Gram-negative Bacterial Flora Research Articles

Clinical Case of Postoperative Infectious Crystalline Keratopathy

Infectious crystalline keratopathy (ICK) is a sluggish infectious inflammation of the cornea. Described for the first time in 1983, it is currently a rare pathology. Most often, the etiological factor is gram-positive bacterial flora, which causes the typical formation of “crystals” in the anterior layers of the corneal stroma. Less often, infiltrates are formed by gram-negative bacterial flora, which is characterized by its location mainly in the posterior parts of the stroma. Atypical etiological agents include Mycobacteria and fungal microflora. The main predisposing factors for the development of ICK are drug immunosuppression and previous corneal surgery (through keratoplasty, layered keratoplasty, laser keratomilesis in situ — LASIK). This article describes an atypical clinical case of monolateral postoperative infectious crystalline keratopathy. The patient’s medical history includes bilateral LASIK surgery followed by drug therapy for postoperative keratitis of the right eye for 1 month.

Особенности культивирования бражника мёртвая голова Acherontia atropos (Linnaeus, 1758) на искусственных питательных средах

The results of testing of the method of cultivation of the deadhead hawk moth Acherontia atropos (Linnaeus, 1758) using solid culture medium are given in this article. Optimal cultivation conditions for all caterpillar stages of this species are discussed. Information about bacterial infection of caterpillars which is caused by Gram-negative rod-shaped bacterial flora, is also noted in the results. Methods of treatment of this bacterial infection were selected empirically and also given use of bactericidal antibiotics (ceftriaxone) and selenopiran. We also trialled the use of a similar method of cultivation on some specific media for rare species of Lepidoptera like Proserpinus proserpina, Eudia pavonia, Saturnia pyri and some other species.

Molecular Identification of Gram-Negative Bacteria in Respiratory Samples of Cystic Fibrosis Patients from a Children Referral Hospital in Tehran

Background: Gram-negative bacteria are a major cause of pulmonary infection in patients with cystic fibrosis (CF). Objectives: The study aimed to conduct the molecular identification of Gram-negative bacterial flora causing pulmonary infection in children with CF. Methods: In this study, sputum samples were taken from 64 CF children undergoing treatment as outpatients or inpatients at a referral children’s hospital in Tehran. The PCR technique was used to detect the presence of Gram-negative bacteria, namely Pseudomonas spp., Acinetobacter baumannii, Stenotrophomonas maltophilia, and Burkholderia cepacia. Results: All samples were positive for 16srRNA. Pseudomonas spp. and A. baumannii were detected in 47% and 14% of the studied samples, respectively. Co-colonization by Pseudomonas spp. and A. baumannii was observed in three (5%) samples. Conclusions: According to this survey, Pseudomonas spp. were the most prevalent Gram-negative bacteria isolated from CF patients with pulmonary infection by molecular assays.

Potential of Surface Water Gram-negative Bacterial Flora as a Reservoir of Heterogeneous Plasmid and Multi-drug Resistance Phenomenon

Potential of Surface Water Gram-negative Bacterial Flora as a Reservoir of Heterogeneous Plasmid and Multi-drug Resistance Phenomenon

Disorders of local pulmonary immune response in patients with chronic obstructive pulmonary diseases during exacerbation

Introduction. Morbidity due to reduced local immune reaction in patients affected by chronic obstructive pulmonary disease (COPD) is extremely high and continues to grow. The results of a research on changes in the local immune response in patients with COPD at the exacerbation stage are discussed in this paper. The pathogenesis of COPD during exacerbation is characterized by deterioration of the local innate and acquired immunity. The process is accompanied by pathological changes of the systemic immunity. Various cells of the immune response are involved in the inflammation process, attracting increased amounts of macrophages, neutrophils, T- and B-lymphocytes, and dendritic cells. The number of neutrophils and B-lymphocytes are observed in patients suffering from a severe disorder. Most common symptoms of COPD are irreversible narrowing of the airways, destruction of the parenchyma of the lung accompanied by emphysema, and progression of the obstructive pulmonary disease. The aim of the study – to learn the changes in functionality of bronchoalveolar lavage (BAL) cells and peripheral blood cells (PBC) in COPD patients and provide an explanation for these changes in light of pathogenetic characteristics to predict the course of the disease and justify the necessity of a local immunotherapy in comprehensive treatment of COPD patients. Research Methods. The focus of the research was on BAL cells and PBC of patients with COPD at different stages and on blood serum. CD3, CD4, CD8, CD16 and CD19 of BAL and PBC cells were identified using different specific monoclonal antibodies. Receptor expression to IL-2 (CD25) was examined, adhesive molecules were identified using CD54, proliferation levels were measured using IPO-38, as well as was measured the expression of class II antigens MHC (HLA-DR) in the blast transformation reaction that was induced by PHA and Con A mitogens. Phagocytic activity of phagocytizing neutrophils cells, alveolar macrophages (AM), and phagocytizing PBC cells was evaluated. Levels of free radical processes and antioxidant defence were studied using a chemiluminescence method. Results and Discussion. The amount of AM cells in COPD patients declined significantly, whereas the amount of neutrophils notably increased, as well as concentrations of the myeloperoxidase and the eosinophil cationic protein. Examination of phlegm and BAL cells obtained from COPD patients at the exacerbation stage of the disease indicate that 23 % of samples displayed gram-negative bacterial flora (primary pathogens being Pseudomones aeruginosa, Haemophillus influensae, Enterobacter spp.), 15 % – candidas, 61 % – pathogen type was not identified. Researching local and systemic immune response in COPD patients and functional activity changes of BAL and PBC indicated that patients showed significant changes in their local immune system, which manifested in significant reduction in the amount of neutrophils in the lavage, reduction in CD3, CD19, and increased expression of receptors to HLA-DR antigen expression. Summary. Parallel study of the local and systemic immunological responses contributes to expand our knowledge and understanding of pathogenesis of COPD. It is useful in determining methods to help decrease the number of complications and aid in COPD prophylaxis in persons of working age. It also provides information on which local immunotherapy will prove to be most effective. Exploring the subject further should provide fundamental understanding of similar and different symptoms of various disorders in patients with inflammation processes at the local immune level in different body locations, such as respiratory organs during COPD, in the peritoneal cavity during peritonitis, dermal lesions or any other changes in the local immune system of a different body location.

Airborne Endotoxins and Airborne Gram-Negative Bacteria in a Residential Neighborhood

Ambient outdoor concentrations of airborne endotoxins and airborne gram-negative bacteria were measured in a residential area. Further, the species composition of the airborne gram-negative bacterial flora was investigated. The results demonstrated that humans and other mammals are exposed to airborne endotoxins in the outdoor air, but at levels where a development of adverse health effects is unlikely. The total amount of inhalable endotoxins ranged from <3.0 EU/m3 to 27.8 EU/m3. Airborne gram-negative bacteria were detected only at low concentrations (maximum 7.9 cfu/m3). Most gram-negative bacterial isolates belonged to the family Enterobacteriaceae and Pseudomonadaceae. Furthermore, the results of this study suggest that soil and vegetation are potential sources of airborne endotoxins and airborne gram-negative bacteria in the outdoor air of this environment.

Airborne gram-negative bacterial flora in animal houses.

The concentration and the species composition of airborne gram-negative bacteria were studied in four cattle houses, one pig house and one poultry barn. On average only between 0.02 and 5.2% of the total number of culturable aerobic bacteria were identified as gram-negative bacteria. Obligate anaerobic gram-negative bacteria were not isolated at all. In the airborne gram-negative bacterial flora the following bacterial families dominated: the Enterobacteriaceae, the Pseudomonadaceae and the Neisseriaceae. Within the family of the Enterobacteriaceae the species Escherichia coli and Enterobacter agglomerans were predominant. In animal houses using straw as bedding material Ent. agglomerans was most frequent, whereas in animal houses without litter E. coli was mainly found. Airborne Neisseriaceae were isolated very frequently in cow barns with Acinetobacter lowffii as the primary species. Airborne Pseudomonadaceae were found in high concentrations during periods of high air humidity. The results presented may also give some indications on the origin and sources of airborne endotoxins in animal housing.

Gram-negative bacterial flora on the root surface of wheat (Triticum aestivum) grown under different soil conditions

Gram-negative bacterial flora on the root surface of wheat (Triticum aestivum) grown under different soil conditions

Gram-negative bacterial flora on the root surface of wheat (Triticum aestivum) grown under different soil conditions

We identified 108 Gram-positive bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into four groups based on morphological and physiological characteristics, but most appeared to be coryneform. The taxonomic position of the various groups was verified by the guanine+cytosine DNA contents of the strains. In general, the ranges of these values agreed with those described for the respective taxonomic positions in the literature, with a few exceptions. With soil improvement the distribution of the various groups on the root surface changed, with the coryneform group becoming dominant. This group was further divided into five subgroups, according to cell wall components, cellulose-decomposition, and morphological characteristics, and were identified to genus level. The distribution of these subgroups on the root surface of wheat did not alter with soil improvement. The genus Arthrobacter, the dominant subgroup, predominated in every plot.

Postoperative Selective Bowel Decontamination Prevents Gram-Negative Bacterial Translocation in Small-Bowel Graft Recipients

Gram-negative septic episodes are a potential risk of small-bowel transplantation; bacterial translocation through the graft is considered the mechanism. As a measure to prevent this complication, we evaluated postoperative selective bowel decontamination (SBD) in the rat model of orthotopic small-bowel transplantation [Lewis (LEW) and Brown-Norway (BN) rats as donors and recipients]. For 4 days after transplantation we gave FK 506, 2 mg/kg, which prevents rejection and results in indefinite recipient survival. For SBD, 24 mg/kg/day polymyxin E and 20 mg/kg/day tobramycin were administered via orogastric gavage to allograft recipients, both with and without FK 506 therapy. On Day 9, all rats were sacrificed, the peritoneal cavity was swabbed, and mesenteric lymph nodes (MLN), spleen, liver, and ileum were harvested for microbial qualitative and quantitative analysis. Animals with positive peritoneal swab cultures were excluded. SBD resulted in a significant reduction of the quantitative gram-negative bacterial flora in the ileum and cecum and of bacterial translocation to the MLN [0% versus 50% (no FK 506 therapy) and 8% versus 50% (FK 506 treated)]. In the allograft groups not treated with FK 506, SBD failed to significantly prolong survival, suggesting that acute rejection is not hastened by infection (bacterial translocation). We conclude that SBD in small-bowel-graft recipients prevents bacterial translocation by reducing intestinal gram-negative bacterial flora; this may reduce local and systemic infections by gut-derived organisms.

Effects on intestinal microflora, gastrointestinal tolerability and antiinflammatory efficacy of diclofenac and nitrofenac in adjuvant arthritic rats

Since it is known that nitric oxide plays an important protective role in maintaining the tissue integrity and is cytotoxic for invasive micro-organisms, diclofenac and a new original diclofenac-derivate, nitrofenac (containing the nitric oxide group), was administered at doses of 0.3 and 3 mg kg −1 per os to adjuvant arthritic rats. At the 14th, 21st and 28th days after arthritis induction, the anti-inflammatory efficacy and the effects on intestinal microflora of the two drugs were evaluated; moreover, at the end of the study period, the gastrointestinal tract was examined macroscopically for any presence of lesions. Daily oral administration of diclofenac and nitrofenac at 3 mg kg −1 markedly and significantly inhibited arthritis development until the end of the study period. Some significant changes were observed in anaerobic and Gram-negative bacterial flora, particularly the total disappearance, in all treated rats, of Escherichia coli 1, also 7 days after the last drug administration. Finally, no ulcers or severe damage were observed macroscopically with either drug, even if some alterations in the mucosa and haemorrhagic effusions were more evident in rats treated with diclofenac at 3 mg kg −1. In conclusion, in this chronic model a similar therapeutic efficacy of diclofenac and nitrofenac is shown in arthritic rats. The better gastrointestinal tolerability observed in nitrofenac-treated rats could be attributed to the release of nitric oxide.

Effective prophylaxis for recurrent urinary tract infections during pregnancy.

Effective prevention of recurrent urinary tract infections (UTIs) and possible acute pyelonephritis is of major importance during pregnancy. During 39 pregnancies, 33 women with a history of recurrent UTIs (and, in some instances, pyelonephritis) received postcoital prophylaxis consisting of a single oral dose of either cephalexin (250 mg) or nitrofurantoin macrocrystals (50 mg). While 130 UTIs occurred during a mean observation period of 7 months before prophylaxis, only a single UTI occurred during pregnancy after prophylaxis; this difference was highly significant. Thus the use of one of these effective regimens is strongly recommended for any pregnant woman with a history of recurrent UTIs. The treatment's effectiveness can be explained by two features of the two antibacterial agents involved: both reach high bactericidal concentrations in the urinary tract and induce no (or minimal) resistance in the introital gram-negative bacterial flora.

The use of the PhP-KE biochemical fingerprinting system in epidemiological studies of faecalEnterobacter cloacaestrains from infants in Swedish neonatal wards

The PhenePlate (PhP) biochemical fingerprinting system is an automated method for typing of bacteria, based on the evaluation of the kinetics of biochemical reactions, performed in microtitre plates. In the present study the PhP-Klebsiella/Enterobacter (KE) system was evaluated for typing of Enterobacter cloacae and employed to study the epidemiology of faecal E. cloacae strains isolated from infants in 22 Swedish neonatal wards. The PhP-KE system showed a high reproducibility and discrimination for E. cloacae isolates. Among 64 epidemiologically unrelated E. cloacae strains, 49 distinct phenotypes were found, and the diversity index was 0.985. E. cloacae was found as a part of the dominating Gram-negative aerobic bacterial flora in 83 out of 953 infants studied. The incidences of E. cloacae colonization varied between 0 and 35% in different wards, but in contrast to previous data for Klebsiella spp. and Escherichia coli, there was little evidence of spread of particular strains in the wards. We also discuss two different measures of nosocomial transmission of bacterial strains: transmissible strains and epidemic index.

The bacterial flora of non-carbonated, natural mineral water from the springs to reservoir and glass and plastic bottles

Quantitative and qualitative determinations of the bacterial flora of non-carbonated natural mineral water at the most important steps during bottling at a large water source yielded the following results: (i) Colony counts (on 1 :10 diluted plate count agar, incubated at 20°C for 14 days) for water of the five springs and the mixed water were less than 1 to 4 cfu ml −1. The Gram-negative bacterial flora ( n = 50 isolates) showed a very different but constant spring specific species distributions with predominance of either eutrophic fluorescent pseudomonads, oligotrophic non-fluorescent pseudomonads or oligotrophic yellow bacteria. (ii) In the reservoir and immediately after bottling the counts were in the range of 10 cfu m1 −1. But nearly 30% of the species of the spring water were no longer detectable and there was a significant increase of Gram-positive bacteria. (iii) After 1 week of storage at 2°C colony counts of more than 10 5 cfu ml −1 were found in plastic bottles, but only about 10 4 cfu ml −1 in glass bottles Besides, a very distinct change of the composition of the microflora occurred. In glass bottles slow-growing oligotrophic non-fluorescent pseudomonads, yellow bacteria and Acinetobacter predominated. In plastic bottles fast-growing eutrophic and mesotrophic fluorescent pseudomonads, Flexibacter and Acinebacter were dominating. In mineral water, bottled into thoroughly cleaned glass bottles, colony counts of more than 10 5 cfu ml −1 were found within 4 days. In bottles, cleaned mechanically as usual, the increase was significantly slower with a maximum of only 5 × 10 3 cfu ml −1 after 8 days. The results of inoculation experiments in sterile filtered mineral and distilled water led to the suggestion that the difference between the two types of bottles is caused firstly by an inhibition of growth due to residues of cleaning detergents in the glass bottles. Growth promotion by dissolved organic substances in the plastic bottles only played a minor role. After repairing of the pump at a depth of 300 m in a warm mineral water spring, the colony counts at 20, 37 and 42°C on 1: 10 diluted and normal plate count agar increased beyond the limits required by the EC directive for mineral water stored a month. Then colony counts decreased slowly and reached the initial level after 1 year, except for the colony counts 1 : 10 diluted agar at 20°C which stabilized at a relatively high number and a significant alteration of the microflora. Before the repair of the pump, the flora consisted exclusively of non-fluorescent pseudomonads, whereas non-motile and motile yellow bacteria were found afterwards.

Effective Prophylaxis of Recurrent Urinary Tract Infections in Premenopausal Women by Postcoital Administration of Cephalexin

A total of 31 sexually active premenopausal women, prone to have recurrent urinary tract infections but who otherwise were healthy, underwent postcoital prophylaxis consisting of a single oral dose of 250mg. cephalexin. While 127 urinary tract infections occurred in these patients during a mean of 6 months before treatment, only 1 occurred during a mean of 12 months after postcoital cephalexin prophylaxis. This difference was statistically highly significant. Each of these patients ingested approximately 120 cephalexin tablets per year of postcoital prophylaxis.Postcoital oral cephalexin prophylaxis is highly effective in the prevention of recurrent urinary tract infection in the nonpregnant as well as pregnant premenopausal women because of easy compliance, the high urine concentration achieved and the minimal induction of resistance to cephalexin in the introital gram-negative bacterial flora. Postcoital cephalexin prophylaxis achieves identical results to daily cephalexin prophylaxis but uses only a third of the tablets required in the daily regimens. Finally, cephalexin represents an additional valuable antibacterial drug in postcoital prophylaxis along with cotrimoxazole, nitrofurantoin and cinoxacin. (J. Urol., 142:1276-1278, 1989)

Background (spontaneous) immunoglobulin production in the murine small intestine before and after weaning

The ontogeny of the murine intestinal B-cell compartment before and after weaning was studied by quantitative analysis of immunoglobulin-secreting cells (Ig-SC) in the small intestine (SI). Before weaning, few Ig-SC were detected in the SI, whereas spleen and bone marrow already contained many Ig-SC. The number of Ig-SC in the SI started to increase immediately after weaning. Comparing early-weaned mice with non-weaned mice of the same age clearly demonstrated that weaning brought on the development of Ig-SC in the SI. The influence of a gut flora on the number of Ig-SC in the SI was examined by comparing the number of Ig-SC in the SI of conventionally housed, specific pathogen free (SPF) and germ-free mice. A bacterial flora was apparently needed for the normal development of Ig-SC in the SI. Comparing mice containing an aerobic Gram-negative bacterial flora with mice containing only an anaerobic Gram-positive bacterial flora demonstrated that the type of bacterial flora is relatively unimportant. No evidence was found that circulating maternal antibodies suppressed the development of the “spontaneous” intestinal and systemic B cell response. The results show that bacterial colonization of the intestine plays a pivotal role in the development of the Ig-SC compartment in the SI.

Rapid nighttime evacuation of a veterans hospital

Loss of essential utilities and danger of explosion forced a rapid nighttime winter evacuation of 229 patients from an acute-care Veterans Administration hospital. Although distribution of patients to recipient hospitals was not optimal, and the location of several patients could not be documented for more than 24 hours, the evacuation in subfreezing weather went smoothly. Continuity of care and careful planning permitted an orderly return to the hospital five days later. Although financial costs were high, no excess mortality or morbidity was associated with the evacuation. No changes in pharyngeal gram-negative bacterial flora of the patients were noted. Further, a critique is presented to aid in planning for similar emergencies elsewhere.

Requirement for a Bacterial Flora before Mice Generate Cells Capable of Mediating the Delayed Hypersensitivity Reaction to Sheep Red Blood Cells

A delayed-type hypersensitivity (DTH) reaction can be elicited by an injection of 10(8) sheep red blood cells (SRBC) into a rear footpad of conventional (CV) mice previously immunized with small doses of SRBC. In contrast, immunization of germ-free (GF) mice with the same doses of SRBC produced no DTH when immunization was by the intravenous (i.v.) route, and only weak reactions when immunization was by the subcutaneous (footpad) route. Varying the immunizing dose of SRBC, or the time at which DTH was elicited, did not produce a state of DTH responsiveness in i.v. immunized GF mice. However, the transfer of lymphocytes from CV mice, immunized 4 to 5 days previously with SRBC, into GF mice, conferred on GF mice the capacity to express DTH. Although DTH was not readily demonstrable in GF mice immunized with SRBC, they nevertheless produced normal levels of hemagglutinating antibody to SRBC. Finally, it was shown that GF mice could generate a normal DTH response to SRBC if they were first monoassociated with a Gram-negative bacterial flora.

Septicemia in Children With Cancer

Because of the persistently high mortality from sepsis in cancer patients, a retrospective study was designed to identify the causative organisms and to determine the factors affecting the outcome of sepsis. A total of 84 episodes of septicemia in 61 children with cancer were studied. The more frequently isolated organisms were: Staphylococcus aureus (21.4%); Escherichia coli (18%); Klebsiella (7.1%); Pseudomonas (6%); and Bacteroides fragilis (6%). Other isolates included Proteus, Serratia, Acinetobacter, hemolytic Streptococcus, and Bacillus cereus. In 10.7% of septic episodes, mixed bacterial infections were documented. Twenty-four (28.6%) resulted in death; in 13 (54%) death occurred within 24 hours after admission. The fatality rate was high in cases associated with absolute polymorphonuclear leukocyte counts of less than 100/cu mm, in neoplastic relapse, and when infection with gram-negative, anaerobic and mixed bacterial flora occurred.

Surgical suppurating infections and surgical abdominal infections treated with fosfomycin.

Two groups of patients suffering surgical infections were treated with fosfomycin. The first includes 21 suppurating dermic of soft underlying tissue lesions. The second group includes 29 surgical abdominal infections. The bacteriology of the first group was made up of gram-positive and gram-negative germs predominantly S. aureus and E. coli, all the isolated species appeared to be sensitive to fosfomycin. In the second group a gram-negative bacterial flora predominantly E. coli was obtained; with a sensitivity to this antibiotic of 90.5%. Surgical treatment accompanied the treatment with fosfomycin. In the first group, all the patients were cured with the oral administration of 2-6 g/day and in an average time less than that of the similar control group which did not receive the antibiotic. In the second group surgical treatment was necessary in 25 of the 29 patients and in all of them parenteral treatment was done with fosfomycin, preferably intramuscularly and in general the dosage was 4 g daily. All patients were cured except for one who was not operated on and who suffered from a fever of undetermined origin.