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Biomedical subjects

N J Legakis

Publications and source records attributed to N J Legakis.

At least 127 records · Page 7Linked to original sources
PubMed1983

Phagocytosis and antimicrobicidal activity of polymorphonuclear leucocytes against gentamicin-sensitive and resistant strains of Pseudomonas aeruginosa.

The ability of human polymorphonuclear leucocytes (PMNs) to ingest and kill gentamicin-sensitive and resistant Pseudomonas aeruginosa strains was studied. Strains becoming resistant to gentamicin either by laboratory training or through an R-factor were more susceptible to the phagocytic and bactericidal function of the PMNs. These results may explain previous clinical and laboratory observations indicating that gentamicin-resistant strains are less virulent.

Anti-Bacterial Agents↗
PubMed1983

Effect of the pH and osmolality of urine on the antibacterial activity of gentamicin.

The antibacterial activity of gentamicin against five strains each of Escherichia coli and Pseudomonas aeruginosa was followed by kinetic killing studies. Human urine having a variable osmolality and adjusted to pH 5.0 or 6.0 was used. Gentamicin was added at a final concentration of 10 or 50 mg/l. It was shown that human urine inhibited the action of gentamicin and that effect was enhanced in acid urine and depressed when the osmolality of the urine was lower. The pH and osmolality of urine variably affected the activity of gentamicin depending on the bacterial species. Lower osmolality rendered Ps. aeruginosa strains more easily susceptible to gentamicin as compared to E. coli. The data of the present study may be useful in clinical practice in the treatment of urinary infections; in cases of urine with low osmolality relatively low doses of gentamicin might be sufficient. In contrast, problems may be encountered in urinary infections in patients with renal insufficiency where reduced dosage of the drug is suggested. In those cases dilution and alkalinization of urine would be beneficial.

Bacteria↗
PubMed1982

Serotypes of Pseudomonas aeruginosa in clinical specimens in relation to antibiotic susceptibility.

Ninety-eight hospital strains of Pseudomonas aeruginosa isolated from six different hospitals in Athens were serotyped by a slide agglutination test with unabsorbed commercial antisera. Serotypes O6, O11, O12, and "pool E" strains (strains that agglutinated only in pool E, which contained antisera against O2, O5, O15, and O16 antigens, but did not agglutinate in the individual antisera) predominated, accounting for more than 62% of all isolates tested. In respect to serotypes, (i) there was no apparent correlation with hospital of origin, (ii) most strains of serotypes O6 and O11 were sensitive to gentamicin and carbenicillin (iii) most strains of pool E were from urine and were resistant to these drugs, (iv) all 9 strains of serotype O12 tested were resistant to carbenicillin and all 5 strains tested hydrolyzed this drug, and (v) 24 of 25 strains of pool E were resistant to carbenicillin but only 2 of 17 strains hydrolyzed it.

Anti-Bacterial Agents↗
PubMed1982

Fecal neutral sterols in patients with colon cancer.

Fecal cholesterol and its metabolites were measured in 10 patients with colon cancer and 10 control subjects. All individuals were consuming a mixed western diet of collection of stool specimens. The fecal concentration of total neutral sterols and coprostanol was greater in the control subjects as compared to the colon cancer patients, but the difference was not statistically significant. The same was the case for the metabolic conversion rate of cholesterol. The frequency distribution of the latter was bimodal especially among control subjects, with 3 subjects having an extremely high conversion rate. The level of neutral sterols is lower from stated values in most reports for colon cancer patients but higher to that reported for high risk populations for colon cancer and to this respect our finding are relevant with the increasing incidence of colon cancer in Greece.

Aged↗
PubMed1982

The direct immunofluorescence in the presumptive identification of Bacteroides species.

Two kits containing fluorescein labeled-polyvalent antisera to Bacteroides fragilis, Bacteroides distasonis, Bacteroides ovatus, Bacteroides thetaiotaomicron, Bacteroides vulgatus (Fluoretec-F) and to Bacteroides melaninogenicus subsp. melaninogenicus and intermedius and to Bacteroides asaccharolyticus (non-oral strains) (Fluoretec-M) were evaluated for the identification of the respective organisms in bacterial cultures and clinical specimens. In both cases immunofluorescent tests were compared to the bacteriological data. The results clearly demonstrated that Fluoretec-F has a specificity 97% and a sensitivity 96%. The corresponding values for Fluoretec-M were 99% and 87.5% respectively, either clinical specimens or pure cultures were examined. The presence of aerobic of facultative anaerobic bacteria and obligate anaerobic bacteria other than those to which antisera were included in the test kits did not seem to influence the test result. No cross-reactivity between Fluoretec-F and -M were observed. Also, no positive fluorescence was obtained when other anaerobic bacteria than Bacteroides spp. were tested. The same was also the case with various aerobic or facultative anaerobic bacteria. The use of Fluoretec-F and -M is considered as a useful tool for the early accurate identification of the Bacteroides species mentioned, which may serve as a guide for an appropriate prompt therapy which is especially needed in serious anaerobic infections.

Bacteriological Techniques↗
PubMed1981

Faecal bacterial flora in patients with colon cancer and control subjects.

Faeces from 10 colon cancer patients and from 10 control subjects were studied by quantitative and qualitative aerobic and anaerobic techniques using a variety of non selective, selective and differential media. In several cases, there were significantly different numbers of organisms of specific types recovered from the two groups studied. Most prominent and meaningful findings were the higher frequency of isolation and counts of Bacteroides species (especially B. fragilis group) and of C. paraputrificum in the patient group. Apart from the demonstration of the altered faecal bacterial flora in colon cancer patients and of the possible etiologic role of C. paraputrificum and B. fragilis in colon carcinogenesis, the bacteriological data, confirmed by more extensive studies, could be used as an index for colon cancer or for populations at high risk.

Aged↗
PubMed1980

Enhanced chemotaxis to gentamicin-resistant strains of Pseudomonas aeruginosa.

The chemotactic response of human polymorphonuclear leukocytes (PMNLs) to gentamicin-sensitive and gentamicin-resistant strains of Pseudomonas aeruginosa was studied. Filtrates from the resistant strains markedly enhanced the chemotactic response of human PMNLs (leukotactic index [LI] = 40.4 micron), in contrast to the filtrates from the sensitive strains, which induced less migration of PMNLs (LI = 26.8 micron). This finding may explain previous observations that suggested that gentamicin-resistant strains of P. aeruginosa are less virulent than gentamicin-sensitive strains.

Chemotaxis, Leukocyte↗
PubMed1980

Antibacterial activity of HR-756, cefoxitin and cefuroxine against multiply antibiotic-resistant strains of Enterobacteriaceae and Pseudomonas aeruginosa.

The in vitro antibacterial activity of HR-756 compared to cefoxitin and cefuroxime. 122 multiresistant clinical isolates including Enterobacteriaceae (104) and P. aeruginosa (18), which present particular problems in antibiotic chemotherapy, were selected for study. HR-756 inhibited all the stains of S. marcescens, P. mirabilis and indole-positive Proteus spp. at a concentration of 1,3 and 12 micrograms/ml, respectively; beta-lactamase-producing strains were also susceptible. 90% of K. pneumoniae and more than half of the Enterobacter and P. aeruginosa were inhibited from the drug at a concentration 16 microgram/ml. Cefoxitin and cefuroxime were less active than HR-756. Cefoxitin was more effective against S. marcescens and P. mirabilis while the same was the case with cefuroxime against K. pneumoniae strains. The greater efficiency of HR-756 over cefoxitin and cefuroxime against these multiply resistant isolates seems to be due not only to its indifference to the beta-lactamases but also to its easier penetrability into the bacterial cell.

Bacteria↗
PubMed1980

Comparative in vitro activity of netilmicin, amikacin, tobramycin and sisomicin against gentamicin highly-resistant enterobacteriaceae.

Netilmicin was compared with sisomicin, tobramycin and amikacin against 65 recent clinical enterobacterial isolates found to be highly resistant to gentamicin (MIC larger than or equal to 80 microgram/ml). Netilmicin showed a high activity against 20 out of 65 strains tested. Most of the sensitive strains (60%) to netilmicin required a concentration of gentamicin equal or lower than 160 microgram/ml for inhibition. Amikacin proved to be extremely effective in all the organisms tested. Tobramycin was consistently less active than either netilmicin or amikacin and the same was the case with sisomicin. The MIC was determined in both solid and liquid media for 24 strains. Depending upon which aminoglycoside was used, we found that 10-30% of the enterobacteriaceae exhibited a twofold diminution of MIC when tested in broth as compared to agar, while the greater proportion of strains was characterized by a higher MIC tested in broth as compared to agar.

Amikacin↗
PubMed1979

In vitro sensitivity of Proteus organisms to gentamicin and sisomicin.

The antibacterial activity of gentamicin and sisomicin was studied in 148 recent clinical isolates of Proteus obtained from patients hospitalized in Athens. Both gentamicin and sisomicin were found to be active with sisomicin generally being the more active of the two; P. mirabilis strains were less susceptible than the indole-positive strains, but P. mirabilis organisms isolated from the respiratory tract were more sensitive to sisomicin than those isolated from the urine. Susceptibility testing with the two aminoglycoside antibiotics was affected by inoculum size and by the test broth used. Sisomicin sensitivity testing with the disc-agar diffusion method and broth dilution method was reliable for the indole-positive strains of Proteus but did not separate all sensitive from resistant strains of P. mirabilis. An in vitro synergism was demonstrated between sisomicin and the semisynthetic penicillin, ticarcillin.

Bacteriuria↗
PubMed1978

Differentiation of Serratia marcescens and Serratia liquefaciens by tests for lipase and phospholipase production.

The production of lipase and phospolipase by certain members of the Enterobacteriaceae was examined by thin-layer chromatography of resting-cell suspensions incubated with triolein or lecithin. Most strains of Serratia marcescens produced both enzymes while most strains of Serratia liquefaciens exhibited strong lipase but only a minor phospholipase activity. Enterobacter spp. (25 strains), Klebsiella pneumoniae (20 strains), Escherichia coli (15 strains), Citrobacter freundii (7 strains) and Proteus spp. (20 strains) lacked both types of enzymic activity except for the following: three strains of Enterobacter cloacae, two of Proteus mirabilis and three of Proteus vulgaris possessed slight lipase activity; about one-half of the Enterobacter aerogenes and Enterobacter hafniae strains examined produced slight phospholipase activity. It is suggested that tests for lipase and phospholipase should be used in conjunction with those for DNAase production and sugar fermentation for the differentiation of S. marcescens and S. liquefaciens.

Arabinose↗
PubMed1978

Lipid composition of Escherichia coli in relation to resistance to penicillin.

Clinical isolates of Escherichia coli sensitive and resistant to penicillin were compared in lipid composition and 14C-labelled penicillin uptake, as possible factors in resistance. Except for a slight increase in the triglyceride fraction in sensitive strains there were no qualitative or quantitative differences in the classes of extractable lipids present. Gas-liquid chromatography of the phospholipid and triglyceride fatty acids of the polar and non-polar fatty acids of the bound lipids showed that the same kinds of fatty acids were present. There was an increase of myristate in the chloroform-methanol extractable lipids of highly resistant strains accompanied by a rather general decrease of other fatty acids. Gas-chromatographic analysis of the polar-bound lipids showed an increase of the beta-hydroxydecanoic acid in the resistant strains. By studying the uptake of 14C-labelled benzylpenicillin and the crypticity of the beta-lactamase, evidence has been produced that a decreased permeability of resistant strains to penicillin cooperates with beta-lactamase to induce a high level of resistance. The altered lipid metabolism may reflect the special architectural changes in the cell wall which cause decreased permeability.

Cell Membrane Permeability↗