Growth of nodule bacteria in soil]

As was found with the aid of capillary microscopy, the nodule bacteria of pea and lupine in soil are encountered as rods, bacteroids, and cocci. The rod-like cells form bacteroids not only in the nodules but also outside, in soil. The bacteroids are viable and later reproduce the coccoid cells (arthrospores). The rods and bacteroids prevail in soil during flowering of the legumes, and the cocci are predominant at the end of vegetation.     

临床常见病原性细菌对抗生素的耐药性分析

目的了解长春地区部分医院临床分离的致病菌对抗菌药物的耐药情况。方法收集吉林大学中日联谊医院和长春中医药大学附属医院临床分离的致病菌,采用K—B法进行抗生素敏感性试验,参照CLSI2009年版的标准判断结果。结果从这两家医院共分离细菌447株,其中革兰阴性菌353株,占78．9％,革兰阳性菌94株,占21．1％。肠杆菌科细菌对氨苄西林的耐药率在70％以上,对庆大霉素的耐药率超过了50％,但对亚胺培南保持较高的敏感性（耐药率〈5％）。金黄色葡萄球菌和表皮葡萄球菌对红霉素耐药率分别为65．2％和82．1％,对万古霉素的耐药率较低,分别为4．5％和3．6％。非发酵革兰阴性杆菌对头孢他啶的耐药率超过50％,铜绿假单胞菌对氨曲南的耐药率达到了62．9％,对他唑巴坦复合制剂、亚胺培南、美罗培南和阿米卡星较为敏感,而鲍曼不动杆菌对各类抗生素的耐药率都较高。结论细菌对抗生素的耐药性仍表现出增长趋势,加强细菌耐药性的检测,对于指导临床正确、合理使用抗生素,减少耐药菌的产生和传播具有重要意义。     

Plasmid-determined streptococcal resistance to antibiotics]

The analysis of the genetic organization of the determinant ERLI by means of obtaining and studying the antibiotic sensitive mutants from the strain resistant to erythromycin and lincomycin provided experiment data in favour of the fact that inducable resistance to erythromycin and lincomycin determined by the plasmid might be defined by the same or closely linked genes.     

Structure of salmonellal transmissive resistance to antibiotics]

The structure of transmissive resistance to antibiotics was studied in 1260 Salmonella strains of 57 serotypes and R-plasmid resistance was found in the representatives of 13 (31.6 per cent) serotypes. The transmissive resistance correlated with multiple resistance to 4--10 antibiotics. The rate of occurrence of the transmissive R-plasmids was markedly higher in the bipathogenic serotypes. The structure of the R-plasmid resistance was most pronounced and diverse in S. typhimurium. It was usually revealed simultaneously with registration of the hospital infection. The plasmid with the determinants of resistance to erythromycin and benzylpenicillin was found only in this serotype. The nature of resistance and spectrum of transmissive resistance to antibiotics in Salmonella may serve as an additional epidemiological feature of the strains.     

Association of qacE and qacEDelta1 with multiple resistance to antibiotics and antiseptics in clinical isolates of Gram-negative bacteria

Clinical isolates of Enterobacter cloacae, Citrobacter freundii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia were tested for resistance to antibiotics and to the antiseptics benzalkonium chloride and cetyltrimethylammonium bromide. Furthermore, they were examined for the presence of the resistance genes qacE and qacEDelta1. qacEDelta1 was detected by PCR in 10% of all (n=103) and in 81% of multiply antibiotic-resistant strains (n=15). qacE was found in only one of 37 P. aeruginosa strains. The minimum inhibitory concentrations of benzalkonium chloride, cetyltrimethylammonium bromide, and ethidium bromide were not significantly different for qacEDelta1/qacE-positive or -negative strains. Our data indicate that multiply antibiotic-resistant Gram-negative bacteria are not necessarily more resistant to quaternary ammonium compounds than antibiotic-sensitive strains even though qacE or qacEDelta1 is present.     

Study of the adaptation resistance in bacteria to membrane active polypeptide antibiotics

Variants of Micrococcus lysodeikticus resistant to 100 micrograms/ml of gramicidin S with preserved resistance in subcultures on media without the antibiotic were isolated as a result of prolonged adaptation on a solid medium with increasing concentrations of gramicidin. The sensitive and resistant cells did not differ by their ability to bind gramicidin. Under the antibiotic effect permeability of the cytoplasmic membranes of the intact cells in the sensitive bacteria appeared to be impaired to a greater extent than that of the membranes of the cells in the resistant variant. Comparison of the lytic activity of gramicidin and its derivatives with respect to the protoplasts prepared with the cells of the initial and resistant variants of M. lysodeikticus revealed much higher resistance of the resistant variant protoplasts to the membrane-disorganizing effect of the preparations. Malate dehydrogenase and NADH-oxidase in the membrane preparations of the resistant variant cells differed from analogous enzymes from the membranes of the initial strain by the levels of their activity and sensitivity to gramicidin. It is likely that during adaptation of M. lysodeikticus to gramicidin significant changes in the cell cytoplasmic membranes occurred.     

Influence of cytokine preparations on the in vitro resistance of bacteria to antibiotics

Recombinant tumor necrosis factor-alpha and gamma-interferon were found in vitro to increase the sensitivity of bacteria to antibiotics both alone and in combination; alpha2-interferon decreased this sensitivity.     

Further data concerning the resistance of rhizosphere bacteria of sugar-beet to antibiotics

Изучалась устойчивость по отношению к 6 антибиотикам у 16 штаммов бактерий, выделенных из ризосферы сахарной свеклы. Для изучения резистентности бактерий применялся метод тестов на панелях. Были приготовлены серии разведений тнтибиотиков, и определялась наиболее низкая эффективная концентрация антибиотика. Было установлено, что бактерии ризосферы весьма устойчивы к различным антибиотикам.     

'DNA' as contaminants in antibiotics and its capacity to transform bacteria to drug resistance

DNA/and deoxyribose sugars were detected in streptomycin (Sm), kanamycin, polymyxin, penicillin G, ampicillin, methicillin, cloxacillin and mitomycin C in small amounts/traces. Stained DNA could be feebly visualized directly in Sm run in agarose gel, which improved after its separation and concentration. These DNA materials were DNase sensitive, RNase and pronase resistant, and appeared to consist of fragments, c. less than or equal to 6 Mdal; this could repeatedly transform to SmR several recipient enterobacteria and vibrios; E. coli C600 and S. typhi 57, after such transformation revealed similar plasmid DNA bands that were absent in their wild-types. G + C mole% of plasmid and chromosomal DNA of recipient (57) along with that of Streptomyces griseus reference strain, suggested an extraneous origin for the plasmid DNA.     

Combined action of antibiotics and deoxyribonuclease on bacteria]

The impact of DNase on formation of biofilms by grampositive and gramnegative bacteria was studied. The enzyme was shown to inhibit the biofilm formation and have no toxicity to bacteria. When applied to the formed associations, DNase potentiated the effect of antibiotics on the bacteria located in them. An increase in the antimicrobial effect of various nonrelated antibiotics was not connected with a change in the bacteria susceptibility but likely resulted from a break of the genetic cooperation of the cells' community, connected with functions of extracellular DNA of the biofilm's matrix.     

Root nodule bacteria to improve yield of wheat

Summary Beneficial effects on yield and N-assimilation in wheat cv. HD2329 due to inoculation with nine strains belonging to six species and cowpea miscellany of genus rhizobium and Azotobacter were observed. Stimulation of soil Azotobacter and Azospirillum in the root region of wheat occurred due to seed inoculation with Rhizobium.