with resurging frequency for multidrug resistant gram negative bacterial infections. It is associated with nephrotoxicity in humans in up to 55% of cases. Little is known regarding genes involved in colistin nephrotoxicity. A murine model of colistin-mediated kidney injury was developed. C57/BL6 mice were administered saline or colistin at a dose of 16 mg/kg/day in 2 divided intraperitoneal doses and killed after either 3 or 15 days of colistin. After 15 days, mice exposed to colistin had elevated blood urea nitrogen (BUN), creatinine, and pathologic evidence of acute tubular necrosis and apoptosis. After 3 days, mice had neither BUN elevation nor substantial pathologic injury; however, urinary neutrophil gelatinase-associated lipocalin was elevated (P = 0.017). An Illumina gene expression array was performed on kidney RNA harvested 72 h after first colistin dose to identify differentially expressed genes early in drug treatment. Array data revealed 21 differentially expressed genes (false discovery rate < 0.1) between control and colistin-exposed mice, including LGALS3 and CCNB1. The gene signature was significantly enriched for genes involved in cell cycle proliferation. RT-PCR, immunoblot, and immunostaining validated the relevance of key genes and proteins. This murine model offers insights into the potential mechanism of colistin-mediated nephrotoxicity. Further studies will determine whether the identified genes play a causative or protective role in colistin-induced nephrotoxicity.

A multi centre laboratory study of Gram negative bacterial blood stream infections in Sri Lanka

Data on causative agents and antibiotic susceptibility patterns of blood stream infections in Sri Lanka is scarce. Information on trends of antibiotic resistance is necessary for the prescribers to treat patients effectively and policy makers to develop policies and guidelines. To lay the foundation for a national data base on antimicrobial resistance in Sri Lanka. A prospective study was carried out in seven hospitals to study the Gram negative aetiological agents and their susceptibility patterns in patients suspected of having bacteraemia. We reviewed 817 patients with clinically significant blood cultures including both adults and children. Data were complete for analysis in 733 Gram negative isolates only. Of the 733 isolates, 488 were from adults (> 12 years), 109 were from children (1-12 years) and 136 were from infants (<1 year). Intensive care units represented 18.4% of the isolates (123 adult patients and 27 paediatric patients). The highest number of isolates (33.7%) was from patients with septicaemia of unknown origin. Enteric fever, pyelonephritis and respiratory tract infections accounted for 20% of the isolates. Bacteraemia with underline malignancies were responsible for 24.5% of infections. Salmonella paratyphi A was the commonest cause of enteric fever in adults with 92% resistance to ciprofloxacin. The prevalence of extended spectrum beta lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae was high in this study population. It is essential to introduce multidisciplinary interventions to reduce the inappropriate use of antibiotics to increase the lifespan of precious antibiotics. Introduction of a National antibiotic policy with strict implementation and a well-planned stewardship programme is essential to control antimicrobial resistance in our country.

Review of clinical profile and bacterial spectrum and sensitivity patterns of pathogens in febrile neutropenic patients in hematological malignancies: A retrospective analysis from a single center

Background:The aim of this study was to study clinical profile with bacterial spectrum and susceptibility patterns of pathogens in culture positive febrile neutropenic (FN) patients of hematological malignancies.Materials and Methods:We retrospectively reviewed the medical records of 23 hematological malignancy patients admitted with chemotherapy induced febrile neutropenia with culture positive results, at our institute between June 2011 and December 2011.Results:A total of 23 patients were studied 12 males and 11 females, with a median age of 35 years. Most common diagnosis was acute leukemia (78%) with the majority of patients developing febrile neutropenia during the induction phase of treatment. Most common presenting symptoms were fever, cough, dyspnea, and diarrhea. Primary site of infection was not found in 47% of patients while the rest had lung, gastro-intestinal and skin/soft-tissue infection. Overall 23 organisms were isolated during the study period, from blood (56%), sputum (46%), stool (23%), and nasal swab from one patient. Gram negative bacteria accounted for 78% of organisms while gram positive organisms accounted for 22% of the total isolates. The most common organisms were: Escherichia coli (43%), Staphylococcus aureus (22%), Pseudomonas aeruginosa (17.4%) and Klebsiella pneumonia (17.4%). Antibiotic sensitivity patterns of these bacteria were studied. Gram negative bacterial infections were associated with higher mortality (89%).Conclusions:Induction phase of treatment in acute leukemia is the major cause of FN in hematological malignancies at our institute and gram negative organisms are the predominant organisms with E. coli as major isolate while S. aureus represents the most common gram positive organism. Amikacin and cefoperazone/sulbactum appears to be initial antibiotic appropriate to cover most gram negative pathogens while vancomycin to be added for suspected gram positive infections. FN represents a major cause of morbidity and mortality in hematological malignancy patients, high index of suspicion and early empirical antibiotics with supportive care are main interventions to reduce high mortality for these patients. Antibiotics should be modified according to culture sensitive report as soon as possible.

A Single, Ultra‐High Dose Aminoglycoside Therapy in a Rat Model of E. coli Induced Septic Shock

IntroductionSeptic shock is a life threatening condition often due to Gram negative bacterial infections and is responsible for around 200,000 deaths every year in United States of America alone. Our research focuses on determining the potential of a single, ultrahigh dose aminoglycoside therapy for accelerated bacterial clearance with minimal to manageable side effects in a rat model of E. coli induced septic shock.Methods: Study in uninfected animalsGentamicin was administered intravenously at 80 and 160 mg/kg doses to anesthetized and intubated Sprague Dawley rats. Mean arterial pressure, heart rate, respiratory rate and percentage oxygen saturation were determined. The occurrence and time course of neuromuscular paralysis/ventilator dependency, renal injury and auditory toxicity after ultra‐high dosing of gentamicin was determined. Renal injury was determined by Creatinine clearance and histology. Auditory brain stem response studies were performed to assess the auditory toxicity.Septic shock induced animalsSeptic shock was induced in rats by surgical, intra‐peritoneal implantation of a gelatin capsule containing E. coli bort (ATCC 700973) in a fibrinogen and alfa‐cellulose matrix. Gentamicin was intravenously administered at 5, 10, 20, 40, 80 and 160 mg/kg doses.ResultsUltra high gentamicin dosed animals were found to develop neuromuscular paralysis with ventilator dependency for 20 – 40 minutes and recovered thereafter. Rats did not exhibit any auditory and renal toxicity. Complete eradication of bacterial counts from blood occurred following ultra‐high doses.ConclusionRats were able to tolerate single, ultra‐high doses of gentamicin with complete eradication of bacterial counts from blood.Research is supported by University of Manitoba

Identification of novel antimicrobial resistance genes from microbiota on retail spinach

BackgroundDrug resistance genes and their mobile genetic elements are frequently identified from environmental saprophytic organisms. It is widely accepted that the use of antibiotics in animal husbandry selects for drug resistant microorganisms, which are then spread from the farm environment to humans through the consumption of contaminated food products. We wished to identify novel drug resistance genes from microbial communities on retail food products. Here, we chose to study the microbial communities on retail spinach because it is commonly eaten raw and has previously been associated with outbreaks of bacterial infections.ResultsWe created metagenomic plasmid libraries from microbiota isolated from retail spinach samples. We identified five unique plasmids that increased resistance to antimicrobial drugs in the E. coli host. These plasmids were identified in E. coli that grew on plates that contained ampicillin (pAMP), aztreonam (pAZT), ciprofloxacin (pCIP), trimethoprim (pTRM), and trimethoprim-sulfamethoxazole (pSXT). We identified open reading frames with similarity to known classes of drug resistance genes in the DNA inserts of all 5 plasmids. These drug resistance genes conferred resistance to fluoroquinolones, cephalosporins, and trimethoprim, which are classes of antimicrobial drugs frequently used to treat human Gram negative bacterial infections. These results show that novel drug resistance genes are found in microbiota on retail produce items.ConclusionsHere we show that microbiota of retail spinach contains DNA sequences previously unidentified as conferring antibiotic resistance. Many of these novel sequences show similarity to genes found in species of bacteria, which have previously been identified as commensal or saprophytic bacteria found on plants. We showed that these resistance genes are capable of conferring clinically relevant levels of resistance to antimicrobial agents. Food saprophytes may serve as an important reservoir for new drug-resistance determinants in human pathogens.

Evaluation of Predictors of Adverse Outcome in Febrile Neutropenic Episodes in Pediatric Oncology Patients

To identify predictors associated with adverse outcome in febrile neutropenic episodes among pediatric oncology patients between 1 and 18 y age, to ascertain the prevalence of invasive bacterial or fungal infection/mortality, to determine the common organisms causing invasive bacterial infection in children with febrile neutropenia and to evaluate their current antimicrobial sensitivity pattern. It was an observational descriptive study conducted between February 2009 through July 2010. Febrile neutropenic episodes satisfying the inclusion criteria were enrolled. Relevant history was taken followed by a detailed clinical examination and laboratory examination. Logistic Regression analysis was used to identify significant predictors of adverse outcome in febrile neutropenic episodes. Out of the 155 febrile neutropenic episodes studied, adverse outcome occurred in 53(34 %) of the episodes. History of three or more previous episodes of febrile neutropenia, child being already on oral antibiotics and Chest Radiograph abnormality at presentation were found to be significantly associated with adverse outcome on multivariate logistic regression analysis. Documented invasive bacterial and fungal infection was seen in 27.8 % and 14.2 % episodes. Mortality occurred in 8 (5 %) of episodes. Gram negative bacterial infections were more common. Most common bacteria isolated was Escherichia coli and the commonest gram positive organism isolated was Staphylococcus aureus (MSSA). On multivariate analysis, the variables found to be significantly associated with adverse outcome in febrile neutropenic episodes were three or more previous episodes of febrile neutropenia, child being already on oral antibiotics and Chest Radioraph abnormality at presentation.

Effect of some natural plant extracts against gram negative bacteria in Njran Area, Saudi Arabia

This study aimed to evaluate the growth inhibitory effect ofSyzygium aromaticum (clove), Nigella sativa (black cumin), Commiphora molmol (myrrh) and Allium sativum (garlic) on Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii. Water, 80% ethanol and n-hexane plant extracts either alone or in combination were tested against 4 gram negative bacteria. Gel diffusion method, minimum inhibitory concentration (MIC) values were used in this investigation. The findings indicated that individual S. aromaticum, C. molmoland A. sativum extracts had growth inhibitory effect against tested bacteria. Ethanolic extract of S. aromaticum exhibited the highest inhibitory effect on all tested microorganisms. Individual water, ethanolic and hexanic extracts of N. sativa did not show any growth inhibitory effect against all tested microorganisms. Synergistic inhibitory effects of ethanolic and hexanic extracts combination of the four plants were able to prevent the growth of the tested bacteria. Combination of water extracts of the 4 plants inhibit the growth of P. aeruginosa and A. baumannii, while E. coli and K. pneumonia were not inhibited. We are of the opinion that individual ethanolic and hexanic extracts of the clove and combinations of ethanolic and hexanic extracts of the four tested plants could potentially be used for treatment of gram negative bacterial infection especially to the tested microorganisms.

ANTIMICROBIAL ACTIVITY OF SHEA BUTTER ON CLINICAL ISOLATES OF SKIN INFECTIONS FROM UNIVERSITY OF BENIN TEACHING HOSPITAL, BENIN CITY, NIGERIA

The antimicrobial activity of shea butter was tested against Gram positive and Gram negative bacterial and fungal skin infections isolates from the University of Benin Teaching Hospital, Benin City, Nigeria. The isolates were identified by standard microbiological methods. The isolates were Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Shea butter purchased from a local market in Benin City, was tested against these isolates using agar-well diffusion method. When the crude and ethanol extracts of shea butter were tested with the test organisms, the results showed significant inhibitory effect against the test organisms. The crude extracts of shea butter and varying concentration of ethanol extracts on shea butter, was inhibitory against all the test isolates with Pseudomonas aeruginosa (22 mm) and Staphylococcus aureus (20 mm) having the highest zones of inhibition. This was followed by Candida albicans (16 mm), Staphylococcus epidermidis (15 mm) and Streptococcus pyogenes (13 mm). The lowest (11 mm) was observed in Escherichia coli. Varying multiple resistances to conventional antibiotics was observed from the test isolates. Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes showed great resistance to the antibiotics. The minimum inhibitory concentration (MIC) showed that the ethanol extracts inhibited the growth of all the test organisms at 3.125 mg/ml, indicating the good antimicrobial activity of shea butter. This suggests that shea butter may represent a better therapeutic agent to control some skin infections.

Ludwigs Angina: lessons learned

<h3>Introduction</h3> Ludwigs Angina is a rapidly progressive gangrenous cellulitis of the submandibular space historically associated with a high mortality rate due to airway obstruction. In 90% of adults the aetiology is odontogenic whilst in children an odontogenic source accounts for a third of cases. The microorganisms implicated include a range of bacteria, particularly streptococcal species, gram-negative rods and anaerobes. <h3>Objective</h3> This clinical case presentation aims to highlight the lessons learnt in the management of a young child with Ludwig9s Angina. <h3>Population and Methods</h3> A previously well 13-month-old girl presented with pyrexia and acute swelling of the neck and floor of mouth following a coryzal illness. Intravenous antibiotic therapy was commenced at her local hospital. Despite this she deteriorated rapidly with increasing respiratory compromise requiring intubation and transfer to the regional PICU. We describe her further conservative yet aggressive management with steroids, antibiotics and conservative ENT care in a tertiary care setting. <h3>Results</h3> Neck ultrasound showed extensive subcutaneous oedema with no focal abscess. A clinical diagnosis of Ludwig9s Angina was made after specialist paediatric ENT assessment. The neck swelling and upper airway oedema improved but her clinical course was complicated by lower respiratory tract infection. Tracheal secretions were positive for parainfluenzae type 3. Haemophilus influenzae and Moraxella catarrhalis were isolated from bronchoalveolar lavage fluid. In total she required PICU care for 7 days and ventilatory support for 5 days. <h3>Conclusions</h3> Valuable lessons can be learned from this clinical case: (1)Ludwigs Angina has a typical bull neck appearance with diffuse brawny swelling of the neck. (2)It is a cause of acute rapidly progressive airway obstruction and may present as a life threatening airway emergency. (3)It may be complicated by contiguous spread of infection within the respiratory tract. (4)Viral upper respiratory tract infection followed by Gram negative bacterial infection is a recognised infectious aetiology with the viral infection facilitating polymicrobial infection. Microbiological diagnosis is helpful to guide prognosis as well as management. (5)Early recognition of this soft tissue cellulitis is essential for prompt airway and antibiotic management.

Nucleotide Sequencing and SNP Detection of Toll-Like Receptor-4 Gene in Murrah Buffalo (Bubalus bubalis).

Toll-like receptor-4 (TLR-4) has an important pattern recognition receptor that recognizes endotoxins associated with gram negative bacterial infections. The present investigation was carried out to study nucleotide sequencing and SNP detection by PCR-RFLP analysis of the TLR-4 gene in Murrah buffalo. Genomic DNA was isolated from 102 lactating Murrah buffalo from NDRI herd. The amplified PCR fragments of TLR-4 comprised of exon 1, exon 2, exon 3.1, and exon 3.2 were examined to RFLP. PCR products were obtained with sizes of 165, 300, 478, and 409 bp. TLR-4 gene of investigated Murrah buffaloes was highly polymorphic with AA, AB, and BB genotypes as revealed by PCR-RFLP analysis using Dra I, Hae III, and Hinf I REs. Nucleotide sequencing of the amplified fragment of TLR-4 gene of Murrah buffalo was done. Twelve SNPs were identified. Six SNPs were nonsynonymous resulting in change in amino acids. Murrah is an indigenous Buffalo breed and the presence of the nonsynonymous SNP is indicative of its unique genomic architecture. Sequence alignment and homology across species using BLAST analysis revealed 97%, 97%, 99%, 98%, and 80% sequence homology with Bos taurus, Bos indicus, Ovis aries, Capra hircus, and Homo sapiens, respectively.

Infectious Complications In Patients with AL (Immunoglobulin Light Chain) Amyloidosis Undergoing Treatment with High-Dose Melphalan and Autologous Stem-Cell Transplantation (HDM/SCT)

Abstract 2041High dose melphalan and autologous stem cell transplantation (HDM/SCT) can lead to hematologic and organ responses and improved survival in selected patients with AL amyloidosis. Intrinsic and extrinsic risk factors for infections in these patients include functional hyposplenism, hypogammaglobulinemia, melphalan-induced neutropenia, mucositis, and nosocomial exposures. We performed a retrospective review of 493 patients with AL amyloidosis who underwent treatment with HDM/SCT at Boston Medical Center from August 1994 to August 2009. Patients received outpatient treatment from October 1996 onwards. The objectives of this study were to determine the rate of infections, identify infections leading to treatment-related mortality (TRM, defined as death within 100 days), and compare the impact of patient and treatment characteristics on rates of infection. Microbiologically documented infections after HDM/SCT were identified in 119 patients (24%, n=119/493). The median number of days to post- SCT infection was 8 days (range, 0–47). The mean number of days of body temperature more than 100.50 F (38° C) was 3 (95% CI 1.7–4.31). There were 48 deaths (10%) within 100 days of HDM/SCT. Among patients with documented infection, 25 had TRM (21%, n=25/119). Two hundred and forty five patients had febrile neutropenia. One hundred and forty seven of these had negative cultures. Therefore, the rate of culture negative febrile neutropenia was 60% (n=147/245). Identified pathogens included gram positive bacteria (51%), anaerobic bacteria (15%), gram negative bacteria (13%), fungi (8%) and viruses (6%). The majority of these organisms were identified in blood (50%), followed by respiratory secretions (20%) and stool (15%). Of the positive cultures, gram positive infections included staphylococci (29%), streptococci (10%), and enterococci (10%). C. difficile was the most commonly identified anaerobe, accounting for 11% of the total number of positive cultures. Gram negative bacterial infections included enterobacteriacae (8%) and pseudomonas (3%). Fungal infections included candida species (7%), aspergillus (4%) and pneumocystis (1%). Viral infections included herpes (3%), paramyxoviridae (3%) and cytomegalovirus (0.4%). In the unadjusted bivariate analyses, serum creatinine > 2 mg/dL was significantly associated with increased risk of post-HDM/SCT infections (38% versus 21%, p= 0.0007) with an odds ratio (OR) of 2.27 (95% CI 1.40–3.68). In addition, TRM was found to have a significant association with post-HDM/SCT infections (52% versus 21%, p = < 0.0001) with an OR of 3.82 (95% CI 2.01–7.26). The relative risk of TRM in a patient with documented infection was 3.42 (95% CI 2.02–5.79). In multivariate analyses, serum creatinine > 2 mg/dL remained significantly associated with post-SCT infection with an OR of 2.29 (95% CI 1.41–3.73). No significant association was found for age, gender, cardiac involvement, prior steroid therapy, dose of melphalan, time to neutrophil engraftment, number of organs involved in amyloidosis, or dose of infused CD34+ cells, both in unadjusted and adjusted analyses. In conclusion, serum creatinine >2 mg/dL is a risk factor for infections in patients with AL amyloidosis undergoing HDM/SCT. The relative risk of TRM in a patient with a documented infection was 3.34. A broad spectrum of infections, similar to those reported in other SCT patients, is seen in this population. Disclosures:No relevant conflicts of interest to declare.

BURN PATIENTS

Objectives: To study the micro flora in wounds of the burn patients from three tertiary care medical hospitals in Karachi. Introduction: In burn patient infections arise from multiple sources and infect burn wounds by a variety of micro-organisms. Gram negative bacterial infection results from translocation from colon, further more burn patients are infected by Hospital acquired bacteria by various invasive and non invasive procedures. Period: July 2002 to December 2002. Setting: This study was conducted at the Department of Microbiology, Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre, Karachi. Study Design: Observational study. Material &amp; Methods: A retrospective study of fifty five patients with burn wound infection was carried out at burn units of Civil Hospital Karachi, National Institute of Child health Karachi and Abbasi Shaheed Hospital, Karachi. Patients who received burn injuries with clinical signs and symptoms of infection were included in this study. Results: In the present study 46(29%) isolates of P. aeruginosa were recovered, in which most strains were MDR and their sensitivity against Imipenem was 38 (78%). The over all prevalence of the Oxidase negative Gram negative coli form bacteria was more than 70%, in which the most prevalent organism belongs to Proteus Spp;(27%) follows the Enterobacter Spp;.(15.5%). Conclusions: Bacteria belongs with family Enterobacteriacae were more prevalent i.e. &gt;70% while P. aeruginosa was individually more prevalent than any member of family Enterobacteriacae and was most resistant to multiple antibiotics than any other bacteria. Imipenem was the most effective drug against all gram negative bacteria follows the 4th. generation Cephalosporin Cefepime.

Evaluation of the antioxidant protective effect of oxytocin and silymarin against gentamicin-induced nephrotoxicity in rat

Gentamicin is an effective aminoglycoside antibiotic against severe infections. In spite of inducing nephrotoxicity and oxidative damage, gentamicin is used clinically due to its wide spectrum of activities against Gram negative bacterial infections. Its nephrotoxicity occurs by selective accumulation in renal proximal convoluting tubules. Its nephrotoxicity involves renal free radical generation and reduction in antioxidant defense mechanisms. A potential therapeutic approach to protect or reverse gentamicin-induced oxidative stressand nephrotoxicity would have more importance for clinical consequences. Therefore, thepresent study was designed to investigate the possible antioxidant protective effects of oxytocin and silymarin against gentamicin-induced renal damage in rats. A total of 40 adult male albino rats were divided into four groups. The first group is the control group that received normal saline (1ml/kg/i.p/day for 8 consecutive days), the second group was treated withgentamicin(80mg/kg/i.p/day for 8 days), the third group was treated with gentamicin (80mg/kg/i.p/day for 8 days) and oxytocin (5 I.U/kg/i.p/day for 8 days) and the fourth group was treated with gentamicin (80mg/kg/i.p/day for 8 days) and salymarin in a dose of (50 mg/kg orally/day for 8 days). Some biochemical and histopathological examinations of kidneys were performed after treatment for evaluation of the oxidative stress and renal nephrotoxicity. Gentamicin treatment significantly increased serum urea and creatinine levels and AST activities. Also gentamicin significantly decreased the total antioxidant capacity and catalase activity in renal tissues. Renal tissue malondialdehyde (MDA) has a non significant increase, while renal reduced glutathione (GSH) wasn't changed. Study of renal morphology showed degenerative changes in the form of cloudy swelling, hydropic degeneration and glomerular necrosis in gentamicin group. Administration of oxytocin and silymarin with gentamicin ameliorated to some degree the biochemical changes and oxidative stress parameters against gentamicin-induced nephrotoxicity. It was concluded that treatments with these antioxidants could have beneficial effects in treatment of gentamicin induced nephrotoxicity.

Thalidomide treatment modulates macrophage pro-inflammatory function and cytokine levels in Klebsiella pneumoniae B5055 induced pneumonia in BALB/c mice

Lung innate immune response plays an important role in the clearance of pathogens from lungs, however, profound activation of innate immune cells (alveolar macrophages or neutrophils) can lead to development of acute lung inflammation or injury by producing various pro-inflammatory molecules (IL-1, TNF-α and H 2O 2 etc.). Present study is designed to investigate the immunomodulatory action of thalidomide in Klebsiella pneumoniae B5055 induced acute lung infection in BALB/c mice. Acute lung inflammation was induced by intranasal instillation of K. pneumoniae B5055 into mice without any anaesthesia and treated with thalidomide (30 mg/kg/day/po) or normal saline orally using a treatment schedule shown to modulate pro-inflammatory innate immune response. Thalidomide treatment modulated pro-inflammatory function of alveolar macrophages by significantly ( p < 0.05) decreasing their phagocytic potential in terms of phagocytic uptake and intracellular killing, spreading and hydrogen peroxide (H 2O 2) release. Besides that thalidomide treatment also significantly ( p < 0.05) decreased neutrophil infiltration into the lung alveoli. Remarkably, the levels of pro-inflammatory cytokines (IL-1α and TNF-α) were found to be decreased significantly ( p < 0.05) in thalidomide treated group but the levels of IL-10 were found to be significantly ( p < 0.05) elevated. Thus thalidomide proved a promising immunomodulatory agent in acute lung inflammation associated with pneumonia caused by gram negative bacterial infection.

Contribution of bacterial and viral infections to attributable mortality in patients with severe burns: An autopsy series

Bacterial infections are a common cause of mortality in burn patients and viral infections, notably herpes simplex virus (HSV) and cytomegalovirus (CMV) have also been associated with mortality. This study is a retrospective review of all autopsy reports from patients with severe thermal burns treated at the US Army Institute of Research (USAISR) burn unit over 12 years. The review focused on those patients with death attributed to a bacterial or viral cause by autopsy report. Of 3751 admissions, 228 patients died with 97 undergoing autopsy. Death was attributed to bacteria for 27 patients and to virus for 5 patients. Bacterial pathogens associated with mortality included Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. This association with mortality was independent of % total body surface area burn, % full-thickness burn, inhalation injury, and day of death post-burn. Bloodstream infection was the most common cause of bacteria related death (50%), followed by pneumonia (44%) and wound infection (6%). Time to death following burn was ≤7 days in 30%, ≤14 days in 59% and ≤21 days in 67%. All of the viral infections associated with mortality involved the lower respiratory tract, HSV for 4 and CMV for 1. Four of these 5 patients had evidence of inhalation injury by bronchoscopy, all had facial and neck burns, and 2 had concomitant Staphylococcus pneumonia. Time to death following burn ranged from 14 to 42 days for the 5 patients. Despite advances in care, gram negative bacterial infections and infection with S. aureus remain the most common cause of bacteria related mortality early in the hospital course. Viral infections are also associated with mortality and numbers have remained stable when compared to data from prior years.

Persistent pneumonia: Underlying cause and outcome

To identify the causes and contributing factors of persistent pneumonia in children. 41 cases with persistent pneumonia were investigated (biochemical, microbiological, histopathological, immunological and radiological tests) to find out the underlying cause. Out of 41 cases, 8 had pulmonary tuberculosis and 12 had Gram negative bacterial infections, 12 had aspiration due to gastroesophageal reflux disease or oil instillation, 3 had immunodeficiency due to HIV infection, 2 had congenital lung malformation, 2 had cardiac disorders and one had foreign body aspiration as causes of persistent pneumonia. The etiology could not be established in one case. The most common underlying cause of persistent pneumonia were persistent infection followed by aspiration and acquired immunodeficiency.

Pentoxifylline Ameliorates Glomerular Basement Membrane Ultrastructural Changes Caused by Gentamicin Administration in Rats

Gentamicin is commonly used for the treatment of severe gram negative bacterial infections but inevitably cause renal failure during prolonged use. The aim of our study was to emphasize protective effects of pentoxifylline on glomerular basement membrane (GBM) alterations induced by gentamicin in rats. Experiments were done on 40 male Wistar rats divided in three experimental groups. GM-group was treated daily with gentamicin in dose of 100 mg/kg during 8 days. PTX-group was treated daily with pentoxifylline in dose of 45 mg/kg and the same dose of gentamicin as in GM-group during 8 days. The control group received 1 ml/day saline intraperitoneally. Morphometric parameter measured during the analysis was glomerular basement membrane thickness. In GM-group of animals glomeruli were enlarged and GMB was diffusely and unequally thickened with neutrophil cells infiltration. In proximal tubules epithelial cells, vacuolization of cytoplasm with coagulation-type necrosis were observed. In PTX-group of animals glomeruli were somewhat enlarged and GBM was thickened only in some segments. Coagulation-type necrosis was not found. Blood urea and serum creatinine concentration in GM-group were significantly elevated in comparison with PTX-group while potassium level was decreased. Our results suggest that PTX has protective effects on GBM and proximal tubules in GM-treated rats.

Immunomodulatory activity of synthetic innate defence regulators (IDRs) (134.45)

Abstract Cationic host defence (antimicrobial) peptides, e.g. cathelicidin LL-37, have a variety of immunomodulatory activities that favour the safe resolution of infections. We have studied novel synthetic cationic innate defence regulator peptides that are not directly antimicrobial but are anti-infective in vivo, due to modulation of innate immunity. A range of peptides derived from the small bovine peptide bactenecin were screened for immunomodulatory activities in vitro; e.g. promotion of chemokine production and suppression of pro-inflammatory cytokines. Since innate immunity is complex, involving &amp;gt;1,500 gene products, a systems biology approach was utilized to characterize peptide modulation of innate immunity, including analysis of receptors, signalling pathways, transcription factors and downstream genes. To permit visualization and bioinformatic analysis of complex events, an innate immunity database (www.innatedb.ca), a network visualization tool (Cerebral) and downstream analysis tools (e.g. pathway overrepresentation analysis) were developed and provided insight into how this selective modulation occurs. In vivo data indicate that these activities provide protection in animal model infections of Gram positive and Gram negative bacterial infections as well as severe malaria. Thus IDRs have great potential for use as novel anti-infective agents. Supported by Genome BC, FNIH and CIHR.