Structure of the peptidoglycans of Moraxella glucidolytica and Moraxella lwoffi grown on hydrocarbons

The peptidoglycans of Moraxella glucidolytica and Moraxella lwoffi grown on aliphatic hydrocarbons were isolated. They contained muramic acid. glucosamine, alanine, d-glutamic acid and meso-diaminopimelic acid in a molar ratio of about 0.5:0.5:1.6:1.0:1.0 (M. glucidolytica) and 0.8:0.7:1.3:1.0:1.0 (M. lwoffi).The peptidoglycans were lysozyme-resistant. However, when treated with formamide, they could be partially degraded by lysozyme. The fragments were purified and their structure determined. In both strains, the peptide subunits consisted mainly of tripeptides (l-Ala-d-Glu-meso-DAP) and tetrapeptides (l-Ala-d-Glu-meso-DAP-d-Ala), most of them being directly cross-linked. It is concluded that in both strains the primary structures of the peptidoglycans are closely related.     

Chemical composition and ultrastructure of cellular and extracellular Moraxella glucidolytica lipopolysaccharides

A cellular (LPS I) and extracellular (LPS II) lipopolysaccharide were isolated from Moraxella glucidolytica cells grown on ethanol and from the culture fluid, respectively. Both LPS were toxic when injected to mice and chick embryos. These LPS contained glucose, galactose, glucosamine, galactosamine, 2-keto-3-deoxyoctonate and lipids. By permethylation studies, glucose was found to be linked (16) and (13) in LPS I and only (16) in LPS II. Galactose was the terminal non-reducing sugar. Branching occurred at positions 3 and 4 of galactose residues. LPS I was rich in - and -hydroxylauric and -hydroxymyristic acids and LPS II contained mainly stearic and -hydroxymyristic acids. LPS I was detoxified by mild acid and alkaline treatments. It was also dissociated by sodium deoxycholate and chromatographed on Sephadex G-75. The main fraction was reassociated by removing the surfactant by dialysis. The morphology of LPS I and LPS II was examined by electron microscopy. LPS I (original and reassociated fractions) consisted exclusively of ribbons while LPS II contained ribbons and vesicles.Non-Standard Abbreviations KDO 2-Keto-3-deoxyoctonic acids - LPS Lipopolysaccharide - NaD Sodium deoxycholate     

Novel carbenicillin-hydrolyzing β-lactamase (CARB-5) from Acinetobacter calcoaceticus var. anitratus

A strain of Acinetobacter calcoaceticus var. anitratus highly resistant to ticarcillin but susceptible to ticarcillin in combination with clavulanic acid (2 mg/l) was found to produce a constitutive beta-lactamase. This enzyme was periplasmic with a characteristic substrate profile of a carbenicillin-hydrolyzing enzyme. Enzyme inhibition was detected with antiserum (anti-CARB-3), pCMB, cloxacillin, clavulanic acid and sulbactam. This novel enzyme with a molecular mass of 28,000 resembles other plasmid-mediated carbenicillinases (CARB) but differs in its apparent isoelectric point estimated as 6.3 and has been designated CARB-5 on this basis.     

多重耐药鲍曼不动杆菌同源性分析

目的研究台州医院中心重症监护病房（ICU）及脑外重症监护病房（SICU）2006年1月出现的多重耐药鲍曼不动杆菌（MDR-AB）的耐药性、碳青霉烯酶基因型及同源性。方法运用VITEK-60全自动微生物仪对分离自2006年1月ICU和SICU患者多重耐药鲍曼不动杆菌8株进行菌种的重新鉴定,采用微量板稀释法测定β-内酰胺类、氨基糖苷类、氟喹喏酮类等17种抗菌药物的体外最低抑菌浓度（MIC）（其中头孢哌酮／舒巴坦、美洛配能采用K-B法测定耐药性）。采用PCR对8株菌株进行OXA型碳青霉烯酶基因型检测,运用脉冲场凝胶电泳分析菌株的同源性。结果8株菌株仅对头孢哌酮／舒巴坦敏感,对头孢菌素类、氨基糖苷类、氟喹喏酮类和碳青霉烯类等抗菌药物均显示出较高水平的耐药;8株菌株均产OXA-23型碳青霉烯酶;脉冲场凝胶电泳证实其为同一克隆。结论本组鲍曼不动杆菌为多重耐药株,同一克隆株在不同感染个体的相互传播,导致了这次院内感染的流行。     

694株鲍曼不动杆菌的耐药性分析

目的了解大连市友谊医院临床分离的鲍曼不动杆菌的分布及耐药状况,为临床治疗鲍曼不动杆菌感染提供参考。方法对该院2007年至2009年住院患者送检的标本中分离到的694株鲍曼不动杆菌的分布及药敏结果做回顾性分析。结果鲍曼不动杆菌2007年检出112株（7．1％）,2008年检出210（11．3％）株,2009年检出372（14．7％）株;在所有临床送检的标本中,痰标本中的检出率最高,占88．7％;在对13种抗生素的药敏试验中,对美罗培南最为敏感,其次对头孢哌酮／舒巴坦较为敏感。结论鲍曼不动杆菌的检出率逐年增高,耐药率也逐年增高。     

Rapid epidemiological analysis of Acinetobacter strains by Raman spectroscopy

From earlier publications, we noticed that Raman spectra could potentially be used for subspecies identification of microorganisms. Here we evaluated the technique for its use as a typing tool of Acinetobacter species, using a collection of well-characterised strains from five hospital outbreaks. The strains were previously analysed using molecular techniques as cell envelope protein profiling and ribotyping. In this study, we have typed the strains by AFLP analysis and Raman spectroscopy. We compared the results using hierarchical cluster analysis, which showed highly similar groupings by both techniques. There seemed to be some misclassification between two sets of outbreak strains in the Raman analysis. We ascribe this to the clonal relationship between the strains of both outbreaks, described earlier. This results from a highly similar biochemical composition of the strains involved, and hence a highly similar Raman spectrum. We conclude that Raman spectroscopy could be an easy-to-use alternative in epidemiological studies of Acinetobacter strains and a promising starting point for the development of epidemiological studies in general.     

Adhesins of Acinetobacter strains

One of the important factors contributing to the pathogenicity of bacteria is the presence of adhesins on cell surface, which facilitate colonisation in the macroorganism. The presence and type of adhesins occurring in four species of the genus Acinetobacter: A. baumannii (184), A. junii (59), A. lwoffii (65) and A. haemolyticus (22) was determined by haemagglutination test with a 3% suspension of fresh, tannic acid-treated of guinea pig, cow and human group O and AB erythrocytes, with or without the addition of one of sugar inhibitors (D-mannose, alpha-methylmannopyranoside, D-galactose-N-acetyl-D-glucosamine, L-fucose and D-ribose). In strains from all species, adhesines of the mannose-resistant (MR) type dominated. The mannose-sensitive (MS) type was present solely on the surface of one A. lwoffii strains. A. baumannii (36), A. junii (8), A. lwoffii (11) and A. haemolyticus (4) exhibited mannose-resistant hemagglutination in relation to fresh erythrocytes and that reaction was restrained by D-galactose, D-galactose and L-fucose (no other inhibitor used restrained it). The results achieved prove that cell adhesines other than those of MR type must be present on the cell surface. Additional adhesines occurred mainly in strains isolated from the respiratory and urinary tract infection simples, but were not found in isolates from blood cultures.     

Degradation of homogentisate by strains of Bacillus and Moraxella.

The metabolic pathways whereby strains of Moraxella and Bacillus degrade homogentisate (2,5-dihydroxyphenylacetate) are delineated. The Moraxella (strain OA3) is shown to degrade homogentisate via the pathway previously described in liver: homogentisate is cleaved by a 1,2-dioxygenase (E.C 1.13.11.5) yielding maleylacetoacetate which is isomerized by a GSH-dependent isomerase to fumarylacetoacetate before hydrolysis to acetoacetate and fumarate. A strain of Bacillus (B11c) is shown to catabolize homogentisate via a previously undescribed version of the above sequence: homogentisate is cleaved by a 1,2-dioxygenase (E.C 1.13.11.5) yielding maleylacetoacetate which is hydrolyzed directly to acetoacetate and maleate.     

Polyphosphate production by strains of Acinetobacter

Of four strains of Acinetobacter isolated from a pilot plant exhibiting enhanced biological phosphate removal from sewage, two strains (RA3116 and RA3117) accumulated more than 10 times the amount of polyphosphate accumulated by the other two strains (RA3114 and RA3123). Variants isolated from RA3116 and RA3117 showed polyphosphate levels similar to RA3114 and RA3123. No correlation was found between the polyphosphate content of the strains and levels of several enzymes that have been implicated in polyphosphate formation.     

Autoaggregation,hydrophobic, and hydrophylic properties of Moraxella catarrhalis strains

The hydrophobicity of the bacterial cell surface was evaluated via the salt aggregation test (SAT) in 58 strains (19 from the lower and 39 from the upper respiratory tracts) of Moraxella catarrhalis in hospitalized patients aged 25 to 65. Based on the SAT results, the strains were divided into three groups: autoaggregating (highly hydrophobic), hydrophobic, and hydrophilic. At a temperature of 37 degrees C, the autoaggregating, hydrophobic or hydrophilic properties did not depend on the choice of a medium, whereas at 22 degrees C the investigated properties did (p<0.0001). Taking into account the origin of the strains (lower vs. upper respiratory tract), it was found that: in the strains cultivated in liquid medium, both highly hydrophobic, hydrophobic and hydrophilic surfaces were present with a comparative frequency, independent of the strain isolation site and cultivation conditions; strains with highly hydrophobic and hydrophobic surfaces, but only those cultivated on solid media at 22 degrees C, were much more often isolated from sputum rather than from nose and throat swabs, whereas a statistically significant incidence of hydrophilic strains was found in samples from the upper rather than lower respiratory tract.