Characteristics of Pseudomonas aeruginosa pili and an elucidation of their relation to the virulence of the bacteria

The electron microscopic study of 175 P. aeruginosa museum and newly isolated strains has been made and their virulence has been determined. In 32% of these strains the presence of pili has been established. However, among the museum strains those with pili have been found to constitute only 19.5%, while among newly isolated strains pili have been detected in 39.7% of cases (the difference is statistically significant at p less than 0.01). No correlation between the formation of pili and the virulence of P. aeruginosa has been established.     

Screening of plasmids in museum strains of Yersinia pestis isolated from various natural foci

92 strains of Yersinia pestis isolated from different natural foci and stored for 3-40 years in the museum of live cultures have been studied. The strains having three typical plasmids, their different combinations, plasmidless strains or the strains carrying nontypical plasmids with the molecular masses 9, 15, 55, 80, 90 and 150 Md were found. The old museum strains are proposed to be used as a source of plasmids for the genetical research. The current control of plasmid contents in the museum strains is suggested by the plasmid changes in course of storage.     

Pseudomonas aeruginosa bacteriophages isolated in a surgical hospital

New data on P. aeruginosa bacteriophages isolated from patients, as well as from washings obtained from various objects, in a surgical hospital are presented. 14 pure strains of P. aeruginosa bacteriophages have been isolated from 90 specimens of the material under study. The morphology of the colonies, the titer and the spectrum of action of the phages are characterized. The spectrum of action of polyvalent combination obtained by the mechanical mixture of different phages has been studied. The most active phages have been found to lyse 71.1, 63.1, 59.2 and 41.8 per cent of P. aeruginosa museum strains (225 strains).     

Morphological heterogeneity of Bordetella pertussis populations and clones (based on electron microscopy data)

Populations belonging to different serovars of B. pertussis museum strains and antibiotic-resistant clones obtained from them have been studied by electron microscopy. As a result, morphological heterogeneity and differences in the ultrastructure of the cells with respect to the cell-wall structure, the character of the cytoplasm, the size of the cells, cytoplasmic inclusions and intracellular links have been demonstrated and, proceeding from these data, two main morphological variants of the cells have been defined. The cells of the morphological variant characterized by the pliciform surface of the outer membrane and the pronounced periplasmic space prevail among the populations of the museum strains. The possibility of the isolation of antibiotic-resistant clones, differing in their morphological structure and functional properties from the initial population, has been shown. The morphological diversity of B. pertussis population is the necessary condition for the existence and development of microbial populations.     

The level of spontaneous phage production and sensitivity to melioidosis phages of museum cultures of Pseudomonas pseudomallei]

The phage-producing activity and sensitivity of museum cultures of a melioidosis agent to melioidosis phages have been studied. Most cultures show spontaneous phage-production, though its level differs in strains. Some of the melioidosis cultures demonstrate lack of phages. The fact that these strains have different sensitivity to chloroform lysate of cultures producing phages indicates their possible lysogenic state. Electron microscopy has shown the presence of at least tow morphological types of phages in P. pseudomallei C-141. These data confirm existence of polysogeny in the melioidosis agent.     

Potential use of serological methods in detecting cholera toxin

In the study of 50 Vibrio cholerae museum strains, 45 of them producing cholerigenic effect in suckling rabbits, cholera toxin, determined by means of the passive immune hemolysis (PIH) test, has been detected in the supernatant of the culture fluid of only two strains: V. cholerae 569 B, a well-known producer of cholera toxin, and V. cholerae (eltor) 1310, from whose population a toxigenic variant has been obtained by selection. To study the capacity of V. cholerae for producing toxin in vitro, in six cholerigenic strains, besides the supernatant of their culture fluids, also protein fractions, cell lysates and membrane fractions have been studied in the PIH test. In all these strains cholera toxin has been detected only in membrane fractions, which should be taken into consideration in the serological evaluation of the toxigenicity of V. cholerae.     

Comparative study of nutrient media for isolation of the agents of pertussis and parapertussis]

Taking into consideration literature data pointing to a possibility of a marked improvement of the quality of the medium for the isolation of the causative agents of pertussis and parapertussis, an experimental study was made of the sensitivity of the nutrient media produced by the Dagestan Institute of Nutrient Media, a medium made from dry and also of a number of media modified by the authors prepared on its basis. Pure freshly-isolated and museum B. pertussis cultures were used in the observations. Analysis of the results of a comparative study of the indices (detectability of the strains, the appearance of colonies and periods of their formation) allomed a recipee of the most sensitive medium to be elaborated. At the same time there were found considerable differences in the indices of the appearance of B. pertussis colonies and detectability of the museum cultures used for testing the industrial batches and of the freshly-isolated strains.     

Differentiation of the main species of Clostridium by gas chromatography

For the first time in the USSR the properties of microorganisms of the genus Clostridium have been studied with the use of the gas-chromatographic techniques. The analysis of the quantitative and qualitative composition of extracellular alcohols and carboxylic acids in 99 museum and newly isolated strains of 18 Clostridium species has made it possible to classify these microorganisms with 7 sharply differing groups. The above techniques permit the classification of clostridia with one of the groups within 2 hours if the microbial cultures have been grown in glucose-containing peptone yeast medium.     

Interaction of Candida albicans with macrophages

Study of the in vitro interaction of mouse peritoneal macrophages with C. albicans has revealed that these macrophages, though easily phagocytizing C. albicans blastospores, are incapable of destroying the fungus. The phagocytic, but not candidostatic, activity of these macrophages has been found to depend on the conditions on their cultivation, as well as on the age and viability of fungal cells. The representatives of 7 C. albicans strains, obtained from various sources and stored at the museum for different spans of time, have shown practically no difference in the character of their interaction with mouse peritoneal macrophages.     

The adhesive properties of meningococci from serogroups A, B and C

The adhesive properties of 261 meningococcal strains have been studied by the methods of the hemagglutination test, the test of adhesion on buccal epithelial cells and electron microscopy. The study has revealed that adhesive properties can be observed in the strains of all groups under study (A, B and C) isolated from patients and carriers, including those isolated from the nasopharynx, blood and liquor, adhesive properties occurring in newly isolated strains with greater frequency than in museum ones. The simultaneous use of all three above-mentioned methods increases the possibility of the detection of meningococcal strains with adhesive activity.     

Glutamine synthetase content and immunochemical analysis of different strains of Bordetella pertussis

In this investigation 3 groups of strains isolated from pertussis patients have been studied: typical (group 1), atypical in their cultural properties (group 2), unidentified Gram-negative bacilli agglutinated by pertussis and parapertussis antitoxins (group 3). Besides, B. pertussis cultures, obtained by subculturing 2 museum strains and 2 newly isolated strains on synthetic casein-charcoal agar with subinhibiting doses of antibiotics or specific immune sera added, have been studied. As indicated by the results of this study, strains belonging to groups 1 and 2 contain glutamine synthetase, while in strains of group 3 this enzyme is absent. In immunoelectrophoresis strains of group 3 have been found to contain not a single antigen similar to the antigens of strains belonging to groups 1 and 2. Electrophoresis in polyacrylamide gel has revealed to differences in the protein spectrum of the strains of these 3 groups. The investigation has shown that the determination of glutamine synthetase and immunoelectrophoresis can be used for the differentiation of B. pertussis from similar Gram-negative bacilli. B. pertussis strains, changed as the result of experiments with antibiotics and specific immune sera, have also been shown to retain their antigenic composition and protein spectrum and to have no essential difference in the content of glutamine synthetase.     

Characteristics of regression interrelations between the immune reactions to different staphylococcal strains in chronic inflammatory diseases of the upper respiratory tracts

Regressive interrelations between antibody titers to 13 staphylococcal museum strains in the blood serum, polypous fluid and saliva of patients with chronic polypous rhinosinusitis and chronic tonsillitis were studied. The presence of sharply defined positive interrelations between antibody titers in the blood serum and polypous fluid of patients with chronic polypous rhinosinusitis with respect to all staphylococcal strains under study and the absence of significant interrelations between antibody titers in the blood serum and saliva of patients with chronic tonsillitis were shown. The problem of the importance of positive or negative interrelations between individual staphylococcal strains is discussed.     

Ultrastructure of freshly isolated strains of Bordetella pertussis

The study of the electronograms of B. pertussis strains isolated in the foci of pertussis revealed the existence of the morphological variants of these cells, differing in the character of the cell wall, the state of the cytoplasm, the presence of amorphous inclusions of medium electron-optical density. The morphological variants did not correlate with the character of B. pertussis colonies isolated from blood-charcoal agar. The ultrastructure of the cells belonging to the second morphological variant was similar to that of the cells from the museum strain, altered by tetracycline treatment in the course of the experiment.     

In vitro bactericidal action of a complex of natural cytokins on Streptococcus pyogenes

The data on the antimicrobial in vitro action of a complex of natural cytokins (CNC)--the substance and the preparation "Superlymph"--on virulent museum and clinical macrolid-resistant group A beta-hemolytic streptococci, are presented. CNC suppressed the growth of museum test culture of streptococci in the concentration dependent manner. Moreover, the preparation "Superlymph" proved to be an effective antistreptococcal remedy in its action on erythromycin-resistant group A streptococcal (GAS) strains. The substance of the preparation induced the lysis of GAS cells, grown on lawn plates and in the system of spectrophotometric analysis. The effect thus established could be caused by cationic antimicrobial peptides (protegrins), contained in "Superlymph".     

Antagonism between hospital strains of Staphylococcus aureus and lactic acid bacteria in vitro and the use of the latter as a sanitary agent

The study of antagonism between S. aureus hospital strains and lactic acid bacteria, strain 317/402 "Nariné", revealed that the latter possessed high antagonistic activity. A new method for the sanitation of carriers of S. aureus hospital strains was developed; this method made it possible to limit the epidemiological significance of 82% of these strains.     

Do museum specimens accurately represent wild birds? A case study of carotenoid,melanin, and structural colours in long‐tailed manakins Chiroxiphia linearis

Museum specimens continue to be an invaluable resource for taxonomic, systematic, and comparative studies, and are increasingly relied upon for novel research purposes. Evaluating variation in the colour of avian study skins forms the basis for a broad range of research questions, yet few studies have investigated whether the plumage colouration of museum specimens accurately reflects colouration in wild birds. In this study, we use reflectance spectrometry to compare the plumage reflectance of avian museum skins and wild birds. We use long-tailed manakins Chiroxiphia linearis , to investigate these potential differences in colour. Long-tailed manakins are ideal for this type of study as their colourful plumage patches result from three primary plumage colouration mechanisms found in birds: melanin pigmentation, carotenoid pigmentation, and structural colouration. These features of their plumage allowed us to independently assess variation in each plumage colouration mechanism. Reflectance spectra obtained from museum specimens were very similar to those obtained from wild birds, and the colouration of specimens was usually well within the range of variation observed in wild birds. As such, museum specimens can accurately represent the colouration of wild birds. Nevertheless, we found significant differences in colouration between museum skins and wild birds. We documented differences in brightness, hue, saturation, and chroma, although the direction and magnitude of these differences varied by mechanism of colouration. Multivariate analyses revealed that the age of museum specimens and the time of year at which they were collected contributed to some of these differences. We discuss potential proximate causes of these changes in colour, many of which apply to both museum specimens and wild birds, and identify the types of studies that are likely to be most sensitive to these changes.     

Characterizing DNA preservation in degraded specimens of Amara alpina (Carabidae: Coleoptera)

DNA preserved in degraded beetle (Coleoptera) specimens, including those derived from dry‐stored museum and ancient permafrost‐preserved environments, could provide a valuable resource for researchers interested in species and population histories over timescales from decades to millenia. However, the potential of these samples as genetic resources is currently unassessed. Here, using Sanger and Illumina shotgun sequence data, we explored DNA preservation in specimens of the ground beetle Amara alpina, from both museum and ancient environments. Nearly all museum specimens had amplifiable DNA, with the maximum amplifiable fragment length decreasing with age. Amplification of DNA was only possible in 45% of ancient specimens. Preserved mitochondrial DNA fragments were significantly longer than those of nuclear DNA in both museum and ancient specimens. Metagenomic characterization of extracted DNA demonstrated that parasite‐derived sequences, including Wolbachia and Spiroplasma, are recoverable from museum beetle specimens. Ancient DNA extracts contained beetle DNA in amounts comparable to museum specimens. Overall, our data demonstrate that there is great potential for both museum and ancient specimens of beetles in future genetic studies, and we see no reason why this would not be the case for other orders of insect.     

Susceptibility to antimicrobial agents and genotypic relatedness of enterococcal strains isolated from patients and hospital environment

The aim of this study was to evaluate antibiotic susceptibility of Enterococcus sp. strains isolated from two hospitals in ?ód?, during 2005-2006. The second goal was to determine possible transmission of these strains within hospital wards by using melting profile PCR. Enterococcal strains were identified to species according standard microbiological methods. There was isolated 159 strains of E. faecalis, 51 strains of E. faecium and two E. avium, 1 E. durans. Susceptibility to antimicrobial agents was tested by disc diffusion method. None of these strains was resistant to vancomycin, teicoplanin or linezolid. There was high percentage of strains resistant to aminoglicosides, 22% of E. faecalis strains, and 54.9% of E. faecium strains, respectively. Additionally it was shown that 11.7% of E. faecium is resistant to chinuprisin-dalfopristin. The strains with similar pattern of resistance to antibiotics and fenotypic characteristics were genotyped by mpPCR. This technique was useful to confirm relatedness of bacterial strains suspected of being spread within hospital wards.     

Resistance of Staphylococcus aureus strains to quaternary ammonium compounds and chlorhexidine

The level of susceptibility of 90 different Staphylococcus aureus strains to chosen quaternary ammonium compounds: cetyltrimethyl ammonium bromide, benzalkonium chloride and benzethonium chloride as well as to chlorhexidine digluconate were examined. The examined strains consist of three groups: hospital originated MRSA, hospital originated MSSA and non-hospital MSSA. The significant differences between these groups were observed in they susceptibility to the investigated disinfectants. The obtained MIC values showed that the most resistant were hospital MRSA strains, where 55% was estimated as resistant to cetyltrimethyl ammonium bromide, 72% were resistant to benzalkonium chloride and benzethonium chloride and 7% were resistant to chlorhexidine digluconate. Among hospital originated MSSA 3% of strains were resistant to cetyltrimethyl ammonium bromide and 6% were resistant to benzalkonium chloride and benzethonium chloride. 14% non-hospital S. aureus strains were resistant to benzalkonium chloride and benzethonium chloride. None were resistant to chlorhexidine digluconate or cetyltrimethyl ammonium bromide.     

长沙某医院产质粒AmpC酶型肺炎克雷伯菌的多重PCR检测与分析

为了了解湖南长沙某医院临床分离的肺炎克雷伯菌中质粒介导AmpC β-内酰胺酶的产生情况及其基因型,收集了该医院2008年3月至2010年10月临床分离的多重耐药肺炎克雷伯菌104株,用头孢西丁纸片扩散法对这些菌株进行表型初筛,用多重PCR确定ampC耐药基因型;结果发现其中有19株对头孢西丁纸片不敏感,疑为产AmpC酶菌株;再经多重PCR扩增,有12株菌分别在约400 bp（11株）和约350 bp（1株）出现了阳性条带,特异性PCR证明此12株菌分别携带了DHA型（11株）和ACC型（1株）ampC耐药基因;产质粒介导AmpC酶肺炎克雷伯菌的分离率为11.5%（12/104）。该医院产质粒介导AmpC酶肺炎克雷伯菌的分离率较高,应对其检测与监测给予足够重视,以指导临床合理选用抗菌药物。