Hemagglutinating properties of Proteus mirabilis strains isolated from clinical specimens

Haemagglutinating properties of 345 P. mirabilis strains isolated from various clinical samples were determined. Red blood cells of different origin as human group 0, bovine, horse, sheep and rat were used for the study. For the detection of MS and MR/P haemagglutinins the haemagglutination reaction was run with and without D-mannose. On the other hand, for the detection of type MR/K haemagglutinins tanned human and bovine erythrocytes were used. The majority of tested strains (90.14%) was polyhaemagglutinating i.e. showed simultaneously the presence of two or three haemagglutinins. Only three strains of P. mirabilis (0.87%) did not agglutinate any of the erythrocytes used for the study. The majority of strains (95.83-100%) in specific groups of clinical materials showed the presence of MR/K+ while MR/P+ 45.45-93.75% of strains and MS+ 45.83-73.1% of tested strains. Out of P. mirabilis strains isolated from urine, faeces and blood the highest percentage possessed at the same time all three haemagglutinin types (MS+, MR/K+, MR/P+) or pattern MR/K+, MR/P+. Bronchial isolates had usually pattern MR/K+ (31.82%) and strains isolated from skin possessed haemagglutinins of pattern MR/K+, MR/P+ (50%) and MS+, MR/K+, MR/P+ (43.75%). Among strains expressing MR/P+ at 37 degrees C a great differentiation of spectrum activity against tested erythrocytes was seen. Undoubtedly, the majority of MR/P+ strains from specific groups of clinical materials (with the exception of urine) agglutinated sheep and horse erythrocytes with and without D-mannose. The majority of strains isolated from urine agglutinated sheep and bovine erythrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Drug resistance in Vibrio cholerae strains isolated from clinical specimens

Cholera is a serious epidemic and endemic disease caused by the Gram-negative bacterium Vibrio cholerae. SXT is an integrative conjugation element (ICE) that was isolated from a V. cholerae; it encodes resistance to the antibiotics chloramphenicol, streptomycin and sulfamethoxazole/trimethoprim. One hundred seven V. cholerae O1 strains were collected from cholera patients in Iran from 2005 to 2007 in order to study the presence of SXT constin and antibiotic resistance.The study examined 107 Vibrio cholerae strains isolated from cholera prevalent in some Iranian provinces. Bacterial isolation and identification were carried out according to standard bacteriological methods. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) to four antibiotics (chloramphenicol, streptomycin, sulfamethoxazole, and trimethoprim) were determined by broth microdilution method. PCR was employed to evaluate the presence of established antibiotic resistance genes and SXT constin using specific primer sets.The resistance of the clinical isolates to sulfamethoxazole, trimethoprime, chloramphenicol, and streptomycin was 97%, 99%, 99%, and 90%, respectively. The data obtained by PCR assay showed that the genes sulII, dfrA1, floR, strB, and sxt element were present in 95.3%, 95.3%, 81.3%, 95.3%, and 95.3% of the V. cholerae isolates.The Vibrio strains showed the typical multidrug-resistance phenotype of an SXT constin. They were resistant to sulfamethoxazole, trimethoprime, chloramphenicol, and streptomycin. The detected antibiotic resistance genes included dfrA for trimethoprim and floR, strB, sulII and int, respectively, for chloramphenicol, streptomycin, sulfamethoxazole, as well as the SXT element.     

Production of 2,3-butanediol by newly isolated Enterobacter cloacae

Enterobacter cloacae NRRL B-23289 was isolated from local decaying wood/corn soil samples while screening for microorganisms for conversion of l-arabinose to fuel ethanol. The major product of fermentation by the bacterium was meso-2,3-butanediol (2,3-BD). In a typical fermentation, a BD yield of 0.4 g/g arabinose was obtained with a corresponding productivity of 0.63 g/l per hour at an initial arabinose concentration of 50 g/l. The effects of initial arabinose concentration, temperature, pH, agitation, various monosaccharides, and multiple sugar mixtures on 2,3-BD production were investigated. BD productivity, yield, and byproduct formation were influenced significantly within these parameters. The bacterium utilized sugars from acid plus enzyme saccharified corn fiber and produced BD (0.35 g/g available sugars). It also produced BD from dilute acid pretreated corn fiber by simultaneous saccharification and fermentation (0.34 g/g theoretical sugars). Received: 17 December 1998 / Revision received: 9 March 1999 / Accepted: 20 March 1999     

A low molecular weight enterotoxic hemolysin from clinical Enterobacter cloacae

Seven of 50 Enterobacter cloacae strains from clinical isolates produced small turbid zones of hemolysis in horse and sheep blood agar plates, and the culture supernatants were also positive for hemolytic activity. The hemolysin was partially purified from the culture supernatant of E. cloacae by ultrafiltration (PM-10 membrane) and extraction with acetone. Semipurified hemolysin was stable to heating (100 degrees C, 30 min) and was soluble in organic solvents (acetone, ethanol, and methanol). The toxin showed no loss of biological activity after treatment with trypsin and was stable to acid treatment at pH 2.0 but not at a pH greater than 7.0. In the rat intestinal loop assay, the hemolysin caused hemorrhagic fluid accumulation and severe histological alterations. These findings indicate that this hemolysin may be a putative virulence factor in E. cloacae infections.     

Restriction endonuclease EcaI from Enterobacter cloacae

Restriction endonuclease EcaI obtained from Enterobacter cloacae DSM30056 recognizes the group of heptanucleotide palindromes 5′-G[unk]G-T-N-A-C-C-3′, and on cleavage (arrow) produces fragments with 5′-terminal pentanucleotide extensions. It is identical in specificity with restriction endonuclease BstEII from Bacillus stearothermophilus ET.     

229株阴沟肠杆菌的标本分布及耐药性分析

目的 了解阴沟肠杆菌在医院感染的标本分布和耐药情况,为临床合理选择和应用抗生素提供依据.方法 采用VITEK 60全自动微生物分析仪和配套的GNI、GNS-143、GNI-448,对229株阴沟肠杆菌进行分离鉴定和药敏试验,药敏结果使用WHONET 5.5软件进行分析.结果 从2007年1月至2011年9月共分离到阴沟肠杆菌229株,59.0％来自于呼吸道标本,其次是尿液占13.5％,再次为创面分泌物/脓液占12.7％.阴沟肠杆菌对美洛培南、亚胺培南和头孢哌酮/舒巴坦的耐药率分别为0.0％、0.4％和2.5％,对氨苄西林、头孢唑啉、头孢西丁的耐药率分别为98.7％、96.9％、97.5％.结论 阴沟肠杆菌耐药机制复杂,对抗生素具有多重耐药性,临床应合理使用抗菌药物,以减少阴沟肠杆菌耐药性的产生和在院内扩散.     

164株阴沟肠杆菌的药物敏感性分析

目的了解阴沟肠杆菌的药物敏感性情况以指导临床合理用药。方法对中山大学附属第一医院近3年分离出的阴沟肠杆菌的标本分布及耐药情况进行回顾性分析。结果共分离出164株阴沟肠杆菌,其对亚胺培南、头孢吡肟、阿米卡星和氧氟沙星的敏感性较高。结论阴沟肠杆菌对3代头孢菌素耐药严重,呈多重耐药性,亚胺培南仍为治疗阴沟肠杆菌严重感染的首选用药。     

Genetic similarity of vancomycin resistant strains of Enterococcus faecium isolated from clinical specimens

Twenty vancomycin resistant E. faecium strains (VRE) isolated from patients of three different hospital wards in 2005-2008 were examined. The strains originated from patients of intensive therapy, urological and internistic wards. The chosen wards differ significantly in their specificity. In all cases the presence of o vanA and lack of vanB, vanD, vanE and vanG genes and were found. Strains were compared by using RFLP-PFGE, the reference method for molecular typing of VRE. One group including fourteen strains showing similarity higher than 79.5% was distinguished. This group was divided into subgroups. The greatest similarity was found among strains from patients of intensive therapy ward. Two subgroups of strains showing similarity more than 93.3%, of four strains each were identified. The similarity between these two subgroups was 79.5%. Most strains from other two wards showed less than 79.5% similarity and they could be recognised as not related. Only one strain from internal ward and two strains from urologic ward were similar in 82.1 - 86.4% to one of subgroups of strains originated from intensive therapy.     

Composition of O-antigenic lipopolysaccharides from Enterobacter cloacae

Analyses have been carried out on lipopolysaccharides (LPS) from 14 strains of Enterobacter cloacae representing different O serotypes. All of the products appeared to have a composition and architecture typical of enterobacterial LPS, but points of interest include the absence of phosphate residues from the core oligosaccharide, the presence of both L-glycero-D-mannoheptose and D-glycero-D-mannoheptose (ratio usually about 4:1), and the presence in lipid A of small amounts of fatty acids with odd numbers of carbon atoms (mainly C13) in addition to tetradecanoic acid and 3-hydroxytetradecanoic acid. Monosaccharides identified as components of polymeric fractions from the LPS were glucose, galactose, mannose, rhamnose, glucosamine, galactosamine, fucosamine, and galacturonic acid. Most polymeric fractions also probably contained an O-acetyl substituent. Closely similar chemotypes found for the polymeric fractions from the LPS of cross-reacting serotypes support the view that these fractions contain the O-antigenic determinants and represent the side chains of the LPS.     

Properties of Purine Nucleoside Phosphorylase from Enterobacter cloacae

Purine nucleoside phosphorylase from Enterobacter cloacae KY3074 was partially purified by ammonium sulfate fractionation, column chromatography on DEAE-cellulose and DEAE-Sephadex A-50, and gel filtration on Sephadex G-100 and Sepharose 4B. The molecular weight of the enzyme was calculated to be about 87,000 by a gel filtration method on Sephadex G-200. The enzyme was found to be most active at pH 7.5 to 8.5 and 50°C, stable between pH 7.0 and 7.3, and the activity was nearly lost above 70°C. The enzyme split 2´-deoxyinosine and ribonucleosides. Lineweaver-Burk plots for phosphate were non-linear, showing substrate activation. The break-down of inosine approached an equilibrium when approximately 14% of inosine was phosphorylated.     

复方明矾散对妇科阴道炎病原菌的抑菌作用研究

目的 探讨复方明矾散对妇科阴道炎病原菌的抑菌作用。方法 从临床妇科阴道炎患者分离病原菌为受试菌,采用美国临床实验室标准化委员会（NCCLS）M27-A大量肉汤稀释法和琼脂稀释法分别检测复方明矾散对140株受试菌的最低抑菌浓度（MIC）。结果 总MIC范围：0．07～10mg／ml。念珠菌MIC范围：0．07～1．25mg／ml,MIC50 0．30mg／ml,MIC90：0．61mg／ml。结论 复方明矾散对所有受试菌均有不同程度的抑菌作用,对念珠菌的效果最好。     

Environment and virulence factors of Vibrio cholerae strains isolated in Argentina

AIMS: To determine the presence of Vibrio cholerae in different areas of Argentina in three sample types, to determine the composition of planktonic communities in areas at which this pathogen was detected and to characterize the virulence properties and antimicrobial resistance of the recovered environmental isolates. METHODS AND RESULTS: Water and plankton samples were collected in marine, brackish and freshwater environments. Vibrio cholerae non-O1, non-O139 was isolated in 36.1% of the samples analysed. The micro-organism was detected in freshwater but not in marine or brackish samples. No relationship was found between isolation of V. cholerae and presence of any species of plankton. All the isolates presented very similar virulence profiles by PCR, lacking ctxA and tcpA El Tor and containing hlyA (98.7%), rtxA (99.0%), toxR (98.7%) and stn-sto (1.9%). Resistance to ampicillin was found in both Tucumán (21%) and Buenos Aires isolates (45%). CONCLUSIONS: We identified two geographic areas in Argentina where V. cholerae was present: freshwaters of the rivers from Tucumán and the Río de la Plata. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of V. cholerae strains in the environment, carrying both virulence factors and resistance to antimicrobial agents, highlight the need for a continuous and active surveillance of this pathogen.     

Lack of virulence factors in Escherichia coli strains of enteropathogenic serogroups isolated from water.

Thirty-eight Escherichia coli strains belonging to 14 human enteropathogenic serogroups were isolated from 33 of 208 water samples studied. No virulence factor or virulence-related gene sequences were found in any of the 38 strains analyzed. The results point out the importance of detecting specific virulence factors before incriminating water as a source of human diarrhea.     

Lack of virulence factors in Escherichia coli strains of enteropathogenic serogroups isolated from water.

Thirty-eight Escherichia coli strains belonging to 14 human enteropathogenic serogroups were isolated from 33 of 208 water samples studied. No virulence factor or virulence-related gene sequences were found in any of the 38 strains analyzed. The results point out the importance of detecting specific virulence factors before incriminating water as a source of human diarrhea.     

Purification and Properties of Uricase from Enterobacter cloacae

Uricase activity was found in Enterobacter cloacae KY3074 grown on guanine, hypoxanthine, uric acid, and xanthine media. The enzyme was purified from cells grown on uric acid as a source of nitrogen. The purification procedure included ammonium sulfate fractionation, gel filtration on Sephadex G-150, and column chromatography on DEAE-cellulose and DEAE-Sephadex. The enzyme had a molecular weight of about 105,000 and was specific for uric acid. The optimum pH was around 9.5, and the activity was inhibited by the presence of potassium cyanide, Ag⁺ or Cu²⁺. This uricase can be used for estimation of uric acid.     

Purification and characterization of thermostable cellulase from Enterobacter cloacae IP8 isolated from decayed plant leaf litter

Cellulases are important in the hydrolysis of lignocellulosic materials and thereby contribute to biomass conversion into fuels and chemicals. A cellulase-producing bacterium was isolated from decayed plant leaf litter in soil of a botanical garden. Based on morphological, biochemical and 16S rRNA gene sequencing, it was identified as Enterobacter cloacae IP8, with gene bank accession number NR118568.1. The bacterial cellulase was purified in a three-step procedure using lyophilization, ion exchange chromatography (QAE Sephadex A-50) and gel filtration (Biogel P-100). Two isoforms of the enzyme were purified 1.21 and 1.23 folds, respectively, with yields of 30 and 29% for isoforms A and B, respectively. Apparent molecular weights of 36.61?±?1.40 and 14.1?±?0.10?kDa were obtained for isoforms A and B, respectively, using gel filtration chromatography. Kinetic parameters K_m and V_max were 0.13?±?0.04?mg/ml and 3.84?±?0.05?U/ml/min, respectively, for isoform A and 0.58?±?0.06?mg/ml and 13.8?±?0.10?U/ml/min, respectively, for isoform B. Optimum pH (7.0) and temperature (60?°C) of cellulase activity were determined for both isoforms A and B. Na⁺ and Ca²⁺ enhanced the activities of both isoforms. Mg²⁺ inhibited the enzyme activity at concentrations 4–15?mM but, while it stimulated the activity of isoform A at concentrations 15–200?mM, it inhibited that of isoform B at same concentration range. The strong inhibition of the enzyme by ethylenediaminetetraacetic acid (EDTA) confirmed the enzyme as a metalloenzyme. These results reveal the purified cellulase from E. cloacae IP8 as a thermostable, acidic to neutral metalloenzyme, suggesting that it has good potential for biotechnological applications.     

Enterobacter cloacae complex: clinical impact and emerging antibiotic resistance

Species of the Enterobacter cloacae complex are widely encountered in nature, but they can act as pathogens. The biochemical and molecular studies on E. cloacae have shown genomic heterogeneity, comprising six species: Enterobacter cloacae, Enterobacter asburiae, Enterobacter hormaechei, Enterobacter kobei, Enterobacter ludwigii and Enterobacter nimipressuralis, E. cloacae and E. hormaechei are the most frequently isolated in human clinical specimens. Phenotypic identification of all species belonging to this taxon is usually difficult and not always reliable; therefore, molecular methods are often used. Although the E. cloacae complex strains are among the most common Enterobacter spp. causing nosocomial bloodstream infections in the last decade, little is known about their virulence-associated properties. By contrast, much has been published on the antibiotic-resistance features of these microorganisms. In fact, they are capable of overproducing AmpC β-lactamases by derepression of a chromosomal gene or by the acquisition of a transferable ampC gene on plasmids conferring the antibiotic resistance. Many other resistance determinants that are able to render ineffective almost all antibiotic families have been recently acquired. Most studies on antimicrobial susceptibility are focused on E. cloacae, E. hormaechei and E. asburiae; these studies reported small variations between the species, and the only significant differences had no discriminating features.     

MIC and MBC of quinupristin/dalfopristin of erythromycin-resistant MRSA strains isolated from clinical specimens

The MICs and MBCs of quinupristin/dalfopristin were determined for 22 clinical strains MRSA with inducible type of resistance to MLS-B and for 15 of their derivatives with constitutive resistance to MLS-B. For MRSA strains with inducible resistance to MLS-B the obtained results for quinupristin/ dalfopristin were: MIC50 = 0.25, MIC90 = 0.5, MBC50 = 1.0 and MBC90 = 1.0. Mutants of the same strains characterized with the following values for quinopristin/dalfopristin: MIC50 = 0.5, MIC90 = 1.5, MBC50 = 4.0 and MTC90 = 8.0.