Numbers Of Gram-negative Bacteria Research Articles

Frequency and Distribution of Gram Negative Bacteria among Hospital and Community Acquired UTI Patients

Background: Gram negative bacteria create a great problem during the treatment of urinary tract infection patients. Objective: This study was undertaken to determine the frequency and distribution of Gram negative bacteria among the UTI patients. Methodology: This cross sectional study was carried out in the Department of Microbiology at Sir Salimullah Medical College, Dhaka from June 2007 to May 2008 for a period of 1(one) year. All the patients presented with the clinically suspected UTI at any age with both sexes were selected as study population. Patients who were hospitalized for at least 2 days or more received different antibiotics were designated as hospital acquired UTI; on the other hand patients who were attended in OPD for the first time were considered as community acquired UTI patients. All urine samples were inoculated in Blood agar and MacConkeys agar media. Gram negative bacteria were isolated and identified by colony morphology, Gram staining and biochemical tests. Result: A total of 220 urine samples were collected from patients suspected to urinary tract infections of which 116 samples were from hospitalized patients and 104 samples were from community patients. Among 220 samples, 132(60.0%) Gram negative bacteria were isolated of which 88(66.7%) isolates were from hospitalized acquired UTI and 44(33.3%) bacteria were isolated from community acquired UTI patients. The difference was statistically significant (p=0.0001). In hospitalized patients out of 88(75.9%) isolated Gram negative bacteria, 67(76.1%) isolates were Escherichia coli, 10(11.4%) isolates were Klebsiella species, 5(5.7%) isolates were Proteus species and 6(6.8%) isolates were Pseudomonas species. Among the isolated bacteria 44(42.3%) bacterial isolates were from community patients of which 36(81.8%) isolates were Escherichia coli, 4(9.1 %) isolates were Klebsiella species, 2(4.5%) isolates were Proteus species and 2(4.5%) bacteria were Pseudomonas species. Conclusion: In the present study, it was observed that considerable numbers of Gram negative bacteria were detected from urinary tract infection cases.Bangladesh Journal of Infectious Diseases 2014;1(2):24-26

Aetiology of Bacterial Pathogens from Adult Patients with Community-Acquired Pneumonia in Arba Minch Hospital, South Ethiopia

Background: Community-acquired pneumonia (CAP) is major causes of morbidity and mortality. The etiology of CAP varies by geographic region; knowing the etiology might help for the management of the case in case of emergency and to guide treatment. So, in resource limited countries it is wise to identify the most common pathogens of CAP. The objective of this study was to determine bacterial etiology of CAP among adult patients visiting Arba Minch Hospital. Methods: A cross sectional study was conducted in Arba Minch Hospital, Southern Ethiopia from March 01 to June 01, 2013. Data was collected from adult patients with CAP visiting Arba Minch Hospital using face to face interviews, observation using checklist and laboratory examinations. Sputum specimens were collected and microbiological investigations were performed using standard procedures. Data was processed and analyzed with SPSS version16.0 and Excel 2007. Results: Out of 170 cases, only 68 (40%) were culture positive. One pathogen was demonstrated in 63 (92.6%) patients and 6 (7.4%) had mixed infection. The common isolates of single bacterial pathogens from sputum specimens were S. pneumoniae 20 (11.8%), S. aureus 15 (8.8%), P. aeruginosa 10 (5.8%), K. pneumoniae 8 (4.7%), E. coli 4 (2.4%), H. influenzae 4 (2.4%), P. mirabilis 1 (0.6%), and P. vulgaris 1 (0.6%). The commonest mixed bacterial isolate was K. pneumoniae and P. aeruginosa 2(1.2%). Conclusion: In this study, common bacteria isolated were S. pneumoniae, S. aureus and gram negative bacteria. Significant numbers of Gram negative bacteria were isolated which may indicate a shift of infection trend to Gram negative bacteria. Hence, periodic monitoring of etiologic agents with their drug resistant pattern is essential for better management of CAP and treatment strategies.

Antimicrobial susceptibility pattern of extended-spectrum β-lactamase-producing bacteria causing nosocomial urinary tract infections in an Iranian referral teaching hospital.

Objective:Gram-negative bacilli are the most important cause of nosocomial urinary tract infections (UTIs). The production of extended-spectrum β-lactamase (ESBL) enzymes is a common mechanism of resistance among these bacteria. The aim of this study was to determine the rate of ESBL producing Gram-negative bacteria causing nosocomial UTI in a referral hospital as well as their susceptibility pattern to the most commonly used antibiotics.Methods:In a prospective cross-sectional study performed over a 6-month period, urinary specimens obtained from hospitalized patients with documented culture-proved nosocomial UTI (age range of 1-87 years). Isolated aerobic Gram-negative bacteria underwent further microbiologic tests for detection of ESBL, as well as antimicrobial susceptibility test using Kirby-Bauer (disk diffusion) and E-test methods.Findings:During the study period, 213 urine samples were detected to have growth of Gram-negative organism. Escherichia coli was the most frequently isolated organism (61%). ESBL was detected in 102 isolates including 38.5% of E. coli, 39.5% of Klebsiella pneumonia, 88.5% of Pseudomonas aeruginosa, and 100% of Acinetobacter baumannii strains. Imipenem and meropenem were the most effective antibiotics on E. coli and K. pneumoniae strains. P. aeruginosa and A. baumannii strains showed high resistance to all tested antibiotics.Conclusion:Large numbers of Gram-negative bacteria causing nosocomial UTIs produce ESBL with most being multidrug-resistant. Therefore, routine ESBL detection testing and subsequent antibiogram with disk diffusion method could be useful to determine the best treatment options for UTI.

Contact Lens Case Contamination During Daily Wear of Silicone Hydrogels

Contamination of contact lens cases has been associated with the production of adverse responses in the eye during contact lens wear. This study aimed to evaluate the contamination rate and types of microbes contaminating cases during use of contact lens disinfecting solutions and silicone hydrogel lenses. Two hundred thirty-two participants were allocated to one or more groups. The participants wore one or more of three silicone hydrogel lenses and used one or more of four contact lens disinfecting solutions. Cases were collected after use for 1 month and sent for routine microbial testing. The rate of contamination of cases and the types of microbes contaminating cases were evaluated. Between 76 and 92% of all cases were contaminated. Use of different contact lenses did not affect contamination rate or the types of microbes isolated from cases. Use of AQuify (PHMB as disinfectant) was associated with the highest contamination rate (92%; p = 0.015) of cases for any microbe. Level and type of contamination with use of ClearCare (H2O2) was similar to use of PHMB (polyhexamethylene biguanide)- or Polyquat/Aldox-containing solutions. There was no difference in contamination rate of cases by fungi or Gram-positive bacteria, but for Gram-negative bacteria, use of Opti-Free Express (Polyquat and Aldox as disinfectants) resulted in a lower contamination rate (7% vs. 29 to 45%; p < 0.001). The average number of microbes contaminating a case was significantly less for Opti-Free Express (223 +/- 1357 cfu/case) compared with Opti-Free RepleniSH (Polyquat and Aldox as disinfectants; 63,244 +/- 140,630 cfu/case; p < 0.001), driven mostly by differences in numbers of Gram-negative bacteria, particularly contamination by Delftia acidovorans in cases exposed to Opti-Free RepleniSH. Different disinfecting solutions used during storage in cases result in different levels of contamination and contamination by different types of microbes. These differences are not simply because of the types of disinfectants used, suggesting that other excipients in, or formulation of, the solution affect contact lens storage case contamination.

Estimation of abundance dynamics of gram-negative bacteria in soil

Bacterial succession in soil was studied for two variants of initiation (moistening and moistening with addition of glucose). To determine the numbers of viable gram-negative bacteria, the modified nalidixic acid method was applied. The numbers of gram-negative bacteria revealed by this method were 2 to 3.5 times higher than those determined by the traditional method. In a developing community, the highest total bacterial numbers were observed on day 7; afterwards their numbers decreased and stabilized at a level exceeding four- to fivefold the initial one. In both experimental variants, the highest numbers of viable gram-negative bacteria were revealed on day 15 (75-85% of the total bacterial numbers). Morphology of these bacteria suggests their classification as cytophagas (chitinophagas) utilizing chitin from the dead fungal mycelium.

Biological contamination parameters of cotton lint as biomarkers for fibre quality; a preliminary study

It has been reported for several decades that microbes, which naturally contaminate cotton fibres during crop growth and subsequent storage can have an adverse effect on the structural quality of cotton lint. Although several studies have analysed the relationship between numbers of Gram-negative bacteria or bacterial endotoxin and particular physical properties, these studies have been limited to cotton from the United States, and the possible effects of fungal contamination have not been examined in detail. This study quantified the Gram-negative bacteria and fungal cells, as well as measuring concentrations of bacterial endotoxin and fungal glucan, on cotton lint samples from international sources. Spearman’s rank correlation coefficients calculated between these results and quality data analysed by an automated testing instrument revealed several significant correlations. Findings included inverse correlations between the biological contamination parameters and fibre elongation, micronaire and reflectance. The possible causes and implications of these findings were also discussed.

Microbial biomass, metabolic activity and nutritional status determined from fatty acid patterns and poly-hydroxybutyrate in agriculturally-managed soils

Soil microbial biomass, fatty acid pattern, poly-β-hydroxybutyrate content and selected physiological variables were studied in agriculturally-managed soils with different cropping histories: crop rotation, hops and grassland. Significant correlation was observed between substrate-induced respiration, the amounts of adenine nucleotides and the total amounts of phospholipid fatty acids. The highest microbial biomass was found in a grassland soil, the lowest in soils which were formerly cultivated with hops. Additionally, the highest ratio of poly-β-hydroxybutyrate: total phospholipid fatty acids, the largest specific respiration rate and the lowest amounts of the adenylate energy charge were obtained in one of the former hop yards. Due to the frequent treatment of hop plants with fungicides a large amount of copper had accumulated in this former hop yard. The condition of the soil had resulted in the creation of a microbial community with markedly different biochemical characteristics compared to communities associated with grassland soil or crop rotation soil. The principal component analysis was able to discriminate the different soils when applied to hydroxy fatty acids. The profile of fatty acids in the copper-contaminated soil indicated an increase in numbers of Gram-negative bacteria. A lower concentration of branched chain fatty acids revealed a decreased proportion of Gram-positive bacteria in both former hop yard soils.

Seasonal Dynamics of Bacterial Colonization of Cotton Fiber and Effects of Moisture on Growth of Bacteria within the Cotton Boll

A highly replicated 3-year field study was conducted to determine the seasonal patterns of bacterial colonization of cotton fiber from the time of dehiscence of the bolls (the point at which the bolls just begin to open) through harvest and commercial ginning. Bacterial numbers on fiber samples from 16 plots were determined by dilution pour plating with tryptic soy agar containing cycloheximide, and numbers of gram-negative bacteria were determined by plating on tryptic soy agar containing vancomycin and cycloheximide. Populations of bacteria varied from year to year, but in all three seasons the pattern of colonization was generally a pattern consisting of a rapid increase following opening of the bolls and a more or less stable number thereafter throughout the growing season. Gram-negative bacteria accounted for 50% or more of the recoverable bacterial population. We hypothesized that the luxuriant bacterial flora developed as a result of the availability of sufficient free water in the bolls to allow bacterial proliferation with the carbon sources remaining after fiber maturation. Therefore, laboratory experiments were conducted to determine the threshold moisture level allowing growth of bacteria on fiber in the bolls. Bacterial proliferation occurred when as little as 2% moisture was added to air-dried fiber. Using simulated bolls, we demonstrated bacterial growth resulting from dew formation on fiber held in controlled-humidity chambers.

Bacterial Flora in Buckwheat Seeds

Bacteria contaminating buckwheat seeds, flour and noodles were examined by use of various selective media. Buckweat seeds examined were harvested in Nagano and Hokkaido, and noodles were prepared from buckwheat seeds harvested in Hokkaido.All the seed samples examined contained bacteria in the range of 105-108/g. The number of gram-negative bacteria was almost the same as that of gram-positive bacteria in most of the samples, but there were appreciable differences in the numbers of glucose-fermentative gram-negative bacteria and glucose-nonfermentative bacteria among the samples examined.Enterobacteriaceae were dominant in buckwheat flour used for the preparation of noodles and the number of bacteria in noodles was about one-hundredth of that in the flour.

Positive stain for light and electron microscopic demonstration of spirochetes in subgingival plaque and crevicular fluid samples from periodontal diseased sites

In a recent study of 400 subgingival plaque samples from over 110 adult periodontitis patients, spirochetes were the overwhelming microbial type, averaging about 45% of the microbial count. This finding supports earlier arguments that spirochetes are pathognomonic in periodontal disease. Other studies had shown clear-cut differences in the microbial composition of healthy and diseased subgingival sites — the proportion of spirochetes being significantly higher in the latter. Another study indicated that periodontal deterioration at these sites could be predicted better by increased proportions of motile rods and spirochetes than by clinical measurements. However, spirochetes of all sizes and species do not show the same degree of association with periodontal breakdown. Moreover, spirochetes are usually difficult to culture and stain; they are generally monitored by darkfield or phase contrast microscopy.The PATS reaction, a modified periodic acid-Schiff(PAS) reaction which deposits silver for light and electron microscopy appears to stain Gram(-) bacteria positively as well as neutrophils and activated macrophages. When studying the stained Gram(-) bacteria on coverslip smears of subgingival plaque or crevicular fluid samples of patients by light microscopy, varying numbers of intensely stained spirochetes of different sizes were observed (Figs. 1,2). More spirochetes were usually seen in samples from diseased sites. After drying replicate PATS-stained coverslips with hexamethyldisilazane they were sputter coated with gold, and. then examined by the SEI and BEI modes of scanning electron microscopy (Figs. 3-6). A permanent record of the proportions of large, medium and small spirochetes at each site could thus be obtained. Generally, greater numbers of gram negative bacteria including some spirochetes were stained in samples from diseased sites. At some sites, however, spirochetes were the predominant microbes in both crevicular fluid and subgingival plaque (Fig. 1).

Investigation of organic aerosols generated during sugar beet slicing.

A description is given of a hygiene investigation made to determine workers' exposure to airborne microorganisms and antigen in the slicing area of a sugar beet refinery following complaints by the workers of work-related respiratory symptoms. Dust concentrations in the slicing area were not high (up to 3.5 mg/m3), but there were many airborne microorganisms (200,000 colony forming units/m3), mostly gram-positive bacteria. Of 15 workers, 7 had precipitins to a sugar beet extract. Of these 7, there were 5 who also had precipitins to an extract of dust collected on a 'Staplex' filter. There was a line of identity between the beet and dust extracts, indicating the dust contained appreciable quantities of beet antigen. As a result of these findings, local exhaust ventilation was installed before the next slicing season. Further investigations were made near the beginning and end of this second season. The results showed lower dust concentrations and markedly fewer numbers of airborne bacteria. Although total numbers of bacteria fell, numbers of gram-negative bacteria increased and, at the end of the season, comprised 20% of the total bacterial numbers. Specific immunoglobulin G (IgG) concentration in the workers' serums fell between the two slicing seasons and then remained constant through the next slicing season. This reflected the environmental measurements that showed lower dust concentrations after the installation of exhaust ventilation equipment.

Counts of Six Types of Bacteria on Lamb Carcasses Dipped or Sprayed with Acetic Acid at 25° or 55°C and Stored Vacuum Packaged at 0°C

This study evaluates the sanitizing effectiveness of applying, by spraying or dipping, 1.5 or 3.0% acetic acid at either 25°C or 55°C to freshly slaughtered lamb carcasses. After vacuum packaging and during extended storage at 0°C, samples were examined for microbial populations. Each treatment reduced counts significantly compared with counts of untreated controls. Numbers of gram negative bacteria and lactobacilli were affected significantly by the temperature of acid solutions. Other variables caused insignificant differences in the amounts that counts were reduced by sanitization. Overall, dipping in 3% acetic acid at 55°C was the most effective treatment.

Effect of increasing pentachlorophenol (PCP) concentrations on bacterial populations in glycine-percolated soils

Population changes of several bacterial groups were compared between soils percolated with glycine and amended with different amounts of pentachlorophenol (PCP). PCP retarded the increase in total viable bacteria with increasing doses of PCP. The increase was followed by a gradual decrease, but the numbers in the soil remained at the maximum level for a short time in the presence of large amounts of PCP. The numbers of Gram-negative bacteria and PCP-tolerant bacterial cells increased dramatically, being followed by a comparable decrease, although the former was always slightly larger than the latter. PCP reduced spore counts. PCP and glycine in the percolation fluid dissipated during the percolation, but the dissipation of glycine was slowed by the presence of increased amounts of PCP. Large portions of PCP were detected in the liquid at the late stage of percolation. Changes in pH suggested biochemical reactions in the percolated soil. The changes differed according to the amount of PCP.

Antibacterial activity of norfloxacin in the gastrointestinal tracts of rats.

The capacities of norfloxacin (MK-0366) and neomycin to reduce the numbers of bacteria in the gastrointestinal tracts of rats were evaluated. Results of a 3-day treatment with norfloxacin were compared with those of a 3-day treatment with neomycin. Both drugs significantly decreased gram-negative and gram-positive bacteria. Norfloxacin effected a significantly greater reduction in numbers of gram-negative bacteria than did neomycin. Norfloxacin also significantly increased the number of anaerobic bacteria. Although neomycin reduced gram-positive bacteria more effectively than did norfloxacin, this difference between the two drugs was not significant. Norfloxacin merits further study for potential as a bowel sterilant.

Gram-negative Bacteria on Cotton with Particular Reference to Climatic Conditions

Various factors that control the contamination of the cotton plant by Gram-negative Bacteria (GNB) were studied. The following cotton plant parts were contaminated with decreasing numbers of GNB: senescent bracts, pericarps, green bracts, seed cotton and leaves. Freezing of green cotton capsules (fruit) caused a significant increase in numbers of GNB on both bracts and seed cotton. Raw cotton derived from cotton plants harvested late in the autumn contained significantly larger numbers of GNB and higher levels of endotoxin than cotton collected early in the harvest season.

Acinetobacter infection associated with pneumonia in an orangutan

A 23-year old male orangutan (Pongo pygmaeus) had been treated for two years for respiratory disease believed to be tuberculosis. Terminally, the animal developed mucopurulent rhinitis and refused food. Necropsy examination revealed diffuse, severe, bilateral chronic pleuritis, fibrinous bronchopneumonia and air sacculitis. Large numbers of gram-negative bacteria seen in the lung histologically were cultured from both the lung and air sacs and identified asAcinetobacter calcoaceticus varietylwoffi. The resistance of the isolatein vitro to ampicillin may have accounted for the lack of clinical response of the ill orangutan.

The Limulus Lysate Endotoxin Assay as a Test of Microbial Quality of Ground Beef

The Limulus lysate test (LLT) for endotoxin assay has been found to be an excellent, simple and rapid test of microbial quality of refrigerated ground beef. In fresh ground beef held at 5°C for 7–12 d, LLT titres increased from 102–105 and correlated very highly with extract‐release volume (ERV) data and total viable Gram negative counts at both 5° and 30°C. The LLT was negative for fresh beef containing low numbers of bacteria and on aged beef in the absence of increasing numbers of Gram negative bacteria. Of 14 Gram negative meat isolates, all gave a positive LLT while none of eight miscellaneous Gram positive bacteria did. The use of this test provides objective information on the microbial quality of fresh refrigerated ground meats in 1 h. Based upon this study, it is suggested that a 0·1 ml inoculum from a 103 dilution of good quality ground beef should produce a negative lysate test and thus serve as an additional rapid screening test of meat microbial quality.

Gram-Negative Bacteria in Raw Milk

A study was conducted to determine the relationship between the numbers of gram-negative bacteria in raw bulk tank milk and the results from other microbiological tests used to evaluate the sanitation of milk production. Samples taken from quarters of individual cows were either free of gram-negative organisms or counts were very low. However, when farm bulk tank milk was examined, this group of bacteria was frequently noticed in large numbers in spite of relatively low standard plate counts. The enumeration of gram-negative organisms in raw milk was found to provide more valuable information about dairy farm sanitation than either coliform tests or standard plate counts, but should be complemented with a thermoduric count for more accuracy. Results indicate that gram-negative bacteria counts of < 1,000/ml are easily obtainable and, depending on local factors, counts of 500/ml or less should be aimed for in raw market milk.